dvc: bump to 1.2.2

Turns out macs are not happy with double-forks without exec.

Fixes #4294

.codeclimate.yml

@@ -1,5 +0,0 @@
-languages:
-    Python: true
-
-exclude_paths:
-    - tests/

.deepsource.toml

@@ -1,15 +0,0 @@
-version = 1
-
-test_patterns = [
-  'tests/**'
-]
-
-exclude_patterns = [
-  'dvc/utils/compat.py'
-]
-
-[[analyzers]]
-name = 'python'
-enabled = true
-runtime_version = '3.x.x'
-

.dvc/.gitignore

@@ -9,3 +9,4 @@
 /pkg
 /repos
 /tmp
+/experiments

.flake8

@@ -1,7 +0,0 @@
-[flake8]
-ignore =
-    E203, # Whitespace before ':'
-    E266, # Too many leading '#' for block comment
-    W503, # Line break occurred before a binary operator
-max-line-length = 79
-select = B,C,E,F,W,T4,B9

.github/FUNDING.yml

@@ -0,0 +1,3 @@
+# These are supported funding model platforms
+
+patreon: DVCorg

.github/ISSUE_TEMPLATE/bug_report.md

@@ -1,10 +1,18 @@
 ---
-name: Bug report
-about: Create a report to help us improve
-
+name: "\U0001F41B Bug Report"
+about: Create a bug report to help us improve DVC
 ---
 
+## Bug Report
 
-**Please provide information about your setup**
-DVC version(i.e. `dvc --version`), Platform and method of installation (pip, homebrew, pkg Mac, exe (Windows), DEB(Linux), RPM(Linux))
+### Please provide information about your setup
 
+**Output of `dvc version`:**
+
+```console
+$ dvc version
+```
+
+**Additional Information (if any):**
+
+If applicable, please also provide a `--verbose` output of the command, eg: `dvc add --verbose`.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: "🤗 Need help?"
+    url: https://dvc.org/chat
+    about: If you have a question, ask us on Discord. Please join with this invite 👉

.github/ISSUE_TEMPLATE/feature_request.md

@@ -1,6 +1,5 @@
 ---
-name: Feature request
+name: "\U0001F680 Feature Request"
 about: Suggest an idea for this project
-
 ---
 

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,7 +1,5 @@
 * [ ] ❗ I have followed the [Contributing to DVC](https://dvc.org/doc/user-guide/contributing/core) checklist.
 
-* [ ] 📖 If this PR requires [documentation](https://dvc.org/doc) updates, I have created a separate PR (or issue, at least) in [dvc.org](https://github.com/iterative/dvc.org) and linked it here. If the CLI API is changed, I have updated [tab completion scripts](https://github.com/iterative/dvc/tree/master/scripts/completion).
-
-* [ ] ❌ I will check DeepSource, CodeClimate, and other sanity checks below. (We consider them recommendatory and don't expect everything to be addressed. Please fix things that actually improve code or fix bugs.)
+* [ ] 📖 If this PR requires [documentation](https://dvc.org/doc) updates, I have created a separate PR (or issue, at least) in [dvc.org](https://github.com/iterative/dvc.org) and linked it here.
 
 Thank you for the contribution - we'll try to review it as soon as possible. 🙏

.github/workflows/check-patch.yaml

@@ -0,0 +1,19 @@
+name: Lint Python
+
+on: [push, pull_request]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v1
+    - name: Set up Python 3.8
+      uses: actions/setup-python@v1
+      with:
+        python-version: 3.8
+    - name: Install requirements
+      run: bash ./scripts/ci/install.sh
+    - name: Check Patch
+      run: ./scripts/ci/check_patch.sh

.pre-commit-config.yaml

@@ -1,35 +1,75 @@
 repos:
-- hooks:
-  - id: black
-    language_version: python3
-  repo: https://github.com/ambv/black
-  rev: 19.10b0
-- hooks:
-  - id: flake8
-    language_version: python3
-  repo: https://gitlab.com/pycqa/flake8
-  rev: master
-- hooks:
-  - args:
-    - -i
-    - '2'
-    id: beautysh
-    language_version: python3
-  repo: https://github.com/lovesegfault/beautysh
-  rev: master
-- hooks:
-  - id: dvc-pre-commit
-    language_version: python3
-    stages:
-    - commit
-  - id: dvc-pre-push
-    language_version: python3
-    stages:
-    - push
-  - always_run: true
-    id: dvc-post-checkout
-    language_version: python3
-    stages:
-    - post-checkout
-  repo: https://github.com/iterative/dvc
-  rev: master
+  - hooks:
+      - id: black
+        language_version: python3
+    repo: https://github.com/ambv/black
+    rev: 19.10b0
+  - repo: https://github.com/asottile/seed-isort-config
+    rev: v2.1.1
+    hooks:
+      - id: seed-isort-config
+  - hooks:
+      - id: isort
+        language_version: python3
+    repo: https://github.com/timothycrosley/isort
+    rev: 4.3.21
+  - hooks:
+      - id: flake8
+        language_version: python3
+        additional_dependencies:
+          - flake8-bugbear
+          - flake8-comprehensions
+          - flake8-debugger
+          - flake8-string-format
+    repo: https://gitlab.com/pycqa/flake8
+    rev: 3.7.9
+  - repo: local
+    hooks:
+    - id: pylint
+      name: pylint
+      entry: pylint
+      language: system
+      types: [python]
+  - hooks:
+      - args:
+          - -i
+          - "2"
+        id: beautysh
+        language_version: python3
+    repo: https://github.com/lovesegfault/beautysh
+    rev: master
+  - hooks:
+      - args:
+          - git-hook
+          - pre-commit
+        entry: dvc
+        id: dvc-pre-commit
+        language: system
+        name: DVC pre-commit
+        stages:
+          - commit
+        verbose: true
+        require_serial: true
+      - args:
+          - git-hook
+          - pre-push
+        entry: dvc
+        id: dvc-pre-push
+        language: system
+        name: DVC pre-push
+        stages:
+          - push
+        require_serial: true
+      - always_run: true
+        args:
+          - git-hook
+          - post-checkout
+        entry: dvc
+        id: dvc-post-checkout
+        language: system
+        minimum_pre_commit_version: 2.2.0
+        name: DVC post-checkout
+        stages:
+          - post-checkout
+        require_serial: true
+    repo: local

.pre-commit-hooks.yaml

@@ -6,8 +6,10 @@
   language: python
   language_version: python3
   name: DVC pre-commit
+  require_serial: true
   stages:
   - commit
+  verbose: true
 - args:
   - git-hook
   - pre-push
@@ -16,6 +18,7 @@
   language: python
   language_version: python3
   name: DVC pre-push
+  require_serial: true
   stages:
   - push
 - always_run: true
@@ -28,5 +31,6 @@
   language_version: python3
   minimum_pre_commit_version: 2.2.0
   name: DVC post-checkout
+  require_serial: true
   stages:
   - post-checkout

.pylintrc

@@ -15,7 +15,11 @@ ignore-patterns=
 
 # Python code to execute, usually for sys.path manipulation such as
 # pygtk.require().
-#init-hook=
+init-hook="import sys; \
+           from pathlib import Path; \
+           from pylint.config import find_pylintrc; \
+           sys.path.append(Path(find_pylintrc()).parent / 'tests');"
+
 
 # Use multiple processes to speed up Pylint. Specifying 0 will auto-detect the
 # number of processors available to use.
@@ -28,7 +32,7 @@ limit-inference-results=100
 
 # List of plugins (as comma separated values of python modules names) to load,
 # usually to register additional checkers.
-load-plugins=
+load-plugins=pylint_pytest,pylint_plugin_disable
 
 # Pickle collected data for later comparisons.
 persistent=yes
@@ -60,7 +64,16 @@ confidence=
 # --enable=similarities". If you want to run only the classes checker, but have
 # no Warning level messages displayed, use "--disable=all --enable=classes
 # --disable=W".
-disable=print-statement,
+disable=format,
+        # ^ most of them are covered by flake8,
+        # and are conventions rather than warnings or errors
+        refactoring,  # will be noisy if it starts giving suggestions
+        spelling,
+        # design is too-few-* and too-many-* checks, too-much-* for us right now
+        design,
+        # following were generated by default
+        # most of them are redundant Py3 checks for Py2+3 codebase
+        print-statement,
         parameter-unpacking,
         unpacking-in-except,
         old-raise-syntax,
@@ -139,9 +152,33 @@ disable=print-statement,
         deprecated-sys-function,
         exception-escape,
         comprehension-escape,
-        useless-object-inheritance,
-        missing-docstring,
-        bad-continuation
+        # custom disables start here
+        no-self-use,
+        invalid-name,
+        # already a check enabled for `wildcard-import`
+        unused-wildcard-import,
+        misplaced-comparison-constant,
+        # probably soon: https://github.com/iterative/dvc/issues/1843
+        logging-format-interpolation,
+        logging-fstring-interpolation,
+        # we don't have proper docstrings yet
+        # even if we do, we'll be doing it gradually
+        missing-function-docstring,
+        missing-module-docstring,
+        missing-class-docstring,
+        duplicate-code,
+        # too noisy, and detects issues even when import is inside a function
+        # see: https://github.com/PyCQA/pylint/issues/850
+        cyclic-import,
+        # isort should cover these:
+        wrong-import-order,
+        wrong-import-position,
+        ungrouped-imports,
+        multiple-imports,
+        # we use it to speedup/optimize
+        import-outside-toplevel,
+        fixme,
+
 
 # Enable the message, report, category or checker with the given id(s). You can
 # either give multiple identifier separated by comma (,) or put this option
@@ -228,7 +265,7 @@ contextmanager-decorators=contextlib.contextmanager
 # List of members which are set dynamically and missed by pylint inference
 # system, and so shouldn't trigger E1101 when accessed. Python regular
 # expressions are accepted.
-generated-members=
+generated-members=pytest.lazy_fixture,logging.TRACE,logger.trace,sys.getwindowsversion
 
 # Tells whether missing members accessed in mixin class should be ignored. A
 # mixin class is detected if its name ends with "mixin" (case insensitive).
@@ -249,7 +286,7 @@ ignore-on-opaque-inference=yes
 # List of class names for which member attributes should not be checked (useful
 # for classes with dynamically set attributes). This supports the use of
 # qualified names.
-ignored-classes=optparse.Values,thread._local,_thread._local
+ignored-classes=optparse.Values,thread._local,_thread._local,Dvcfile
 
 # List of module names for which member attributes should not be checked
 # (useful for modules/projects where namespaces are manipulated during runtime
@@ -290,7 +327,7 @@ dummy-variables-rgx=_+$|(_[a-zA-Z0-9_]*[a-zA-Z0-9]+?$)|dummy|^ignored_|^unused_
 
 # Argument names that match this expression will be ignored. Default to name
 # with leading underscore.
-ignored-argument-names=_.*|^ignored_|^unused_
+ignored-argument-names=_.*|^ignored_|^unused_|args|kwargs
 
 # Tells whether we should check for unused import in __init__ files.
 init-import=no

.restyled.yaml

@@ -9,3 +9,12 @@ restylers:
     - "**/*.py"
     interpreters:
     - python
+  - name: isort
+    image: restyled/restyler-isort:v4.3.21
+    command:
+    - isort
+    arguments: []
+    include:
+    - "**/*.py"
+    interpreters:
+    - python

.travis.yml

@@ -29,7 +29,7 @@ jobs:
     os: linux
     language: python
     python: 3.7
-    before_install:
+    before_install: bash ./scripts/ci/install.sh
     install:
     script: ./scripts/ci/check_patch.sh
   # test jobs
@@ -46,9 +46,6 @@ jobs:
     env:
       - PYTHON_VERSION=3.8.0
       - PATH=/c/Python38:/c/Python38/Scripts:$PATH
-  - name: "3.5 on Linux"
-    language: python
-    python: 3.5
   - name: "3.6 on Linux"
     language: python
     python: 3.6
@@ -101,8 +98,12 @@ jobs:
      - name: lxd
        channel: stable
     env:
-    - SNAPCRAFT_IMAGE_INFO: '{"build_url": "$TRAVIS_BUILD_URL"}'
+    - SNAPCRAFT_IMAGE_INFO: |
+        '{"build_url": "$TRAVIS_JOB_WEB_URL"}'
+    - SNAPCRAFT_BUILD_ENVIRONMENT: lxd
+    - SNAPCRAFT_BUILD_INFO: 1  # https://snapcraft.io/blog/introducing-developer-notifications-for-snap-security-updates
     install:
+    - sudo usermod --append --groups lxd $USER
     - sudo /snap/bin/lxd.migrate -yes
     - sudo /snap/bin/lxd waitready
     - sudo /snap/bin/lxd init --auto
@@ -151,12 +152,11 @@ deploy:
       tags: true
       repo: iterative/dvc
       stage: build
-  - provider: snap
-    snap: dvc_*.snap
-    channel: $SNAP_CHANNEL
+  - provider: script
     skip_cleanup: true
+    script: "(echo $SNAP_TOKEN | snapcraft login --with -) && timeout 600 snapcraft push dvc_*.snap --release $SNAP_CHANNEL || echo timed out"
     on:
       all_branches: true
-      condition: "$(./scripts/ci/deploy_condition.sh dvc_*.snap) && ($TRAVIS_BRANCH = master || -n $TRAVIS_TAG)"
+      condition: "$(./scripts/ci/deploy_condition.sh dvc_*.snap) && ($TRAVIS_BRANCH = master || -n $TRAVIS_TAG) && -n $SNAP_CHANNEL"
       repo: iterative/dvc
       stage: build

README.rst

@@ -10,7 +10,7 @@
 
 |Release| |CI| |Maintainability| |Coverage| |Donate| |DOI|
 
-|Snap| |Choco| |Brew| |Conda| |PyPI| |Packages|
+|PyPI| |Packages| |Brew| |Conda| |Choco| |Snap|
 
 |
 
@@ -101,7 +101,8 @@ Snap (Snapcraft/Linux)
    snap install dvc --classic
 
 This corresponds to the latest tagged release.
-Add ``--edge`` for the latest ``master`` version.
+Add ``--beta`` for the latest tagged release candidate,
+or ``--edge`` for the latest ``master`` version.
 
 Choco (Chocolatey/Windows)
 --------------------------
@@ -130,8 +131,6 @@ Conda (Anaconda)
 
    conda install -c conda-forge dvc
 
-Currently, this includes support for Python versions 2.7, 3.6 and 3.7.
-
 pip (PyPI)
 ----------
 
@@ -255,7 +254,7 @@ Citation
 Iterative, *DVC: Data Version Control - Git for Data & Models* (2020)
 `DOI:10.5281/zenodo.012345 <https://doi.org/10.5281/zenodo.3677553>`_.
 
-.. |Banner| image:: https://dvc.org/static/img/logo-github-readme.png
+.. |Banner| image:: https://dvc.org/img/logo-github-readme.png
    :target: https://dvc.org
    :alt: DVC logo
 
@@ -307,6 +306,6 @@ Iterative, *DVC: Data Version Control - Git for Data & Models* (2020)
    :target: https://doi.org/10.5281/zenodo.3677553
    :alt: DOI
 
-.. |Flowchart| image:: https://dvc.org/static/img/flow.gif
-   :target: https://dvc.org/static/img/flow.gif
+.. |Flowchart| image:: https://dvc.org/img/flow.gif
+   :target: https://dvc.org/img/flow.gif
    :alt: how_dvc_works

dvc/__init__.py

@@ -3,17 +3,7 @@ DVC
 ----
 Make your data science projects reproducible and shareable.
 """
-import warnings
-
 import dvc.logger
 from dvc.version import __version__  # noqa: F401
 
-
 dvc.logger.setup()
-
-# Ignore numpy's runtime warnings: https://github.com/numpy/numpy/pull/432.
-# We don't directly import numpy, but our dependency networkx does, causing
-# these warnings in some environments. Luckily these warnings are benign and
-# we can simply ignore them so that they don't show up when you are using dvc.
-warnings.filterwarnings("ignore", message="numpy.dtype size changed")
-warnings.filterwarnings("ignore", message="numpy.ufunc size changed")

dvc/analytics.py

@@ -2,12 +2,12 @@ import json
 import logging
 import os
 import platform
-import requests
 import sys
 import tempfile
 import uuid
 
 import distro
+import requests
 
 from dvc import __version__
 from dvc.config import Config, to_bool
@@ -20,7 +20,6 @@ from dvc.scm.base import SCMError
 from dvc.utils import env2bool, is_binary
 from dvc.utils.fs import makedirs
 
-
 logger = logging.getLogger(__name__)
 
 
@@ -36,7 +35,7 @@ def collect_and_send_report(args=None, return_code=None):
     report as a JSON, where the _collector_ generates it and the _sender_
     removes it after sending it.
     """
-    report = _runtime_info()
+    report = {}
 
     # Include command execution information on the report only when available.
     if args and hasattr(args, "func"):
@@ -62,7 +61,7 @@ def is_enabled():
     return enabled
 
 
-def send(report):
+def send(path):
     """
     Side effect: Removes the report after sending it.
 
@@ -73,13 +72,17 @@ def send(report):
     url = "https://analytics.dvc.org"
     headers = {"content-type": "application/json"}
 
-    with open(report, "rb") as fobj:
-        try:
-            requests.post(url, data=fobj, headers=headers, timeout=5)
-        except requests.exceptions.RequestException:
-            logger.debug("failed to send analytics report", exc_info=True)
+    with open(path) as fobj:
+        report = json.load(fobj)
 
-    os.remove(report)
+    report.update(_runtime_info())
+
+    try:
+        requests.post(url, json=report, headers=headers, timeout=5)
+    except requests.exceptions.RequestException:
+        logger.debug("failed to send analytics report", exc_info=True)
+
+    os.remove(path)
 
 
 def _scm_in_use():
@@ -155,7 +158,7 @@ def _find_or_create_user_id():
     try:
         with Lock(lockfile):
             try:
-                with open(fname, "r") as fobj:
+                with open(fname) as fobj:
                     user_id = json.load(fobj)["user_id"]
 
             except (FileNotFoundError, ValueError, KeyError):
@@ -167,6 +170,4 @@ def _find_or_create_user_id():
             return user_id
 
     except LockError:
-        logger.debug(
-            "Failed to acquire '{lockfile}'".format(lockfile=lockfile)
-        )
+        logger.debug(f"Failed to acquire '{lockfile}'")

dvc/api.py

@@ -1,16 +1,17 @@
 import os
-from contextlib import contextmanager, _GeneratorContextManager as GCM
+from contextlib import _GeneratorContextManager as GCM
+from contextlib import contextmanager
 
-from dvc.repo import Repo
 from dvc.exceptions import DvcException, NotDvcRepoError
 from dvc.external_repo import external_repo
+from dvc.repo import Repo
 
 
 class UrlNotDvcRepoError(DvcException):
     """Thrown if the given URL is not a DVC repository."""
 
     def __init__(self, url):
-        super().__init__("'{}' is not a DVC repository.".format(url))
+        super().__init__(f"'{url}' is not a DVC repository.")
 
 
 def get_url(path, repo=None, rev=None, remote=None):
@@ -26,13 +27,15 @@ def get_url(path, repo=None, rev=None, remote=None):
     """
     with _make_repo(repo, rev=rev) as _repo:
         if not isinstance(_repo, Repo):
-            raise UrlNotDvcRepoError(_repo.url)
+            raise UrlNotDvcRepoError(_repo.url)  # pylint: disable=no-member
         out = _repo.find_out_by_relpath(path)
         remote_obj = _repo.cloud.get_remote(remote)
-        return str(remote_obj.checksum_to_path_info(out.checksum))
+        return str(remote_obj.tree.hash_to_path_info(out.checksum))
 
 
-def open(path, repo=None, rev=None, remote=None, mode="r", encoding=None):
+def open(  # noqa, pylint: disable=redefined-builtin
+    path, repo=None, rev=None, remote=None, mode="r", encoding=None
+):
     """
     Open file in the supplied path tracked in a repo (both DVC projects and
     plain Git repos are supported). For Git repos, HEAD is used unless a rev
@@ -57,7 +60,9 @@ def open(path, repo=None, rev=None, remote=None, mode="r", encoding=None):
 
 
 class _OpenContextManager(GCM):
-    def __init__(self, func, args, kwds):
+    def __init__(
+        self, func, args, kwds
+    ):  # pylint: disable=super-init-not-called
         self.gen = func(*args, **kwds)
         self.func, self.args, self.kwds = func, args, kwds
 

dvc/cache.py

@@ -1,104 +0,0 @@
-"""Manages cache of a DVC repo."""
-from collections import defaultdict
-
-from funcy import cached_property
-
-
-def _make_remote_property(name):
-    """
-    The config file is stored in a way that allows you to have a
-    cache for each remote.
-
-    This is needed when specifying external outputs
-    (as they require you to have an external cache location).
-
-    Imagine a config file like the following:
-
-            ['remote "dvc-storage"']
-            url = ssh://localhost/tmp
-            ask_password = true
-
-            [cache]
-            ssh = dvc-storage
-
-    This method creates a cached property, containing cache named `name`:
-
-        self.config == {'ssh': 'dvc-storage'}
-        self.ssh  # a RemoteSSH instance
-    """
-
-    def getter(self):
-        from dvc.remote import Remote
-
-        remote = self.config.get(name)
-        if not remote:
-            return None
-
-        return Remote(self.repo, name=remote)
-
-    getter.__name__ = name
-    return cached_property(getter)
-
-
-class Cache(object):
-    """Class that manages cache locations of a DVC repo.
-
-    Args:
-        repo (dvc.repo.Repo): repo instance that this cache belongs to.
-    """
-
-    CACHE_DIR = "cache"
-
-    def __init__(self, repo):
-        from dvc.remote import Remote
-
-        self.repo = repo
-        self.config = config = repo.config["cache"]
-
-        local = config.get("local")
-
-        if local:
-            settings = {"name": local}
-        else:
-            settings = {**config, "url": config["dir"]}
-
-        self.local = Remote(repo, **settings)
-
-    s3 = _make_remote_property("s3")
-    gs = _make_remote_property("gs")
-    ssh = _make_remote_property("ssh")
-    hdfs = _make_remote_property("hdfs")
-    azure = _make_remote_property("azure")
-
-
-class NamedCache(object):
-    def __init__(self):
-        self._items = defaultdict(lambda: defaultdict(set))
-        self.external = defaultdict(set)
-
-    @classmethod
-    def make(cls, scheme, checksum, name):
-        cache = cls()
-        cache.add(scheme, checksum, name)
-        return cache
-
-    def __getitem__(self, key):
-        return self._items[key]
-
-    def add(self, scheme, checksum, name):
-        self._items[scheme][checksum].add(name)
-
-    def add_external(self, url, rev, path):
-        self.external[url, rev].add(path)
-
-    def update(self, cache, suffix=""):
-        for scheme, src in cache._items.items():
-            dst = self._items[scheme]
-            for checksum, names in src.items():
-                if suffix:
-                    dst[checksum].update(n + suffix for n in names)
-                else:
-                    dst[checksum].update(names)
-
-        for repo_pair, files in cache.external.items():
-            self.external[repo_pair].update(files)

dvc/cache/__init__.py

@@ -0,0 +1,171 @@
+"""Manages cache of a DVC repo."""
+from collections import defaultdict
+
+from funcy import cached_property
+
+
+def _make_remote_property(name):
+    """
+    The config file is stored in a way that allows you to have a
+    cache for each remote.
+
+    This is needed when specifying external outputs
+    (as they require you to have an external cache location).
+
+    Imagine a config file like the following:
+
+            ['remote "dvc-storage"']
+            url = ssh://localhost/tmp
+            ask_password = true
+
+            [cache]
+            ssh = dvc-storage
+
+    This method creates a cached property, containing cache named `name`:
+
+        self.config == {'ssh': 'dvc-storage'}
+        self.ssh  # a RemoteSSH instance
+    """
+
+    def getter(self):
+        from ..tree import get_cloud_tree
+        from .base import CloudCache
+
+        remote = self.config.get(name)
+        if not remote:
+            return None
+
+        tree = get_cloud_tree(self.repo, name=remote)
+        return CloudCache(tree)
+
+    getter.__name__ = name
+    return cached_property(getter)
+
+
+class Cache:
+    """Class that manages cache locations of a DVC repo.
+
+    Args:
+        repo (dvc.repo.Repo): repo instance that this cache belongs to.
+    """
+
+    CACHE_DIR = "cache"
+
+    def __init__(self, repo):
+        from ..tree import get_cloud_tree
+        from .local import LocalCache
+
+        self.repo = repo
+        self.config = config = repo.config["cache"]
+
+        local = config.get("local")
+
+        if local:
+            settings = {"name": local}
+        else:
+            settings = {**config, "url": config["dir"]}
+
+        tree = get_cloud_tree(repo, **settings)
+        self.local = LocalCache(tree)
+
+    s3 = _make_remote_property("s3")
+    gs = _make_remote_property("gs")
+    ssh = _make_remote_property("ssh")
+    hdfs = _make_remote_property("hdfs")
+    azure = _make_remote_property("azure")
+
+
+class NamedCacheItem:
+    def __init__(self):
+        self.names = set()
+        self.children = defaultdict(NamedCacheItem)
+
+    def __eq__(self, other):
+        return self.names == other.names and self.children == other.children
+
+    def child_keys(self):
+        for key, child in self.children.items():
+            yield key
+            yield from child.child_keys()
+
+    def child_names(self):
+        for key, child in self.children.items():
+            yield key, child.names
+            yield from child.child_names()
+
+    def add(self, checksum, item):
+        self.children[checksum].update(item)
+
+    def update(self, item, suffix=""):
+        if suffix:
+            self.names.update(n + suffix for n in item.names)
+        else:
+            self.names.update(item.names)
+        for checksum, child_item in item.children.items():
+            self.children[checksum].update(child_item)
+
+
+class NamedCache:
+    # pylint: disable=protected-access
+    def __init__(self):
+        self._items = defaultdict(lambda: defaultdict(NamedCacheItem))
+        self.external = defaultdict(set)
+
+    @classmethod
+    def make(cls, scheme, checksum, name):
+        cache = cls()
+        cache.add(scheme, checksum, name)
+        return cache
+
+    def __getitem__(self, key):
+        return self._items[key]
+
+    def add(self, scheme, checksum, name):
+        """Add a mapped name for the specified checksum."""
+        self._items[scheme][checksum].names.add(name)
+
+    def add_child_cache(self, checksum, cache, suffix=""):
+        """Add/update child cache for the specified checksum."""
+        for scheme, src in cache._items.items():
+            dst = self._items[scheme][checksum].children
+            for child_checksum, item in src.items():
+                dst[child_checksum].update(item, suffix=suffix)
+
+        for repo_pair, files in cache.external.items():
+            self.external[repo_pair].update(files)
+
+    def add_external(self, url, rev, path):
+        self.external[url, rev].add(path)
+
+    def update(self, cache, suffix=""):
+        for scheme, src in cache._items.items():
+            dst = self._items[scheme]
+            for checksum, item in src.items():
+                dst[checksum].update(item, suffix=suffix)
+
+        for repo_pair, files in cache.external.items():
+            self.external[repo_pair].update(files)
+
+    def scheme_keys(self, scheme):
+        """Iterate over a flat list of all keys for the specified scheme,
+        including children.
+        """
+        for key, item in self._items[scheme].items():
+            yield key
+            yield from item.child_keys()
+
+    def scheme_names(self, scheme):
+        """Iterate over a flat list of checksum, names items for the specified
+        scheme, including children.
+        """
+        for key, item in self._items[scheme].items():
+            yield key, item.names
+            yield from item.child_names()
+
+    def dir_keys(self, scheme):
+        return (
+            key for key, item in self._items[scheme].items() if item.children
+        )
+
+    def child_keys(self, scheme, checksum):
+        return self._items[scheme][checksum].child_keys()

dvc/cache/base.py

@@ -0,0 +1,554 @@
+import json
+import logging
+from copy import copy
+
+from shortuuid import uuid
+
+import dvc.prompt as prompt
+from dvc.exceptions import CheckoutError, ConfirmRemoveError, DvcException
+from dvc.path_info import WindowsPathInfo
+from dvc.progress import Tqdm
+from dvc.remote.slow_link_detection import slow_link_guard
+
+from ..tree.base import RemoteActionNotImplemented
+
+logger = logging.getLogger(__name__)
+
+STATUS_OK = 1
+STATUS_MISSING = 2
+STATUS_NEW = 3
+STATUS_DELETED = 4
+
+STATUS_MAP = {
+    # (local_exists, remote_exists)
+    (True, True): STATUS_OK,
+    (False, False): STATUS_MISSING,
+    (True, False): STATUS_NEW,
+    (False, True): STATUS_DELETED,
+}
+
+
+class DirCacheError(DvcException):
+    def __init__(self, hash_):
+        super().__init__(
+            f"Failed to load dir cache for hash value: '{hash_}'."
+        )
+
+
+class CloudCache:
+    """Cloud cache class."""
+
+    DEFAULT_CACHE_TYPES = ["copy"]
+    CACHE_MODE = None
+
+    def __init__(self, tree):
+        self.tree = tree
+        self.repo = tree.repo
+
+        self.cache_types = tree.config.get("type") or copy(
+            self.DEFAULT_CACHE_TYPES
+        )
+        self.cache_type_confirmed = False
+        self._dir_info = {}
+
+    def get_dir_cache(self, hash_):
+        assert hash_
+
+        dir_info = self._dir_info.get(hash_)
+        if dir_info:
+            return dir_info
+
+        try:
+            dir_info = self.load_dir_cache(hash_)
+        except DirCacheError:
+            dir_info = []
+
+        self._dir_info[hash_] = dir_info
+        return dir_info
+
+    def load_dir_cache(self, hash_):
+        path_info = self.tree.hash_to_path_info(hash_)
+
+        try:
+            with self.tree.open(path_info, "r") as fobj:
+                d = json.load(fobj)
+        except (ValueError, FileNotFoundError) as exc:
+            raise DirCacheError(hash_) from exc
+
+        if not isinstance(d, list):
+            logger.error(
+                "dir cache file format error '%s' [skipping the file]",
+                path_info,
+            )
+            return []
+
+        if self.tree.PATH_CLS == WindowsPathInfo:
+            # only need to convert it for Windows
+            for info in d:
+                # NOTE: here is a BUG, see comment to .as_posix() below
+                relpath = info[self.tree.PARAM_RELPATH]
+                info[self.tree.PARAM_RELPATH] = relpath.replace(
+                    "/", self.tree.PATH_CLS.sep
+                )
+
+        return d
+
+    def changed(self, path_info, hash_info):
+        """Checks if data has changed.
+
+        A file is considered changed if:
+            - It doesn't exist on the working directory (was unlinked)
+            - Hash value is not computed (saving a new file)
+            - The hash value stored is different from the given one
+            - There's no file in the cache
+
+        Args:
+            path_info: dict with path information.
+            hash: expected hash value for this data.
+
+        Returns:
+            bool: True if data has changed, False otherwise.
+        """
+
+        logger.debug(
+            "checking if '%s'('%s') has changed.", path_info, hash_info
+        )
+
+        if not self.tree.exists(path_info):
+            logger.debug("'%s' doesn't exist.", path_info)
+            return True
+
+        hash_ = hash_info.get(self.tree.PARAM_CHECKSUM)
+        if hash_ is None:
+            logger.debug("hash value for '%s' is missing.", path_info)
+            return True
+
+        if self.changed_cache(hash_):
+            logger.debug("cache for '%s'('%s') has changed.", path_info, hash_)
+            return True
+
+        actual = self.tree.get_hash(path_info)
+        if hash_ != actual:
+            logger.debug(
+                "hash value '%s' for '%s' has changed (actual '%s').",
+                hash_,
+                actual,
+                path_info,
+            )
+            return True
+
+        logger.debug("'%s' hasn't changed.", path_info)
+        return False
+
+    def link(self, from_info, to_info):
+        self._link(from_info, to_info, self.cache_types)
+
+    def _link(self, from_info, to_info, link_types):
+        assert self.tree.isfile(from_info)
+
+        self.tree.makedirs(to_info.parent)
+
+        self._try_links(from_info, to_info, link_types)
+
+    def _verify_link(self, path_info, link_type):
+        if self.cache_type_confirmed:
+            return
+
+        is_link = getattr(self.tree, f"is_{link_type}", None)
+        if is_link and not is_link(path_info):
+            self.tree.remove(path_info)
+            raise DvcException(f"failed to verify {link_type}")
+
+        self.cache_type_confirmed = True
+
+    @slow_link_guard
+    def _try_links(self, from_info, to_info, link_types):
+        while link_types:
+            link_method = getattr(self.tree, link_types[0])
+            try:
+                self._do_link(from_info, to_info, link_method)
+                self._verify_link(to_info, link_types[0])
+                return
+
+            except DvcException as exc:
+                logger.debug(
+                    "Cache type '%s' is not supported: %s", link_types[0], exc
+                )
+                del link_types[0]
+
+        raise DvcException("no possible cache types left to try out.")
+
+    def _do_link(self, from_info, to_info, link_method):
+        if self.tree.exists(to_info):
+            raise DvcException(f"Link '{to_info}' already exists!")
+
+        link_method(from_info, to_info)
+
+        logger.debug(
+            "Created '%s': %s -> %s", self.cache_types[0], from_info, to_info,
+        )
+
+    def _save_file(self, path_info, tree, hash_, save_link=True, **kwargs):
+        assert hash_
+
+        cache_info = self.tree.hash_to_path_info(hash_)
+        if tree == self.tree:
+            if self.changed_cache(hash_):
+                self.tree.move(path_info, cache_info, mode=self.CACHE_MODE)
+                self.link(cache_info, path_info)
+            elif self.tree.iscopy(path_info) and self._cache_is_copy(
+                path_info
+            ):
+                # Default relink procedure involves unneeded copy
+                self.tree.unprotect(path_info)
+            else:
+                self.tree.remove(path_info)
+                self.link(cache_info, path_info)
+
+            if save_link:
+                self.tree.state.save_link(path_info)
+            # we need to update path and cache, since in case of reflink,
+            # or copy cache type moving original file results in updates on
+            # next executed command, which causes md5 recalculation
+            self.tree.state.save(path_info, hash_)
+        else:
+            if self.changed_cache(hash_):
+                with tree.open(path_info, mode="rb") as fobj:
+                    # if tree has fetch enabled, DVC out will be fetched on
+                    # open and we do not need to read/copy any data
+                    if not (
+                        tree.isdvc(path_info, strict=False) and tree.fetch
+                    ):
+                        self.tree.copy_fobj(fobj, cache_info)
+                callback = kwargs.get("download_callback")
+                if callback:
+                    callback(1)
+
+        self.tree.state.save(cache_info, hash_)
+        return {self.tree.PARAM_CHECKSUM: hash_}
+
+    def _cache_is_copy(self, path_info):
+        """Checks whether cache uses copies."""
+        if self.cache_type_confirmed:
+            return self.cache_types[0] == "copy"
+
+        if set(self.cache_types) <= {"copy"}:
+            return True
+
+        workspace_file = path_info.with_name("." + uuid())
+        test_cache_file = self.tree.path_info / ".cache_type_test_file"
+        if not self.tree.exists(test_cache_file):
+            with self.tree.open(test_cache_file, "wb") as fobj:
+                fobj.write(bytes(1))
+        try:
+            self.link(test_cache_file, workspace_file)
+        finally:
+            self.tree.remove(workspace_file)
+            self.tree.remove(test_cache_file)
+
+        self.cache_type_confirmed = True
+        return self.cache_types[0] == "copy"
+
+    def _save_dir(self, path_info, tree, hash_, save_link=True, **kwargs):
+        dir_info = self.get_dir_cache(hash_)
+        for entry in Tqdm(
+            dir_info, desc="Saving " + path_info.name, unit="file"
+        ):
+            entry_info = path_info / entry[self.tree.PARAM_RELPATH]
+            entry_hash = entry[self.tree.PARAM_CHECKSUM]
+            self._save_file(
+                entry_info, tree, entry_hash, save_link=False, **kwargs
+            )
+
+        if save_link:
+            self.tree.state.save_link(path_info)
+        if self.tree.exists(path_info):
+            self.tree.state.save(path_info, hash_)
+
+        cache_info = self.tree.hash_to_path_info(hash_)
+        self.tree.state.save(cache_info, hash_)
+        return {self.tree.PARAM_CHECKSUM: hash_}
+
+    def save(self, path_info, tree, hash_info, save_link=True, **kwargs):
+        if path_info.scheme != self.tree.scheme:
+            raise RemoteActionNotImplemented(
+                f"save {path_info.scheme} -> {self.tree.scheme}",
+                self.tree.scheme,
+            )
+
+        if not hash_info:
+            hash_info = self.tree.save_info(path_info, tree=tree, **kwargs)
+        hash_ = hash_info[self.tree.PARAM_CHECKSUM]
+        return self._save(path_info, tree, hash_, save_link, **kwargs)
+
+    def _save(self, path_info, tree, hash_, save_link=True, **kwargs):
+        to_info = self.tree.hash_to_path_info(hash_)
+        logger.debug("Saving '%s' to '%s'.", path_info, to_info)
+
+        if tree.isdir(path_info):
+            return self._save_dir(path_info, tree, hash_, save_link, **kwargs)
+        return self._save_file(path_info, tree, hash_, save_link, **kwargs)
+
+    # Override to return path as a string instead of PathInfo for clouds
+    # which support string paths (see local)
+    def hash_to_path(self, hash_):
+        return self.tree.hash_to_path_info(hash_)
+
+    def changed_cache_file(self, hash_):
+        """Compare the given hash with the (corresponding) actual one.
+
+        - Use `State` as a cache for computed hashes
+            + The entries are invalidated by taking into account the following:
+                * mtime
+                * inode
+                * size
+                * hash
+
+        - Remove the file from cache if it doesn't match the actual hash
+        """
+        # Prefer string path over PathInfo when possible due to performance
+        cache_info = self.hash_to_path(hash_)
+        if self.tree.is_protected(cache_info):
+            logger.debug(
+                "Assuming '%s' is unchanged since it is read-only", cache_info
+            )
+            return False
+
+        actual = self.tree.get_hash(cache_info)
+
+        logger.debug(
+            "cache '%s' expected '%s' actual '%s'", cache_info, hash_, actual,
+        )
+
+        if not hash_ or not actual:
+            return True
+
+        if actual.split(".")[0] == hash_.split(".")[0]:
+            # making cache file read-only so we don't need to check it
+            # next time
+            self.tree.protect(cache_info)
+            return False
+
+        if self.tree.exists(cache_info):
+            logger.warning("corrupted cache file '%s'.", cache_info)
+            self.tree.remove(cache_info)
+
+        return True
+
+    def _changed_dir_cache(self, hash_, path_info=None, filter_info=None):
+        if self.changed_cache_file(hash_):
+            return True
+
+        for entry in self.get_dir_cache(hash_):
+            entry_hash = entry[self.tree.PARAM_CHECKSUM]
+
+            if path_info and filter_info:
+                entry_info = path_info / entry[self.tree.PARAM_RELPATH]
+                if not entry_info.isin_or_eq(filter_info):
+                    continue
+
+            if self.changed_cache_file(entry_hash):
+                return True
+
+        return False
+
+    def changed_cache(self, hash_, path_info=None, filter_info=None):
+        if self.tree.is_dir_hash(hash_):
+            return self._changed_dir_cache(
+                hash_, path_info=path_info, filter_info=filter_info
+            )
+        return self.changed_cache_file(hash_)
+
+    def already_cached(self, path_info):
+        current = self.tree.get_hash(path_info)
+
+        if not current:
+            return False
+
+        return not self.changed_cache(current)
+
+    def safe_remove(self, path_info, force=False):
+        if not self.tree.exists(path_info):
+            return
+
+        if not force and not self.already_cached(path_info):
+            msg = (
+                "file '{}' is going to be removed."
+                " Are you sure you want to proceed?".format(str(path_info))
+            )
+
+            if not prompt.confirm(msg):
+                raise ConfirmRemoveError(str(path_info))
+
+        self.tree.remove(path_info)
+
+    def _checkout_file(
+        self, path_info, hash_, force, progress_callback=None, relink=False
+    ):
+        """The file is changed we need to checkout a new copy"""
+        added, modified = True, False
+        cache_info = self.tree.hash_to_path_info(hash_)
+        if self.tree.exists(path_info):
+            logger.debug("data '%s' will be replaced.", path_info)
+            self.safe_remove(path_info, force=force)
+            added, modified = False, True
+
+        self.link(cache_info, path_info)
+        self.tree.state.save_link(path_info)
+        self.tree.state.save(path_info, hash_)
+        if progress_callback:
+            progress_callback(str(path_info))
+
+        return added, modified and not relink
+
+    def _checkout_dir(
+        self,
+        path_info,
+        hash_,
+        force,
+        progress_callback=None,
+        relink=False,
+        filter_info=None,
+    ):
+        added, modified = False, False
+        # Create dir separately so that dir is created
+        # even if there are no files in it
+        if not self.tree.exists(path_info):
+            added = True
+            self.tree.makedirs(path_info)
+
+        dir_info = self.get_dir_cache(hash_)
+
+        logger.debug("Linking directory '%s'.", path_info)
+
+        for entry in dir_info:
+            relative_path = entry[self.tree.PARAM_RELPATH]
+            entry_hash = entry[self.tree.PARAM_CHECKSUM]
+            entry_cache_info = self.tree.hash_to_path_info(entry_hash)
+            entry_info = path_info / relative_path
+
+            if filter_info and not entry_info.isin_or_eq(filter_info):
+                continue
+
+            entry_hash_info = {self.tree.PARAM_CHECKSUM: entry_hash}
+            if relink or self.changed(entry_info, entry_hash_info):
+                modified = True
+                self.safe_remove(entry_info, force=force)
+                self.link(entry_cache_info, entry_info)
+                self.tree.state.save(entry_info, entry_hash)
+            if progress_callback:
+                progress_callback(str(entry_info))
+
+        modified = (
+            self._remove_redundant_files(path_info, dir_info, force)
+            or modified
+        )
+
+        self.tree.state.save_link(path_info)
+        self.tree.state.save(path_info, hash_)
+
+        # relink is not modified, assume it as nochange
+        return added, not added and modified and not relink
+
+    def _remove_redundant_files(self, path_info, dir_info, force):
+        existing_files = set(self.tree.walk_files(path_info))
+
+        needed_files = {
+            path_info / entry[self.tree.PARAM_RELPATH] for entry in dir_info
+        }
+        redundant_files = existing_files - needed_files
+        for path in redundant_files:
+            self.safe_remove(path, force)
+
+        return bool(redundant_files)
+
+    def checkout(
+        self,
+        path_info,
+        hash_info,
+        force=False,
+        progress_callback=None,
+        relink=False,
+        filter_info=None,
+    ):
+        if path_info.scheme not in ["local", self.tree.scheme]:
+            raise NotImplementedError
+
+        hash_ = hash_info.get(self.tree.PARAM_CHECKSUM)
+        failed = None
+        skip = False
+        if not hash_:
+            logger.warning(
+                "No file hash info found for '%s'. " "It won't be created.",
+                path_info,
+            )
+            self.safe_remove(path_info, force=force)
+            failed = path_info
+
+        elif not relink and not self.changed(path_info, hash_info):
+            logger.debug("Data '%s' didn't change.", path_info)
+            skip = True
+
+        elif self.changed_cache(
+            hash_, path_info=path_info, filter_info=filter_info
+        ):
+            logger.warning(
+                "Cache '%s' not found. File '%s' won't be created.",
+                hash_,
+                path_info,
+            )
+            self.safe_remove(path_info, force=force)
+            failed = path_info
+
+        if failed or skip:
+            if progress_callback:
+                progress_callback(
+                    str(path_info),
+                    self.get_files_number(
+                        self.tree.path_info, hash_, filter_info
+                    ),
+                )
+            if failed:
+                raise CheckoutError([failed])
+            return
+
+        logger.debug("Checking out '%s' with cache '%s'.", path_info, hash_)
+
+        return self._checkout(
+            path_info, hash_, force, progress_callback, relink, filter_info,
+        )
+
+    def _checkout(
+        self,
+        path_info,
+        hash_,
+        force=False,
+        progress_callback=None,
+        relink=False,
+        filter_info=None,
+    ):
+        if not self.tree.is_dir_hash(hash_):
+            return self._checkout_file(
+                path_info, hash_, force, progress_callback, relink
+            )
+
+        return self._checkout_dir(
+            path_info, hash_, force, progress_callback, relink, filter_info
+        )
+
+    def get_files_number(self, path_info, hash_, filter_info):
+        from funcy.py3 import ilen
+
+        if not hash_:
+            return 0
+
+        if not self.tree.is_dir_hash(hash_):
+            return 1
+
+        if not filter_info:
+            return len(self.get_dir_cache(hash_))
+
+        return ilen(
+            filter_info.isin_or_eq(path_info / entry[self.tree.PARAM_CHECKSUM])
+            for entry in self.get_dir_cache(hash_)
+        )

dvc/cache/local.py

@@ -0,0 +1,431 @@
+import errno
+import logging
+import os
+from concurrent.futures import ThreadPoolExecutor, as_completed
+from functools import partial, wraps
+
+from funcy import cached_property, concat
+
+from dvc.exceptions import DownloadError, UploadError
+from dvc.path_info import PathInfo
+from dvc.progress import Tqdm
+
+from ..remote.base import index_locked
+from ..tree.local import LocalTree
+from .base import (
+    STATUS_DELETED,
+    STATUS_MAP,
+    STATUS_MISSING,
+    STATUS_NEW,
+    CloudCache,
+)
+
+logger = logging.getLogger(__name__)
+
+
+def _log_exceptions(func, operation):
+    @wraps(func)
+    def wrapper(from_info, to_info, *args, **kwargs):
+        try:
+            func(from_info, to_info, *args, **kwargs)
+            return 0
+        except Exception as exc:  # pylint: disable=broad-except
+            # NOTE: this means we ran out of file descriptors and there is no
+            # reason to try to proceed, as we will hit this error anyways.
+            # pylint: disable=no-member
+            if isinstance(exc, OSError) and exc.errno == errno.EMFILE:
+                raise
+
+            logger.exception(
+                "failed to %s '%s' to '%s'", operation, from_info, to_info
+            )
+            return 1
+
+    return wrapper
+
+
+class LocalCache(CloudCache):
+    DEFAULT_CACHE_TYPES = ["reflink", "copy"]
+    CACHE_MODE = LocalTree.CACHE_MODE
+
+    def __init__(self, tree):
+        super().__init__(tree)
+        self.cache_dir = tree.config.get("url")
+
+    @property
+    def cache_dir(self):
+        return self.tree.path_info.fspath if self.tree.path_info else None
+
+    @cache_dir.setter
+    def cache_dir(self, value):
+        self.tree.path_info = PathInfo(value) if value else None
+
+    @classmethod
+    def supported(cls, config):  # pylint: disable=unused-argument
+        return True
+
+    @cached_property
+    def cache_path(self):
+        return os.path.abspath(self.cache_dir)
+
+    def hash_to_path(self, hash_):
+        # NOTE: `self.cache_path` is already normalized so we can simply use
+        # `os.sep` instead of `os.path.join`. This results in this helper
+        # being ~5.5 times faster.
+        return f"{self.cache_path}{os.sep}{hash_[0:2]}{os.sep}{hash_[2:]}"
+
+    def hashes_exist(
+        self, hashes, jobs=None, name=None
+    ):  # pylint: disable=unused-argument
+        return [
+            hash_
+            for hash_ in Tqdm(
+                hashes,
+                unit="file",
+                desc="Querying "
+                + ("cache in " + name if name else "local cache"),
+            )
+            if not self.changed_cache_file(hash_)
+        ]
+
+    def already_cached(self, path_info):
+        assert path_info.scheme in ["", "local"]
+
+        current_md5 = self.tree.get_hash(path_info)
+
+        if not current_md5:
+            return False
+
+        return not self.changed_cache(current_md5)
+
+    def _verify_link(self, path_info, link_type):
+        if link_type == "hardlink" and self.tree.getsize(path_info) == 0:
+            return
+
+        super()._verify_link(path_info, link_type)
+
+    @index_locked
+    def status(
+        self,
+        named_cache,
+        remote,
+        jobs=None,
+        show_checksums=False,
+        download=False,
+    ):
+        # Return flattened dict containing all status info
+        dir_status, file_status, _ = self._status(
+            named_cache,
+            remote,
+            jobs=jobs,
+            show_checksums=show_checksums,
+            download=download,
+        )
+        return dict(dir_status, **file_status)
+
+    def _status(
+        self,
+        named_cache,
+        remote,
+        jobs=None,
+        show_checksums=False,
+        download=False,
+    ):
+        """Return a tuple of (dir_status_info, file_status_info, dir_contents).
+
+        dir_status_info contains status for .dir files, file_status_info
+        contains status for all other files, and dir_contents is a dict of
+        {dir_hash: set(file_hash, ...)} which can be used to map
+        a .dir file to its file contents.
+        """
+        logger.debug(
+            f"Preparing to collect status from {remote.tree.path_info}"
+        )
+        md5s = set(named_cache.scheme_keys(self.tree.scheme))
+
+        logger.debug("Collecting information from local cache...")
+        local_exists = frozenset(
+            self.hashes_exist(md5s, jobs=jobs, name=self.cache_dir)
+        )
+
+        # This is a performance optimization. We can safely assume that,
+        # if the resources that we want to fetch are already cached,
+        # there's no need to check the remote storage for the existence of
+        # those files.
+        if download and local_exists == md5s:
+            remote_exists = local_exists
+        else:
+            logger.debug("Collecting information from remote cache...")
+            remote_exists = set()
+            dir_md5s = set(named_cache.dir_keys(self.tree.scheme))
+            if dir_md5s:
+                remote_exists.update(
+                    self._indexed_dir_hashes(named_cache, remote, dir_md5s)
+                )
+                md5s.difference_update(remote_exists)
+            if md5s:
+                remote_exists.update(
+                    remote.hashes_exist(
+                        md5s, jobs=jobs, name=str(remote.tree.path_info)
+                    )
+                )
+        return self._make_status(
+            named_cache, show_checksums, local_exists, remote_exists
+        )
+
+    def _make_status(
+        self, named_cache, show_checksums, local_exists, remote_exists
+    ):
+        def make_names(hash_, names):
+            return {"name": hash_ if show_checksums else " ".join(names)}
+
+        dir_status = {}
+        file_status = {}
+        dir_contents = {}
+        for hash_, item in named_cache[self.tree.scheme].items():
+            if item.children:
+                dir_status[hash_] = make_names(hash_, item.names)
+                dir_contents[hash_] = set()
+                for child_hash, child in item.children.items():
+                    file_status[child_hash] = make_names(
+                        child_hash, child.names
+                    )
+                    dir_contents[hash_].add(child_hash)
+            else:
+                file_status[hash_] = make_names(hash_, item.names)
+
+        self._fill_statuses(dir_status, local_exists, remote_exists)
+        self._fill_statuses(file_status, local_exists, remote_exists)
+
+        self._log_missing_caches(dict(dir_status, **file_status))
+
+        return dir_status, file_status, dir_contents
+
+    def _indexed_dir_hashes(self, named_cache, remote, dir_md5s):
+        # Validate our index by verifying all indexed .dir hashes
+        # still exist on the remote
+        indexed_dirs = set(remote.index.dir_hashes())
+        indexed_dir_exists = set()
+        if indexed_dirs:
+            indexed_dir_exists.update(
+                remote.tree.list_hashes_exists(indexed_dirs)
+            )
+            missing_dirs = indexed_dirs.difference(indexed_dir_exists)
+            if missing_dirs:
+                logger.debug(
+                    "Remote cache missing indexed .dir hashes '{}', "
+                    "clearing remote index".format(", ".join(missing_dirs))
+                )
+                remote.index.clear()
+
+        # Check if non-indexed (new) dir hashes exist on remote
+        dir_exists = dir_md5s.intersection(indexed_dir_exists)
+        dir_exists.update(
+            remote.tree.list_hashes_exists(dir_md5s - dir_exists)
+        )
+
+        # If .dir hash exists on the remote, assume directory contents
+        # still exists on the remote
+        for dir_hash in dir_exists:
+            file_hashes = list(
+                named_cache.child_keys(self.tree.scheme, dir_hash)
+            )
+            if dir_hash not in remote.index:
+                logger.debug(
+                    "Indexing new .dir '{}' with '{}' nested files".format(
+                        dir_hash, len(file_hashes)
+                    )
+                )
+                remote.index.update([dir_hash], file_hashes)
+            yield dir_hash
+            yield from file_hashes
+
+    @staticmethod
+    def _fill_statuses(hash_info_dir, local_exists, remote_exists):
+        # Using sets because they are way faster for lookups
+        local = set(local_exists)
+        remote = set(remote_exists)
+
+        for md5, info in hash_info_dir.items():
+            status = STATUS_MAP[(md5 in local, md5 in remote)]
+            info["status"] = status
+
+    def _get_plans(self, download, remote, status_info, status):
+        cache = []
+        path_infos = []
+        names = []
+        hashes = []
+        for md5, info in Tqdm(
+            status_info.items(), desc="Analysing status", unit="file"
+        ):
+            if info["status"] == status:
+                cache.append(self.tree.hash_to_path_info(md5))
+                path_infos.append(remote.tree.hash_to_path_info(md5))
+                names.append(info["name"])
+                hashes.append(md5)
+
+        if download:
+            to_infos = cache
+            from_infos = path_infos
+        else:
+            to_infos = path_infos
+            from_infos = cache
+
+        return from_infos, to_infos, names, hashes
+
+    def _process(
+        self,
+        named_cache,
+        remote,
+        jobs=None,
+        show_checksums=False,
+        download=False,
+    ):
+        logger.debug(
+            "Preparing to {} '{}'".format(
+                "download data from" if download else "upload data to",
+                remote.tree.path_info,
+            )
+        )
+
+        if download:
+            func = partial(
+                _log_exceptions(remote.tree.download, "download"),
+                dir_mode=self.tree.dir_mode,
+                file_mode=self.tree.file_mode,
+            )
+            status = STATUS_DELETED
+            desc = "Downloading"
+        else:
+            func = _log_exceptions(remote.tree.upload, "upload")
+            status = STATUS_NEW
+            desc = "Uploading"
+
+        if jobs is None:
+            jobs = remote.tree.JOBS
+
+        dir_status, file_status, dir_contents = self._status(
+            named_cache,
+            remote,
+            jobs=jobs,
+            show_checksums=show_checksums,
+            download=download,
+        )
+
+        dir_plans = self._get_plans(download, remote, dir_status, status)
+        file_plans = self._get_plans(download, remote, file_status, status)
+
+        total = len(dir_plans[0]) + len(file_plans[0])
+        if total == 0:
+            return 0
+
+        with Tqdm(total=total, unit="file", desc=desc) as pbar:
+            func = pbar.wrap_fn(func)
+            with ThreadPoolExecutor(max_workers=jobs) as executor:
+                if download:
+                    from_infos, to_infos, names, _ = (
+                        d + f for d, f in zip(dir_plans, file_plans)
+                    )
+                    fails = sum(
+                        executor.map(func, from_infos, to_infos, names)
+                    )
+                else:
+                    # for uploads, push files first, and any .dir files last
+
+                    file_futures = {}
+                    for from_info, to_info, name, hash_ in zip(*file_plans):
+                        file_futures[hash_] = executor.submit(
+                            func, from_info, to_info, name
+                        )
+                    dir_futures = {}
+                    for from_info, to_info, name, dir_hash in zip(*dir_plans):
+                        wait_futures = {
+                            future
+                            for file_hash, future in file_futures.items()
+                            if file_hash in dir_contents[dir_hash]
+                        }
+                        dir_futures[dir_hash] = executor.submit(
+                            self._dir_upload,
+                            func,
+                            wait_futures,
+                            from_info,
+                            to_info,
+                            name,
+                        )
+                    fails = sum(
+                        future.result()
+                        for future in concat(
+                            file_futures.values(), dir_futures.values()
+                        )
+                    )
+
+        if fails:
+            if download:
+                remote.index.clear()
+                raise DownloadError(fails)
+            raise UploadError(fails)
+
+        if not download:
+            # index successfully pushed dirs
+            for dir_hash, future in dir_futures.items():
+                if future.result() == 0:
+                    file_hashes = dir_contents[dir_hash]
+                    logger.debug(
+                        "Indexing pushed dir '{}' with "
+                        "'{}' nested files".format(dir_hash, len(file_hashes))
+                    )
+                    remote.index.update([dir_hash], file_hashes)
+
+        return len(dir_plans[0]) + len(file_plans[0])
+
+    @staticmethod
+    def _dir_upload(func, futures, from_info, to_info, name):
+        for future in as_completed(futures):
+            if future.result():
+                # do not upload this .dir file if any file in this
+                # directory failed to upload
+                logger.debug(
+                    "failed to upload full contents of '{}', "
+                    "aborting .dir file upload".format(name)
+                )
+                logger.error(f"failed to upload '{from_info}' to '{to_info}'")
+                return 1
+        return func(from_info, to_info, name)
+
+    @index_locked
+    def push(self, named_cache, remote, jobs=None, show_checksums=False):
+        return self._process(
+            named_cache,
+            remote,
+            jobs=jobs,
+            show_checksums=show_checksums,
+            download=False,
+        )
+
+    @index_locked
+    def pull(self, named_cache, remote, jobs=None, show_checksums=False):
+        return self._process(
+            named_cache,
+            remote,
+            jobs=jobs,
+            show_checksums=show_checksums,
+            download=True,
+        )
+
+    @staticmethod
+    def _log_missing_caches(hash_info_dict):
+        missing_caches = [
+            (md5, info)
+            for md5, info in hash_info_dict.items()
+            if info["status"] == STATUS_MISSING
+        ]
+        if missing_caches:
+            missing_desc = "\n".join(
+                "name: {}, md5: {}".format(info["name"], md5)
+                for md5, info in missing_caches
+            )
+            msg = (
+                "Some of the cache files do not exist neither locally "
+                "nor on remote. Missing cache files:\n{}".format(missing_desc)
+            )
+            logger.warning(msg)

dvc/cli.py

@@ -8,38 +8,40 @@ from .command import (
     cache,
     checkout,
     commit,
+    completion,
     config,
     daemon,
+    dag,
     data_sync,
     destroy,
     diff,
+    experiments,
+    freeze,
     gc,
     get,
     get_url,
+    git_hook,
     imp,
     imp_url,
     init,
     install,
     ls,
-    lock,
     metrics,
     move,
-    pipeline,
+    params,
+    plots,
     remote,
     remove,
     repro,
     root,
     run,
-    tag,
     unprotect,
     update,
     version,
-    git_hook,
 )
 from .command.base import fix_subparsers
 from .exceptions import DvcParserError
 
-
 logger = logging.getLogger(__name__)
 
 COMMANDS = [
@@ -62,35 +64,55 @@ COMMANDS = [
     remote,
     cache,
     metrics,
+    params,
     install,
     root,
     ls,
-    lock,
-    pipeline,
+    freeze,
+    dag,
     daemon,
     commit,
-    tag,
+    completion,
     diff,
     version,
     update,
     git_hook,
+    plots,
+    experiments,
 ]
 
 
+def _find_parser(parser, cmd_cls):
+    defaults = parser._defaults  # pylint: disable=protected-access
+    if not cmd_cls or cmd_cls == defaults.get("func"):
+        parser.print_help()
+        raise DvcParserError()
+
+    actions = parser._actions  # pylint: disable=protected-access
+    for action in actions:
+        if not isinstance(action.choices, dict):
+            # NOTE: we are only interested in subparsers
+            continue
+        for subparser in action.choices.values():
+            _find_parser(subparser, cmd_cls)
+
+
 class DvcParser(argparse.ArgumentParser):
     """Custom parser class for dvc CLI."""
 
-    def error(self, message):
-        """Custom error method.
-        Args:
-            message (str): error message.
-
-        Raises:
-            dvc.exceptions.DvcParser: dvc parser exception.
-        """
+    def error(self, message, cmd_cls=None):  # pylint: disable=arguments-differ
         logger.error(message)
-        self.print_help()
-        raise DvcParserError()
+        _find_parser(self, cmd_cls)
+
+    def parse_args(self, args=None, namespace=None):
+        # NOTE: overriding to provide a more granular help message.
+        # E.g. `dvc plots diff --bad-flag` would result in a `dvc plots diff`
+        # help message instead of generic `dvc` usage.
+        args, argv = self.parse_known_args(args, namespace)
+        if argv:
+            msg = "unrecognized arguments: %s"
+            self.error(msg % " ".join(argv), getattr(args, "func", None))
+        return args
 
 
 class VersionAction(argparse.Action):  # pragma: no cover
@@ -115,28 +137,16 @@ def get_parent_parser():
 
     log_level_group = parent_parser.add_mutually_exclusive_group()
     log_level_group.add_argument(
-        "-q", "--quiet", action="store_true", default=False, help="Be quiet."
+        "-q", "--quiet", action="count", default=0, help="Be quiet."
     )
     log_level_group.add_argument(
-        "-v",
-        "--verbose",
-        action="store_true",
-        default=False,
-        help="Be verbose.",
+        "-v", "--verbose", action="count", default=0, help="Be verbose."
     )
 
     return parent_parser
 
 
-def parse_args(argv=None):
-    """Parses CLI arguments.
-
-    Args:
-        argv: optional list of arguments to parse. sys.argv is used by default.
-
-    Raises:
-        dvc.exceptions.DvcParserError: raised for argument parsing errors.
-    """
+def get_main_parser():
     parent_parser = get_parent_parser()
 
     # Main parser
@@ -184,6 +194,18 @@ def parse_args(argv=None):
     for cmd in COMMANDS:
         cmd.add_parser(subparsers, parent_parser)
 
-    args = parser.parse_args(argv)
+    return parser
 
+
+def parse_args(argv=None):
+    """Parses CLI arguments.
+
+    Args:
+        argv: optional list of arguments to parse. sys.argv is used by default.
+
+    Raises:
+        dvc.exceptions.DvcParserError: raised for argument parsing errors.
+    """
+    parser = get_main_parser()
+    args = parser.parse_args(argv)
     return args

dvc/command/add.py

@@ -1,7 +1,8 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link, CmdBase
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link
 from dvc.exceptions import DvcException, RecursiveAddingWhileUsingFilename
 
 logger = logging.getLogger(__name__)
@@ -18,6 +19,7 @@ class CmdAdd(CmdBase):
                 recursive=self.args.recursive,
                 no_commit=self.args.no_commit,
                 fname=self.args.file,
+                external=self.args.external,
             )
 
         except DvcException:
@@ -50,11 +52,17 @@ def add_parser(subparsers, parent_parser):
         help="Don't put files/directories into cache.",
     )
     parser.add_argument(
-        "-f",
-        "--file",
-        help="Specify name of the DVC-file this command will generate.",
+        "--external",
+        action="store_true",
+        default=False,
+        help="Allow targets that are outside of the DVC repository.",
     )
     parser.add_argument(
-        "targets", nargs="+", help="Input files/directories to add."
+        "--file",
+        help="Specify name of the DVC-file this command will generate.",
+        metavar="<filename>",
     )
+    parser.add_argument(
+        "targets", nargs="+", help="Input files/directories to add.",
+    ).complete = completion.FILE
     parser.set_defaults(func=CmdAdd)

dvc/command/base.py

@@ -1,5 +1,5 @@
 import logging
-
+from abc import ABC, abstractmethod
 
 logger = logging.getLogger(__name__)
 
@@ -27,7 +27,7 @@ def append_doc_link(help_message, path):
     )
 
 
-class CmdBase(object):
+class CmdBase(ABC):
     def __init__(self, args):
         from dvc.repo import Repo
         from dvc.updater import Updater
@@ -36,23 +36,22 @@ class CmdBase(object):
         self.config = self.repo.config
         self.args = args
         hardlink_lock = self.config["core"].get("hardlink_lock", False)
-        updater = Updater(self.repo.dvc_dir, hardlink_lock=hardlink_lock)
+        updater = Updater(self.repo.tmp_dir, hardlink_lock=hardlink_lock)
         updater.check()
 
     @property
     def default_targets(self):
-        """Default targets for `dvc repro` and `dvc pipeline`."""
-        from dvc.stage import Stage
+        """Default targets for `dvc repro`."""
+        from dvc.dvcfile import PIPELINE_FILE
 
-        msg = "assuming default target '{}'.".format(Stage.STAGE_FILE)
-        logger.warning(msg)
-        return [Stage.STAGE_FILE]
+        logger.debug(f"assuming default target '{PIPELINE_FILE}'.")
+        return [PIPELINE_FILE]
 
-    # Abstract methods that have to be implemented by any inheritance class
+    @abstractmethod
     def run(self):
-        raise NotImplementedError
+        pass
 
 
 class CmdBaseNoRepo(CmdBase):
-    def __init__(self, args):
+    def __init__(self, args):  # pylint: disable=super-init-not-called
         self.args = args

dvc/command/cache.py

@@ -1,5 +1,6 @@
 import argparse
 
+from dvc.command import completion
 from dvc.command.base import append_doc_link, fix_subparsers
 from dvc.command.config import CmdConfig
 
@@ -55,5 +56,5 @@ def add_parser(subparsers, parent_parser):
         help="Path to cache directory. Relative paths are resolved relative "
         "to the current directory and saved to config relative to the "
         "config file location.",
-    )
+    ).complete = completion.DIR
     cache_dir_parser.set_defaults(func=CmdCacheDir)

dvc/command/checkout.py

@@ -1,39 +1,17 @@
 import argparse
 import logging
+import operator
 
 import colorama
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link
 from dvc.exceptions import CheckoutError
+from dvc.utils.humanize import get_summary
 
 logger = logging.getLogger(__name__)
 
 
-def _human_join(words):
-    words = list(words)
-    if not words:
-        return ""
-
-    return (
-        "{before} and {after}".format(
-            before=", ".join(words[:-1]), after=words[-1],
-        )
-        if len(words) > 1
-        else words[0]
-    )
-
-
-def log_summary(stats):
-    states = ("added", "deleted", "modified")
-    summary = (
-        "{} {}".format(len(stats[state]), state)
-        for state in states
-        if stats.get(state)
-    )
-    logger.info(_human_join(summary))
-
-
 def log_changes(stats):
     colors = [
         ("modified", colorama.Fore.YELLOW,),
@@ -75,7 +53,11 @@ class CmdCheckout(CmdBase):
             stats = exc.stats
 
         if self.args.summary:
-            log_summary(stats)
+            default_message = "No changes."
+            msg = get_summary(
+                sorted(stats.items(), key=operator.itemgetter(0))
+            )
+            logger.info(msg or default_message)
         else:
             log_changes(stats)
 
@@ -130,7 +112,9 @@ def add_parser(subparsers, parent_parser):
     checkout_parser.add_argument(
         "targets",
         nargs="*",
-        help="DVC-files to checkout. Optional. "
-        "(Finds all DVC-files in the workspace by default.)",
-    )
+        help=(
+            "Limit command scope to these tracked files/directories, "
+            ".dvc files, or stage names."
+        ),
+    ).complete = completion.DVC_FILE
     checkout_parser.set_defaults(func=CmdCheckout)

dvc/command/commit.py

@@ -1,11 +1,10 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link
 from dvc.exceptions import DvcException
 
-
 logger = logging.getLogger(__name__)
 
 
@@ -68,5 +67,5 @@ def add_parser(subparsers, parent_parser):
         nargs="*",
         help="DVC-files to commit. Optional. "
         "(Finds all DVC-files in the workspace by default.)",
-    )
+    ).complete = completion.DVC_FILE
     commit_parser.set_defaults(func=CmdCommit)

dvc/command/completion.py

@@ -0,0 +1,57 @@
+import argparse
+import logging
+
+import shtab
+
+from dvc.command.base import CmdBaseNoRepo, append_doc_link
+
+logger = logging.getLogger(__name__)
+FILE = shtab.FILE
+DIR = shtab.DIRECTORY
+DVC_FILE = {
+    "bash": "_dvc_compgen_DVCFiles",
+    "zsh": "_files -g '(*?.dvc|Dvcfile|dvc.yaml)'",
+}
+PREAMBLE = {
+    "bash": """
+# $1=COMP_WORDS[1]
+_dvc_compgen_DVCFiles() {
+  compgen -d -S '/' -- $1  # recurse into subdirs
+  compgen -f -X '!*?.dvc' -- $1
+  compgen -f -X '!*Dvcfile' -- $1
+  compgen -f -X '!*dvc.yaml' -- $1
+}
+""",
+    "zsh": "",
+}
+
+
+class CmdCompletion(CmdBaseNoRepo):
+    def run(self):
+        from dvc.cli import get_main_parser
+
+        parser = get_main_parser()
+        shell = self.args.shell
+        script = shtab.complete(parser, shell=shell, preamble=PREAMBLE)
+        print(script)
+        return 0
+
+
+def add_parser(subparsers, parent_parser):
+    COMPLETION_HELP = "Generate shell tab completion."
+    COMPLETION_DESCRIPTION = "Prints out shell tab completion scripts."
+    completion_parser = subparsers.add_parser(
+        "completion",
+        parents=[parent_parser],
+        description=append_doc_link(COMPLETION_DESCRIPTION, "completion"),
+        help=COMPLETION_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    completion_parser.add_argument(
+        "-s",
+        "--shell",
+        help="Shell syntax for completions.",
+        default="bash",
+        choices=["bash", "zsh"],
+    )
+    completion_parser.set_defaults(func=CmdCompletion)

dvc/command/config.py

@@ -1,7 +1,7 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link, CmdBaseNoRepo
+from dvc.command.base import CmdBaseNoRepo, append_doc_link
 from dvc.config import Config, ConfigError
 
 logger = logging.getLogger(__name__)
@@ -50,21 +50,22 @@ class CmdConfig(CmdBaseNoRepo):
 
 
 parent_config_parser = argparse.ArgumentParser(add_help=False)
-parent_config_parser.add_argument(
+level_group = parent_config_parser.add_mutually_exclusive_group()
+level_group.add_argument(
     "--global",
     dest="level",
     action="store_const",
     const="global",
     help="Use global config.",
 )
-parent_config_parser.add_argument(
+level_group.add_argument(
     "--system",
     dest="level",
     action="store_const",
     const="system",
     help="Use system config.",
 )
-parent_config_parser.add_argument(
+level_group.add_argument(
     "--local",
     dest="level",
     action="store_const",

dvc/command/daemon.py

@@ -1,5 +1,5 @@
-from dvc.command.base import CmdBaseNoRepo
-from dvc.command.base import fix_subparsers
+from dvc.command import completion
+from dvc.command.base import CmdBaseNoRepo, fix_subparsers
 
 
 class CmdDaemonBase(CmdBaseNoRepo):
@@ -15,9 +15,10 @@ class CmdDaemonUpdater(CmdDaemonBase):
 
         root_dir = Repo.find_root()
         dvc_dir = os.path.join(root_dir, Repo.DVC_DIR)
+        tmp_dir = os.path.join(dvc_dir, "tmp")
         config = Config(dvc_dir, validate=False)
         hardlink_lock = config.get("core", {}).get("hardlink_lock", False)
-        updater = Updater(dvc_dir, hardlink_lock=hardlink_lock)
+        updater = Updater(tmp_dir, hardlink_lock=hardlink_lock)
         updater.fetch(detach=False)
 
         return 0
@@ -64,5 +65,7 @@ def add_parser(subparsers, parent_parser):
         description=DAEMON_ANALYTICS_HELP,
         help=DAEMON_ANALYTICS_HELP,
     )
-    daemon_analytics_parser.add_argument("target", help="Analytics file.")
+    daemon_analytics_parser.add_argument(
+        "target", help="Analytics file.",
+    ).complete = completion.FILE
     daemon_analytics_parser.set_defaults(func=CmdDaemonAnalytics)

dvc/command/dag.py

@@ -0,0 +1,115 @@
+import argparse
+import logging
+
+from dvc.command.base import CmdBase, append_doc_link
+from dvc.exceptions import DvcException
+
+logger = logging.getLogger(__name__)
+
+
+def _show_ascii(G):
+    from dvc.repo.graph import get_pipelines
+    from dvc.dagascii import draw
+
+    pipelines = get_pipelines(G)
+
+    ret = []
+    for pipeline in pipelines:
+        ret.append(draw(pipeline.nodes, pipeline.edges))
+
+    return "\n".join(ret)
+
+
+def _show_dot(G):
+    import io
+    from networkx.drawing.nx_pydot import write_dot
+
+    dot_file = io.StringIO()
+    write_dot(G, dot_file)
+    return dot_file.getvalue()
+
+
+def _build(G, target=None, full=False):
+    import networkx as nx
+    from dvc.repo.graph import get_pipeline, get_pipelines
+
+    if target:
+        H = get_pipeline(get_pipelines(G), target)
+        if not full:
+            descendants = nx.descendants(G, target)
+            descendants.add(target)
+            H.remove_nodes_from(set(G.nodes()) - descendants)
+    else:
+        H = G
+
+    def _relabel(stage):
+        return stage.addressing
+
+    return nx.relabel_nodes(H, _relabel, copy=False)
+
+
+class CmdDAG(CmdBase):
+    def run(self):
+        try:
+            target = None
+            if self.args.target:
+                stages = self.repo.collect(self.args.target)
+                if len(stages) > 1:
+                    logger.error(
+                        f"'{self.args.target}' contains more than one stage "
+                        "{stages}, please specify one stage"
+                    )
+                    return 1
+                target = stages[0]
+
+            G = _build(self.repo.graph, target=target, full=self.args.full,)
+
+            if self.args.dot:
+                logger.info(_show_dot(G))
+            else:
+                from dvc.utils.pager import pager
+
+                pager(_show_ascii(G))
+
+            return 0
+        except DvcException:
+            msg = "failed to show "
+            if self.args.target:
+                msg += f"a pipeline for '{target}'"
+            else:
+                msg += "pipelines"
+            logger.exception(msg)
+            return 1
+
+
+def add_parser(subparsers, parent_parser):
+    DAG_HELP = "Visualize DVC project DAG."
+    dag_parser = subparsers.add_parser(
+        "dag",
+        parents=[parent_parser],
+        description=append_doc_link(DAG_HELP, "dag"),
+        help=DAG_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    dag_parser.add_argument(
+        "--dot",
+        action="store_true",
+        default=False,
+        help="Print DAG with .dot format.",
+    )
+    dag_parser.add_argument(
+        "--full",
+        action="store_true",
+        default=False,
+        help=(
+            "Show full DAG that the target belongs too, instead of "
+            "showing DAG consisting only of ancestors."
+        ),
+    )
+    dag_parser.add_argument(
+        "target",
+        nargs="?",
+        help="Stage or output to show pipeline for (optional). "
+        "Finds all stages in the workspace by default.",
+    )
+    dag_parser.set_defaults(func=CmdDAG)

dvc/command/data_sync.py

@@ -1,23 +1,26 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
-from dvc.command.checkout import log_summary
-from dvc.exceptions import DvcException, CheckoutError
-
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link
+from dvc.command.checkout import log_changes
+from dvc.exceptions import CheckoutError, DvcException
+from dvc.utils.humanize import get_summary
 
 logger = logging.getLogger(__name__)
 
 
 class CmdDataBase(CmdBase):
-    @classmethod
-    def check_up_to_date(cls, processed_files_count):
-        if processed_files_count == 0:
-            logger.info("Everything is up to date.")
+    def log_summary(self, stats):
+        default_msg = "Everything is up to date."
+        logger.info(get_summary(stats.items()) or default_msg)
 
 
 class CmdDataPull(CmdDataBase):
+    def log_summary(self, stats):
+        log_changes(stats)
+        super().log_summary(stats)
+
     def run(self):
         try:
             stats = self.repo.pull(
@@ -26,17 +29,18 @@ class CmdDataPull(CmdDataBase):
                 remote=self.args.remote,
                 all_branches=self.args.all_branches,
                 all_tags=self.args.all_tags,
+                all_commits=self.args.all_commits,
                 with_deps=self.args.with_deps,
                 force=self.args.force,
                 recursive=self.args.recursive,
+                run_cache=self.args.run_cache,
             )
-            log_summary(stats)
+            self.log_summary(stats)
         except (CheckoutError, DvcException) as exc:
-            log_summary(getattr(exc, "stats", {}))
+            self.log_summary(getattr(exc, "stats", {}))
             logger.exception("failed to pull data from the cloud")
             return 1
 
-        self.check_up_to_date(stats["downloaded"])
         return 0
 
 
@@ -49,13 +53,15 @@ class CmdDataPush(CmdDataBase):
                 remote=self.args.remote,
                 all_branches=self.args.all_branches,
                 all_tags=self.args.all_tags,
+                all_commits=self.args.all_commits,
                 with_deps=self.args.with_deps,
                 recursive=self.args.recursive,
+                run_cache=self.args.run_cache,
             )
+            self.log_summary({"pushed": processed_files_count})
         except DvcException:
             logger.exception("failed to push data to the cloud")
             return 1
-        self.check_up_to_date(processed_files_count)
         return 0
 
 
@@ -68,13 +74,15 @@ class CmdDataFetch(CmdDataBase):
                 remote=self.args.remote,
                 all_branches=self.args.all_branches,
                 all_tags=self.args.all_tags,
+                all_commits=self.args.all_commits,
                 with_deps=self.args.with_deps,
                 recursive=self.args.recursive,
+                run_cache=self.args.run_cache,
             )
+            self.log_summary({"fetched": processed_files_count})
         except DvcException:
             logger.exception("failed to fetch data from the cloud")
             return 1
-        self.check_up_to_date(processed_files_count)
         return 0
 
 
@@ -82,27 +90,33 @@ def shared_parent_parser():
     from dvc.cli import get_parent_parser
 
     # Parent parser used in pull/push/status
-    shared_parent_parser = argparse.ArgumentParser(
+    parent_parser = argparse.ArgumentParser(
         add_help=False, parents=[get_parent_parser()]
     )
-    shared_parent_parser.add_argument(
-        "-j", "--jobs", type=int, help="Number of jobs to run simultaneously."
+    parent_parser.add_argument(
+        "-j",
+        "--jobs",
+        type=int,
+        help="Number of jobs to run simultaneously.",
+        metavar="<number>",
     )
-    shared_parent_parser.add_argument(
+    parent_parser.add_argument(
         "targets",
         nargs="*",
-        help="Limit command scope to these DVC-files. "
-        "Using -R, directories to search DVC-files in can also be given.",
-    )
+        help=(
+            "Limit command scope to these tracked files/directories, "
+            ".dvc files, or stage names."
+        ),
+    ).complete = completion.DVC_FILE
 
-    return shared_parent_parser
+    return parent_parser
 
 
 def add_parser(subparsers, _parent_parser):
     from dvc.command.status import CmdDataStatus
 
     # Pull
-    PULL_HELP = "Pull data files from a DVC remote storage."
+    PULL_HELP = "Download tracked files or directories from remote storage."
 
     pull_parser = subparsers.add_parser(
         "pull",
@@ -112,7 +126,7 @@ def add_parser(subparsers, _parent_parser):
         formatter_class=argparse.RawDescriptionHelpFormatter,
     )
     pull_parser.add_argument(
-        "-r", "--remote", help="Remote repository to pull from."
+        "-r", "--remote", help="Remote storage to pull from", metavar="<name>",
     )
     pull_parser.add_argument(
         "-a",
@@ -128,6 +142,12 @@ def add_parser(subparsers, _parent_parser):
         default=False,
         help="Fetch cache for all tags.",
     )
+    pull_parser.add_argument(
+        "--all-commits",
+        action="store_true",
+        default=False,
+        help="Fetch cache for all commits.",
+    )
     pull_parser.add_argument(
         "-f",
         "--force",
@@ -149,11 +169,16 @@ def add_parser(subparsers, _parent_parser):
         default=False,
         help="Pull cache for subdirectories of the specified directory.",
     )
+    pull_parser.add_argument(
+        "--run-cache",
+        action="store_true",
+        default=False,
+        help="Fetch run history for all stages.",
+    )
     pull_parser.set_defaults(func=CmdDataPull)
 
     # Push
-    PUSH_HELP = "Uploads files or directories tracked by DVC"
-    " to remote storage."
+    PUSH_HELP = "Upload tracked files or directories to remote storage."
 
     push_parser = subparsers.add_parser(
         "push",
@@ -163,7 +188,7 @@ def add_parser(subparsers, _parent_parser):
         formatter_class=argparse.RawDescriptionHelpFormatter,
     )
     push_parser.add_argument(
-        "-r", "--remote", help="Remote repository to push to."
+        "-r", "--remote", help="Remote storage to push to", metavar="<name>",
     )
     push_parser.add_argument(
         "-a",
@@ -179,6 +204,12 @@ def add_parser(subparsers, _parent_parser):
         default=False,
         help="Push cache for all tags.",
     )
+    push_parser.add_argument(
+        "--all-commits",
+        action="store_true",
+        default=False,
+        help="Push cache for all commits.",
+    )
     push_parser.add_argument(
         "-d",
         "--with-deps",
@@ -191,13 +222,21 @@ def add_parser(subparsers, _parent_parser):
         "--recursive",
         action="store_true",
         default=False,
-        help="Push cache from subdirectories of specified directory.",
+        help="Push cache for subdirectories of specified directory.",
+    )
+    push_parser.add_argument(
+        "--run-cache",
+        action="store_true",
+        default=False,
+        help="Push run history for all stages.",
     )
     push_parser.set_defaults(func=CmdDataPush)
 
     # Fetch
-    FETCH_HELP = "Get files or directories tracked by DVC from remote storage"
-    " into the cache."
+    FETCH_HELP = (
+        "Get tracked files or directories from remote storage"
+        " into the cache."
+    )
 
     fetch_parser = subparsers.add_parser(
         "fetch",
@@ -207,7 +246,10 @@ def add_parser(subparsers, _parent_parser):
         formatter_class=argparse.RawDescriptionHelpFormatter,
     )
     fetch_parser.add_argument(
-        "-r", "--remote", help="Remote repository to fetch from."
+        "-r",
+        "--remote",
+        help="Remote storage to fetch from",
+        metavar="<name>",
     )
     fetch_parser.add_argument(
         "-a",
@@ -223,6 +265,12 @@ def add_parser(subparsers, _parent_parser):
         default=False,
         help="Fetch cache for all tags.",
     )
+    fetch_parser.add_argument(
+        "--all-commits",
+        action="store_true",
+        default=False,
+        help="Fetch cache for all commits.",
+    )
     fetch_parser.add_argument(
         "-d",
         "--with-deps",
@@ -237,6 +285,12 @@ def add_parser(subparsers, _parent_parser):
         default=False,
         help="Fetch cache for subdirectories of specified directory.",
     )
+    fetch_parser.add_argument(
+        "--run-cache",
+        action="store_true",
+        default=False,
+        help="Fetch run history for all stages.",
+    )
     fetch_parser.set_defaults(func=CmdDataFetch)
 
     # Status
@@ -270,7 +324,10 @@ def add_parser(subparsers, _parent_parser):
         help="Show status of a local cache compared to a remote repository.",
     )
     status_parser.add_argument(
-        "-r", "--remote", help="Remote repository to compare local cache to."
+        "-r",
+        "--remote",
+        help="Remote storage to compare local cache to",
+        metavar="<name>",
     )
     status_parser.add_argument(
         "-a",
@@ -288,6 +345,13 @@ def add_parser(subparsers, _parent_parser):
         help="Show status of a local cache compared to a remote repository "
         "for all tags.",
     )
+    status_parser.add_argument(
+        "--all-commits",
+        action="store_true",
+        default=False,
+        help="Show status of a local cache compared to a remote repository "
+        "for all commits.",
+    )
     status_parser.add_argument(
         "-d",
         "--with-deps",
@@ -295,4 +359,18 @@ def add_parser(subparsers, _parent_parser):
         default=False,
         help="Show status for all dependencies of the specified target.",
     )
+    status_parser.add_argument(
+        "-R",
+        "--recursive",
+        action="store_true",
+        default=False,
+        help="Show status of all stages in the specified directory.",
+    )
+    status_parser.add_argument(
+        "--show-json",
+        action="store_true",
+        default=False,
+        help="Show status in JSON format.",
+    )
+
     status_parser.set_defaults(func=CmdDataStatus)

dvc/command/destroy.py

@@ -2,11 +2,9 @@ import argparse
 import logging
 
 import dvc.prompt as prompt
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
+from dvc.command.base import CmdBase, append_doc_link
 from dvc.exceptions import DvcException
 
-
 logger = logging.getLogger(__name__)
 
 
@@ -27,7 +25,7 @@ class CmdDestroy(CmdBase):
                 )
 
             self.repo.destroy()
-        except Exception:
+        except Exception:  # noqa, pylint: disable=broad-except
             logger.exception("failed to destroy DVC")
             return 1
         return 0

dvc/command/diff.py

@@ -8,10 +8,24 @@ import colorama
 from dvc.command.base import CmdBase, append_doc_link
 from dvc.exceptions import DvcException
 
-
 logger = logging.getLogger(__name__)
 
 
+def _show_md(diff):
+    from dvc.utils.diff import table
+
+    rows = []
+    for status in ["added", "deleted", "modified"]:
+        entries = diff.get(status, [])
+        if not entries:
+            continue
+        paths = sorted(entry["path"] for entry in entries)
+        for path in paths:
+            rows.append([status, path])
+
+    return table(["Status", "Path"], rows, True)
+
+
 class CmdDiff(CmdBase):
     @staticmethod
     def _format(diff):
@@ -42,7 +56,7 @@ class CmdDiff(CmdBase):
         """
 
         def _digest(checksum):
-            if type(checksum) is str:
+            if isinstance(checksum, str):
                 return checksum[0:8]
             return "{}..{}".format(checksum["old"][0:8], checksum["new"][0:8])
 
@@ -97,20 +111,17 @@ class CmdDiff(CmdBase):
         try:
             diff = self.repo.diff(self.args.a_rev, self.args.b_rev)
 
-            if not any(diff.values()):
-                return 0
-
             if not self.args.show_hash:
                 for _, entries in diff.items():
                     for entry in entries:
                         del entry["hash"]
 
             if self.args.show_json:
-                res = json.dumps(diff)
-            else:
-                res = self._format(diff)
-
-            logger.info(res)
+                logger.info(json.dumps(diff))
+            elif self.args.show_md:
+                logger.info(_show_md(diff))
+            elif diff:
+                logger.info(self._format(diff))
 
         except DvcException:
             logger.exception("failed to get diff")
@@ -120,9 +131,8 @@ class CmdDiff(CmdBase):
 
 def add_parser(subparsers, parent_parser):
     DIFF_DESCRIPTION = (
-        "Show changes between commits in the DVC repository,"
-        " or between a commit and the workspace."
-        "Prints the list of paths added, modified, or deleted."
+        "Show added, modified, or deleted data between commits in the DVC"
+        " repository, or between a commit and the workspace."
     )
     diff_parser = subparsers.add_parser(
         "diff",
@@ -154,4 +164,10 @@ def add_parser(subparsers, parent_parser):
         action="store_true",
         default=False,
     )
+    diff_parser.add_argument(
+        "--show-md",
+        help="Show tabulated output in the Markdown format (GFM).",
+        action="store_true",
+        default=False,
+    )
     diff_parser.set_defaults(func=CmdDiff)

dvc/command/experiments.py

@@ -0,0 +1,354 @@
+import argparse
+import io
+import logging
+from collections import OrderedDict
+
+from dvc.command.base import CmdBase, append_doc_link, fix_subparsers
+from dvc.command.metrics import DEFAULT_PRECISION
+from dvc.exceptions import DvcException
+
+logger = logging.getLogger(__name__)
+
+
+def _update_names(names, items):
+    from flatten_json import flatten
+
+    for name, item in items:
+        if isinstance(item, dict):
+            item = flatten(item, ".")
+            names.update(item.keys())
+        else:
+            names.add(name)
+
+
+def _collect_names(all_experiments):
+    metric_names = set()
+    param_names = set()
+
+    for _, experiments in all_experiments.items():
+        for exp in experiments.values():
+            _update_names(metric_names, exp.get("metrics", {}).items())
+            _update_names(param_names, exp.get("params", {}).items())
+
+    return sorted(metric_names), sorted(param_names)
+
+
+def _collect_rows(
+    base_rev, experiments, metric_names, param_names, precision=None
+):
+    from flatten_json import flatten
+
+    if precision is None:
+        precision = DEFAULT_PRECISION
+
+    def _round(val):
+        if isinstance(val, float):
+            return round(val, precision)
+
+        return val
+
+    def _extend(row, names, items):
+        for fname, item in items:
+            if isinstance(item, dict):
+                item = flatten(item, ".")
+            else:
+                item = {fname: item}
+            for name in names:
+                if name in item:
+                    row.append(str(_round(item[name])))
+                else:
+                    row.append("-")
+
+    for i, (rev, exp) in enumerate(experiments.items()):
+        row = []
+        style = None
+        if rev == "baseline":
+            row.append(f"{base_rev}")
+            style = "bold"
+        elif i < len(experiments) - 1:
+            row.append(f"├── {rev[:7]}")
+        else:
+            row.append(f"└── {rev[:7]}")
+
+        _extend(row, metric_names, exp.get("metrics", {}).items())
+        _extend(row, param_names, exp.get("params", {}).items())
+
+        yield row, style
+
+
+def _show_experiments(all_experiments, console, precision=None):
+    from rich.table import Table
+    from dvc.scm.git import Git
+
+    metric_names, param_names = _collect_names(all_experiments)
+
+    table = Table()
+    table.add_column("Experiment")
+    for name in metric_names:
+        table.add_column(name, justify="right")
+    for name in param_names:
+        table.add_column(name, justify="left")
+
+    for base_rev, experiments in all_experiments.items():
+        if Git.is_sha(base_rev):
+            base_rev = base_rev[:7]
+
+        for row, _, in _collect_rows(
+            base_rev,
+            experiments,
+            metric_names,
+            param_names,
+            precision=precision,
+        ):
+            table.add_row(*row)
+
+    console.print(table)
+
+
+class CmdExperimentsShow(CmdBase):
+    def run(self):
+        from rich.console import Console
+        from dvc.utils.pager import pager
+
+        if not self.repo.experiments:
+            return 0
+
+        try:
+            all_experiments = self.repo.experiments.show(
+                all_branches=self.args.all_branches,
+                all_tags=self.args.all_tags,
+                all_commits=self.args.all_commits,
+            )
+
+            # Note: rich does not currently include a native way to force
+            # infinite width for use with a pager
+            console = Console(
+                file=io.StringIO(), force_terminal=True, width=9999
+            )
+
+            _show_experiments(all_experiments, console)
+
+            pager(console.file.getvalue())
+        except DvcException:
+            logger.exception("failed to show experiments")
+            return 1
+
+        return 0
+
+
+class CmdExperimentsCheckout(CmdBase):
+    def run(self):
+        if not self.repo.experiments:
+            return 0
+
+        self.repo.experiments.checkout(
+            self.args.experiment, force=self.args.force
+        )
+
+        return 0
+
+
+def _show_diff(
+    diff, title="", markdown=False, no_path=False, old=False, precision=None
+):
+    from dvc.utils.diff import table
+
+    if precision is None:
+        precision = DEFAULT_PRECISION
+
+    def _round(val):
+        if isinstance(val, float):
+            return round(val, precision)
+
+        return val
+
+    rows = []
+    for fname, diff_ in diff.items():
+        sorted_diff = OrderedDict(sorted(diff_.items()))
+        for item, change in sorted_diff.items():
+            row = [] if no_path else [fname]
+            row.append(item)
+            if old:
+                row.append(_round(change.get("old")))
+            row.append(_round(change["new"]))
+            row.append(_round(change.get("diff", "diff not supported")))
+            rows.append(row)
+
+    header = [] if no_path else ["Path"]
+    header.append(title)
+    if old:
+        header.extend(["Old", "New"])
+    else:
+        header.append("Value")
+    header.append("Change")
+
+    return table(header, rows, markdown)
+
+
+class CmdExperimentsDiff(CmdBase):
+    def run(self):
+        if not self.repo.experiments:
+            return 0
+
+        try:
+            diff = self.repo.experiments.diff(
+                a_rev=self.args.a_rev,
+                b_rev=self.args.b_rev,
+                all=self.args.all,
+            )
+
+            if self.args.show_json:
+                import json
+
+                logger.info(json.dumps(diff))
+            else:
+                diffs = [("metrics", "Metric"), ("params", "Param")]
+                for key, title in diffs:
+                    table = _show_diff(
+                        diff[key],
+                        title=title,
+                        markdown=self.args.show_md,
+                        no_path=self.args.no_path,
+                        old=self.args.old,
+                        precision=self.args.precision,
+                    )
+                    if table:
+                        logger.info(table)
+                        logger.info("")
+
+        except DvcException:
+            logger.exception("failed to show experiments diff")
+            return 1
+
+        return 0
+
+
+def add_parser(subparsers, parent_parser):
+    EXPERIMENTS_HELP = "Commands to display and compare experiments."
+
+    experiments_parser = subparsers.add_parser(
+        "experiments",
+        parents=[parent_parser],
+        description=append_doc_link(EXPERIMENTS_HELP, "experiments"),
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+
+    experiments_subparsers = experiments_parser.add_subparsers(
+        dest="cmd",
+        help="Use `dvc experiments CMD --help` to display "
+        "command-specific help.",
+    )
+
+    fix_subparsers(experiments_subparsers)
+
+    EXPERIMENTS_SHOW_HELP = "Print experiments."
+    experiments_show_parser = experiments_subparsers.add_parser(
+        "show",
+        parents=[parent_parser],
+        description=append_doc_link(EXPERIMENTS_SHOW_HELP, "experiments/show"),
+        help=EXPERIMENTS_SHOW_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    experiments_show_parser.add_argument(
+        "-a",
+        "--all-branches",
+        action="store_true",
+        default=False,
+        help="Show metrics for all branches.",
+    )
+    experiments_show_parser.add_argument(
+        "-T",
+        "--all-tags",
+        action="store_true",
+        default=False,
+        help="Show metrics for all tags.",
+    )
+    experiments_show_parser.add_argument(
+        "--all-commits",
+        action="store_true",
+        default=False,
+        help="Show metrics for all commits.",
+    )
+    experiments_show_parser.set_defaults(func=CmdExperimentsShow)
+
+    EXPERIMENTS_CHECKOUT_HELP = "Checkout experiments."
+    experiments_checkout_parser = experiments_subparsers.add_parser(
+        "checkout",
+        parents=[parent_parser],
+        description=append_doc_link(
+            EXPERIMENTS_CHECKOUT_HELP, "experiments/checkout"
+        ),
+        help=EXPERIMENTS_CHECKOUT_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    experiments_checkout_parser.add_argument(
+        "-f",
+        "--force",
+        action="store_true",
+        default=False,
+        help="Overwrite your current workspace with changes from the "
+        "experiment.",
+    )
+    experiments_checkout_parser.add_argument(
+        "experiment", help="Checkout this experiment.",
+    )
+    experiments_checkout_parser.set_defaults(func=CmdExperimentsCheckout)
+
+    EXPERIMENTS_DIFF_HELP = (
+        "Show changes between experiments in the DVC repository."
+    )
+    experiments_diff_parser = experiments_subparsers.add_parser(
+        "diff",
+        parents=[parent_parser],
+        description=append_doc_link(EXPERIMENTS_DIFF_HELP, "experiments/diff"),
+        help=EXPERIMENTS_DIFF_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    experiments_diff_parser.add_argument(
+        "a_rev", nargs="?", help="Old experiment to compare (defaults to HEAD)"
+    )
+    experiments_diff_parser.add_argument(
+        "b_rev",
+        nargs="?",
+        help="New experiment to compare (defaults to the current workspace)",
+    )
+    experiments_diff_parser.add_argument(
+        "--all",
+        action="store_true",
+        default=False,
+        help="Show unchanged metrics/params as well.",
+    )
+    experiments_diff_parser.add_argument(
+        "--show-json",
+        action="store_true",
+        default=False,
+        help="Show output in JSON format.",
+    )
+    experiments_diff_parser.add_argument(
+        "--show-md",
+        action="store_true",
+        default=False,
+        help="Show tabulated output in the Markdown format (GFM).",
+    )
+    experiments_diff_parser.add_argument(
+        "--old",
+        action="store_true",
+        default=False,
+        help="Show old metric/param value.",
+    )
+    experiments_diff_parser.add_argument(
+        "--no-path",
+        action="store_true",
+        default=False,
+        help="Don't show metric/param path.",
+    )
+    experiments_diff_parser.add_argument(
+        "--precision",
+        type=int,
+        help=(
+            "Round metrics/params to `n` digits precision after the decimal "
+            f"point. Rounds to {DEFAULT_PRECISION} digits by default."
+        ),
+        metavar="<n>",
+    )
+    experiments_diff_parser.set_defaults(func=CmdExperimentsDiff)

dvc/command/freeze.py

@@ -0,0 +1,58 @@
+import argparse
+import logging
+
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link
+from dvc.exceptions import DvcException
+
+logger = logging.getLogger(__name__)
+
+
+class CmdFreezeBase(CmdBase):
+    def _run(self, func, name):
+        ret = 0
+        for target in self.args.targets:
+            try:
+                func(target)
+            except DvcException:
+                logger.exception(f"failed to {name} '{target}'")
+                ret = 1
+        return ret
+
+
+class CmdFreeze(CmdFreezeBase):
+    def run(self):
+        return self._run(self.repo.freeze, "freeze")
+
+
+class CmdUnfreeze(CmdFreezeBase):
+    def run(self):
+        return self._run(self.repo.unfreeze, "unfreeze")
+
+
+def add_parser(subparsers, parent_parser):
+    FREEZE_HELP = "Freeze stages or .dvc files."
+    freeze_parser = subparsers.add_parser(
+        "freeze",
+        parents=[parent_parser],
+        description=append_doc_link(FREEZE_HELP, "freeze"),
+        help=FREEZE_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    freeze_parser.add_argument(
+        "targets", nargs="+", help="Stages or .dvc files to freeze",
+    ).complete = completion.DVC_FILE
+    freeze_parser.set_defaults(func=CmdFreeze)
+
+    UNFREEZE_HELP = "Unfreeze stages or .dvc files."
+    unfreeze_parser = subparsers.add_parser(
+        "unfreeze",
+        parents=[parent_parser],
+        description=append_doc_link(UNFREEZE_HELP, "unfreeze"),
+        help=UNFREEZE_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    unfreeze_parser.add_argument(
+        "targets", nargs="+", help="Stages or .dvc files to unfreeze",
+    ).complete = completion.DVC_FILE
+    unfreeze_parser.set_defaults(func=CmdUnfreeze)

dvc/command/gc.py

@@ -3,9 +3,7 @@ import logging
 import os
 
 import dvc.prompt as prompt
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
-
+from dvc.command.base import CmdBase, append_doc_link
 
 logger = logging.getLogger(__name__)
 
@@ -23,7 +21,7 @@ class CmdGC(CmdBase):
 
         msg = "This will remove all cache except items used in "
 
-        msg += "the working tree"
+        msg += "the workspace"
         if self.args.all_commits:
             msg += " and all git commits"
         elif self.args.all_branches and self.args.all_tags:
@@ -79,7 +77,7 @@ def add_parser(subparsers, parent_parser):
         "--workspace",
         action="store_true",
         default=False,
-        help="Keep data files used in the current workspace (working tree).",
+        help="Keep data files used in the current workspace.",
     )
     gc_parser.add_argument(
         "-a",
@@ -109,7 +107,10 @@ def add_parser(subparsers, parent_parser):
         help="Collect garbage in remote repository.",
     )
     gc_parser.add_argument(
-        "-r", "--remote", help="Remote storage to collect garbage in."
+        "-r",
+        "--remote",
+        help="Remote storage to collect garbage in",
+        metavar="<name>",
     )
     gc_parser.add_argument(
         "-f",
@@ -119,7 +120,11 @@ def add_parser(subparsers, parent_parser):
         help="Force garbage collection - automatically agree to all prompts.",
     )
     gc_parser.add_argument(
-        "-j", "--jobs", type=int, help="Number of jobs to run simultaneously."
+        "-j",
+        "--jobs",
+        type=int,
+        help="Number of jobs to run simultaneously.",
+        metavar="<number>",
     )
     gc_parser.add_argument(
         "-p",
@@ -130,5 +135,6 @@ def add_parser(subparsers, parent_parser):
         help="Keep data files required by these projects "
         "in addition to the current one. "
         "Useful if you share a single cache across repos.",
+        metavar="<paths>",
     )
     gc_parser.set_defaults(func=CmdGC)

dvc/command/get.py

@@ -1,10 +1,10 @@
 import argparse
 import logging
 
-from .base import append_doc_link
-from .base import CmdBaseNoRepo
 from dvc.exceptions import DvcException
 
+from . import completion
+from .base import CmdBaseNoRepo, append_doc_link
 
 logger = logging.getLogger(__name__)
 
@@ -63,13 +63,20 @@ def add_parser(subparsers, parent_parser):
         "url", help="Location of DVC or Git repository to download from"
     )
     get_parser.add_argument(
-        "path", help="Path to a file or directory within the repository"
-    )
+        "path", help="Path to a file or directory within the repository",
+    ).complete = completion.FILE
     get_parser.add_argument(
-        "-o", "--out", nargs="?", help="Destination path to download files to"
-    )
+        "-o",
+        "--out",
+        nargs="?",
+        help="Destination path to download files to",
+        metavar="<path>",
+    ).complete = completion.DIR
     get_parser.add_argument(
-        "--rev", nargs="?", help="Git revision (e.g. SHA, branch, tag)"
+        "--rev",
+        nargs="?",
+        help="Git revision (e.g. SHA, branch, tag)",
+        metavar="<commit>",
     )
     get_parser.add_argument(
         "--show-url",

dvc/command/get_url.py

@@ -1,10 +1,10 @@
 import argparse
 import logging
 
-from .base import append_doc_link
-from .base import CmdBaseNoRepo
 from dvc.exceptions import DvcException
 
+from . import completion
+from .base import CmdBaseNoRepo, append_doc_link
 
 logger = logging.getLogger(__name__)
 
@@ -17,7 +17,7 @@ class CmdGetUrl(CmdBaseNoRepo):
             Repo.get_url(self.args.url, out=self.args.out)
             return 0
         except DvcException:
-            logger.exception("failed to get '{}'".format(self.args.url))
+            logger.exception(f"failed to get '{self.args.url}'")
             return 1
 
 
@@ -34,6 +34,6 @@ def add_parser(subparsers, parent_parser):
         "url", help="See `dvc import-url -h` for full list of supported URLs."
     )
     get_parser.add_argument(
-        "out", nargs="?", help="Destination path to put data to."
-    )
+        "out", nargs="?", help="Destination path to put data to.",
+    ).complete = completion.DIR
     get_parser.set_defaults(func=CmdGetUrl)

dvc/command/git_hook.py

@@ -19,6 +19,9 @@ class CmdHookBase(CmdBaseNoRepo):
 
         return self._run()
 
+    def _run(self):
+        raise NotImplementedError
+
 
 class CmdPreCommit(CmdHookBase):
     def _run(self):
@@ -28,7 +31,7 @@ class CmdPreCommit(CmdHookBase):
 
 
 class CmdPostCheckout(CmdHookBase):
-    def run(self):
+    def _run(self):
         # when we are running from pre-commit tool, it doesn't provide CLI
         # flags, but instead provides respective env vars that we could use.
         flag = os.environ.get("PRE_COMMIT_CHECKOUT_TYPE")
@@ -52,7 +55,7 @@ class CmdPostCheckout(CmdHookBase):
 
 
 class CmdPrePush(CmdHookBase):
-    def run(self):
+    def _run(self):
         from dvc.main import main
 
         return main(["push"])

dvc/command/imp.py

@@ -1,11 +1,10 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link
 from dvc.exceptions import DvcException
 
-
 logger = logging.getLogger(__name__)
 
 
@@ -45,12 +44,19 @@ def add_parser(subparsers, parent_parser):
         "url", help="Location of DVC or Git repository to download from"
     )
     import_parser.add_argument(
-        "path", help="Path to a file or directory within the repository"
-    )
+        "path", help="Path to a file or directory within the repository",
+    ).complete = completion.FILE
     import_parser.add_argument(
-        "-o", "--out", nargs="?", help="Destination path to download files to"
-    )
+        "-o",
+        "--out",
+        nargs="?",
+        help="Destination path to download files to",
+        metavar="<path>",
+    ).complete = completion.DIR
     import_parser.add_argument(
-        "--rev", nargs="?", help="Git revision (e.g. SHA, branch, tag)"
+        "--rev",
+        nargs="?",
+        help="Git revision (e.g. SHA, branch, tag)",
+        metavar="<commit>",
     )
     import_parser.set_defaults(func=CmdImport)

dvc/command/imp_url.py

@@ -1,11 +1,10 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link
 from dvc.exceptions import DvcException
 
-
 logger = logging.getLogger(__name__)
 
 
@@ -13,7 +12,10 @@ class CmdImportUrl(CmdBase):
     def run(self):
         try:
             self.repo.imp_url(
-                self.args.url, out=self.args.out, fname=self.args.file
+                self.args.url,
+                out=self.args.out,
+                fname=self.args.file,
+                no_exec=self.args.no_exec,
             )
         except DvcException:
             logger.exception(
@@ -56,9 +58,17 @@ def add_parser(subparsers, parent_parser):
         "remote://myremote/path/to/file (see `dvc remote`)",
     )
     import_parser.add_argument(
-        "out", nargs="?", help="Destination path to put files to."
-    )
+        "out", nargs="?", help="Destination path to put files to.",
+    ).complete = completion.DIR
     import_parser.add_argument(
-        "-f", "--file", help="Specify name of the DVC-file it generates."
+        "--file",
+        help="Specify name of the DVC-file this command will generate.",
+        metavar="<filename>",
+    ).complete = completion.DIR
+    import_parser.add_argument(
+        "--no-exec",
+        action="store_true",
+        default=False,
+        help="Only create DVC-file without actually downloading it.",
     )
     import_parser.set_defaults(func=CmdImportUrl)

dvc/command/init.py

@@ -1,9 +1,7 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBaseNoRepo
-
+from dvc.command.base import CmdBaseNoRepo, append_doc_link
 
 logger = logging.getLogger(__name__)
 
@@ -47,7 +45,7 @@ def add_parser(subparsers, parent_parser):
         action="store_true",
         default=False,
         help="Initiate DVC in directory that is "
-        "not tracked by any scm tool (e.g. git).",
+        "not tracked by any SCM tool (e.g. Git).",
     )
     init_parser.add_argument(
         "-f",

dvc/command/install.py

@@ -1,9 +1,7 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
-
+from dvc.command.base import CmdBase, append_doc_link
 
 logger = logging.getLogger(__name__)
 
@@ -12,7 +10,7 @@ class CmdInstall(CmdBase):
     def run(self):
         try:
             self.repo.install(self.args.use_pre_commit_tool)
-        except Exception:
+        except Exception:  # noqa, pylint:disable=broad-except
             logger.exception("failed to install DVC Git hooks")
             return 1
         return 0

dvc/command/lock.py

@@ -1,61 +0,0 @@
-import argparse
-import logging
-
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
-from dvc.exceptions import DvcException
-
-
-logger = logging.getLogger(__name__)
-
-
-class CmdLockBase(CmdBase):
-    def _run(self, unlock):
-        for target in self.args.targets:
-            try:
-                self.repo.lock_stage(target, unlock=unlock)
-            except DvcException:
-                logger.exception(
-                    "failed to {}lock '{}'".format(
-                        "un" if unlock else "", target
-                    )
-                )
-
-                return 1
-        return 0
-
-
-class CmdLock(CmdLockBase):
-    def run(self):
-        return self._run(False)
-
-
-class CmdUnlock(CmdLockBase):
-    def run(self):
-        return self._run(True)
-
-
-def add_parser(subparsers, parent_parser):
-    LOCK_HELP = "Lock DVC-files."
-    lock_parser = subparsers.add_parser(
-        "lock",
-        parents=[parent_parser],
-        description=append_doc_link(LOCK_HELP, "lock"),
-        help=LOCK_HELP,
-        formatter_class=argparse.RawDescriptionHelpFormatter,
-    )
-    lock_parser.add_argument("targets", nargs="+", help="DVC-files to lock.")
-    lock_parser.set_defaults(func=CmdLock)
-
-    UNLOCK_HELP = "Unlock DVC-files."
-    unlock_parser = subparsers.add_parser(
-        "unlock",
-        parents=[parent_parser],
-        description=append_doc_link(UNLOCK_HELP, "unlock"),
-        help=UNLOCK_HELP,
-        formatter_class=argparse.RawDescriptionHelpFormatter,
-    )
-    unlock_parser.add_argument(
-        "targets", nargs="+", help="DVC-files to unlock."
-    )
-    unlock_parser.set_defaults(func=CmdUnlock)

dvc/command/ls/__init__.py

@@ -2,12 +2,11 @@ import argparse
 import logging
 import sys
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBaseNoRepo
+from dvc.command import completion
+from dvc.command.base import CmdBaseNoRepo, append_doc_link
 from dvc.command.ls.ls_colors import LsColors
 from dvc.exceptions import DvcException
 
-
 logger = logging.getLogger(__name__)
 
 
@@ -33,14 +32,14 @@ class CmdList(CmdBaseNoRepo):
                 self.args.path,
                 rev=self.args.rev,
                 recursive=self.args.recursive,
-                outs_only=self.args.outs_only,
+                dvc_only=self.args.dvc_only,
             )
             if entries:
                 entries = _prettify(entries, sys.stdout.isatty())
                 logger.info("\n".join(entries))
             return 0
         except DvcException:
-            logger.exception("failed to list '{}'".format(self.args.url))
+            logger.exception(f"failed to list '{self.args.url}'")
             return 1
 
 
@@ -64,14 +63,17 @@ def add_parser(subparsers, parent_parser):
         help="Recursively list files.",
     )
     list_parser.add_argument(
-        "--outs-only", action="store_true", help="Show only DVC outputs."
+        "--dvc-only", action="store_true", help="Show only DVC outputs."
     )
     list_parser.add_argument(
-        "--rev", nargs="?", help="Git revision (e.g. branch, tag, SHA)"
+        "--rev",
+        nargs="?",
+        help="Git revision (e.g. SHA, branch, tag)",
+        metavar="<commit>",
     )
     list_parser.add_argument(
         "path",
         nargs="?",
         help="Path to directory within the repository to list outputs for",
-    )
+    ).complete = completion.DIR
     list_parser.set_defaults(func=CmdList)

dvc/command/ls/ls_colors.py

@@ -1,7 +1,7 @@
 import os
 
 
-class LsColors(object):
+class LsColors:
     default = "rs=0:di=01;34:ex=01;32"
 
     def __init__(self, lscolors=None):
@@ -45,4 +45,4 @@ class LsColors(object):
         if not val:
             return text
         rs = self._codes.get("rs", 0)
-        return "\033[{}m{}\033[{}m".format(val, text, rs)
+        return f"\033[{val}m{text}\033[{rs}m"

dvc/command/metrics.py

@@ -1,46 +1,38 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
-from dvc.command.base import fix_subparsers
-from dvc.exceptions import BadMetricError
-from dvc.exceptions import DvcException
-
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link, fix_subparsers
+from dvc.exceptions import BadMetricError, DvcException
 
 logger = logging.getLogger(__name__)
 
 
-def show_metrics(metrics, all_branches=False, all_tags=False):
-    """
-    Args:
-        metrics (list): Where each element is either a `list`
-            if an xpath was specified, otherwise a `str`
-    """
+DEFAULT_PRECISION = 5
+
+
+def show_metrics(
+    metrics, all_branches=False, all_tags=False, all_commits=False
+):
+    from flatten_json import flatten
+    from dvc.utils.diff import format_dict
+
     # When `metrics` contains a `None` key, it means that some files
     # specified as `targets` in `repo.metrics.show` didn't contain any metrics.
     missing = metrics.pop(None, None)
 
     for branch, val in metrics.items():
-        if all_branches or all_tags:
-            logger.info("{branch}:".format(branch=branch))
+        if all_branches or all_tags or all_commits:
+            logger.info(f"{branch}:")
 
         for fname, metric in val.items():
-            if isinstance(metric, dict):
-                lines = list(metric.values())
-            elif isinstance(metric, list):
-                lines = metric
-            else:
-                lines = metric.splitlines()
+            if not isinstance(metric, dict):
+                logger.info("\t{}: {}".format(fname, str(metric)))
+                continue
 
-            if len(lines) > 1:
-                logger.info("\t{fname}:".format(fname=fname))
-
-                for line in lines:
-                    logger.info("\t\t{content}".format(content=line))
-
-            else:
-                logger.info("\t{}: {}".format(fname, metric))
+            logger.info(f"\t{fname}:")
+            for key, value in flatten(format_dict(metric), ".").items():
+                logger.info(f"\t\t{key}: {value}")
 
     if missing:
         raise BadMetricError(missing)
@@ -51,14 +43,23 @@ class CmdMetricsShow(CmdBase):
         try:
             metrics = self.repo.metrics.show(
                 self.args.targets,
-                typ=self.args.type,
-                xpath=self.args.xpath,
                 all_branches=self.args.all_branches,
                 all_tags=self.args.all_tags,
+                all_commits=self.args.all_commits,
                 recursive=self.args.recursive,
             )
 
-            show_metrics(metrics, self.args.all_branches, self.args.all_tags)
+            if self.args.show_json:
+                import json
+
+                logger.info(json.dumps(metrics))
+            else:
+                show_metrics(
+                    metrics,
+                    self.args.all_branches,
+                    self.args.all_tags,
+                    self.args.all_commits,
+                )
         except DvcException:
             logger.exception("failed to show metrics")
             return 1
@@ -66,70 +67,41 @@ class CmdMetricsShow(CmdBase):
         return 0
 
 
-class CmdMetricsModify(CmdBase):
-    def run(self):
-        try:
-            self.repo.metrics.modify(
-                self.args.path, typ=self.args.type, xpath=self.args.xpath
-            )
-        except DvcException:
-            logger.exception("failed to modify metric file settings")
-            return 1
+def _show_diff(diff, markdown=False, no_path=False, old=False, precision=None):
+    from collections import OrderedDict
 
-        return 0
+    from dvc.utils.diff import table
 
+    if precision is None:
+        precision = DEFAULT_PRECISION
 
-class CmdMetricsAdd(CmdBase):
-    def run(self):
-        try:
-            self.repo.metrics.add(
-                self.args.path, self.args.type, self.args.xpath
-            )
-        except DvcException:
-            msg = "failed to add metric file '{}'".format(self.args.path)
-            logger.exception(msg)
-            return 1
+    def _round(val):
+        if isinstance(val, float):
+            return round(val, precision)
 
-        return 0
+        return val
 
-
-class CmdMetricsRemove(CmdBase):
-    def run(self):
-        try:
-            self.repo.metrics.remove(self.args.path)
-        except DvcException:
-            msg = "failed to remove metric file '{}'".format(self.args.path)
-            logger.exception(msg)
-            return 1
-
-        return 0
-
-
-def _show_diff(diff):
-    from texttable import Texttable
-
-    if not diff:
-        return "No changes."
-
-    table = Texttable()
-
-    # remove borders to make it easier for users to copy stuff
-    table.set_chars(("", "", "", ""))
-    table.set_deco(0)
-
-    rows = [["Path", "Metric", "Value", "Change"]]
+    rows = []
     for fname, mdiff in diff.items():
-        for metric, change in mdiff.items():
-            rows.append(
-                [
-                    fname,
-                    metric,
-                    change["new"],
-                    change.get("diff", "diff not supported"),
-                ]
-            )
-    table.add_rows(rows)
-    return table.draw()
+        sorted_mdiff = OrderedDict(sorted(mdiff.items()))
+        for metric, change in sorted_mdiff.items():
+            row = [] if no_path else [fname]
+            row.append(metric)
+            if old:
+                row.append(_round(change.get("old")))
+            row.append(_round(change["new"]))
+            row.append(_round(change.get("diff", "diff not supported")))
+            rows.append(row)
+
+    header = [] if no_path else ["Path"]
+    header.append("Metric")
+    if old:
+        header.extend(["Old", "New"])
+    else:
+        header.append("Value")
+    header.append("Change")
+
+    return table(header, rows, markdown)
 
 
 class CmdMetricsDiff(CmdBase):
@@ -139,9 +111,8 @@ class CmdMetricsDiff(CmdBase):
                 a_rev=self.args.a_rev,
                 b_rev=self.args.b_rev,
                 targets=self.args.targets,
-                typ=self.args.type,
-                xpath=self.args.xpath,
                 recursive=self.args.recursive,
+                all=self.args.all,
             )
 
             if self.args.show_json:
@@ -149,7 +120,15 @@ class CmdMetricsDiff(CmdBase):
 
                 logger.info(json.dumps(diff))
             else:
-                logger.info(_show_diff(diff))
+                table = _show_diff(
+                    diff,
+                    self.args.show_md,
+                    self.args.no_path,
+                    self.args.old,
+                    precision=self.args.precision,
+                )
+                if table:
+                    logger.info(table)
 
         except DvcException:
             logger.exception("failed to show metrics diff")
@@ -159,7 +138,7 @@ class CmdMetricsDiff(CmdBase):
 
 
 def add_parser(subparsers, parent_parser):
-    METRICS_HELP = "Commands to add, manage, collect and display metrics."
+    METRICS_HELP = "Commands to display and compare metrics."
 
     metrics_parser = subparsers.add_parser(
         "metrics",
@@ -176,7 +155,7 @@ def add_parser(subparsers, parent_parser):
 
     fix_subparsers(metrics_subparsers)
 
-    METRICS_SHOW_HELP = "Output metric values."
+    METRICS_SHOW_HELP = "Print metrics, with optional formatting."
     metrics_show_parser = metrics_subparsers.add_parser(
         "show",
         parents=[parent_parser],
@@ -187,20 +166,11 @@ def add_parser(subparsers, parent_parser):
     metrics_show_parser.add_argument(
         "targets",
         nargs="*",
-        help="Metric files or directories (see -R) to show",
-    )
-    metrics_show_parser.add_argument(
-        "-t",
-        "--type",
         help=(
-            "Type of metrics (json/tsv/htsv/csv/hcsv). "
-            "It can be detected by the file extension automatically. "
-            "Unsupported types will be treated as raw."
+            "Limit command scope to these metric files. Using -R, "
+            "directories to search metric files in can also be given."
         ),
-    )
-    metrics_show_parser.add_argument(
-        "-x", "--xpath", help="json/tsv/htsv/csv/hcsv path."
-    )
+    ).complete = completion.FILE
     metrics_show_parser.add_argument(
         "-a",
         "--all-branches",
@@ -215,6 +185,18 @@ def add_parser(subparsers, parent_parser):
         default=False,
         help="Show metrics for all tags.",
     )
+    metrics_show_parser.add_argument(
+        "--all-commits",
+        action="store_true",
+        default=False,
+        help="Show metrics for all commits.",
+    )
+    metrics_show_parser.add_argument(
+        "--show-json",
+        action="store_true",
+        default=False,
+        help="Show output in JSON format.",
+    )
     metrics_show_parser.add_argument(
         "-R",
         "--recursive",
@@ -227,53 +209,10 @@ def add_parser(subparsers, parent_parser):
     )
     metrics_show_parser.set_defaults(func=CmdMetricsShow)
 
-    METRICS_ADD_HELP = "Tag file as a metric file."
-    metrics_add_parser = metrics_subparsers.add_parser(
-        "add",
-        parents=[parent_parser],
-        description=append_doc_link(METRICS_ADD_HELP, "metrics/add"),
-        help=METRICS_ADD_HELP,
-        formatter_class=argparse.RawDescriptionHelpFormatter,
+    METRICS_DIFF_HELP = (
+        "Show changes in metrics between commits in the DVC repository, or "
+        "between a commit and the workspace."
     )
-    metrics_add_parser.add_argument(
-        "-t", "--type", help="Type of metrics (raw/json/tsv/htsv/csv/hcsv)."
-    )
-    metrics_add_parser.add_argument(
-        "-x", "--xpath", help="json/tsv/htsv/csv/hcsv path."
-    )
-    metrics_add_parser.add_argument("path", help="Path to a metric file.")
-    metrics_add_parser.set_defaults(func=CmdMetricsAdd)
-
-    METRICS_MODIFY_HELP = "Modify metric file options."
-    metrics_modify_parser = metrics_subparsers.add_parser(
-        "modify",
-        parents=[parent_parser],
-        description=append_doc_link(METRICS_MODIFY_HELP, "metrics/modify"),
-        help=METRICS_MODIFY_HELP,
-        formatter_class=argparse.RawDescriptionHelpFormatter,
-    )
-    metrics_modify_parser.add_argument(
-        "-t", "--type", help="Type of metrics (raw/json/tsv/htsv/csv/hcsv)."
-    )
-    metrics_modify_parser.add_argument(
-        "-x", "--xpath", help="json/tsv/htsv/csv/hcsv path."
-    )
-    metrics_modify_parser.add_argument("path", help="Path to a metric file.")
-    metrics_modify_parser.set_defaults(func=CmdMetricsModify)
-
-    METRICS_REMOVE_HELP = "Remove files's metric tag."
-    metrics_remove_parser = metrics_subparsers.add_parser(
-        "remove",
-        parents=[parent_parser],
-        description=append_doc_link(METRICS_REMOVE_HELP, "metrics/remove"),
-        help=METRICS_REMOVE_HELP,
-        formatter_class=argparse.RawDescriptionHelpFormatter,
-    )
-    metrics_remove_parser.add_argument("path", help="Path to a metric file.")
-    metrics_remove_parser.set_defaults(func=CmdMetricsRemove)
-
-    METRICS_DIFF_HELP = "Show changes in metrics between commits"
-    " in the DVC repository, or between a commit and the workspace."
     metrics_diff_parser = metrics_subparsers.add_parser(
         "diff",
         parents=[parent_parser],
@@ -287,28 +226,17 @@ def add_parser(subparsers, parent_parser):
     metrics_diff_parser.add_argument(
         "b_rev",
         nargs="?",
-        help=("New Git commit to compare (defaults to the current workspace)"),
+        help="New Git commit to compare (defaults to the current workspace)",
     )
     metrics_diff_parser.add_argument(
         "--targets",
         nargs="*",
         help=(
-            "Metric files or directories (see -R) to show diff for. "
-            "Shows diff for all metric files by default."
+            "Limit command scope to these metric files. Using -R, "
+            "directories to search metric files in can also be given."
         ),
-    )
-    metrics_diff_parser.add_argument(
-        "-t",
-        "--type",
-        help=(
-            "Type of metrics (json/tsv/htsv/csv/hcsv). "
-            "It can be detected by the file extension automatically. "
-            "Unsupported types will be treated as raw."
-        ),
-    )
-    metrics_diff_parser.add_argument(
-        "-x", "--xpath", help="json/tsv/htsv/csv/hcsv path."
-    )
+        metavar="<paths>",
+    ).complete = completion.FILE
     metrics_diff_parser.add_argument(
         "-R",
         "--recursive",
@@ -319,10 +247,43 @@ def add_parser(subparsers, parent_parser):
             "metric files."
         ),
     )
+    metrics_diff_parser.add_argument(
+        "--all",
+        action="store_true",
+        default=False,
+        help="Show unchanged metrics as well.",
+    )
     metrics_diff_parser.add_argument(
         "--show-json",
         action="store_true",
         default=False,
         help="Show output in JSON format.",
     )
+    metrics_diff_parser.add_argument(
+        "--show-md",
+        action="store_true",
+        default=False,
+        help="Show tabulated output in the Markdown format (GFM).",
+    )
+    metrics_diff_parser.add_argument(
+        "--old",
+        action="store_true",
+        default=False,
+        help="Show old metric value.",
+    )
+    metrics_diff_parser.add_argument(
+        "--no-path",
+        action="store_true",
+        default=False,
+        help="Don't show metric path.",
+    )
+    metrics_diff_parser.add_argument(
+        "--precision",
+        type=int,
+        help=(
+            "Round metrics to `n` digits precision after the decimal point. "
+            f"Rounds to {DEFAULT_PRECISION} digits by default."
+        ),
+        metavar="<n>",
+    )
     metrics_diff_parser.set_defaults(func=CmdMetricsDiff)

dvc/command/move.py

@@ -1,11 +1,10 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link
 from dvc.exceptions import DvcException
 
-
 logger = logging.getLogger(__name__)
 
 
@@ -38,7 +37,9 @@ def add_parser(subparsers, parent_parser):
         formatter_class=argparse.RawDescriptionHelpFormatter,
     )
     move_parser.add_argument(
-        "src", help="Source path to a data file or directory."
-    )
-    move_parser.add_argument("dst", help="Destination path.")
+        "src", help="Source path to a data file or directory.",
+    ).complete = completion.FILE
+    move_parser.add_argument(
+        "dst", help="Destination path.",
+    ).complete = completion.FILE
     move_parser.set_defaults(func=CmdMove)

dvc/command/params.py

@@ -0,0 +1,118 @@
+import argparse
+import logging
+from collections import OrderedDict
+
+from dvc.command.base import CmdBase, append_doc_link, fix_subparsers
+from dvc.exceptions import DvcException
+
+logger = logging.getLogger(__name__)
+
+
+def _show_diff(diff, markdown=False, no_path=False):
+    from dvc.utils.diff import table
+
+    rows = []
+    for fname, pdiff in diff.items():
+        sorted_pdiff = OrderedDict(sorted(pdiff.items()))
+        for param, change in sorted_pdiff.items():
+            row = [] if no_path else [fname]
+            row.append(param)
+            row.append(change["old"])
+            row.append(change["new"])
+            rows.append(row)
+
+    header = [] if no_path else ["Path"]
+    header.append("Param")
+    header.append("Old")
+    header.append("New")
+
+    return table(header, rows, markdown)
+
+
+class CmdParamsDiff(CmdBase):
+    def run(self):
+        try:
+            diff = self.repo.params.diff(
+                a_rev=self.args.a_rev,
+                b_rev=self.args.b_rev,
+                all=self.args.all,
+            )
+
+            if self.args.show_json:
+                import json
+
+                logger.info(json.dumps(diff))
+            else:
+                table = _show_diff(diff, self.args.show_md, self.args.no_path)
+                if table:
+                    logger.info(table)
+
+        except DvcException:
+            logger.exception("failed to show params diff")
+            return 1
+
+        return 0
+
+
+def add_parser(subparsers, parent_parser):
+    PARAMS_HELP = "Commands to display params."
+
+    params_parser = subparsers.add_parser(
+        "params",
+        parents=[parent_parser],
+        description=append_doc_link(PARAMS_HELP, "params"),
+        help=PARAMS_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+
+    params_subparsers = params_parser.add_subparsers(
+        dest="cmd",
+        help="Use `dvc params CMD --help` to display command-specific help.",
+    )
+
+    fix_subparsers(params_subparsers)
+
+    PARAMS_DIFF_HELP = (
+        "Show changes in params between commits in the DVC repository, or "
+        "between a commit and the workspace."
+    )
+    params_diff_parser = params_subparsers.add_parser(
+        "diff",
+        parents=[parent_parser],
+        description=append_doc_link(PARAMS_DIFF_HELP, "params/diff"),
+        help=PARAMS_DIFF_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    params_diff_parser.add_argument(
+        "a_rev", nargs="?", help="Old Git commit to compare (defaults to HEAD)"
+    )
+    params_diff_parser.add_argument(
+        "b_rev",
+        nargs="?",
+        help=("New Git commit to compare (defaults to the current workspace)"),
+    )
+    params_diff_parser.add_argument(
+        "--all",
+        action="store_true",
+        default=False,
+        help="Show unchanged params as well.",
+    )
+    params_diff_parser.add_argument(
+        "--show-json",
+        action="store_true",
+        default=False,
+        help="Show output in JSON format.",
+    )
+    params_diff_parser.add_argument(
+        "--show-md",
+        action="store_true",
+        default=False,
+        help="Show tabulated output in the Markdown format (GFM).",
+    )
+    params_diff_parser.add_argument(
+        "--no-path",
+        action="store_true",
+        default=False,
+        help="Don't show params path.",
+    )
+    params_diff_parser.set_defaults(func=CmdParamsDiff)

dvc/command/pipeline.py

@@ -1,242 +0,0 @@
-import argparse
-import logging
-
-from dvc.command.base import CmdBase, append_doc_link, fix_subparsers
-from dvc.exceptions import DvcException
-
-
-logger = logging.getLogger(__name__)
-
-
-class CmdPipelineShow(CmdBase):
-    def _show(self, target, commands, outs, locked):
-        import networkx
-        from dvc.stage import Stage
-
-        stage = Stage.load(self.repo, target)
-        G = self.repo.graph
-        stages = networkx.dfs_postorder_nodes(G, stage)
-
-        if locked:
-            stages = [s for s in stages if s.locked]
-
-        for stage in stages:
-            if commands:
-                if stage.cmd is None:
-                    continue
-                logger.info(stage.cmd)
-            elif outs:
-                for out in stage.outs:
-                    logger.info(str(out))
-            else:
-                logger.info(stage.path_in_repo)
-
-    def _build_graph(self, target, commands, outs):
-        import networkx
-        from dvc.stage import Stage
-        from dvc.repo.graph import get_pipeline
-
-        target_stage = Stage.load(self.repo, target)
-        G = get_pipeline(self.repo.pipelines, target_stage)
-
-        nodes = set()
-        for stage in networkx.dfs_preorder_nodes(G, target_stage):
-            if commands:
-                if stage.cmd is None:
-                    continue
-                nodes.add(stage.cmd)
-            elif outs:
-                for out in stage.outs:
-                    nodes.add(str(out))
-            else:
-                nodes.add(stage.relpath)
-
-        edges = []
-        for from_stage, to_stage in networkx.edge_dfs(G, target_stage):
-            if commands:
-                if to_stage.cmd is None:
-                    continue
-                edges.append((from_stage.cmd, to_stage.cmd))
-            elif outs:
-                for from_out in from_stage.outs:
-                    for to_out in to_stage.outs:
-                        edges.append((str(from_out), str(to_out)))
-            else:
-                edges.append((from_stage.relpath, to_stage.relpath))
-
-        return list(nodes), edges, networkx.is_tree(G)
-
-    def _show_ascii(self, target, commands, outs):
-        from dvc.dagascii import draw
-
-        nodes, edges, _ = self._build_graph(target, commands, outs)
-
-        if not nodes:
-            return
-
-        draw(nodes, edges)
-
-    def _show_dependencies_tree(self, target, commands, outs):
-        from treelib import Tree
-
-        nodes, edges, is_tree = self._build_graph(target, commands, outs)
-        if not nodes:
-            return
-        if not is_tree:
-            raise DvcException(
-                "DAG is not a tree, can not print it in tree-structure way, "
-                "please use --ascii instead"
-            )
-
-        tree = Tree()
-        tree.create_node(target, target)  # Root node
-        observe_list = [target]
-        while len(observe_list) > 0:
-            current_root = observe_list[0]
-            for edge in edges:
-                if edge[0] == current_root:
-                    tree.create_node(edge[1], edge[1], parent=current_root)
-                    observe_list.append(edge[1])
-            observe_list.pop(0)
-        tree.show()
-
-    def _write_dot(self, target, commands, outs):
-        import io
-        import networkx
-        from networkx.drawing.nx_pydot import write_dot
-
-        _, edges, _ = self._build_graph(target, commands, outs)
-        edges = [edge[::-1] for edge in edges]
-
-        simple_g = networkx.DiGraph()
-        simple_g.add_edges_from(edges)
-
-        dot_file = io.StringIO()
-        write_dot(simple_g, dot_file)
-        logger.info(dot_file.getvalue())
-
-    def run(self):
-        if not self.args.targets:
-            self.args.targets = self.default_targets
-
-        for target in self.args.targets:
-            try:
-                if self.args.ascii:
-                    self._show_ascii(
-                        target, self.args.commands, self.args.outs
-                    )
-                elif self.args.dot:
-                    self._write_dot(target, self.args.commands, self.args.outs)
-                elif self.args.tree:
-                    self._show_dependencies_tree(
-                        target, self.args.commands, self.args.outs
-                    )
-                else:
-                    self._show(
-                        target,
-                        self.args.commands,
-                        self.args.outs,
-                        self.args.locked,
-                    )
-            except DvcException:
-                msg = "failed to show pipeline for '{}'".format(target)
-                logger.exception(msg)
-                return 1
-        return 0
-
-
-class CmdPipelineList(CmdBase):
-    def run(self):
-        pipelines = self.repo.pipelines
-        for pipeline in pipelines:
-            for stage in pipeline:
-                logger.info(stage.relpath)
-            if len(pipeline) != 0:
-                logger.info("=" * 80)
-        logger.info("{} pipelines total".format(len(pipelines)))
-
-        return 0
-
-
-def add_parser(subparsers, parent_parser):
-    PIPELINE_HELP = "Manage pipelines."
-    pipeline_parser = subparsers.add_parser(
-        "pipeline",
-        parents=[parent_parser],
-        description=append_doc_link(PIPELINE_HELP, "pipeline"),
-        help=PIPELINE_HELP,
-        formatter_class=argparse.RawDescriptionHelpFormatter,
-    )
-
-    pipeline_subparsers = pipeline_parser.add_subparsers(
-        dest="cmd",
-        help="Use `dvc pipeline CMD --help` for command-specific help.",
-    )
-
-    fix_subparsers(pipeline_subparsers)
-
-    PIPELINE_SHOW_HELP = "Show pipelines."
-    pipeline_show_parser = pipeline_subparsers.add_parser(
-        "show",
-        parents=[parent_parser],
-        description=append_doc_link(PIPELINE_SHOW_HELP, "pipeline/show"),
-        help=PIPELINE_SHOW_HELP,
-        formatter_class=argparse.RawDescriptionHelpFormatter,
-    )
-    pipeline_show_group = pipeline_show_parser.add_mutually_exclusive_group()
-    pipeline_show_group.add_argument(
-        "-c",
-        "--commands",
-        action="store_true",
-        default=False,
-        help="Print commands instead of paths to DVC-files.",
-    )
-    pipeline_show_group.add_argument(
-        "-o",
-        "--outs",
-        action="store_true",
-        default=False,
-        help="Print output files instead of paths to DVC-files.",
-    )
-    pipeline_show_parser.add_argument(
-        "-l",
-        "--locked",
-        action="store_true",
-        default=False,
-        help="Print locked DVC stages",
-    )
-    pipeline_show_parser.add_argument(
-        "--ascii",
-        action="store_true",
-        default=False,
-        help="Output DAG as ASCII.",
-    )
-    pipeline_show_parser.add_argument(
-        "--dot",
-        action="store_true",
-        default=False,
-        help="Print DAG with .dot format.",
-    )
-    pipeline_show_parser.add_argument(
-        "--tree",
-        action="store_true",
-        default=False,
-        help="Output DAG as Dependencies Tree.",
-    )
-    pipeline_show_parser.add_argument(
-        "targets",
-        nargs="*",
-        help="DVC-files to show pipeline for. Optional. "
-        "(Finds all DVC-files in the workspace by default.)",
-    )
-    pipeline_show_parser.set_defaults(func=CmdPipelineShow)
-
-    PIPELINE_LIST_HELP = "List pipelines."
-    pipeline_list_parser = pipeline_subparsers.add_parser(
-        "list",
-        parents=[parent_parser],
-        description=append_doc_link(PIPELINE_LIST_HELP, "pipeline/list"),
-        help=PIPELINE_LIST_HELP,
-        formatter_class=argparse.RawDescriptionHelpFormatter,
-    )
-    pipeline_list_parser.set_defaults(func=CmdPipelineList)

dvc/command/plots.py

@@ -0,0 +1,233 @@
+import argparse
+import logging
+import os
+
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link, fix_subparsers
+from dvc.exceptions import DvcException
+from dvc.schema import PLOT_PROPS
+from dvc.utils import format_link
+
+logger = logging.getLogger(__name__)
+
+PAGE_HTML = """<!DOCTYPE html>
+<html>
+<head>
+    <title>DVC Plot</title>
+    <script src="https://cdn.jsdelivr.net/npm/[email protected]"></script>
+    <script src="https://cdn.jsdelivr.net/npm/[email protected]"></script>
+    <script src="https://cdn.jsdelivr.net/npm/[email protected]"></script>
+</head>
+<body>
+    {divs}
+</body>
+</html>"""
+
+DIV_HTML = """<div id = "{id}"></div>
+<script type = "text/javascript">
+    var spec = {vega_json};
+    vegaEmbed('#{id}', spec);
+</script>"""
+
+
+class CmdPlots(CmdBase):
+    def _func(self, *args, **kwargs):
+        raise NotImplementedError
+
+    def _props(self):
+        # Pass only props specified by user, to not shadow ones from plot def
+        props = {p: getattr(self.args, p) for p in PLOT_PROPS}
+        return {k: v for k, v in props.items() if v is not None}
+
+    def run(self):
+        if self.args.show_vega:
+            if not self.args.targets:
+                logger.error("please specify a target for `--show-vega`")
+                return 1
+            if len(self.args.targets) > 1:
+                logger.error(
+                    "you can only specify one target for `--show-vega`"
+                )
+                return 1
+
+        try:
+            plots = self._func(targets=self.args.targets, props=self._props())
+
+            if self.args.show_vega:
+                target = self.args.targets[0]
+                logger.info(plots[target])
+                return 0
+
+            divs = [
+                DIV_HTML.format(id=f"plot{i}", vega_json=plot)
+                for i, plot in enumerate(plots.values())
+            ]
+            html = PAGE_HTML.format(divs="\n".join(divs))
+            path = self.args.out or "plots.html"
+
+            with open(path, "w") as fobj:
+                fobj.write(html)
+
+            logger.info(
+                "file://{}".format(os.path.join(self.repo.root_dir, path))
+            )
+
+        except DvcException:
+            logger.exception("")
+            return 1
+
+        return 0
+
+
+class CmdPlotsShow(CmdPlots):
+    def _func(self, *args, **kwargs):
+        return self.repo.plots.show(*args, **kwargs)
+
+
+class CmdPlotsDiff(CmdPlots):
+    def _func(self, *args, **kwargs):
+        return self.repo.plots.diff(*args, revs=self.args.revisions, **kwargs)
+
+
+class CmdPlotsModify(CmdPlots):
+    def run(self):
+        self.repo.plots.modify(
+            self.args.target, props=self._props(), unset=self.args.unset,
+        )
+        return 0
+
+
+def add_parser(subparsers, parent_parser):
+    PLOTS_HELP = (
+        "Commands to visualize and compare plot metrics in structured files "
+        "(JSON, YAML, CSV, TSV)"
+    )
+
+    plots_parser = subparsers.add_parser(
+        "plots",
+        parents=[parent_parser],
+        description=append_doc_link(PLOTS_HELP, "plots"),
+        help=PLOTS_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    plots_subparsers = plots_parser.add_subparsers(
+        dest="cmd",
+        help="Use `dvc plots CMD --help` to display command-specific help.",
+    )
+
+    fix_subparsers(plots_subparsers)
+
+    SHOW_HELP = "Generate plots from metric files."
+    plots_show_parser = plots_subparsers.add_parser(
+        "show",
+        parents=[parent_parser],
+        description=append_doc_link(SHOW_HELP, "plots/show"),
+        help=SHOW_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    plots_show_parser.add_argument(
+        "targets",
+        nargs="*",
+        help="Plots files to visualize. Shows all plots by default.",
+    ).complete = completion.FILE
+    _add_props_arguments(plots_show_parser)
+    _add_output_arguments(plots_show_parser)
+    plots_show_parser.set_defaults(func=CmdPlotsShow)
+
+    PLOTS_DIFF_HELP = (
+        "Show multiple versions of plot metrics "
+        "by plotting them in a single image."
+    )
+    plots_diff_parser = plots_subparsers.add_parser(
+        "diff",
+        parents=[parent_parser],
+        description=append_doc_link(PLOTS_DIFF_HELP, "plots/diff"),
+        help=PLOTS_DIFF_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    plots_diff_parser.add_argument(
+        "--targets",
+        nargs="*",
+        help="Plots file to visualize. Shows all plots by default.",
+        metavar="<path>",
+    ).complete = completion.FILE
+    plots_diff_parser.add_argument(
+        "revisions", nargs="*", default=None, help="Git commits to plot from",
+    )
+    _add_props_arguments(plots_diff_parser)
+    _add_output_arguments(plots_diff_parser)
+    plots_diff_parser.set_defaults(func=CmdPlotsDiff)
+
+    PLOTS_MODIFY_HELP = "Modify display properties of plot metric files."
+    plots_modify_parser = plots_subparsers.add_parser(
+        "modify",
+        parents=[parent_parser],
+        description=append_doc_link(PLOTS_MODIFY_HELP, "plots/modify"),
+        help=PLOTS_MODIFY_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    plots_modify_parser.add_argument(
+        "target", help="Metric file to set properties to",
+    ).complete = completion.FILE
+    _add_props_arguments(plots_modify_parser)
+    plots_modify_parser.add_argument(
+        "--unset",
+        nargs="*",
+        metavar="<property>",
+        help="Unset one or more display properties.",
+    )
+    plots_modify_parser.set_defaults(func=CmdPlotsModify)
+
+
+def _add_props_arguments(parser):
+    parser.add_argument(
+        "-t",
+        "--template",
+        nargs="?",
+        default=None,
+        help=(
+            "Special JSON or HTML schema file to inject with the data. "
+            "See {}".format(
+                format_link("https://man.dvc.org/plots#plot-templates")
+            )
+        ),
+        metavar="<path>",
+    ).complete = completion.FILE
+    parser.add_argument(
+        "-x", default=None, help="Field name for X axis.", metavar="<field>"
+    )
+    parser.add_argument(
+        "-y", default=None, help="Field name for Y axis.", metavar="<field>"
+    )
+    parser.add_argument(
+        "--no-header",
+        action="store_false",
+        dest="header",
+        default=None,  # Use default None to distinguish when it's not used
+        help="Provided CSV or TSV datafile does not have a header.",
+    )
+    parser.add_argument(
+        "--title", default=None, metavar="<text>", help="Plot title."
+    )
+    parser.add_argument(
+        "--x-label", default=None, help="X axis label", metavar="<text>"
+    )
+    parser.add_argument(
+        "--y-label", default=None, help="Y axis label", metavar="<text>"
+    )
+
+
+def _add_output_arguments(parser):
+    parser.add_argument(
+        "-o",
+        "--out",
+        default=None,
+        help="Destination path to save plots to",
+        metavar="<path>",
+    ).complete = completion.DIR
+    parser.add_argument(
+        "--show-vega",
+        action="store_true",
+        default=False,
+        help="Show output in Vega format.",
+    )

dvc/command/remote.py

@@ -1,9 +1,9 @@
 import argparse
 import logging
 
-from dvc.config import ConfigError
 from dvc.command.base import append_doc_link, fix_subparsers
 from dvc.command.config import CmdConfig
+from dvc.config import ConfigError
 from dvc.utils import format_link
 
 logger = logging.getLogger(__name__)
@@ -18,17 +18,13 @@ class CmdRemote(CmdConfig):
 
     def _check_exists(self, conf):
         if self.args.name not in conf["remote"]:
-            raise ConfigError(
-                "remote '{}' doesn't exists.".format(self.args.name)
-            )
+            raise ConfigError(f"remote '{self.args.name}' doesn't exists.")
 
 
 class CmdRemoteAdd(CmdRemote):
     def run(self):
         if self.args.default:
-            logger.info(
-                "Setting '{}' as a default remote.".format(self.args.name)
-            )
+            logger.info(f"Setting '{self.args.name}' as a default remote.")
 
         with self.config.edit(self.args.level) as conf:
             if self.args.name in conf["remote"] and not self.args.force:
@@ -66,7 +62,11 @@ class CmdRemoteModify(CmdRemote):
     def run(self):
         with self.config.edit(self.args.level) as conf:
             self._check_exists(conf)
-            conf["remote"][self.args.name][self.args.option] = self.args.value
+            section = conf["remote"][self.args.name]
+            if self.args.unset:
+                section.pop(self.args.option, None)
+            else:
+                section[self.args.option] = self.args.value
         return 0
 
 
@@ -85,7 +85,18 @@ class CmdRemoteDefault(CmdRemote):
                 if self.args.unset:
                     conf["core"].pop("remote", None)
                 else:
-                    conf["core"]["remote"] = self.args.name
+                    merged_conf = self.config.load_config_to_level(
+                        self.args.level
+                    )
+                    if (
+                        self.args.name in conf["remote"]
+                        or self.args.name in merged_conf["remote"]
+                    ):
+                        conf["core"]["remote"] = self.args.name
+                    else:
+                        raise ConfigError(
+                            "default remote must be present in remote list."
+                        )
         return 0
 
 
@@ -97,10 +108,39 @@ class CmdRemoteList(CmdRemote):
         return 0
 
 
+class CmdRemoteRename(CmdRemote):
+    def _rename_default(self, conf):
+        if conf["core"].get("remote") == self.args.name:
+            conf["core"]["remote"] = self.args.new
+
+    def run(self):
+        all_config = self.config.load_config_to_level(None)
+        if self.args.new in all_config.get("remote", {}):
+            raise ConfigError(
+                "Rename failed. Remote name '{}' already exists.".format(
+                    {self.args.new}
+                )
+            )
+
+        with self.config.edit(self.args.level) as conf:
+            self._check_exists(conf)
+            conf["remote"][self.args.new] = conf["remote"][self.args.name]
+            del conf["remote"][self.args.name]
+            self._rename_default(conf)
+
+        for level in reversed(self.config.LEVELS):
+            if level == self.args.level:
+                break
+            with self.config.edit(level) as level_conf:
+                self._rename_default(level_conf)
+
+        return 0
+
+
 def add_parser(subparsers, parent_parser):
     from dvc.command.config import parent_config_parser
 
-    REMOTE_HELP = "Manage remote storage configuration."
+    REMOTE_HELP = "Set up and manage data remotes."
     remote_parser = subparsers.add_parser(
         "remote",
         parents=[parent_parser],
@@ -116,7 +156,7 @@ def add_parser(subparsers, parent_parser):
 
     fix_subparsers(remote_subparsers)
 
-    REMOTE_ADD_HELP = "Add remote."
+    REMOTE_ADD_HELP = "Add a new data remote."
     remote_add_parser = remote_subparsers.add_parser(
         "add",
         parents=[parent_config_parser, parent_parser],
@@ -147,7 +187,7 @@ def add_parser(subparsers, parent_parser):
     )
     remote_add_parser.set_defaults(func=CmdRemoteAdd)
 
-    REMOTE_DEFAULT_HELP = "Set/unset default remote."
+    REMOTE_DEFAULT_HELP = "Set/unset the default data remote."
     remote_default_parser = remote_subparsers.add_parser(
         "default",
         parents=[parent_config_parser, parent_parser],
@@ -167,20 +207,7 @@ def add_parser(subparsers, parent_parser):
     )
     remote_default_parser.set_defaults(func=CmdRemoteDefault)
 
-    REMOTE_REMOVE_HELP = "Remove remote."
-    remote_remove_parser = remote_subparsers.add_parser(
-        "remove",
-        parents=[parent_config_parser, parent_parser],
-        description=append_doc_link(REMOTE_REMOVE_HELP, "remote/remove"),
-        help=REMOTE_REMOVE_HELP,
-        formatter_class=argparse.RawDescriptionHelpFormatter,
-    )
-    remote_remove_parser.add_argument(
-        "name", help="Name of the remote to remove."
-    )
-    remote_remove_parser.set_defaults(func=CmdRemoteRemove)
-
-    REMOTE_MODIFY_HELP = "Modify remote."
+    REMOTE_MODIFY_HELP = "Modify the configuration of a data remote."
     remote_modify_parser = remote_subparsers.add_parser(
         "modify",
         parents=[parent_config_parser, parent_parser],
@@ -204,7 +231,7 @@ def add_parser(subparsers, parent_parser):
     )
     remote_modify_parser.set_defaults(func=CmdRemoteModify)
 
-    REMOTE_LIST_HELP = "List available remotes."
+    REMOTE_LIST_HELP = "List all available data remotes."
     remote_list_parser = remote_subparsers.add_parser(
         "list",
         parents=[parent_config_parser, parent_parser],
@@ -213,3 +240,27 @@ def add_parser(subparsers, parent_parser):
         formatter_class=argparse.RawDescriptionHelpFormatter,
     )
     remote_list_parser.set_defaults(func=CmdRemoteList)
+
+    REMOTE_REMOVE_HELP = "Remove a data remote."
+    remote_remove_parser = remote_subparsers.add_parser(
+        "remove",
+        parents=[parent_config_parser, parent_parser],
+        description=append_doc_link(REMOTE_REMOVE_HELP, "remote/remove"),
+        help=REMOTE_REMOVE_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    remote_remove_parser.add_argument(
+        "name", help="Name of the remote to remove."
+    )
+    remote_remove_parser.set_defaults(func=CmdRemoteRemove)
+    REMOTE_RENAME_HELP = "Rename a DVC remote"
+    remote_rename_parser = remote_subparsers.add_parser(
+        "rename",
+        parents=[parent_config_parser, parent_parser],
+        description=append_doc_link(REMOTE_RENAME_HELP, "remote/rename"),
+        help=REMOTE_RENAME_HELP,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    remote_rename_parser.add_argument("name", help="Remote to be renamed")
+    remote_rename_parser.add_argument("new", help="New name of the remote")
+    remote_rename_parser.set_defaults(func=CmdRemoteRename)

dvc/command/remove.py

@@ -1,48 +1,28 @@
 import argparse
 import logging
 
-import dvc.prompt as prompt
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link
 from dvc.exceptions import DvcException
 
-
 logger = logging.getLogger(__name__)
 
 
 class CmdRemove(CmdBase):
-    def _is_outs_only(self, target):
-        if not self.args.purge:
-            return True
-
-        if self.args.force:
-            return False
-
-        msg = "Are you sure you want to remove '{}' with its outputs?".format(
-            target
-        )
-
-        if prompt.confirm(msg):
-            return False
-
-        raise DvcException(
-            "Cannot purge without a confirmation from the user."
-            " Use `-f` to force."
-        )
-
     def run(self):
         for target in self.args.targets:
             try:
-                outs_only = self._is_outs_only(target)
-                self.repo.remove(target, outs_only=outs_only)
+                self.repo.remove(target, outs=self.args.outs)
             except DvcException:
-                logger.exception("failed to remove '{}'".format(target))
+                logger.exception(f"failed to remove '{target}'")
                 return 1
         return 0
 
 
 def add_parser(subparsers, parent_parser):
-    REMOVE_HELP = "Remove DVC-file outputs."
+    REMOVE_HELP = (
+        "Remove stage entry, remove .gitignore entry and unprotect outputs"
+    )
     remove_parser = subparsers.add_parser(
         "remove",
         parents=[parent_parser],
@@ -50,29 +30,13 @@ def add_parser(subparsers, parent_parser):
         help=REMOVE_HELP,
         formatter_class=argparse.RawDescriptionHelpFormatter,
     )
-    remove_parser_group = remove_parser.add_mutually_exclusive_group()
-    remove_parser_group.add_argument(
-        "-o",
+    remove_parser.add_argument(
         "--outs",
         action="store_true",
-        default=True,
-        help="Only remove DVC-file outputs. (Default)",
-    )
-    remove_parser_group.add_argument(
-        "-p",
-        "--purge",
-        action="store_true",
         default=False,
-        help="Remove DVC-file and all its outputs.",
+        help="Remove outputs as well.",
     )
     remove_parser.add_argument(
-        "-f",
-        "--force",
-        action="store_true",
-        default=False,
-        help="Force purge.",
-    )
-    remove_parser.add_argument(
-        "targets", nargs="+", help="DVC-files to remove."
-    )
+        "targets", nargs="+", help="DVC-files to remove.",
+    ).complete = completion.DVC_FILE
     remove_parser.set_defaults(func=CmdRemove)

dvc/command/repro.py

@@ -2,13 +2,13 @@ import argparse
 import logging
 import os
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link
 from dvc.command.metrics import show_metrics
 from dvc.command.status import CmdDataStatus
+from dvc.dvcfile import PIPELINE_FILE
 from dvc.exceptions import DvcException
 
-
 logger = logging.getLogger(__name__)
 
 
@@ -35,10 +35,12 @@ class CmdRepro(CmdBase):
                     interactive=self.args.interactive,
                     pipeline=self.args.pipeline,
                     all_pipelines=self.args.all_pipelines,
-                    ignore_build_cache=self.args.ignore_build_cache,
+                    run_cache=not self.args.no_run_cache,
                     no_commit=self.args.no_commit,
                     downstream=self.args.downstream,
                     recursive=self.args.recursive,
+                    force_downstream=self.args.force_downstream,
+                    experiment=self.args.experiment,
                 )
 
                 if len(stages) == 0:
@@ -57,7 +59,9 @@ class CmdRepro(CmdBase):
 
 
 def add_parser(subparsers, parent_parser):
-    REPRO_HELP = "Check for changes and reproduce stages and dependencies."
+    REPRO_HELP = (
+        "Reproduce complete or partial pipelines by executing their stages."
+    )
     repro_parser = subparsers.add_parser(
         "repro",
         parents=[parent_parser],
@@ -68,8 +72,8 @@ def add_parser(subparsers, parent_parser):
     repro_parser.add_argument(
         "targets",
         nargs="*",
-        help="DVC-file to reproduce. 'Dvcfile' by default.",
-    )
+        help=f"Stages to reproduce. '{PIPELINE_FILE}' by default.",
+    ).complete = completion.DVC_FILE
     repro_parser.add_argument(
         "-f",
         "--force",
@@ -90,6 +94,7 @@ def add_parser(subparsers, parent_parser):
         "--cwd",
         default=os.path.curdir,
         help="Directory within your repo to reproduce from.",
+        metavar="<path>",
     )
     repro_parser.add_argument(
         "-m",
@@ -135,7 +140,16 @@ def add_parser(subparsers, parent_parser):
         help="Reproduce all stages in the specified directory.",
     )
     repro_parser.add_argument(
-        "--ignore-build-cache",
+        "--no-run-cache",
+        action="store_true",
+        default=False,
+        help=(
+            "Execute stage commands even if they have already been run with "
+            "the same command/dependencies/outputs/etc before."
+        ),
+    )
+    repro_parser.add_argument(
+        "--force-downstream",
         action="store_true",
         default=False,
         help="Reproduce all descendants of a changed stage even if their "
@@ -153,4 +167,11 @@ def add_parser(subparsers, parent_parser):
         default=False,
         help="Start from the specified stages when reproducing pipelines.",
     )
+    repro_parser.add_argument(
+        "-e",
+        "--experiment",
+        action="store_true",
+        default=False,
+        help=argparse.SUPPRESS,
+    )
     repro_parser.set_defaults(func=CmdRepro)

dvc/command/root.py

@@ -1,8 +1,7 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBaseNoRepo
+from dvc.command.base import CmdBaseNoRepo, append_doc_link
 from dvc.utils import relpath
 
 logger = logging.getLogger(__name__)
@@ -17,7 +16,7 @@ class CmdRoot(CmdBaseNoRepo):
 
 
 def add_parser(subparsers, parent_parser):
-    ROOT_HELP = "Relative path to the repository's directory."
+    ROOT_HELP = "Return the relative path to the root of the DVC project."
     root_parser = subparsers.add_parser(
         "root",
         parents=[parent_parser],

dvc/command/run.py

@@ -1,18 +1,14 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
+from dvc.command.base import CmdBase, append_doc_link
 from dvc.exceptions import DvcException
 
-
 logger = logging.getLogger(__name__)
 
 
 class CmdRun(CmdBase):
     def run(self):
-        overwrite = self.args.yes or self.args.overwrite_dvcfile
-
         if not any(
             [
                 self.args.deps,
@@ -20,15 +16,18 @@ class CmdRun(CmdBase):
                 self.args.outs_no_cache,
                 self.args.metrics,
                 self.args.metrics_no_cache,
+                self.args.plots,
+                self.args.plots_no_cache,
                 self.args.outs_persist,
                 self.args.outs_persist_no_cache,
+                self.args.params,
                 self.args.command,
             ]
         ):  # pragma: no cover
             logger.error(
                 "too few arguments. Specify at least one: `-d`, `-o`, `-O`, "
-                "`-m`, `-M`, `--outs-persist`, `--outs-persist-no-cache`, "
-                "`command`."
+                "`-m`, `-M`, `-p`, `--plots`, `--plots-no-cache`, "
+                "`--outs-persist`, `--outs-persist-no-cache`, `command`."
             )
             return 1
 
@@ -39,21 +38,25 @@ class CmdRun(CmdBase):
                 outs_no_cache=self.args.outs_no_cache,
                 metrics=self.args.metrics,
                 metrics_no_cache=self.args.metrics_no_cache,
+                plots=self.args.plots,
+                plots_no_cache=self.args.plots_no_cache,
                 deps=self.args.deps,
+                params=self.args.params,
                 fname=self.args.file,
-                cwd=self.args.cwd,
                 wdir=self.args.wdir,
                 no_exec=self.args.no_exec,
-                overwrite=overwrite,
-                ignore_build_cache=self.args.ignore_build_cache,
-                remove_outs=self.args.remove_outs,
+                force=self.args.force,
+                run_cache=not self.args.no_run_cache,
                 no_commit=self.args.no_commit,
                 outs_persist=self.args.outs_persist,
                 outs_persist_no_cache=self.args.outs_persist_no_cache,
                 always_changed=self.args.always_changed,
+                name=self.args.name,
+                single_stage=self.args.single_stage,
+                external=self.args.external,
             )
         except DvcException:
-            logger.exception("failed to run command")
+            logger.exception("")
             return 1
 
         return 0
@@ -77,7 +80,7 @@ class CmdRun(CmdBase):
         if " " not in argument or '"' in argument:
             return argument
 
-        return '"{}"'.format(argument)
+        return f'"{argument}"'
 
 
 def add_parser(subparsers, parent_parser):
@@ -95,6 +98,10 @@ def add_parser(subparsers, parent_parser):
         action="append",
         default=[],
         help="Declare dependencies for reproducible cmd.",
+        metavar="<path>",
+    )
+    run_parser.add_argument(
+        "-n", "--name", help="Stage name.",
     )
     run_parser.add_argument(
         "-o",
@@ -102,6 +109,7 @@ def add_parser(subparsers, parent_parser):
         action="append",
         default=[],
         help="Declare output file or directory.",
+        metavar="<filename>",
     )
     run_parser.add_argument(
         "-O",
@@ -110,32 +118,54 @@ def add_parser(subparsers, parent_parser):
         default=[],
         help="Declare output file or directory "
         "(do not put into DVC cache).",
+        metavar="<filename>",
+    )
+    run_parser.add_argument(
+        "-p",
+        "--params",
+        action="append",
+        default=[],
+        help="Declare parameter to use as additional dependency.",
+        metavar="[<filename>:]<params_list>",
     )
     run_parser.add_argument(
         "-m",
         "--metrics",
         action="append",
         default=[],
-        help="Declare output metric file or directory.",
+        help="Declare output metric file.",
+        metavar="<path>",
     )
     run_parser.add_argument(
         "-M",
         "--metrics-no-cache",
         action="append",
         default=[],
-        help="Declare output metric file or directory "
-        "(do not put into DVC cache).",
+        help="Declare output metric file (do not put into DVC cache).",
+        metavar="<path>",
     )
     run_parser.add_argument(
-        "-f", "--file", help="Specify name of the DVC-file it generates."
+        "--plots",
+        action="append",
+        default=[],
+        help="Declare output plot file.",
+        metavar="<path>",
     )
     run_parser.add_argument(
-        "-c", "--cwd", help="Deprecated, use -w and -f instead."
+        "--plots-no-cache",
+        action="append",
+        default=[],
+        help="Declare output plot file (do not put into DVC cache).",
+        metavar="<path>",
+    )
+    run_parser.add_argument(
+        "--file", metavar="<filename>", help=argparse.SUPPRESS,
     )
     run_parser.add_argument(
         "-w",
         "--wdir",
         help="Directory within your repo to run your command in.",
+        metavar="<path>",
     )
     run_parser.add_argument(
         "--no-exec",
@@ -144,30 +174,20 @@ def add_parser(subparsers, parent_parser):
         help="Only create stage file without actually running it.",
     )
     run_parser.add_argument(
-        "-y",
-        "--yes",
+        "-f",
+        "--force",
         action="store_true",
         default=False,
-        help="Deprecated, use --overwrite-dvcfile instead",
+        help="Overwrite existing stage",
     )
     run_parser.add_argument(
-        "--overwrite-dvcfile",
+        "--no-run-cache",
         action="store_true",
         default=False,
-        help="Overwrite existing DVC-file without asking for confirmation.",
-    )
-    run_parser.add_argument(
-        "--ignore-build-cache",
-        action="store_true",
-        default=False,
-        help="Run this stage even if it has been already ran with the same "
-        "command/dependencies/outputs/etc before.",
-    )
-    run_parser.add_argument(
-        "--remove-outs",
-        action="store_true",
-        default=False,
-        help="Deprecated, this is now the default behavior",
+        help=(
+            "Execute the command even if this stage has already been run "
+            "with the same command/dependencies/outputs/etc before."
+        ),
     )
     run_parser.add_argument(
         "--no-commit",
@@ -181,6 +201,7 @@ def add_parser(subparsers, parent_parser):
         default=[],
         help="Declare output file or directory that will not be "
         "removed upon repro.",
+        metavar="<filename>",
     )
     run_parser.add_argument(
         "--outs-persist-no-cache",
@@ -188,6 +209,7 @@ def add_parser(subparsers, parent_parser):
         default=[],
         help="Declare output file or directory that will not be "
         "removed upon repro (do not put into DVC cache).",
+        metavar="<filename>",
     )
     run_parser.add_argument(
         "--always-changed",
@@ -195,6 +217,18 @@ def add_parser(subparsers, parent_parser):
         default=False,
         help="Always consider this DVC-file as changed.",
     )
+    run_parser.add_argument(
+        "--single-stage",
+        action="store_true",
+        default=False,
+        help=argparse.SUPPRESS,
+    )
+    run_parser.add_argument(
+        "--external",
+        action="store_true",
+        default=False,
+        help="Allow outputs that are outside of the DVC repository.",
+    )
     run_parser.add_argument(
         "command", nargs=argparse.REMAINDER, help="Command to execute."
     )

dvc/command/status.py

@@ -2,7 +2,6 @@ import logging
 
 from dvc.command.data_sync import CmdDataBase
 
-
 logger = logging.getLogger(__name__)
 
 
@@ -20,7 +19,7 @@ class CmdDataStatus(CmdDataBase):
         ind = indent * self.STATUS_INDENT
 
         if isinstance(status, str):
-            logger.info("{}{}".format(ind, status))
+            logger.info(f"{ind}{status}")
             return
 
         if isinstance(status, list):
@@ -34,7 +33,7 @@ class CmdDataStatus(CmdDataBase):
             if isinstance(value, str):
                 logger.info("{}{}{}".format(ind, self._normalize(value), key))
             elif value:
-                logger.info("{}{}:".format(ind, key))
+                logger.info(f"{ind}{key}:")
                 self._show(value, indent + 1)
 
     def run(self):
@@ -47,17 +46,24 @@ class CmdDataStatus(CmdDataBase):
                 remote=self.args.remote,
                 all_branches=self.args.all_branches,
                 all_tags=self.args.all_tags,
+                all_commits=self.args.all_commits,
                 with_deps=self.args.with_deps,
+                recursive=self.args.recursive,
             )
-            if st:
-                if self.args.quiet:
-                    return 1
-                else:
-                    self._show(st, indent)
+
+            if self.args.quiet:
+                return bool(st)
+
+            if self.args.show_json:
+                import json
+
+                logger.info(json.dumps(st))
+            elif st:
+                self._show(st, indent)
             else:
                 logger.info(self.UP_TO_DATE_MSG)
 
-        except Exception:
+        except Exception:  # noqa, pylint: disable=broad-except
             logger.exception("failed to obtain data status")
             return 1
         return 0

dvc/command/tag.py

@@ -1,156 +0,0 @@
-import logging
-
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
-from dvc.command.base import fix_subparsers
-from dvc.exceptions import DvcException
-from dvc.utils import to_yaml_string
-
-
-logger = logging.getLogger(__name__)
-
-
-class CmdTagAdd(CmdBase):
-    def run(self):
-        for target in self.args.targets:
-            try:
-                self.repo.tag.add(
-                    self.args.tag,
-                    target=target,
-                    with_deps=self.args.with_deps,
-                    recursive=self.args.recursive,
-                )
-            except DvcException:
-                logger.exception("failed to add tag")
-                return 1
-        return 0
-
-
-class CmdTagRemove(CmdBase):
-    def run(self):
-        for target in self.args.targets:
-            try:
-                self.repo.tag.remove(
-                    self.args.tag,
-                    target=target,
-                    with_deps=self.args.with_deps,
-                    recursive=self.args.recursive,
-                )
-            except DvcException:
-                logger.exception("failed to remove tag")
-                return 1
-        return 0
-
-
-class CmdTagList(CmdBase):
-    def run(self):
-        for target in self.args.targets:
-            try:
-                tags = self.repo.tag.list(
-                    target,
-                    with_deps=self.args.with_deps,
-                    recursive=self.args.recursive,
-                )
-                if tags:
-                    logger.info(to_yaml_string(tags))
-            except DvcException:
-                logger.exception("failed list tags")
-                return 1
-        return 0
-
-
-def add_parser(subparsers, parent_parser):
-    TAG_HELP = "A set of commands to manage DVC tags."
-    tag_parser = subparsers.add_parser(
-        "tag",
-        parents=[parent_parser],
-        description=append_doc_link(TAG_HELP, "tag"),
-        add_help=False,
-    )
-
-    tag_subparsers = tag_parser.add_subparsers(
-        dest="cmd",
-        help="Use DVC tag CMD --help to display command-specific help.",
-    )
-
-    fix_subparsers(tag_subparsers)
-
-    TAG_ADD_HELP = "Add DVC tag."
-    tag_add_parser = tag_subparsers.add_parser(
-        "add",
-        parents=[parent_parser],
-        description=append_doc_link(TAG_ADD_HELP, "tag-add"),
-        help=TAG_ADD_HELP,
-    )
-    tag_add_parser.add_argument("tag", help="Dvc tag.")
-    tag_add_parser.add_argument(
-        "targets", nargs="*", default=[None], help="DVC-files."
-    )
-    tag_add_parser.add_argument(
-        "-d",
-        "--with-deps",
-        action="store_true",
-        default=False,
-        help="Add tag for all dependencies of the specified DVC-file.",
-    )
-    tag_add_parser.add_argument(
-        "-R",
-        "--recursive",
-        action="store_true",
-        default=False,
-        help="Add tag for subdirectories of the specified directory.",
-    )
-    tag_add_parser.set_defaults(func=CmdTagAdd)
-
-    TAG_REMOVE_HELP = "Remove DVC tag."
-    tag_remove_parser = tag_subparsers.add_parser(
-        "remove",
-        parents=[parent_parser],
-        description=append_doc_link(TAG_REMOVE_HELP, "tag-remove"),
-        help=TAG_REMOVE_HELP,
-    )
-    tag_remove_parser.add_argument("tag", help="Dvc tag.")
-    tag_remove_parser.add_argument(
-        "targets", nargs="*", default=[None], help="DVC-files."
-    )
-    tag_remove_parser.add_argument(
-        "-d",
-        "--with-deps",
-        action="store_true",
-        default=False,
-        help="Remove tag for all dependencies of the specified DVC-file.",
-    )
-    tag_remove_parser.add_argument(
-        "-R",
-        "--recursive",
-        action="store_true",
-        default=False,
-        help="Remove tag for subdirectories of the specified directory.",
-    )
-    tag_remove_parser.set_defaults(func=CmdTagRemove)
-
-    TAG_LIST_HELP = "List DVC tags."
-    tag_list_parser = tag_subparsers.add_parser(
-        "list",
-        parents=[parent_parser],
-        description=append_doc_link(TAG_LIST_HELP, "tag-list"),
-        help=TAG_LIST_HELP,
-    )
-    tag_list_parser.add_argument(
-        "targets", nargs="*", default=[None], help="DVC-files."
-    )
-    tag_list_parser.add_argument(
-        "-d",
-        "--with-deps",
-        action="store_true",
-        default=False,
-        help="List tags for all dependencies of the specified DVC-file.",
-    )
-    tag_list_parser.add_argument(
-        "-R",
-        "--recursive",
-        action="store_true",
-        default=False,
-        help="List tags for subdirectories of the specified directory.",
-    )
-    tag_list_parser.set_defaults(func=CmdTagList)

dvc/command/unprotect.py

@@ -1,11 +1,10 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link
 from dvc.exceptions import DvcException
 
-
 logger = logging.getLogger(__name__)
 
 
@@ -15,7 +14,7 @@ class CmdUnprotect(CmdBase):
             try:
                 self.repo.unprotect(target)
             except DvcException:
-                msg = "failed to unprotect '{}'".format(target)
+                msg = f"failed to unprotect '{target}'"
                 logger.exception(msg)
                 return 1
         return 0
@@ -34,6 +33,6 @@ def add_parser(subparsers, parent_parser):
         formatter_class=argparse.RawDescriptionHelpFormatter,
     )
     unprotect_parser.add_argument(
-        "targets", nargs="+", help="Data files/directories to unprotect."
-    )
+        "targets", nargs="+", help="Data files/directories to unprotect.",
+    ).complete = completion.FILE
     unprotect_parser.set_defaults(func=CmdUnprotect)

dvc/command/update.py

@@ -1,23 +1,25 @@
 import argparse
 import logging
 
-from dvc.command.base import append_doc_link
-from dvc.command.base import CmdBase
+from dvc.command import completion
+from dvc.command.base import CmdBase, append_doc_link
 from dvc.exceptions import DvcException
 
-
 logger = logging.getLogger(__name__)
 
 
 class CmdUpdate(CmdBase):
     def run(self):
         ret = 0
-        for target in self.args.targets:
-            try:
-                self.repo.update(target, self.args.rev)
-            except DvcException:
-                logger.exception("failed to update '{}'.".format(target))
-                ret = 1
+        try:
+            self.repo.update(
+                targets=self.args.targets,
+                rev=self.args.rev,
+                recursive=self.args.recursive,
+            )
+        except DvcException:
+            logger.exception("failed update data")
+            ret = 1
         return ret
 
 
@@ -31,9 +33,19 @@ def add_parser(subparsers, parent_parser):
         formatter_class=argparse.RawDescriptionHelpFormatter,
     )
     update_parser.add_argument(
-        "targets", nargs="+", help="DVC-files to update."
+        "targets", nargs="+", help="DVC-files to update.",
+    ).complete = completion.DVC_FILE
+    update_parser.add_argument(
+        "--rev",
+        nargs="?",
+        help="Git revision (e.g. SHA, branch, tag)",
+        metavar="<commit>",
     )
     update_parser.add_argument(
-        "--rev", nargs="?", help="Git revision (e.g. SHA, branch, tag)"
+        "-R",
+        "--recursive",
+        action="store_true",
+        default=False,
+        help="Update all stages in the specified directory.",
     )
     update_parser.set_defaults(func=CmdUpdate)

dvc/command/version.py

@@ -2,21 +2,23 @@ import argparse
 import itertools
 import logging
 import os
+import pathlib
 import platform
 import uuid
-import pathlib
+
+from dvc.command.base import CmdBaseNoRepo, append_doc_link
+from dvc.exceptions import DvcException, NotDvcRepoError
+from dvc.scm.base import SCMError
+from dvc.system import System
+from dvc.utils import is_binary, relpath
+from dvc.utils.pkg import PKG
+from dvc.version import __version__
 
 try:
     import psutil
 except ImportError:
     psutil = None
 
-from dvc.utils import is_binary, relpath
-from dvc.command.base import CmdBaseNoRepo, append_doc_link
-from dvc.version import __version__
-from dvc.exceptions import DvcException, NotDvcRepoError
-from dvc.system import System
-from dvc.utils.pkg import PKG
 
 logger = logging.getLogger(__name__)
 
@@ -26,12 +28,12 @@ class CmdVersion(CmdBaseNoRepo):
         from dvc.repo import Repo
 
         info = [
-            "DVC version: {}".format(__version__),
-            "Python version: {}".format(platform.python_version()),
-            "Platform: {}".format(platform.platform()),
-            "Binary: {}".format(is_binary()),
-            "Package: {}".format(PKG),
-            "Supported remotes: {}".format(self.get_supported_remotes()),
+            f"DVC version: {__version__}",
+            f"Python version: {platform.python_version()}",
+            f"Platform: {platform.platform()}",
+            f"Binary: {is_binary()}",
+            f"Package: {PKG}",
+            f"Supported remotes: {self.get_supported_remotes()}",
         ]
 
         try:
@@ -49,7 +51,7 @@ class CmdVersion(CmdBaseNoRepo):
                 if psutil:
                     fs_type = self.get_fs_type(repo.cache.local.cache_dir)
                     info.append(
-                        "Filesystem type (cache directory): {}".format(fs_type)
+                        f"Filesystem type (cache directory): {fs_type}"
                     )
             else:
                 logger.warning(
@@ -62,10 +64,15 @@ class CmdVersion(CmdBaseNoRepo):
 
         except NotDvcRepoError:
             root_directory = os.getcwd()
+        except SCMError:
+            root_directory = os.getcwd()
+            info.append("Repo: dvc, git (broken)")
+        else:
+            info.append("Repo: {}".format(_get_dvc_repo_info(repo)))
 
         if psutil:
             fs_root = self.get_fs_type(os.path.abspath(root_directory))
-            info.append("Filesystem type (workspace): {}".format(fs_root))
+            info.append(f"Filesystem type (workspace): {fs_root}")
 
         logger.info("\n".join(info))
         return 0
@@ -108,26 +115,37 @@ class CmdVersion(CmdBaseNoRepo):
                 os.unlink(dst)
             except DvcException:
                 status = "not supported"
-            cache.append("{name} - {status}".format(name=name, status=status))
+            cache.append(f"{name} - {status}")
         os.remove(src)
 
         return ", ".join(cache)
 
     @staticmethod
     def get_supported_remotes():
-        from dvc.remote import REMOTES
+        from dvc.tree import TREES
 
         supported_remotes = []
-        for remote in REMOTES:
-            if not remote.get_missing_deps():
-                supported_remotes.append(remote.scheme)
+        for tree_cls in TREES:
+            if not tree_cls.get_missing_deps():
+                supported_remotes.append(tree_cls.scheme)
 
         return ", ".join(supported_remotes)
 
 
-def add_parser(subparsers, parent_parser):
-    VERSION_HELP = "Show DVC version and system/environment information."
+def _get_dvc_repo_info(repo):
+    if repo.config.get("core", {}).get("no_scm", False):
+        return "dvc (no_scm)"
 
+    if repo.root_dir != repo.scm.root_dir:
+        return "dvc (subdir), git"
+
+    return "dvc, git"
+
+
+def add_parser(subparsers, parent_parser):
+    VERSION_HELP = (
+        "Display the DVC version and system/environment information."
+    )
     version_parser = subparsers.add_parser(
         "version",
         parents=[parent_parser],

dvc/compat.py

@@ -1,42 +0,0 @@
-"""Python version compatibility code"""
-
-# Backport os.fspath() from Python 3.6
-try:
-    from os import fspath  # noqa: F821
-
-    fspath_py35 = lambda s: s  # noqa: E731
-except ImportError:
-
-    def fspath(path):
-        """Return the path representation of a path-like object.
-
-        If str or bytes is passed in, it is returned unchanged. Otherwise the
-        os.PathLike interface is used to get the path representation. If the
-        path representation is not str or bytes, TypeError is raised. If the
-        provided path is not str, bytes, or os.PathLike, TypeError is raised.
-        """
-        if isinstance(path, (str, bytes)):
-            return path
-
-        # Work from the object's type to match method resolution of other magic
-        # methods.
-        path_type = type(path)
-        try:
-            path_repr = path_type.__fspath__(path)
-        except AttributeError:
-            if hasattr(path_type, "__fspath__"):
-                raise
-            else:
-                raise TypeError(
-                    "expected str, bytes or os.PathLike object, "
-                    "not " + path_type.__name__
-                )
-        if isinstance(path_repr, (str, bytes)):
-            return path_repr
-        else:
-            raise TypeError(
-                "expected {}.__fspath__() to return str or bytes, "
-                "not {}".format(path_type.__name__, type(path_repr).__name__)
-            )
-
-    fspath_py35 = fspath

dvc/config.py

@@ -1,16 +1,27 @@
 """DVC config objects."""
-from contextlib import contextmanager
 import logging
 import os
 import re
+from contextlib import contextmanager
+from functools import partial
 from urllib.parse import urlparse
 
-from funcy import cached_property, re_find, walk_values, compact
 import configobj
-from voluptuous import Schema, Optional, Invalid, ALLOW_EXTRA
-from voluptuous import All, Any, Lower, Range, Coerce
+from funcy import cached_property, compact, re_find, walk_values
+from voluptuous import (
+    ALLOW_EXTRA,
+    All,
+    Any,
+    Coerce,
+    Invalid,
+    Lower,
+    Optional,
+    Range,
+    Schema,
+)
 
 from dvc.exceptions import DvcException, NotDvcRepoError
+from dvc.path_info import PathInfo
 from dvc.utils import relpath
 
 logger = logging.getLogger(__name__)
@@ -20,7 +31,7 @@ class ConfigError(DvcException):
     """DVC config exception."""
 
     def __init__(self, msg):
-        super().__init__("config file error: {}".format(msg))
+        super().__init__(f"config file error: {msg}")
 
 
 class NoRemoteError(ConfigError):
@@ -78,7 +89,7 @@ def ByUrl(mapping):
         if os.name == "nt" and len(parsed.scheme) == 1 and parsed.netloc == "":
             return schemas[""](data)
         if parsed.scheme not in schemas:
-            raise Invalid("Unsupported URL type {}://".format(parsed.scheme))
+            raise Invalid(f"Unsupported URL type {parsed.scheme}://")
 
         return schemas[parsed.scheme](data)
 
@@ -92,7 +103,7 @@ class RelPath(str):
 REMOTE_COMMON = {
     "url": str,
     "checksum_jobs": All(Coerce(int), Range(1)),
-    "no_traverse": Bool,
+    Optional("no_traverse"): Bool,  # obsoleted
     "verify": Bool,
 }
 LOCAL_COMMON = {
@@ -116,6 +127,7 @@ SCHEMA = {
         Optional("analytics", default=True): Bool,
         Optional("hardlink_lock", default=False): Bool,
         Optional("no_scm", default=False): Bool,
+        Optional("experiments", default=False): Bool,
     },
     "cache": {
         "local": str,
@@ -137,9 +149,12 @@ SCHEMA = {
                     "profile": str,
                     "credentialpath": str,
                     "endpointurl": str,
+                    "access_key_id": str,
+                    "secret_access_key": str,
                     Optional("listobjects", default=False): Bool,
                     Optional("use_ssl", default=True): Bool,
                     "sse": str,
+                    "sse_kms_key_id": str,
                     "acl": str,
                     "grant_read": str,
                     "grant_read_acp": str,
@@ -179,6 +194,7 @@ SCHEMA = {
                     "gdrive_service_account_email": str,
                     "gdrive_service_account_user_email": str,
                     "gdrive_service_account_p12_file_path": str,
+                    Optional("gdrive_trash_only", default=False): Bool,
                     **REMOTE_COMMON,
                 },
                 "http": {**HTTP_COMMON, **REMOTE_COMMON},
@@ -218,7 +234,11 @@ class Config(dict):
     CONFIG = "config"
     CONFIG_LOCAL = "config.local"
 
-    def __init__(self, dvc_dir=None, validate=True):
+    def __init__(
+        self, dvc_dir=None, validate=True, tree=None,
+    ):  # pylint: disable=super-init-not-called
+        from dvc.tree.local import LocalTree
+
         self.dvc_dir = dvc_dir
 
         if not dvc_dir:
@@ -231,6 +251,9 @@ class Config(dict):
         else:
             self.dvc_dir = os.path.abspath(os.path.realpath(dvc_dir))
 
+        self.wtree = LocalTree(None, {"url": self.dvc_dir})
+        self.tree = tree or self.wtree
+
         self.load(validate=validate)
 
     @classmethod
@@ -277,10 +300,7 @@ class Config(dict):
         Raises:
             ConfigError: thrown if config has an invalid format.
         """
-        conf = {}
-        for level in self.LEVELS:
-            if level in self.files:
-                _merge(conf, self.load_one(level))
+        conf = self.load_config_to_level()
 
         if validate:
             conf = self.validate(conf)
@@ -292,11 +312,33 @@ class Config(dict):
         if not self["cache"].get("dir") and self.dvc_dir:
             self["cache"]["dir"] = os.path.join(self.dvc_dir, "cache")
 
+    def _load_config(self, level):
+        filename = self.files[level]
+
+        if self.tree.exists(filename, use_dvcignore=False):
+            with self.tree.open(filename) as fobj:
+                conf_obj = configobj.ConfigObj(fobj)
+        else:
+            conf_obj = configobj.ConfigObj()
+        return _parse_remotes(_lower_keys(conf_obj.dict()))
+
+    def _save_config(self, level, conf_dict):
+        filename = self.files[level]
+
+        logger.debug(f"Writing '{filename}'.")
+
+        self.tree.makedirs(os.path.dirname(filename))
+
+        config = configobj.ConfigObj(_pack_remotes(conf_dict))
+        with self.tree.open(filename, "wb") as fobj:
+            config.write(fobj)
+        config.filename = filename
+
     def load_one(self, level):
-        conf = _load_config(self.files[level])
+        conf = self._load_config(level)
         conf = self._load_paths(conf, self.files[level])
 
-        # Autovivify sections
+        # Auto-verify sections
         for key in COMPILED_SCHEMA.schema:
             conf.setdefault(key, {})
 
@@ -313,25 +355,42 @@ class Config(dict):
 
         return Config._map_dirs(conf, resolve)
 
+    @staticmethod
+    def _to_relpath(conf_dir, path):
+        if re.match(r"\w+://", path):
+            return path
+
+        if isinstance(path, RelPath) or not os.path.isabs(path):
+            path = relpath(path, conf_dir)
+
+        return PathInfo(path).as_posix()
+
     @staticmethod
     def _save_paths(conf, filename):
         conf_dir = os.path.dirname(filename)
-
-        def rel(path):
-            if re.match(r"\w+://", path):
-                return path
-
-            if isinstance(path, RelPath) or not os.path.isabs(path):
-                return relpath(path, conf_dir)
-            return path
+        rel = partial(Config._to_relpath, conf_dir)
 
         return Config._map_dirs(conf, rel)
 
     @staticmethod
     def _map_dirs(conf, func):
-        dirs_schema = {"cache": {"dir": func}, "remote": {str: {"url": func}}}
+        dirs_schema = {
+            "cache": {"dir": func},
+            "remote": {
+                str: {"url": func, "gdrive_user_credentials_file": func}
+            },
+        }
         return Schema(dirs_schema, extra=ALLOW_EXTRA)(conf)
 
+    def load_config_to_level(self, level=None):
+        merged_conf = {}
+        for merge_level in self.LEVELS:
+            if merge_level == level:
+                break
+            if merge_level in self.files:
+                _merge(merged_conf, self.load_one(merge_level))
+        return merged_conf
+
     @contextmanager
     def edit(self, level="repo"):
         if level in {"repo", "local"} and self.dvc_dir is None:
@@ -341,7 +400,12 @@ class Config(dict):
         yield conf
 
         conf = self._save_paths(conf, self.files[level])
-        _save_config(self.files[level], conf)
+
+        merged_conf = self.load_config_to_level(level)
+        _merge(merged_conf, conf)
+        self.validate(merged_conf)
+
+        self._save_config(level, conf)
         self.load()
 
     @staticmethod
@@ -352,20 +416,6 @@ class Config(dict):
             raise ConfigError(str(exc)) from None
 
 
-def _load_config(filename):
-    conf_obj = configobj.ConfigObj(filename)
-    return _parse_remotes(_lower_keys(conf_obj.dict()))
-
-
-def _save_config(filename, conf_dict):
-    logger.debug("Writing '{}'.".format(filename))
-    os.makedirs(os.path.dirname(filename), exist_ok=True)
-
-    config = configobj.ConfigObj(_pack_remotes(conf_dict))
-    config.filename = filename
-    config.write()
-
-
 def _parse_remotes(conf):
     result = {"remote": {}}
 
@@ -385,7 +435,7 @@ def _pack_remotes(conf):
 
     # Transform remote.name -> 'remote "name"'
     for name, val in conf["remote"].items():
-        result['remote "{}"'.format(name)] = val
+        result[f'remote "{name}"'] = val
     result.pop("remote", None)
 
     return result

dvc/daemon.py

@@ -3,13 +3,12 @@
 import inspect
 import logging
 import os
+import platform
 import sys
 from subprocess import Popen
 
 from dvc.env import DVC_DAEMON
-from dvc.utils import fix_env
-from dvc.utils import is_binary
-
+from dvc.utils import fix_env, is_binary
 
 logger = logging.getLogger(__name__)
 
@@ -17,6 +16,14 @@ CREATE_NEW_PROCESS_GROUP = 0x00000200
 DETACHED_PROCESS = 0x00000008
 
 
+def _popen(cmd, **kwargs):
+    prefix = [sys.executable]
+    if not is_binary():
+        prefix += [sys.argv[0]]
+
+    return Popen(prefix + cmd, close_fds=True, shell=False, **kwargs)
+
+
 def _spawn_windows(cmd, env):
     from subprocess import STARTUPINFO, STARTF_USESHOWWINDOW
 
@@ -25,17 +32,14 @@ def _spawn_windows(cmd, env):
     startupinfo = STARTUPINFO()
     startupinfo.dwFlags |= STARTF_USESHOWWINDOW
 
-    Popen(
-        cmd,
-        env=env,
-        close_fds=True,
-        shell=False,
-        creationflags=creationflags,
-        startupinfo=startupinfo,
+    _popen(
+        cmd, env=env, creationflags=creationflags, startupinfo=startupinfo,
     ).communicate()
 
 
 def _spawn_posix(cmd, env):
+    from dvc.main import main
+
     # NOTE: using os._exit instead of sys.exit, because dvc built
     # with PyInstaller has trouble with SystemExit exception and throws
     # errors such as "[26338] Failed to execute script __main__"
@@ -48,7 +52,6 @@ def _spawn_posix(cmd, env):
         os._exit(1)  # pylint: disable=protected-access
 
     os.setsid()
-    os.umask(0)
 
     try:
         pid = os.fork()
@@ -62,13 +65,19 @@ def _spawn_posix(cmd, env):
     sys.stdout.close()
     sys.stderr.close()
 
-    Popen(cmd, env=env, close_fds=True, shell=False).communicate()
+    if platform.system() == "Darwin":
+        # workaround for MacOS bug
+        # https://github.com/iterative/dvc/issues/4294
+        _popen(cmd, env=env).communicate()
+    else:
+        os.environ.update(env)
+        main(cmd)
 
     os._exit(0)  # pylint: disable=protected-access
 
 
 def _spawn(cmd, env):
-    logger.debug("Trying to spawn '{}'".format(cmd))
+    logger.debug(f"Trying to spawn '{cmd}'")
 
     if os.name == "nt":
         _spawn_windows(cmd, env)
@@ -77,7 +86,7 @@ def _spawn(cmd, env):
     else:
         raise NotImplementedError
 
-    logger.debug("Spawned '{}'".format(cmd))
+    logger.debug(f"Spawned '{cmd}'")
 
 
 def daemon(args):
@@ -90,10 +99,7 @@ def daemon(args):
         logger.debug("skipping launching a new daemon.")
         return
 
-    cmd = [sys.executable]
-    if not is_binary():
-        cmd += [sys.argv[0]]
-    cmd += ["daemon", "-q"] + args
+    cmd = ["daemon", "-q"] + args
 
     env = fix_env()
     file_path = os.path.abspath(inspect.stack()[0][1])

dvc/dagascii.py

@@ -6,12 +6,9 @@ import os
 import pydoc
 import sys
 
-from grandalf.graphs import Edge
-from grandalf.graphs import Graph
-from grandalf.graphs import Vertex
+from grandalf.graphs import Edge, Graph, Vertex
 from grandalf.layouts import SugiyamaLayout
-from grandalf.routing import EdgeViewer
-from grandalf.routing import route_with_lines
+from grandalf.routing import EdgeViewer, route_with_lines
 
 from dvc.env import DVC_PAGER
 from dvc.utils import format_link
@@ -40,7 +37,7 @@ def find_pager():
     if env_pager:
         return make_pager(env_pager)
 
-    if os.system("({}) 2>{}".format(DEFAULT_PAGER, os.devnull)) == 0:
+    if os.system(f"({DEFAULT_PAGER}) 2>{os.devnull}") == 0:
         return make_pager(DEFAULT_PAGER_FORMATTED)
 
     logger.warning(
@@ -52,7 +49,7 @@ def find_pager():
     return pydoc.plainpager
 
 
-class VertexViewer(object):
+class VertexViewer:
     """Class to define vertex box boundaries that will be accounted for during
     graph building by grandalf.
 
@@ -78,7 +75,7 @@ class VertexViewer(object):
         return self._w
 
 
-class AsciiCanvas(object):
+class AsciiCanvas:
     """Class for drawing in ASCII.
 
     Args:
@@ -95,14 +92,13 @@ class AsciiCanvas(object):
         self.cols = cols
         self.lines = lines
 
-        self.canvas = [[" "] * cols for l in range(lines)]
+        self.canvas = [[" "] * cols for line in range(lines)]
 
     def draw(self):
         """Draws ASCII canvas on the screen."""
-        pager = find_pager()
         lines = map("".join, self.canvas)
         joined_lines = os.linesep.join(lines)
-        pager(joined_lines)
+        return joined_lines
 
     def point(self, x, y, char):
         """Create a point on ASCII canvas.
@@ -148,21 +144,21 @@ class AsciiCanvas(object):
                 if dx == 0:
                     y = y0
                 else:
-                    y = y0 + int(round((x - x0) * dy / float((dx))))
+                    y = y0 + int(round((x - x0) * dy / float(dx)))
                 self.point(x, y, char)
         elif y0 < y1:
             for y in range(y0, y1 + 1):
                 if dy == 0:
                     x = x0
                 else:
-                    x = x0 + int(round((y - y0) * dx / float((dy))))
+                    x = x0 + int(round((y - y0) * dx / float(dy)))
                 self.point(x, y, char)
         else:
             for y in range(y1, y0 + 1):
                 if dy == 0:
                     x = x0
                 else:
-                    x = x1 + int(round((y - y1) * dx / float((dy))))
+                    x = x1 + int(round((y - y1) * dx / float(dy)))
                 self.point(x, y, char)
 
     def text(self, x, y, text):
@@ -216,7 +212,7 @@ def _build_sugiyama_layout(vertexes, edges):
     # Y
     #
 
-    vertexes = {v: Vertex(" {} ".format(v)) for v in vertexes}
+    vertexes = {v: Vertex(f" {v} ") for v in vertexes}
     # NOTE: reverting edges to correctly orientate the graph
     edges = [Edge(vertexes[e], vertexes[s]) for s, e in edges]
     vertexes = vertexes.values()
@@ -226,7 +222,7 @@ def _build_sugiyama_layout(vertexes, edges):
         vertex.view = VertexViewer(vertex.data)
 
     # NOTE: determine min box length to create the best layout
-    minw = min([v.view.w for v in vertexes])
+    minw = min(v.view.w for v in vertexes)
 
     for edge in edges:
         edge.view = EdgeViewer()
@@ -319,4 +315,4 @@ def draw(vertexes, edges):
             int(round(x - minx)) + 1, int(round(y - miny)) + 1, vertex.data
         )
 
-    canvas.draw()
+    return canvas.draw()

dvc/data_cloud.py

@@ -3,13 +3,12 @@
 import logging
 
 from dvc.config import NoRemoteError
-from dvc.remote import Remote
-
+from dvc.remote import get_remote
 
 logger = logging.getLogger(__name__)
 
 
-class DataCloud(object):
+class DataCloud:
     """Class that manages dvc remotes.
 
     Args:
@@ -23,12 +22,12 @@ class DataCloud(object):
     def __init__(self, repo):
         self.repo = repo
 
-    def get_remote(self, remote=None, command="<command>"):
-        if not remote:
-            remote = self.repo.config["core"].get("remote")
+    def get_remote(self, name=None, command="<command>"):
+        if not name:
+            name = self.repo.config["core"].get("remote")
 
-        if remote:
-            return self._init_remote(remote)
+        if name:
+            return self._init_remote(name)
 
         if bool(self.repo.config["remote"]):
             error_msg = (
@@ -45,55 +44,60 @@ class DataCloud(object):
 
         raise NoRemoteError(error_msg)
 
-    def _init_remote(self, remote):
-        return Remote(self.repo, name=remote)
+    def _init_remote(self, name):
+        return get_remote(self.repo, name=name)
 
-    def push(self, cache, jobs=None, remote=None, show_checksums=False):
+    def push(
+        self, cache, jobs=None, remote=None, show_checksums=False,
+    ):
         """Push data items in a cloud-agnostic way.
 
         Args:
             cache (NamedCache): named checksums to push to the cloud.
             jobs (int): number of jobs that can be running simultaneously.
-            remote (dvc.remote.base.RemoteBASE): optional remote to push to.
+            remote (dvc.remote.base.BaseRemote): optional remote to push to.
                 By default remote from core.remote config option is used.
             show_checksums (bool): show checksums instead of file names in
                 information messages.
         """
+        remote = self.get_remote(remote, "push")
+
         return self.repo.cache.local.push(
-            cache,
-            jobs=jobs,
-            remote=self.get_remote(remote, "push"),
-            show_checksums=show_checksums,
+            cache, jobs=jobs, remote=remote, show_checksums=show_checksums,
         )
 
-    def pull(self, cache, jobs=None, remote=None, show_checksums=False):
+    def pull(
+        self, cache, jobs=None, remote=None, show_checksums=False,
+    ):
         """Pull data items in a cloud-agnostic way.
 
         Args:
             cache (NamedCache): named checksums to pull from the cloud.
             jobs (int): number of jobs that can be running simultaneously.
-            remote (dvc.remote.base.RemoteBASE): optional remote to pull from.
+            remote (dvc.remote.base.BaseRemote): optional remote to pull from.
                 By default remote from core.remote config option is used.
             show_checksums (bool): show checksums instead of file names in
                 information messages.
         """
         remote = self.get_remote(remote, "pull")
+
         downloaded_items_num = self.repo.cache.local.pull(
             cache, jobs=jobs, remote=remote, show_checksums=show_checksums
         )
 
-        if not remote.verify:
+        if not remote.tree.verify:
             self._save_pulled_checksums(cache)
 
         return downloaded_items_num
 
     def _save_pulled_checksums(self, cache):
-        for checksum in cache["local"].keys():
-            cache_file = self.repo.cache.local.checksum_to_path_info(checksum)
-            if self.repo.cache.local.exists(cache_file):
-                # We can safely save here, as existing corrupted files will be
-                # removed upon status, while files corrupted during download
-                # will not be moved from tmp_file (see `RemoteBASE.download()`)
+        for checksum in cache.scheme_keys("local"):
+            cache_file = self.repo.cache.local.tree.hash_to_path_info(checksum)
+            if self.repo.cache.local.tree.exists(cache_file):
+                # We can safely save here, as existing corrupted files will
+                # be removed upon status, while files corrupted during
+                # download will not be moved from tmp_file
+                # (see `RemoteBASE.download()`)
                 self.repo.state.save(cache_file, checksum)
 
     def status(self, cache, jobs=None, remote=None, show_checksums=False):
@@ -102,7 +106,7 @@ class DataCloud(object):
         Args:
             cache (NamedCache): named checksums to check status for.
             jobs (int): number of jobs that can be running simultaneously.
-            remote (dvc.remote.base.RemoteBASE): optional remote to compare
+            remote (dvc.remote.base.BaseRemote): optional remote to compare
                 cache to. By default remote from core.remote config option
                 is used.
             show_checksums (bool): show checksums instead of file names in

dvc/dependency/__init__.py

@@ -1,37 +1,42 @@
+from collections import defaultdict
 from urllib.parse import urlparse
 
 import dvc.output as output
-from dvc.dependency.gs import DependencyGS
-from dvc.dependency.hdfs import DependencyHDFS
-from dvc.dependency.http import DependencyHTTP
-from dvc.dependency.https import DependencyHTTPS
-from dvc.dependency.local import DependencyLOCAL
-from dvc.dependency.s3 import DependencyS3
-from dvc.dependency.ssh import DependencySSH
-from dvc.output.base import OutputBase
-from dvc.remote import Remote
+from dvc.dependency.azure import AzureDependency
+from dvc.dependency.gs import GSDependency
+from dvc.dependency.hdfs import HDFSDependency
+from dvc.dependency.http import HTTPDependency
+from dvc.dependency.https import HTTPSDependency
+from dvc.dependency.local import LocalDependency
+from dvc.dependency.param import ParamsDependency
+from dvc.dependency.s3 import S3Dependency
+from dvc.dependency.ssh import SSHDependency
+from dvc.output.base import BaseOutput
 from dvc.scheme import Schemes
-from .repo import DependencyREPO
 
+from ..tree import get_cloud_tree
+from .repo import RepoDependency
 
 DEPS = [
-    DependencyGS,
-    DependencyHDFS,
-    DependencyHTTP,
-    DependencyHTTPS,
-    DependencyS3,
-    DependencySSH,
-    # NOTE: DependencyLOCAL is the default choice
+    AzureDependency,
+    GSDependency,
+    HDFSDependency,
+    HTTPDependency,
+    HTTPSDependency,
+    S3Dependency,
+    SSHDependency,
+    # NOTE: LocalDependency is the default choice
 ]
 
 DEP_MAP = {
-    Schemes.LOCAL: DependencyLOCAL,
-    Schemes.SSH: DependencySSH,
-    Schemes.S3: DependencyS3,
-    Schemes.GS: DependencyGS,
-    Schemes.HDFS: DependencyHDFS,
-    Schemes.HTTP: DependencyHTTP,
-    Schemes.HTTPS: DependencyHTTPS,
+    Schemes.LOCAL: LocalDependency,
+    Schemes.SSH: SSHDependency,
+    Schemes.S3: S3Dependency,
+    Schemes.AZURE: AzureDependency,
+    Schemes.GS: GSDependency,
+    Schemes.HDFS: HDFSDependency,
+    Schemes.HTTP: HTTPDependency,
+    Schemes.HTTPS: HTTPSDependency,
 }
 
 
@@ -40,39 +45,69 @@ DEP_MAP = {
 # cached, see -o and -O flags for `dvc run`) and 'metric' (whether or not
 # output is a metric file and how to parse it, see `-M` flag for `dvc run`).
 SCHEMA = output.SCHEMA.copy()
-del SCHEMA[OutputBase.PARAM_CACHE]
-del SCHEMA[OutputBase.PARAM_METRIC]
-SCHEMA[DependencyREPO.PARAM_REPO] = DependencyREPO.REPO_SCHEMA
+del SCHEMA[BaseOutput.PARAM_CACHE]
+del SCHEMA[BaseOutput.PARAM_METRIC]
+SCHEMA.update(RepoDependency.REPO_SCHEMA)
+SCHEMA.update(ParamsDependency.PARAM_SCHEMA)
 
 
 def _get(stage, p, info):
-    parsed = urlparse(p)
+    parsed = urlparse(p) if p else None
+    if parsed and parsed.scheme == "remote":
+        tree = get_cloud_tree(stage.repo, name=parsed.netloc)
+        return DEP_MAP[tree.scheme](stage, p, info, tree=tree)
 
-    if parsed.scheme == "remote":
-        remote = Remote(stage.repo, name=parsed.netloc)
-        return DEP_MAP[remote.scheme](stage, p, info, remote=remote)
+    if info and info.get(RepoDependency.PARAM_REPO):
+        repo = info.pop(RepoDependency.PARAM_REPO)
+        return RepoDependency(repo, stage, p, info)
 
-    if info and info.get(DependencyREPO.PARAM_REPO):
-        repo = info.pop(DependencyREPO.PARAM_REPO)
-        return DependencyREPO(repo, stage, p, info)
+    if info and info.get(ParamsDependency.PARAM_PARAMS):
+        params = info.pop(ParamsDependency.PARAM_PARAMS)
+        return ParamsDependency(stage, p, params)
 
     for d in DEPS:
         if d.supported(p):
             return d(stage, p, info)
-    return DependencyLOCAL(stage, p, info)
+    return LocalDependency(stage, p, info)
 
 
 def loadd_from(stage, d_list):
     ret = []
     for d in d_list:
-        p = d.pop(OutputBase.PARAM_PATH)
+        p = d.pop(BaseOutput.PARAM_PATH, None)
         ret.append(_get(stage, p, d))
     return ret
 
 
 def loads_from(stage, s_list, erepo=None):
-    ret = []
-    for s in s_list:
-        info = {DependencyREPO.PARAM_REPO: erepo} if erepo else {}
-        ret.append(_get(stage, s, info))
-    return ret
+    assert isinstance(s_list, list)
+    info = {RepoDependency.PARAM_REPO: erepo} if erepo else {}
+    return [_get(stage, s, info.copy()) for s in s_list]
+
+
+def _merge_params(s_list):
+    d = defaultdict(list)
+    default_file = ParamsDependency.DEFAULT_PARAMS_FILE
+    for key in s_list:
+        if isinstance(key, str):
+            d[default_file].append(key)
+            continue
+        if not isinstance(key, dict):
+            msg = "Only list of str/dict is supported. Got: "
+            msg += f"'{type(key).__name__}'."
+            raise ValueError(msg)
+
+        for k, params in key.items():
+            if not isinstance(params, list):
+                msg = "Expected list of params for custom params file "
+                msg += f"'{k}', got '{type(params).__name__}'."
+                raise ValueError(msg)
+            d[k].extend(params)
+    return d
+
+
+def loads_params(stage, s_list):
+    d = _merge_params(s_list)
+    return [
+        ParamsDependency(stage, path, params) for path, params in d.items()
+    ]

dvc/dependency/azure.py

@@ -0,0 +1,8 @@
+from dvc.dependency.base import BaseDependency
+from dvc.output.base import BaseOutput
+
+from ..tree.azure import AzureTree
+
+
+class AzureDependency(BaseDependency, BaseOutput):
+    TREE_CLS = AzureTree

dvc/dependency/base.py

@@ -3,24 +3,22 @@ from dvc.exceptions import DvcException
 
 class DependencyDoesNotExistError(DvcException):
     def __init__(self, path):
-        msg = "dependency '{}' does not exist".format(path)
+        msg = f"dependency '{path}' does not exist"
         super().__init__(msg)
 
 
 class DependencyIsNotFileOrDirError(DvcException):
     def __init__(self, path):
-        msg = "dependency '{}' is not a file or directory".format(path)
+        msg = f"dependency '{path}' is not a file or directory"
         super().__init__(msg)
 
 
 class DependencyIsStageFileError(DvcException):
     def __init__(self, path):
-        super().__init__(
-            "Stage file '{}' cannot be a dependency.".format(path)
-        )
+        super().__init__(f"Stage file '{path}' cannot be a dependency.")
 
 
-class DependencyBase(object):
+class BaseDependency:
     IS_DEPENDENCY = True
 
     DoesNotExistError = DependencyDoesNotExistError

dvc/dependency/gs.py

@@ -1,6 +1,6 @@
-from dvc.dependency.base import DependencyBase
-from dvc.output.gs import OutputGS
+from dvc.dependency.base import BaseDependency
+from dvc.output.gs import GSOutput
 
 
-class DependencyGS(DependencyBase, OutputGS):
+class GSDependency(BaseDependency, GSOutput):
     pass

dvc/dependency/hdfs.py

@@ -1,6 +1,6 @@
-from dvc.dependency.base import DependencyBase
-from dvc.output.hdfs import OutputHDFS
+from dvc.dependency.base import BaseDependency
+from dvc.output.hdfs import HDFSOutput
 
 
-class DependencyHDFS(DependencyBase, OutputHDFS):
+class HDFSDependency(BaseDependency, HDFSOutput):
     pass

dvc/dependency/http.py

@@ -1,7 +1,8 @@
-from dvc.dependency.base import DependencyBase
-from dvc.output.base import OutputBase
-from dvc.remote.http import RemoteHTTP
+from dvc.dependency.base import BaseDependency
+from dvc.output.base import BaseOutput
+
+from ..tree.http import HTTPTree
 
 
-class DependencyHTTP(DependencyBase, OutputBase):
-    REMOTE = RemoteHTTP
+class HTTPDependency(BaseDependency, BaseOutput):
+    TREE_CLS = HTTPTree

dvc/dependency/https.py

@@ -1,6 +1,6 @@
-from .http import DependencyHTTP
-from dvc.remote.https import RemoteHTTPS
+from ..tree.https import HTTPSTree
+from .http import HTTPDependency
 
 
-class DependencyHTTPS(DependencyHTTP):
-    REMOTE = RemoteHTTPS
+class HTTPSDependency(HTTPDependency):
+    TREE_CLS = HTTPSTree

dvc/dependency/local.py

@@ -1,6 +1,6 @@
-from dvc.dependency.base import DependencyBase
-from dvc.output.local import OutputLOCAL
+from dvc.dependency.base import BaseDependency
+from dvc.output.local import LocalOutput
 
 
-class DependencyLOCAL(DependencyBase, OutputLOCAL):
+class LocalDependency(BaseDependency, LocalOutput):
     pass

dvc/dependency/param.py

@@ -0,0 +1,120 @@
+import os
+from collections import defaultdict
+
+import dpath.util
+import toml
+import yaml
+from voluptuous import Any
+
+from dvc.dependency.local import LocalDependency
+from dvc.exceptions import DvcException
+
+
+class MissingParamsError(DvcException):
+    pass
+
+
+class BadParamFileError(DvcException):
+    pass
+
+
+class ParamsDependency(LocalDependency):
+    PARAM_PARAMS = "params"
+    PARAM_SCHEMA = {PARAM_PARAMS: Any(dict, list, None)}
+    DEFAULT_PARAMS_FILE = "params.yaml"
+    PARAMS_FILE_LOADERS = defaultdict(lambda: yaml.safe_load)
+    PARAMS_FILE_LOADERS.update({".toml": toml.load})
+
+    def __init__(self, stage, path, params):
+        info = {}
+        self.params = []
+        if params:
+            if isinstance(params, list):
+                self.params = params
+            else:
+                assert isinstance(params, dict)
+                self.params = list(params.keys())
+                info = params
+
+        super().__init__(
+            stage,
+            path
+            or os.path.join(stage.repo.root_dir, self.DEFAULT_PARAMS_FILE),
+            info=info,
+        )
+
+    def fill_values(self, values=None):
+        """Load params values dynamically."""
+        if not values:
+            return
+        for param in self.params:
+            if param in values:
+                self.info[param] = values[param]
+
+    def save(self):
+        super().save()
+        self.info = self.save_info()
+
+    def status(self):
+        status = super().status()
+
+        if status[str(self)] == "deleted":
+            return status
+
+        status = defaultdict(dict)
+        info = self.read_params()
+        for param in self.params:
+            if param not in info.keys():
+                st = "deleted"
+            elif param not in self.info:
+                st = "new"
+            elif info[param] != self.info[param]:
+                st = "modified"
+            else:
+                assert info[param] == self.info[param]
+                continue
+
+            status[str(self)][param] = st
+
+        return status
+
+    def dumpd(self):
+        return {
+            self.PARAM_PATH: self.def_path,
+            self.PARAM_PARAMS: self.info or self.params,
+        }
+
+    def read_params(self):
+        if not self.exists:
+            return {}
+
+        with self.repo.tree.open(self.path_info, "r") as fobj:
+            try:
+                config = self.PARAMS_FILE_LOADERS[
+                    self.path_info.suffix.lower()
+                ](fobj)
+            except (yaml.YAMLError, toml.TomlDecodeError) as exc:
+                raise BadParamFileError(
+                    f"Unable to read parameters from '{self}'"
+                ) from exc
+
+        ret = {}
+        for param in self.params:
+            try:
+                ret[param] = dpath.util.get(config, param, separator=".")
+            except KeyError:
+                pass
+        return ret
+
+    def save_info(self):
+        info = self.read_params()
+
+        missing_params = set(self.params) - set(info.keys())
+        if missing_params:
+            raise MissingParamsError(
+                "Parameters '{}' are missing from '{}'.".format(
+                    ", ".join(missing_params), self,
+                )
+            )
+
+        return info

dvc/dependency/repo.py

@@ -2,28 +2,31 @@ import os
 
 from voluptuous import Required
 
-from .local import DependencyLOCAL
 from dvc.exceptions import OutputNotFoundError
 from dvc.path_info import PathInfo
 
+from .local import LocalDependency
 
-class DependencyREPO(DependencyLOCAL):
+
+class RepoDependency(LocalDependency):
     PARAM_REPO = "repo"
     PARAM_URL = "url"
     PARAM_REV = "rev"
     PARAM_REV_LOCK = "rev_lock"
 
     REPO_SCHEMA = {
-        Required(PARAM_URL): str,
-        PARAM_REV: str,
-        PARAM_REV_LOCK: str,
+        PARAM_REPO: {
+            Required(PARAM_URL): str,
+            PARAM_REV: str,
+            PARAM_REV_LOCK: str,
+        }
     }
 
     def __init__(self, def_repo, stage, *args, **kwargs):
         self.def_repo = def_repo
         super().__init__(stage, *args, **kwargs)
 
-    def _parse_path(self, remote, path):
+    def _parse_path(self, tree, path):
         return None
 
     @property
@@ -47,13 +50,22 @@ class DependencyREPO(DependencyLOCAL):
         return external_repo(d["url"], rev=rev)
 
     def _get_checksum(self, locked=True):
+        from dvc.repo.tree import RepoTree
+
         with self._make_repo(locked=locked) as repo:
             try:
                 return repo.find_out_by_relpath(self.def_path).info["md5"]
             except OutputNotFoundError:
                 path = PathInfo(os.path.join(repo.root_dir, self.def_path))
+
+                # we want stream but not fetch, so DVC out directories are
+                # walked, but dir contents is not fetched
+                tree = RepoTree(repo, stream=True)
+
                 # We are polluting our repo cache with some dir listing here
-                return self.repo.cache.local.get_checksum(path)
+                if tree.isdir(path):
+                    return self.repo.cache.local.tree.get_hash(path, tree=tree)
+                return tree.get_file_hash(path)
 
     def status(self):
         current_checksum = self._get_checksum(locked=True)
@@ -73,16 +85,22 @@ class DependencyREPO(DependencyLOCAL):
     def download(self, to):
         with self._make_repo() as repo:
             if self.def_repo.get(self.PARAM_REV_LOCK) is None:
-                self.def_repo[self.PARAM_REV_LOCK] = repo.scm.get_rev()
+                self.def_repo[self.PARAM_REV_LOCK] = repo.get_rev()
 
-            if hasattr(repo, "cache"):
-                repo.cache.local.cache_dir = self.repo.cache.local.cache_dir
-
-            repo.pull_to(self.def_path, to.path_info)
+            cache = self.repo.cache.local
+            with repo.use_cache(cache):
+                _, _, cache_infos = repo.fetch_external([self.def_path])
+            cache.checkout(to.path_info, cache_infos[0])
 
     def update(self, rev=None):
         if rev:
             self.def_repo[self.PARAM_REV] = rev
 
         with self._make_repo(locked=False) as repo:
-            self.def_repo[self.PARAM_REV_LOCK] = repo.scm.get_rev()
+            self.def_repo[self.PARAM_REV_LOCK] = repo.get_rev()
+
+    def changed_checksum(self):
+        # From current repo point of view what describes RepoDependency is its
+        # origin project url and rev_lock, and it makes RepoDependency
+        # immutable, hence its impossible for checksum to change.
+        return False

dvc/dependency/s3.py

@@ -1,6 +1,6 @@
-from dvc.dependency.base import DependencyBase
-from dvc.output.s3 import OutputS3
+from dvc.dependency.base import BaseDependency
+from dvc.output.s3 import S3Output
 
 
-class DependencyS3(DependencyBase, OutputS3):
+class S3Dependency(BaseDependency, S3Output):
     pass

dvc/dependency/ssh.py

@@ -1,6 +1,6 @@
-from dvc.dependency.base import DependencyBase
-from dvc.output.ssh import OutputSSH
+from dvc.dependency.base import BaseDependency
+from dvc.output.ssh import SSHOutput
 
 
-class DependencySSH(DependencyBase, OutputSSH):
+class SSHDependency(BaseDependency, SSHOutput):
     pass

dvc/dvcfile.py

@@ -0,0 +1,308 @@
+import collections
+import contextlib
+import logging
+import os
+
+from voluptuous import MultipleInvalid
+
+from dvc.exceptions import DvcException
+from dvc.stage import serialize
+from dvc.stage.exceptions import (
+    StageFileBadNameError,
+    StageFileDoesNotExistError,
+    StageFileFormatError,
+    StageFileIsNotDvcFileError,
+)
+from dvc.stage.loader import SingleStageLoader, StageLoader
+from dvc.utils import relpath
+from dvc.utils.collections import apply_diff
+from dvc.utils.yaml import dump_yaml, parse_yaml, parse_yaml_for_update
+
+logger = logging.getLogger(__name__)
+
+DVC_FILE = "Dvcfile"
+DVC_FILE_SUFFIX = ".dvc"
+PIPELINE_FILE = "dvc.yaml"
+PIPELINE_LOCK = "dvc.lock"
+
+
+class LockfileCorruptedError(DvcException):
+    pass
+
+
+def is_valid_filename(path):
+    return path.endswith(DVC_FILE_SUFFIX) or os.path.basename(path) in [
+        DVC_FILE,
+        PIPELINE_FILE,
+    ]
+
+
+def is_dvc_file(path):
+    return os.path.isfile(path) and (
+        is_valid_filename(path) or os.path.basename(path) == PIPELINE_LOCK
+    )
+
+
+def check_dvc_filename(path):
+    if not is_valid_filename(path):
+        raise StageFileBadNameError(
+            "bad DVC-file name '{}'. DVC-files should be named "
+            "'Dvcfile' or have a '.dvc' suffix (e.g. '{}.dvc').".format(
+                relpath(path), os.path.basename(path)
+            )
+        )
+
+
+class FileMixin:
+    SCHEMA = None
+
+    def __init__(self, repo, path, **kwargs):
+        self.repo = repo
+        self.path = path
+
+    def __repr__(self):
+        return "{}: {}".format(
+            self.__class__.__name__, relpath(self.path, self.repo.root_dir)
+        )
+
+    def __hash__(self):
+        return hash(self.path)
+
+    def __eq__(self, other):
+        return self.repo == other.repo and os.path.abspath(
+            self.path
+        ) == os.path.abspath(other.path)
+
+    def __str__(self):
+        return f"{self.__class__.__name__}: {self.relpath}"
+
+    @property
+    def relpath(self):
+        return relpath(self.path)
+
+    def exists(self):
+        return self.repo.tree.exists(self.path)
+
+    def _load(self):
+        # it raises the proper exceptions by priority:
+        # 1. when the file doesn't exists
+        # 2. filename is not a DVC-file
+        # 3. path doesn't represent a regular file
+        if not self.exists():
+            raise StageFileDoesNotExistError(self.path)
+        check_dvc_filename(self.path)
+        if not self.repo.tree.isfile(self.path):
+            raise StageFileIsNotDvcFileError(self.path)
+
+        with self.repo.tree.open(self.path) as fd:
+            stage_text = fd.read()
+        d = parse_yaml(stage_text, self.path)
+        self.validate(d, self.relpath)
+        return d, stage_text
+
+    @classmethod
+    def validate(cls, d, fname=None):
+        assert isinstance(cls.SCHEMA, collections.abc.Callable)
+        try:
+            cls.SCHEMA(d)  # pylint: disable=not-callable
+        except MultipleInvalid as exc:
+            raise StageFileFormatError(f"'{fname}' format error: {exc}")
+
+    def remove(self, force=False):  # pylint: disable=unused-argument
+        with contextlib.suppress(FileNotFoundError):
+            os.unlink(self.path)
+
+    def dump(self, stage, **kwargs):
+        raise NotImplementedError
+
+
+class SingleStageFile(FileMixin):
+    from dvc.schema import COMPILED_SINGLE_STAGE_SCHEMA as SCHEMA
+
+    @property
+    def stage(self):
+        data, raw = self._load()
+        return SingleStageLoader.load_stage(self, data, raw)
+
+    @property
+    def stages(self):
+        data, raw = self._load()
+        return SingleStageLoader(self, data, raw)
+
+    def dump(self, stage, **kwargs):
+        """Dumps given stage appropriately in the dvcfile."""
+        from dvc.stage import PipelineStage
+
+        assert not isinstance(stage, PipelineStage)
+        check_dvc_filename(self.path)
+        logger.debug(
+            "Saving information to '{file}'.".format(file=relpath(self.path))
+        )
+        dump_yaml(self.path, serialize.to_single_stage_file(stage))
+        self.repo.scm.track_file(self.relpath)
+
+    def remove_stage(self, stage):  # pylint: disable=unused-argument
+        self.remove()
+
+
+class PipelineFile(FileMixin):
+    """Abstraction for pipelines file, .yaml + .lock combined."""
+
+    from dvc.schema import COMPILED_MULTI_STAGE_SCHEMA as SCHEMA
+
+    @property
+    def _lockfile(self):
+        return Lockfile(self.repo, os.path.splitext(self.path)[0] + ".lock")
+
+    def dump(
+        self, stage, update_pipeline=False, no_lock=False, **kwargs
+    ):  # pylint: disable=arguments-differ
+        """Dumps given stage appropriately in the dvcfile."""
+        from dvc.stage import PipelineStage
+
+        assert isinstance(stage, PipelineStage)
+        check_dvc_filename(self.path)
+
+        if update_pipeline and not stage.is_data_source:
+            self._dump_pipeline_file(stage)
+
+        if not no_lock:
+            self._dump_lockfile(stage)
+
+    def _dump_lockfile(self, stage):
+        self._lockfile.dump(stage)
+
+    def _dump_pipeline_file(self, stage):
+        data = {}
+        if self.exists():
+            with open(self.path) as fd:
+                data = parse_yaml_for_update(fd.read(), self.path)
+        else:
+            logger.info("Creating '%s'", self.relpath)
+            open(self.path, "w+").close()
+
+        data["stages"] = data.get("stages", {})
+        stage_data = serialize.to_pipeline_file(stage)
+        existing_entry = stage.name in data["stages"]
+
+        action = "Modifying" if existing_entry else "Adding"
+        logger.info("%s stage '%s' in '%s'", action, stage.name, self.relpath)
+
+        if existing_entry:
+            orig_stage_data = data["stages"][stage.name]
+            if "meta" in orig_stage_data:
+                stage_data[stage.name]["meta"] = orig_stage_data["meta"]
+            apply_diff(stage_data[stage.name], orig_stage_data)
+        else:
+            data["stages"].update(stage_data)
+
+        dump_yaml(self.path, data)
+        self.repo.scm.track_file(self.relpath)
+
+    @property
+    def stage(self):
+        raise DvcException(
+            "PipelineFile has multiple stages. Please specify it's name."
+        )
+
+    @property
+    def stages(self):
+        data, _ = self._load()
+        lockfile_data = self._lockfile.load()
+        return StageLoader(self, data.get("stages", {}), lockfile_data)
+
+    def remove(self, force=False):
+        if not force:
+            logger.warning("Cannot remove pipeline file.")
+            return
+
+        super().remove()
+        self._lockfile.remove()
+
+    def remove_stage(self, stage):
+        self._lockfile.remove_stage(stage)
+        if not self.exists():
+            return
+
+        with open(self.path, "r") as f:
+            d = parse_yaml_for_update(f.read(), self.path)
+
+        self.validate(d, self.path)
+        if stage.name not in d.get("stages", {}):
+            return
+
+        logger.debug("Removing '%s' from '%s'", stage.name, self.path)
+        del d["stages"][stage.name]
+
+        if d["stages"]:
+            dump_yaml(self.path, d)
+        else:
+            super().remove()
+
+
+class Lockfile(FileMixin):
+    from dvc.schema import COMPILED_LOCKFILE_SCHEMA as SCHEMA
+
+    def load(self):
+        if not self.exists():
+            return {}
+        with self.repo.tree.open(self.path) as fd:
+            data = parse_yaml(fd.read(), self.path)
+        try:
+            self.validate(data, fname=self.relpath)
+        except StageFileFormatError:
+            raise LockfileCorruptedError(
+                f"Lockfile '{self.relpath}' is corrupted."
+            )
+        return data
+
+    def dump(self, stage, **kwargs):
+        stage_data = serialize.to_lockfile(stage)
+        if not self.exists():
+            modified = True
+            logger.info("Generating lock file '%s'", self.relpath)
+            data = stage_data
+            open(self.path, "w+").close()
+        else:
+            with self.repo.tree.open(self.path, "r") as fd:
+                data = parse_yaml_for_update(fd.read(), self.path)
+            modified = data.get(stage.name, {}) != stage_data.get(
+                stage.name, {}
+            )
+            if modified:
+                logger.info("Updating lock file '%s'", self.relpath)
+            data.update(stage_data)
+        dump_yaml(self.path, data)
+        if modified:
+            self.repo.scm.track_file(self.relpath)
+
+    def remove_stage(self, stage):
+        if not self.exists():
+            return
+
+        with open(self.path) as f:
+            d = parse_yaml_for_update(f.read(), self.path)
+        self.validate(d, self.path)
+
+        if stage.name not in d:
+            return
+
+        logger.debug("Removing '%s' from '%s'", stage.name, self.path)
+        del d[stage.name]
+
+        if d:
+            dump_yaml(self.path, d)
+        else:
+            self.remove()
+
+
+class Dvcfile:
+    def __new__(cls, repo, path, **kwargs):
+        assert path
+        assert repo
+
+        _, ext = os.path.splitext(path)
+        if ext in [".yaml", ".yml"]:
+            return PipelineFile(repo, path, **kwargs)
+        # fallback to single stage file for better error messages
+        return SingleStageFile(repo, path, **kwargs)

dvc/exceptions.py

@@ -1,11 +1,16 @@
 """Exceptions raised by the dvc."""
+from funcy import first
 
-from dvc.utils import relpath, format_link
+from dvc.utils import format_link, relpath
 
 
 class DvcException(Exception):
     """Base class for all dvc exceptions."""
 
+    def __init__(self, msg, *args):
+        assert msg
+        super().__init__(msg, *args)
+
 
 class InvalidArgumentError(ValueError, DvcException):
     """Thrown if arguments are invalid."""
@@ -23,12 +28,17 @@ class OutputDuplicationError(DvcException):
     def __init__(self, output, stages):
         assert isinstance(output, str)
         assert all(hasattr(stage, "relpath") for stage in stages)
-        msg = (
-            "file/directory '{}' is specified as an output in more than one "
-            "stage: {}\n"
-            "This is not allowed. Consider using a different output name."
-        ).format(output, "\n    ".join(s.relpath for s in stages))
+        if len(stages) == 1:
+            msg = "output '{}' is already specified in {}.".format(
+                output, first(stages)
+            )
+        else:
+            msg = "output '{}' is already specified in stages:\n{}".format(
+                output, "\n".join(f"\t- {s.addressing}" for s in stages),
+            )
         super().__init__(msg)
+        self.stages = stages
+        self.output = output
 
 
 class OutputNotFoundError(DvcException):
@@ -60,8 +70,8 @@ class StagePathAsOutputError(DvcException):
     def __init__(self, stage, output):
         assert isinstance(output, str)
         super().__init__(
-            "'{stage}' is within an output '{output}' of another stage".format(
-                stage=stage.relpath, output=output
+            "{stage} is within an output '{output}' of another stage".format(
+                stage=stage, output=output
             )
         )
 
@@ -77,10 +87,7 @@ class CircularDependencyError(DvcException):
     def __init__(self, dependency):
         assert isinstance(dependency, str)
 
-        msg = (
-            "file/directory '{}' is specified as an output and as a "
-            "dependency."
-        )
+        msg = "'{}' is specified as an output and as a dependency."
         super().__init__(msg.format(dependency))
 
 
@@ -94,7 +101,7 @@ class ArgumentDuplicationError(DvcException):
 
     def __init__(self, path):
         assert isinstance(path, str)
-        super().__init__("file '{}' is specified more than once.".format(path))
+        super().__init__(f"file '{path}' is specified more than once.")
 
 
 class MoveNotDataSourceError(DvcException):
@@ -129,12 +136,8 @@ class DvcParserError(DvcException):
 class CyclicGraphError(DvcException):
     def __init__(self, stages):
         assert isinstance(stages, list)
-        stages = "\n".join("\t- {}".format(stage.relpath) for stage in stages)
-        msg = (
-            "you've introduced a cycle in your pipeline that involves "
-            "the following stages:"
-            "\n"
-            "{stages}".format(stages=stages)
+        msg = "Pipeline has a cycle involving: {}.".format(
+            ", ".join(s.addressing for s in stages)
         )
         super().__init__(msg)
 
@@ -142,7 +145,7 @@ class CyclicGraphError(DvcException):
 class ConfirmRemoveError(DvcException):
     def __init__(self, path):
         super().__init__(
-            "unable to remove '{}' without a confirmation from the user. Use "
+            "unable to remove '{}' without a confirmation. Use "
             "`-f` to force.".format(path)
         )
 
@@ -154,7 +157,7 @@ class InitError(DvcException):
 class ReproductionError(DvcException):
     def __init__(self, dvc_file_name):
         self.path = dvc_file_name
-        super().__init__("failed to reproduce '{}'".format(dvc_file_name))
+        super().__init__(f"failed to reproduce '{dvc_file_name}'")
 
 
 class BadMetricError(DvcException):
@@ -162,7 +165,7 @@ class BadMetricError(DvcException):
         super().__init__(
             "the following metrics do not exist, "
             "are not metric files or are malformed: {paths}".format(
-                paths=", ".join("'{}'".format(path) for path in paths)
+                paths=", ".join(f"'{path}'" for path in paths)
             )
         )
 
@@ -170,17 +173,24 @@ class BadMetricError(DvcException):
 class NoMetricsError(DvcException):
     def __init__(self):
         super().__init__(
-            "no metric files in this repository. "
-            "Use `dvc metrics add` to add a metric file to track."
+            "no metric files in this repository. Use `-m/-M` options for "
+            "`dvc run` to mark stage outputs as  metrics."
         )
 
 
-class StageFileCorruptedError(DvcException):
+class NoPlotsError(DvcException):
+    def __init__(self):
+        super().__init__(
+            "no plots in this repository. Use `--plots/--plots-no-cache` "
+            "options for `dvc run` to mark stage outputs as plots."
+        )
+
+
+class YAMLFileCorruptedError(DvcException):
     def __init__(self, path):
         path = relpath(path)
         super().__init__(
-            "unable to read DVC-file: {} "
-            "YAML file structure is corrupted".format(path)
+            f"unable to read: '{path}', YAML file structure is corrupted"
         )
 
 
@@ -200,7 +210,7 @@ class OverlappingOutputPathsError(DvcException):
 
 class CheckoutErrorSuggestGit(DvcException):
     def __init__(self, target):
-        super().__init__("Did you mean `git checkout {}`?".format(target))
+        super().__init__(f"Did you mean `git checkout {target}`?")
 
 
 class ETagMismatchError(DvcException):
@@ -212,10 +222,11 @@ class ETagMismatchError(DvcException):
 
 
 class FileMissingError(DvcException):
-    def __init__(self, path):
+    def __init__(self, path, hint=None):
         self.path = path
+        hint = "" if hint is None else f". {hint}"
         super().__init__(
-            "Can't find '{}' neither locally nor on remote".format(path)
+            f"Can't find '{path}' neither locally nor on remote{hint}"
         )
 
 
@@ -241,18 +252,14 @@ class DownloadError(DvcException):
     def __init__(self, amount):
         self.amount = amount
 
-        super().__init__(
-            "{amount} files failed to download".format(amount=amount)
-        )
+        super().__init__(f"{amount} files failed to download")
 
 
 class UploadError(DvcException):
     def __init__(self, amount):
         self.amount = amount
 
-        super().__init__(
-            "{amount} files failed to upload".format(amount=amount)
-        )
+        super().__init__(f"{amount} files failed to upload")
 
 
 class CheckoutError(DvcException):
@@ -274,7 +281,7 @@ class CollectCacheError(DvcException):
 class NoRemoteInExternalRepoError(DvcException):
     def __init__(self, url):
         super().__init__(
-            "No DVC remote is specified in target repository '{}'.".format(url)
+            f"No DVC remote is specified in target repository '{url}'."
         )
 
 
@@ -289,7 +296,7 @@ class NoOutputInExternalRepoError(DvcException):
 
 class HTTPError(DvcException):
     def __init__(self, code, reason):
-        super().__init__("'{} {}'".format(code, reason))
+        super().__init__(f"'{code} {reason}'")
 
 
 class PathMissingError(DvcException):
@@ -297,19 +304,15 @@ class PathMissingError(DvcException):
         "The path '{}' does not exist in the target repository '{}'"
         " neither as a DVC output nor as a Git-tracked file."
     )
-    default_msg_output_only = (
+    default_msg_dvc_only = (
         "The path '{}' does not exist in the target repository '{}'"
         " as an DVC output."
     )
 
-    def __init__(self, path, repo, output_only=False):
-        msg = (
-            self.default_msg
-            if not output_only
-            else self.default_msg_output_only
-        )
+    def __init__(self, path, repo, dvc_only=False):
+        msg = self.default_msg if not dvc_only else self.default_msg_dvc_only
         super().__init__(msg.format(path, repo))
-        self.output_only = output_only
+        self.dvc_only = dvc_only
 
 
 class RemoteCacheRequiredError(DvcException):
@@ -327,5 +330,17 @@ class RemoteCacheRequiredError(DvcException):
         )
 
 
-class IsADirectoryError(DvcException):
+class IsADirectoryError(DvcException):  # noqa,pylint:disable=redefined-builtin
     """Raised when a file operation is requested on a directory."""
+
+
+class NoOutputOrStageError(DvcException):
+    """
+    Raised when the target is neither an output nor a stage name in dvc.yaml
+    """
+
+    def __init__(self, target, file):
+        super().__init__(
+            f"'{target}' "
+            f"does not exist as an output or a stage name in '{file}'"
+        )

dvc/external_repo.py

@@ -1,23 +1,28 @@
 import logging
 import os
 import tempfile
+import threading
 from contextlib import contextmanager
 from distutils.dir_util import copy_tree
-import threading
+from typing import Iterable
 
-from funcy import retry, suppress, wrap_with, cached_property
+from funcy import cached_property, retry, wrap_with
 
-from dvc.path_info import PathInfo
-from dvc.compat import fspath
-from dvc.repo import Repo
 from dvc.config import NoRemoteError, NotDvcRepoError
-from dvc.exceptions import NoRemoteInExternalRepoError, CheckoutError
-from dvc.exceptions import OutputNotFoundError, NoOutputInExternalRepoError
-from dvc.exceptions import FileMissingError, PathMissingError
-from dvc.utils.fs import remove, fs_copy, move
-from dvc.utils import tmp_fname
+from dvc.exceptions import (
+    FileMissingError,
+    NoOutputInExternalRepoError,
+    NoRemoteInExternalRepoError,
+    OutputNotFoundError,
+    PathMissingError,
+)
+from dvc.path_info import PathInfo
+from dvc.repo import Repo
+from dvc.repo.tree import RepoTree
+from dvc.scm.base import CloneError
 from dvc.scm.git import Git
-
+from dvc.tree.local import LocalTree
+from dvc.utils.fs import remove
 
 logger = logging.getLogger(__name__)
 
@@ -26,10 +31,15 @@ logger = logging.getLogger(__name__)
 def external_repo(url, rev=None, for_write=False):
     logger.debug("Creating external repo %s@%s", url, rev)
     path = _cached_clone(url, rev, for_write=for_write)
+    if not rev:
+        # Local HEAD points to the tip of whatever branch we first cloned from
+        # (which may not be the default branch), use origin/HEAD here to get
+        # the tip of the default branch
+        rev = "refs/remotes/origin/HEAD"
     try:
-        repo = ExternalRepo(path, url)
+        repo = ExternalRepo(path, url, rev, for_write=for_write)
     except NotDvcRepoError:
-        repo = ExternalGitRepo(path, url)
+        repo = ExternalGitRepo(path, url, rev)
 
     try:
         yield repo
@@ -53,7 +63,7 @@ CACHE_DIRS = {}
 
 def clean_repos():
     # Outside code should not see cache while we are removing
-    paths = list(CLONES.values()) + list(CACHE_DIRS.values())
+    paths = [path for path, _ in CLONES.values()] + list(CACHE_DIRS.values())
     CLONES.clear()
     CACHE_DIRS.clear()
 
@@ -61,59 +71,102 @@ def clean_repos():
         _remove(path)
 
 
-class ExternalRepo(Repo):
-    def __init__(self, root_dir, url):
-        super().__init__(root_dir)
+class BaseExternalRepo:
+    # pylint: disable=no-member
+
+    _local_cache = None
+
+    def __str__(self):
+        return self.url
+
+    @property
+    def local_cache(self):
+        if hasattr(self, "cache"):
+            return self.cache.local
+        return self._local_cache
+
+    @contextmanager
+    def use_cache(self, cache):
+        """Use the specified cache in place of default tmpdir cache for
+        download operations.
+        """
+        if hasattr(self, "cache"):
+            save_cache = self.cache.local
+            self.cache.local = cache
+        self._local_cache = cache
+
+        yield
+
+        if hasattr(self, "cache"):
+            self.cache.local = save_cache
+        self._local_cache = None
+
+    @cached_property
+    def repo_tree(self):
+        return RepoTree(self, fetch=True)
+
+    def get_rev(self):
+        if isinstance(self.tree, LocalTree):
+            return self.scm.get_rev()
+        return self.tree.rev
+
+    def fetch_external(self, paths: Iterable, **kwargs):
+        """Fetch specified external repo paths into cache.
+
+        Returns 3-tuple in the form
+            (downloaded, failed, list(cache_infos))
+        where cache_infos can be used as checkout targets for the
+        fetched paths.
+        """
+        download_results = []
+        failed = 0
+
+        paths = [PathInfo(self.root_dir) / path for path in paths]
+
+        def download_update(result):
+            download_results.append(result)
+
+        save_infos = []
+        for path in paths:
+            if not self.repo_tree.exists(path):
+                raise PathMissingError(path, self.url)
+            save_info = self.local_cache.save(
+                path,
+                self.repo_tree,
+                None,
+                save_link=False,
+                download_callback=download_update,
+            )
+            save_infos.append(save_info)
+
+        return sum(download_results), failed, save_infos
+
+    def get_external(self, path, dest):
+        """Convenience wrapper for fetch_external and checkout."""
+        if self.local_cache:
+            # fetch DVC and git files to tmpdir cache, then checkout
+            _, _, save_infos = self.fetch_external([path])
+            self.local_cache.checkout(PathInfo(dest), save_infos[0])
+        else:
+            # git-only erepo with no cache, just copy files directly
+            # to dest
+            path = PathInfo(self.root_dir) / path
+            if not self.repo_tree.exists(path):
+                raise PathMissingError(path, self.url)
+            self.repo_tree.copytree(path, dest)
+
+
+class ExternalRepo(Repo, BaseExternalRepo):
+    def __init__(self, root_dir, url, rev, for_write=False):
+        if for_write:
+            super().__init__(root_dir)
+        else:
+            root_dir = os.path.realpath(root_dir)
+            super().__init__(root_dir, scm=Git(root_dir), rev=rev)
         self.url = url
         self._set_cache_dir()
         self._fix_upstream()
 
-    def pull_to(self, path, to_info):
-        """
-        Pull the corresponding file or directory specified by `path` and
-        checkout it into `to_info`.
-
-        It works with files tracked by Git and DVC, and also local files
-        outside the repository.
-        """
-        out = None
-        path_info = PathInfo(self.root_dir) / path
-
-        with suppress(OutputNotFoundError):
-            (out,) = self.find_outs_by_path(fspath(path_info), strict=False)
-
-        try:
-            if out and out.use_cache:
-                self._pull_cached(out, path_info, to_info)
-                return
-
-            # Check if it is handled by Git (it can't have an absolute path)
-            if os.path.isabs(path):
-                raise FileNotFoundError
-
-            fs_copy(fspath(path_info), fspath(to_info))
-        except FileNotFoundError:
-            raise PathMissingError(path, self.url)
-
-    def _pull_cached(self, out, path_info, dest):
-        with self.state:
-            tmp = PathInfo(tmp_fname(dest))
-            src = tmp / path_info.relative_to(out.path_info)
-
-            out.path_info = tmp
-
-            # Only pull unless all needed cache is present
-            if out.changed_cache(filter_info=src):
-                self.cloud.pull(out.get_used_cache(filter_info=src))
-
-            try:
-                out.checkout(filter_info=src)
-            except CheckoutError:
-                raise FileNotFoundError
-
-            move(src, dest)
-            remove(tmp)
-
     @wrap_with(threading.Lock())
     def _set_cache_dir(self):
         try:
@@ -122,14 +175,23 @@ class ExternalRepo(Repo):
             cache_dir = CACHE_DIRS[self.url] = tempfile.mkdtemp("dvc-cache")
 
         self.cache.local.cache_dir = cache_dir
+        self._local_cache = self.cache.local
 
     def _fix_upstream(self):
         if not os.path.isdir(self.url):
             return
 
-        remote_name = self.config["core"].get("remote")
-        src_repo = Repo(self.url)
         try:
+            src_repo = Repo(self.url)
+        except NotDvcRepoError:
+            # If ExternalRepo does not throw NotDvcRepoError and Repo does,
+            # the self.url might be a bare git repo.
+            # NOTE: This will fail to resolve remote with relative path,
+            # same as if it was a remote DVC repo.
+            return
+
+        try:
+            remote_name = self.config["core"].get("remote")
             if remote_name:
                 self._fix_local_remote(src_repo, remote_name)
             else:
@@ -154,10 +216,11 @@ class ExternalRepo(Repo):
         self.config["core"]["remote"] = "auto-generated-upstream"
 
 
-class ExternalGitRepo:
-    def __init__(self, root_dir, url):
-        self.root_dir = root_dir
+class ExternalGitRepo(BaseExternalRepo):
+    def __init__(self, root_dir, url, rev):
+        self.root_dir = os.path.realpath(root_dir)
         self.url = url
+        self.tree = self.scm.get_tree(rev)
 
     @cached_property
     def scm(self):
@@ -170,22 +233,15 @@ class ExternalGitRepo:
     def find_out_by_relpath(self, path):
         raise OutputNotFoundError(path, self)
 
-    def pull_to(self, path, to_info):
-        try:
-            # Git handled files can't have absolute path
-            if os.path.isabs(path):
-                raise FileNotFoundError
-
-            fs_copy(os.path.join(self.root_dir, path), fspath(to_info))
-        except FileNotFoundError:
-            raise PathMissingError(path, self.url)
-
     @contextmanager
     def open_by_relpath(self, path, mode="r", encoding=None, **kwargs):
+        """Opens a specified resource as a file object."""
+        tree = RepoTree(self)
         try:
-            abs_path = os.path.join(self.root_dir, path)
-            with open(abs_path, mode, encoding=encoding) as fd:
-                yield fd
+            with tree.open(
+                path, mode=mode, encoding=encoding, **kwargs
+            ) as fobj:
+                yield fobj
         except FileNotFoundError:
             raise PathMissingError(path, self.url)
 
@@ -197,14 +253,12 @@ def _cached_clone(url, rev, for_write=False):
     revision checked out. If for_write is set prevents reusing this dir via
     cache.
     """
-    if not for_write and Git.is_sha(rev) and (url, rev) in CLONES:
-        return CLONES[url, rev]
+    # even if we have already cloned this repo, we may need to
+    # fetch/fast-forward to get specified rev
+    clone_path, shallow = _clone_default_branch(url, rev, for_write=for_write)
 
-    clone_path = _clone_default_branch(url, rev)
-    rev_sha = Git(clone_path).resolve_rev(rev or "HEAD")
-
-    if not for_write and (url, rev_sha) in CLONES:
-        return CLONES[url, rev_sha]
+    if not for_write and (url) in CLONES:
+        return CLONES[url][0]
 
     # Copy to a new dir to keep the clone clean
     repo_path = tempfile.mkdtemp("dvc-erepo")
@@ -212,21 +266,20 @@ def _cached_clone(url, rev, for_write=False):
     copy_tree(clone_path, repo_path)
 
     # Check out the specified revision
-    if rev is not None:
+    if for_write:
         _git_checkout(repo_path, rev)
-
-    if not for_write:
-        CLONES[url, rev_sha] = repo_path
+    else:
+        CLONES[url] = (repo_path, shallow)
     return repo_path
 
 
 @wrap_with(threading.Lock())
-def _clone_default_branch(url, rev):
+def _clone_default_branch(url, rev, for_write=False):
     """Get or create a clean clone of the url.
 
     The cloned is reactualized with git pull unless rev is a known sha.
     """
-    clone_path = CLONES.get(url)
+    clone_path, shallow = CLONES.get(url, (None, False))
 
     git = None
     try:
@@ -234,18 +287,55 @@ def _clone_default_branch(url, rev):
             git = Git(clone_path)
             # Do not pull for known shas, branches and tags might move
             if not Git.is_sha(rev) or not git.has_rev(rev):
-                logger.debug("erepo: git pull %s", url)
-                git.pull()
+                if shallow:
+                    # If we are missing a rev in a shallow clone, fallback to
+                    # a full (unshallowed) clone. Since fetching specific rev
+                    # SHAs is only available in certain git versions, if we
+                    # have need to reference multiple specific revs for a
+                    # given repo URL it is easier/safer for us to work with
+                    # full clones in this case.
+                    logger.debug("erepo: unshallowing clone for '%s'", url)
+                    _unshallow(git)
+                    shallow = False
+                    CLONES[url] = (clone_path, shallow)
+                else:
+                    logger.debug("erepo: git pull '%s'", url)
+                    git.pull()
         else:
-            logger.debug("erepo: git clone %s to a temporary dir", url)
+            logger.debug("erepo: git clone '%s' to a temporary dir", url)
             clone_path = tempfile.mkdtemp("dvc-clone")
-            git = Git.clone(url, clone_path)
-            CLONES[url] = clone_path
+            if not for_write and rev and not Git.is_sha(rev):
+                # If rev is a tag or branch name try shallow clone first
+                try:
+                    git = Git.clone(url, clone_path, shallow_branch=rev)
+                    shallow = True
+                    logger.debug(
+                        "erepo: using shallow clone for branch '%s'", rev
+                    )
+                except CloneError:
+                    pass
+            if not git:
+                git = Git.clone(url, clone_path)
+                shallow = False
+            CLONES[url] = (clone_path, shallow)
     finally:
         if git:
             git.close()
 
-    return clone_path
+    return clone_path, shallow
+
+
+def _unshallow(git):
+    if git.repo.head.is_detached:
+        # If this is a detached head (i.e. we shallow cloned a tag) switch to
+        # the default branch
+        origin_refs = git.repo.remotes["origin"].refs
+        ref = origin_refs["HEAD"].reference
+        branch_name = ref.name.split("/")[-1]
+        branch = git.repo.create_head(branch_name, ref)
+        branch.set_tracking_branch(ref)
+        branch.checkout()
+    git.pull(unshallow=True)
 
 
 def _git_checkout(repo_path, rev):

dvc/ignore.py

@@ -1,17 +1,21 @@
 import logging
 import os
+import re
+from itertools import groupby, takewhile
 
-from funcy import cached_property
-from pathspec import PathSpec
 from pathspec.patterns import GitWildMatchPattern
+from pathspec.util import normalize_file
+from pygtrie import StringTrie
 
-from dvc.scm.tree import BaseTree
+from dvc.path_info import PathInfo
+from dvc.pathspec_math import merge_patterns
+from dvc.system import System
 from dvc.utils import relpath
 
 logger = logging.getLogger(__name__)
 
 
-class DvcIgnore(object):
+class DvcIgnore:
     DVCIGNORE_FILE = ".dvcignore"
 
     def __call__(self, root, dirs, files):
@@ -19,124 +23,225 @@ class DvcIgnore(object):
 
 
 class DvcIgnorePatterns(DvcIgnore):
-    def __init__(self, ignore_file_path, tree):
+    def __init__(self, pattern_list, dirname):
+
+        self.pattern_list = pattern_list
+        self.dirname = dirname
+        self.prefix = self.dirname + os.sep
+
+        regex_pattern_list = map(
+            GitWildMatchPattern.pattern_to_regex, pattern_list
+        )
+
+        self.ignore_spec = [
+            (ignore, re.compile("|".join(item[0] for item in group)))
+            for ignore, group in groupby(regex_pattern_list, lambda x: x[1])
+            if ignore is not None
+        ]
+
+    @classmethod
+    def from_files(cls, ignore_file_path, tree):
         assert os.path.isabs(ignore_file_path)
-
-        self.ignore_file_path = ignore_file_path
-        self.dirname = os.path.normpath(os.path.dirname(ignore_file_path))
-
+        dirname = os.path.normpath(os.path.dirname(ignore_file_path))
         with tree.open(ignore_file_path, encoding="utf-8") as fobj:
-            self.ignore_spec = PathSpec.from_lines(GitWildMatchPattern, fobj)
+            path_spec_lines = [
+                line for line in map(str.strip, fobj.readlines()) if line
+            ]
+
+        return cls(path_spec_lines, dirname)
 
     def __call__(self, root, dirs, files):
         files = [f for f in files if not self.matches(root, f)]
-        dirs = [d for d in dirs if not self.matches(root, d)]
+        dirs = [d for d in dirs if not self.matches(root, d, True)]
 
         return dirs, files
 
-    def matches(self, dirname, basename):
-        abs_path = os.path.join(dirname, basename)
-        rel_path = relpath(abs_path, self.dirname)
-
-        if os.pardir + os.sep in rel_path:
+    def matches(self, dirname, basename, is_dir=False):
+        # NOTE: `relpath` is too slow, so we have to assume that both
+        # `dirname` and `self.dirname` are relative or absolute together.
+        if dirname == self.dirname:
+            path = basename
+        elif dirname.startswith(self.prefix):
+            rel = dirname[len(self.prefix) :]
+            # NOTE: `os.path.join` is ~x5.5 slower
+            path = f"{rel}{os.sep}{basename}"
+        else:
             return False
-        return self.ignore_spec.match_file(rel_path)
+
+        if not System.is_unix():
+            path = normalize_file(path)
+        return self.ignore(path, is_dir)
+
+    def ignore(self, path, is_dir):
+        result = False
+        if is_dir:
+            path_dir = f"{path}/"
+            for ignore, pattern in self.ignore_spec:
+                if pattern.match(path) or pattern.match(path_dir):
+                    result = ignore
+        else:
+            for ignore, pattern in self.ignore_spec:
+                if pattern.match(path):
+                    result = ignore
+        return result
 
     def __hash__(self):
-        return hash(self.ignore_file_path)
+        return hash(self.dirname + ":" + "\n".join(self.pattern_list))
 
     def __eq__(self, other):
         if not isinstance(other, DvcIgnorePatterns):
             return NotImplemented
+        return (self.dirname == other.dirname) & (
+            self.pattern_list == other.pattern_list
+        )
 
-        return self.ignore_file_path == other.ignore_file_path
+    def __bool__(self):
+        return bool(self.pattern_list)
 
 
-class DvcIgnoreDirs(DvcIgnore):
-    def __init__(self, basenames):
-        self.basenames = set(basenames)
+class DvcIgnoreFilterNoop:
+    def __init__(self, tree, root_dir):
+        pass
 
     def __call__(self, root, dirs, files):
-        dirs = [d for d in dirs if d not in self.basenames]
-
         return dirs, files
 
-    def __hash__(self):
-        return hash(tuple(self.basenames))
+    def is_ignored_dir(self, _):
+        return False
 
-    def __eq__(self, other):
-        if not isinstance(other, DvcIgnoreDirs):
-            return NotImplemented
-
-        return self.basenames == other.basenames
+    def is_ignored_file(self, _):
+        return False
 
 
-class DvcIgnoreRepo(DvcIgnore):
-    def __call__(self, root, dirs, files):
-        def is_dvc_repo(directory):
-            from dvc.repo import Repo
+class DvcIgnoreFilter:
+    @staticmethod
+    def _is_dvc_repo(root, directory):
+        from dvc.repo import Repo
 
-            return os.path.isdir(os.path.join(directory, Repo.DVC_DIR))
+        return os.path.isdir(os.path.join(root, directory, Repo.DVC_DIR))
 
-        dirs = [d for d in dirs if not is_dvc_repo(d)]
+    def __init__(self, tree, root_dir):
+        from dvc.repo import Repo
 
-        return dirs, files
+        default_ignore_patterns = [".hg/", ".git/", "{}/".format(Repo.DVC_DIR)]
 
-
-class DvcIgnoreFilter(object):
-    def __init__(self, tree):
         self.tree = tree
-        self.ignores = {
-            DvcIgnoreDirs([".git", ".hg", ".dvc"]),
-            DvcIgnoreRepo(),
-        }
-        for root, dirs, files in self.tree.walk(self.tree.tree_root):
-            self._update(root)
-            dirs[:], files[:] = self(root, dirs, files)
+        self.root_dir = root_dir
+        self.ignores_trie_tree = StringTrie(separator=os.sep)
+        self.ignores_trie_tree[root_dir] = DvcIgnorePatterns(
+            default_ignore_patterns, root_dir
+        )
+        self._update(self.root_dir)
 
     def _update(self, dirname):
+        old_pattern = self.ignores_trie_tree.longest_prefix(dirname).value
+        matches = old_pattern.matches(dirname, DvcIgnore.DVCIGNORE_FILE, False)
+
         ignore_file_path = os.path.join(dirname, DvcIgnore.DVCIGNORE_FILE)
-        if self.tree.exists(ignore_file_path):
-            self.ignores.add(DvcIgnorePatterns(ignore_file_path, self.tree))
+        if not matches and self.tree.exists(
+            ignore_file_path, use_dvcignore=False
+        ):
+            new_pattern = DvcIgnorePatterns.from_files(
+                ignore_file_path, self.tree
+            )
+            if old_pattern:
+                self.ignores_trie_tree[dirname] = DvcIgnorePatterns(
+                    *merge_patterns(
+                        old_pattern.pattern_list,
+                        old_pattern.dirname,
+                        new_pattern.pattern_list,
+                        new_pattern.dirname,
+                    )
+                )
+            else:
+                self.ignores_trie_tree[dirname] = new_pattern
+        elif old_pattern:
+            self.ignores_trie_tree[dirname] = old_pattern
+
+        # NOTE: using `walk` + `break` because tree doesn't have `listdir()`
+        for root, dirs, _ in self.tree.walk(dirname, use_dvcignore=False):
+            self._update_sub_repo(root, dirs)
+            break
+
+    def _update_sub_repo(self, root, dirs):
+        for d in dirs:
+            if self._is_dvc_repo(root, d):
+                old_pattern = self.ignores_trie_tree.longest_prefix(root).value
+                if old_pattern:
+                    self.ignores_trie_tree[root] = DvcIgnorePatterns(
+                        *merge_patterns(
+                            old_pattern.pattern_list,
+                            old_pattern.dirname,
+                            ["/{}/".format(d)],
+                            root,
+                        )
+                    )
+                else:
+                    self.ignores_trie_tree[root] = DvcIgnorePatterns(
+                        ["/{}/".format(d)], root
+                    )
 
     def __call__(self, root, dirs, files):
-        for ignore in self.ignores:
-            dirs, files = ignore(root, dirs, files)
+        ignore_pattern = self._get_trie_pattern(root)
+        if ignore_pattern:
+            return ignore_pattern(root, dirs, files)
+        else:
+            return dirs, files
 
-        return dirs, files
+    def _get_trie_pattern(self, dirname):
+        ignore_pattern = self.ignores_trie_tree.get(dirname)
+        if ignore_pattern:
+            return ignore_pattern
 
+        prefix = self.ignores_trie_tree.longest_prefix(dirname).key
+        if not prefix:
+            # outside of the repo
+            return None
 
-class CleanTree(BaseTree):
-    def __init__(self, tree):
-        self.tree = tree
+        dirs = list(
+            takewhile(
+                lambda path: path != prefix,
+                (parent.fspath for parent in PathInfo(dirname).parents),
+            )
+        )
+        dirs.reverse()
+        dirs.append(dirname)
 
-    @cached_property
-    def dvcignore(self):
-        return DvcIgnoreFilter(self.tree)
+        for parent in dirs:
+            self._update(parent)
 
-    @property
-    def tree_root(self):
-        return self.tree.tree_root
+        return self.ignores_trie_tree.get(dirname)
 
-    def open(self, path, mode="r", encoding="utf-8"):
-        return self.tree.open(path, mode, encoding)
+    def _is_ignored(self, path, is_dir=False):
+        if self._outside_repo(path):
+            return True
+        dirname, basename = os.path.split(os.path.normpath(path))
+        ignore_pattern = self._get_trie_pattern(dirname)
+        if ignore_pattern:
+            return ignore_pattern.matches(dirname, basename, is_dir)
+        else:
+            return False
 
-    def exists(self, path):
-        return self.tree.exists(path)
+    def is_ignored_dir(self, path):
+        path = os.path.abspath(path)
+        if path == self.root_dir:
+            return False
 
-    def isdir(self, path):
-        return self.tree.isdir(path)
+        return self._is_ignored(path, True)
 
-    def isfile(self, path):
-        return self.tree.isfile(path)
+    def is_ignored_file(self, path):
+        return self._is_ignored(path, False)
 
-    def walk(self, top, topdown=True):
-        for root, dirs, files in self.tree.walk(top, topdown):
-            dirs[:], files[:] = self.dvcignore(root, dirs, files)
+    def _outside_repo(self, path):
+        path = PathInfo(path)
 
-            yield root, dirs, files
-
-    def walk_files(self, top):
-        for root, _, files in self.walk(top):
-            for file in files:
-                yield os.path.join(root, file)
+        # paths outside of the repo should be ignored
+        path = relpath(path, self.root_dir)
+        if path.startswith("..") or (
+            os.name == "nt"
+            and not os.path.commonprefix(
+                [os.path.abspath(path), self.root_dir]
+            )
+        ):
+            return True
+        return False

dvc/istextfile.py

@@ -7,13 +7,17 @@
 TEXT_CHARS = bytes(range(32, 127)) + b"\n\r\t\f\b"
 
 
-def istextfile(fname, blocksize=512):
+def istextfile(fname, blocksize=512, tree=None):
     """ Uses heuristics to guess whether the given file is text or binary,
         by reading a single block of bytes from the file.
         If more than 30% of the chars in the block are non-text, or there
         are NUL ('\x00') bytes in the block, assume this is a binary file.
     """
-    with open(fname, "rb") as fobj:
+    if tree:
+        open_func = tree.open
+    else:
+        open_func = open
+    with open_func(fname, "rb") as fobj:
         block = fobj.read(blocksize)
 
     if not block:

dvc/lock.py

@@ -5,19 +5,19 @@ import os
 import time
 from datetime import timedelta
 
-import zc.lockfile
 import flufl.lock
+import zc.lockfile
 
 from dvc.exceptions import DvcException
-from dvc.utils import format_link
 from dvc.progress import Tqdm
+from dvc.utils import format_link
 
 DEFAULT_TIMEOUT = 5
 
 FAILED_TO_LOCK_MESSAGE = (
     "cannot perform the command because another DVC process seems to be "
     "running on this project. If that is not the case, manually remove "
-    "`.dvc/lock` and try again."
+    "`.dvc/tmp/lock` and try again."
 )
 
 
@@ -25,7 +25,7 @@ class LockError(DvcException):
     """Thrown when unable to acquire the lock for DVC repo."""
 
 
-class Lock(object):
+class Lock:
     """Class for DVC repo lock.
 
     Uses zc.lockfile as backend.
@@ -47,7 +47,7 @@ class Lock(object):
                 disable=not self._friendly,
                 desc=(
                     "If DVC froze, see `hardlink_lock` in {}".format(
-                        format_link("man.dvc.org/config#core")
+                        format_link("https://man.dvc.org/config#core")
                     )
                 ),
             ):
@@ -88,7 +88,9 @@ class HardlinkLock(flufl.lock.Lock):
         tmp_dir (str): a directory to store claim files.
     """
 
-    def __init__(self, lockfile, tmp_dir=None, **kwargs):
+    def __init__(
+        self, lockfile, tmp_dir=None, **kwargs
+    ):  # pylint: disable=super-init-not-called
         import socket
 
         self._tmp_dir = tmp_dir
@@ -117,7 +119,7 @@ class HardlinkLock(flufl.lock.Lock):
     def lockfile(self):
         return self._lockfile
 
-    def lock(self):
+    def lock(self):  # pylint: disable=arguments-differ
         try:
             super().lock(timedelta(seconds=DEFAULT_TIMEOUT))
         except flufl.lock.TimeOutError:

dvc/logger.py

@@ -7,7 +7,6 @@ import colorama
 
 from dvc.progress import Tqdm
 
-
 FOOTER = (
     "\n{yellow}Having any troubles?{nc}"
     " Hit us up at {blue}https://dvc.org/support{nc},"
@@ -19,20 +18,46 @@ FOOTER = (
 )
 
 
+def addLoggingLevel(levelName, levelNum, methodName=None):
+    """
+    Adds a new logging level to the `logging` module and the
+    currently configured logging class.
+
+    Based on https://stackoverflow.com/questions/2183233
+    """
+    if methodName is None:
+        methodName = levelName.lower()
+
+    assert not hasattr(logging, levelName)
+    assert not hasattr(logging, methodName)
+    assert not hasattr(logging.getLoggerClass(), methodName)
+
+    def logForLevel(self, message, *args, **kwargs):
+        if self.isEnabledFor(levelNum):
+            # pylint: disable=protected-access
+            self._log(levelNum, message, args, **kwargs)
+
+    def logToRoot(message, *args, **kwargs):
+        logging.log(levelNum, message, *args, **kwargs)
+
+    logging.addLevelName(levelNum, levelName)
+    setattr(logging, levelName, levelNum)
+    setattr(logging.getLoggerClass(), methodName, logForLevel)
+    setattr(logging, methodName, logToRoot)
+
+
 class LoggingException(Exception):
     def __init__(self, record):
         msg = "failed to log {}".format(str(record))
         super().__init__(msg)
 
 
-class ExcludeErrorsFilter(logging.Filter):
-    def filter(self, record):
-        return record.levelno < logging.WARNING
+def excludeFilter(level):
+    class ExcludeLevelFilter(logging.Filter):
+        def filter(self, record):
+            return record.levelno < level
 
-
-class ExcludeInfoFilter(logging.Filter):
-    def filter(self, record):
-        return record.levelno < logging.INFO
+    return ExcludeLevelFilter
 
 
 class ColorFormatter(logging.Formatter):
@@ -48,6 +73,7 @@ class ColorFormatter(logging.Formatter):
     """
 
     color_code = {
+        "TRACE": colorama.Fore.GREEN,
         "DEBUG": colorama.Fore.BLUE,
         "WARNING": colorama.Fore.YELLOW,
         "ERROR": colorama.Fore.RED,
@@ -112,12 +138,16 @@ class LoggerHandler(logging.StreamHandler):
             self.flush()
         except RecursionError:
             raise
-        except Exception:
+        except Exception:  # noqa, pylint: disable=broad-except
             self.handleError(record)
 
 
 def _is_verbose():
-    return logging.getLogger("dvc").getEffectiveLevel() == logging.DEBUG
+    return (
+        logging.NOTSET
+        < logging.getLogger("dvc").getEffectiveLevel()
+        <= logging.DEBUG
+    )
 
 
 def _iter_causes(exc):
@@ -143,6 +173,7 @@ def _stack_trace(exc_info):
 
 
 def disable_other_loggers():
+    logging.captureWarnings(True)
     root = logging.root
     for (logger_name, logger) in root.manager.loggerDict.items():
         if logger_name != "dvc" and not logger_name.startswith("dvc."):
@@ -152,12 +183,14 @@ def disable_other_loggers():
 def setup(level=logging.INFO):
     colorama.init()
 
+    addLoggingLevel("TRACE", logging.DEBUG - 5)
     logging.config.dictConfig(
         {
             "version": 1,
             "filters": {
-                "exclude_errors": {"()": ExcludeErrorsFilter},
-                "exclude_info": {"()": ExcludeInfoFilter},
+                "exclude_errors": {"()": excludeFilter(logging.WARNING)},
+                "exclude_info": {"()": excludeFilter(logging.INFO)},
+                "exclude_debug": {"()": excludeFilter(logging.DEBUG)},
             },
             "formatters": {"color": {"()": ColorFormatter}},
             "handlers": {
@@ -175,6 +208,13 @@ def setup(level=logging.INFO):
                     "stream": "ext://sys.stdout",
                     "filters": ["exclude_info"],
                 },
+                "console_trace": {
+                    "class": "dvc.logger.LoggerHandler",
+                    "level": "TRACE",
+                    "formatter": "color",
+                    "stream": "ext://sys.stdout",
+                    "filters": ["exclude_debug"],
+                },
                 "console_errors": {
                     "class": "dvc.logger.LoggerHandler",
                     "level": "WARNING",
@@ -188,6 +228,7 @@ def setup(level=logging.INFO):
                     "handlers": [
                         "console_info",
                         "console_debug",
+                        "console_trace",
                         "console_errors",
                     ],
                 },

dvc/main.py

@@ -6,12 +6,11 @@ import logging
 from dvc import analytics
 from dvc.cli import parse_args
 from dvc.config import ConfigError
-from dvc.exceptions import DvcParserError
-from dvc.exceptions import NotDvcRepoError
+from dvc.exceptions import DvcException, DvcParserError, NotDvcRepoError
 from dvc.external_repo import clean_repos
-from dvc.logger import disable_other_loggers, FOOTER
+from dvc.logger import FOOTER, disable_other_loggers
+from dvc.tree.pool import close_pools
 from dvc.utils import format_link
-from dvc.remote.pool import close_pools
 
 # Workaround for CPython bug. See [1] and [2] for more info.
 # [1] https://github.com/aws/aws-cli/blob/1.16.277/awscli/clidriver.py#L55
@@ -19,7 +18,6 @@ from dvc.remote.pool import close_pools
 
 "".encode("idna")
 
-
 logger = logging.getLogger("dvc")
 
 
@@ -33,18 +31,23 @@ def main(argv=None):
         int: command's return code.
     """
     args = None
-    cmd = None
     disable_other_loggers()
 
     outerLogLevel = logger.level
     try:
         args = parse_args(argv)
 
-        if args.quiet:
-            logger.setLevel(logging.CRITICAL)
-
-        elif args.verbose:
-            logger.setLevel(logging.DEBUG)
+        verbosity = args.verbose - args.quiet
+        if verbosity:
+            logger.setLevel(
+                {
+                    -2: logging.CRITICAL,
+                    -1: logging.ERROR,
+                    1: logging.DEBUG,
+                    2: logging.TRACE,
+                }[max(-2, min(verbosity, 2))]
+            )
+        logger.trace(args)
 
         cmd = args.func(args)
         ret = cmd.run()
@@ -59,8 +62,11 @@ def main(argv=None):
         ret = 253
     except DvcParserError:
         ret = 254
-    except Exception as exc:  # pylint: disable=broad-except
-        if isinstance(exc, OSError) and exc.errno == errno.EMFILE:
+    except DvcException:
+        ret = 255
+        logger.exception("")
+    except OSError as exc:
+        if exc.errno == errno.EMFILE:
             logger.exception(
                 "too many open files, please visit "
                 "{} to see how to handle this "
@@ -72,10 +78,13 @@ def main(argv=None):
         else:
             logger.exception("unexpected error")
         ret = 255
+    except Exception:  # noqa, pylint: disable=broad-except
+        logger.exception("unexpected error")
+        ret = 255
     finally:
         logger.setLevel(outerLogLevel)
 
-        # Closing pools by-hand to prevent wierd messages when closing SSH
+        # Closing pools by-hand to prevent weird messages when closing SSH
         # connections. See https://github.com/iterative/dvc/issues/3248 for
         # more info.
         close_pools()

dvc/output/__init__.py

@@ -1,32 +1,36 @@
+from collections import defaultdict
 from urllib.parse import urlparse
-from voluptuous import Any, Required, Lower, Length, Coerce, And, SetTo
 
-from dvc.output.base import OutputBase
-from dvc.output.gs import OutputGS
-from dvc.output.hdfs import OutputHDFS
-from dvc.output.local import OutputLOCAL
-from dvc.output.s3 import OutputS3
-from dvc.output.ssh import OutputSSH
-from dvc.remote import Remote
-from dvc.remote.hdfs import RemoteHDFS
-from dvc.remote.local import RemoteLOCAL
-from dvc.remote.s3 import RemoteS3
+from funcy import collecting, project
+from voluptuous import And, Any, Coerce, Length, Lower, Required, SetTo
+
+from dvc.output.base import BaseOutput
+from dvc.output.gs import GSOutput
+from dvc.output.hdfs import HDFSOutput
+from dvc.output.local import LocalOutput
+from dvc.output.s3 import S3Output
+from dvc.output.ssh import SSHOutput
 from dvc.scheme import Schemes
 
+from ..tree import get_cloud_tree
+from ..tree.hdfs import HDFSTree
+from ..tree.local import LocalTree
+from ..tree.s3 import S3Tree
+
 OUTS = [
-    OutputHDFS,
-    OutputS3,
-    OutputGS,
-    OutputSSH,
-    # NOTE: OutputLOCAL is the default choice
+    HDFSOutput,
+    S3Output,
+    GSOutput,
+    SSHOutput,
+    # NOTE: LocalOutput is the default choice
 ]
 
 OUTS_MAP = {
-    Schemes.HDFS: OutputHDFS,
-    Schemes.S3: OutputS3,
-    Schemes.GS: OutputGS,
-    Schemes.SSH: OutputSSH,
-    Schemes.LOCAL: OutputLOCAL,
+    Schemes.HDFS: HDFSOutput,
+    Schemes.S3: S3Output,
+    Schemes.GS: GSOutput,
+    Schemes.SSH: SSHOutput,
+    Schemes.LOCAL: LocalOutput,
 }
 
 CHECKSUM_SCHEMA = Any(
@@ -44,35 +48,35 @@ CHECKSUM_SCHEMA = Any(
 # so when a few types of outputs share the same name, we only need
 # specify it once.
 CHECKSUMS_SCHEMA = {
-    RemoteLOCAL.PARAM_CHECKSUM: CHECKSUM_SCHEMA,
-    RemoteS3.PARAM_CHECKSUM: CHECKSUM_SCHEMA,
-    RemoteHDFS.PARAM_CHECKSUM: CHECKSUM_SCHEMA,
+    LocalTree.PARAM_CHECKSUM: CHECKSUM_SCHEMA,
+    S3Tree.PARAM_CHECKSUM: CHECKSUM_SCHEMA,
+    HDFSTree.PARAM_CHECKSUM: CHECKSUM_SCHEMA,
 }
 
-TAGS_SCHEMA = {str: CHECKSUMS_SCHEMA}
-
 SCHEMA = CHECKSUMS_SCHEMA.copy()
-SCHEMA[Required(OutputBase.PARAM_PATH)] = str
-SCHEMA[OutputBase.PARAM_CACHE] = bool
-SCHEMA[OutputBase.PARAM_METRIC] = OutputBase.METRIC_SCHEMA
-SCHEMA[OutputBase.PARAM_TAGS] = TAGS_SCHEMA
-SCHEMA[OutputBase.PARAM_PERSIST] = bool
+SCHEMA[Required(BaseOutput.PARAM_PATH)] = str
+SCHEMA[BaseOutput.PARAM_CACHE] = bool
+SCHEMA[BaseOutput.PARAM_METRIC] = BaseOutput.METRIC_SCHEMA
+SCHEMA[BaseOutput.PARAM_PLOT] = bool
+SCHEMA[BaseOutput.PARAM_PERSIST] = bool
 
 
-def _get(stage, p, info, cache, metric, persist=False, tags=None):
+def _get(
+    stage, p, info=None, cache=True, metric=False, plot=False, persist=False
+):
     parsed = urlparse(p)
 
     if parsed.scheme == "remote":
-        remote = Remote(stage.repo, name=parsed.netloc)
-        return OUTS_MAP[remote.scheme](
+        tree = get_cloud_tree(stage.repo, name=parsed.netloc)
+        return OUTS_MAP[tree.scheme](
             stage,
             p,
             info,
             cache=cache,
-            remote=remote,
+            tree=tree,
             metric=metric,
+            plot=plot,
             persist=persist,
-            tags=tags,
         )
 
     for o in OUTS:
@@ -82,31 +86,31 @@ def _get(stage, p, info, cache, metric, persist=False, tags=None):
                 p,
                 info,
                 cache=cache,
-                remote=None,
+                tree=None,
                 metric=metric,
+                plot=plot,
                 persist=persist,
-                tags=tags,
             )
-    return OutputLOCAL(
+    return LocalOutput(
         stage,
         p,
         info,
         cache=cache,
-        remote=None,
+        tree=None,
         metric=metric,
+        plot=plot,
         persist=persist,
-        tags=tags,
     )
 
 
 def loadd_from(stage, d_list):
     ret = []
     for d in d_list:
-        p = d.pop(OutputBase.PARAM_PATH)
-        cache = d.pop(OutputBase.PARAM_CACHE, True)
-        metric = d.pop(OutputBase.PARAM_METRIC, False)
-        persist = d.pop(OutputBase.PARAM_PERSIST, False)
-        tags = d.pop(OutputBase.PARAM_TAGS, None)
+        p = d.pop(BaseOutput.PARAM_PATH)
+        cache = d.pop(BaseOutput.PARAM_CACHE, True)
+        metric = d.pop(BaseOutput.PARAM_METRIC, False)
+        plot = d.pop(BaseOutput.PARAM_PLOT, False)
+        persist = d.pop(BaseOutput.PARAM_PERSIST, False)
         ret.append(
             _get(
                 stage,
@@ -114,24 +118,67 @@ def loadd_from(stage, d_list):
                 info=d,
                 cache=cache,
                 metric=metric,
+                plot=plot,
                 persist=persist,
-                tags=tags,
             )
         )
     return ret
 
 
-def loads_from(stage, s_list, use_cache=True, metric=False, persist=False):
-    ret = []
-    for s in s_list:
-        ret.append(
-            _get(
-                stage,
-                s,
-                info={},
-                cache=use_cache,
-                metric=metric,
-                persist=persist,
-            )
+def loads_from(
+    stage, s_list, use_cache=True, metric=False, plot=False, persist=False
+):
+    return [
+        _get(
+            stage,
+            s,
+            info={},
+            cache=use_cache,
+            metric=metric,
+            plot=plot,
+            persist=persist,
         )
-    return ret
+        for s in s_list
+    ]
+
+
+def _split_dict(d, keys):
+    return project(d, keys), project(d, d.keys() - keys)
+
+
+def _merge_data(s_list):
+    d = defaultdict(dict)
+    for key in s_list:
+        if isinstance(key, str):
+            d[key].update({})
+            continue
+        if not isinstance(key, dict):
+            raise ValueError(f"'{type(key).__name__}' not supported.")
+
+        for k, flags in key.items():
+            if not isinstance(flags, dict):
+                raise ValueError(
+                    f"Expected dict for '{k}', got: '{type(flags).__name__}'"
+                )
+            d[k].update(flags)
+    return d
+
+
+@collecting
+def load_from_pipeline(stage, s_list, typ="outs"):
+    if typ not in (stage.PARAM_OUTS, stage.PARAM_METRICS, stage.PARAM_PLOTS):
+        raise ValueError(f"'{typ}' key is not allowed for pipeline files.")
+
+    metric = typ == stage.PARAM_METRICS
+    plot = typ == stage.PARAM_PLOTS
+
+    d = _merge_data(s_list)
+
+    for path, flags in d.items():
+        plt_d = {}
+        if plot:
+            from dvc.schema import PLOT_PROPS
+
+            plt_d, flags = _split_dict(flags, keys=PLOT_PROPS.keys())
+        extra = project(flags, ["cache", "persist"])
+        yield _get(stage, path, {}, plot=plt_d or plot, metric=metric, **extra)

dvc/output/base.py

@@ -1,52 +1,68 @@
 import logging
-from urllib.parse import urlparse
+import os
 from copy import copy
+from urllib.parse import urlparse
 
 from voluptuous import Any
 
 import dvc.prompt as prompt
 from dvc.cache import NamedCache
-from dvc.exceptions import CollectCacheError, RemoteCacheRequiredError
-from dvc.exceptions import DvcException
-from dvc.remote.base import RemoteBASE
+from dvc.exceptions import (
+    CollectCacheError,
+    DvcException,
+    RemoteCacheRequiredError,
+)
 
+from ..tree.base import BaseTree
 
 logger = logging.getLogger(__name__)
 
 
 class OutputDoesNotExistError(DvcException):
     def __init__(self, path):
-        msg = "output '{}' does not exist".format(path)
+        msg = f"output '{path}' does not exist"
         super().__init__(msg)
 
 
 class OutputIsNotFileOrDirError(DvcException):
     def __init__(self, path):
-        msg = "output '{}' is not a file or directory".format(path)
+        msg = f"output '{path}' is not a file or directory"
         super().__init__(msg)
 
 
 class OutputAlreadyTrackedError(DvcException):
     def __init__(self, path):
-        msg = "output '{}' is already tracked by scm (e.g. git)".format(path)
+        msg = f""" output '{path}' is already tracked by SCM (e.g. Git).
+    You can remove it from Git, then add to DVC.
+        To stop tracking from Git:
+            git rm -r --cached '{path}'
+            git commit -m "stop tracking {path}" """
         super().__init__(msg)
 
 
 class OutputIsStageFileError(DvcException):
     def __init__(self, path):
-        super().__init__("Stage file '{}' cannot be an output.".format(path))
+        super().__init__(f"Stage file '{path}' cannot be an output.")
 
 
-class OutputBase(object):
+class BaseOutput:
     IS_DEPENDENCY = False
 
-    REMOTE = RemoteBASE
+    TREE_CLS = BaseTree
 
     PARAM_PATH = "path"
     PARAM_CACHE = "cache"
     PARAM_METRIC = "metric"
     PARAM_METRIC_TYPE = "type"
     PARAM_METRIC_XPATH = "xpath"
+    PARAM_PLOT = "plot"
+    PARAM_PLOT_TEMPLATE = "template"
+    PARAM_PLOT_X = "x"
+    PARAM_PLOT_Y = "y"
+    PARAM_PLOT_X_LABEL = "x_label"
+    PARAM_PLOT_Y_LABEL = "y_label"
+    PARAM_PLOT_TITLE = "title"
+    PARAM_PLOT_HEADER = "header"
     PARAM_PERSIST = "persist"
 
     METRIC_SCHEMA = Any(
@@ -58,8 +74,6 @@ class OutputBase(object):
         },
     )
 
-    PARAM_TAGS = "tags"
-
     DoesNotExistError = OutputDoesNotExistError
     IsNotFileOrDirError = OutputIsNotFileOrDirError
     IsStageFileError = OutputIsStageFileError
@@ -71,11 +85,11 @@ class OutputBase(object):
         stage,
         path,
         info=None,
-        remote=None,
+        tree=None,
         cache=True,
         metric=False,
+        plot=False,
         persist=False,
-        tags=None,
     ):
         self._validate_output_path(path)
         # This output (and dependency) objects have too many paths/urls
@@ -92,21 +106,24 @@ class OutputBase(object):
         self.repo = stage.repo if stage else None
         self.def_path = path
         self.info = info
-        self.remote = remote or self.REMOTE(self.repo, {})
+        if tree:
+            self.tree = tree
+        else:
+            self.tree = self.TREE_CLS(self.repo, {})
         self.use_cache = False if self.IS_DEPENDENCY else cache
         self.metric = False if self.IS_DEPENDENCY else metric
+        self.plot = False if self.IS_DEPENDENCY else plot
         self.persist = persist
-        self.tags = None if self.IS_DEPENDENCY else (tags or {})
 
-        self.path_info = self._parse_path(remote, path)
+        self.path_info = self._parse_path(tree, path)
         if self.use_cache and self.cache is None:
             raise RemoteCacheRequiredError(self.path_info)
 
-    def _parse_path(self, remote, path):
-        if remote:
+    def _parse_path(self, tree, path):
+        if tree:
             parsed = urlparse(path)
-            return remote.path_info / parsed.path.lstrip("/")
-        return self.REMOTE.path_cls(path)
+            return tree.path_info / parsed.path.lstrip("/")
+        return self.TREE_CLS.PATH_CLS(path)
 
     def __repr__(self):
         return "{class_name}: '{def_path}'".format(
@@ -118,7 +135,7 @@ class OutputBase(object):
 
     @property
     def scheme(self):
-        return self.REMOTE.scheme
+        return self.TREE_CLS.scheme
 
     @property
     def is_in_repo(self):
@@ -141,26 +158,40 @@ class OutputBase(object):
 
     @classmethod
     def supported(cls, url):
-        return cls.REMOTE.supported(url)
+        return cls.TREE_CLS.supported(url)
 
     @property
     def cache_path(self):
-        return self.cache.checksum_to_path_info(self.checksum).url
+        return self.cache.tree.hash_to_path_info(self.checksum).url
+
+    @property
+    def checksum_type(self):
+        return self.tree.PARAM_CHECKSUM
 
     @property
     def checksum(self):
-        return self.info.get(self.remote.PARAM_CHECKSUM)
+        return self.info.get(self.tree.PARAM_CHECKSUM)
+
+    @checksum.setter
+    def checksum(self, checksum):
+        self.info[self.tree.PARAM_CHECKSUM] = checksum
+
+    def get_checksum(self):
+        return self.tree.get_hash(self.path_info)
 
     @property
     def is_dir_checksum(self):
-        return self.remote.is_dir_checksum(self.checksum)
+        return self.tree.is_dir_hash(self.checksum)
 
     @property
     def exists(self):
-        return self.remote.exists(self.path_info)
+        return self.tree.exists(self.path_info)
+
+    def save_info(self):
+        return self.tree.save_info(self.path_info)
 
     def changed_checksum(self):
-        return self.checksum != self.remote.get_checksum(self.path_info)
+        return self.checksum != self.get_checksum()
 
     def changed_cache(self, filter_info=None):
         if not self.use_cache or not self.checksum:
@@ -190,13 +221,32 @@ class OutputBase(object):
 
     @property
     def is_empty(self):
-        return self.remote.is_empty(self.path_info)
+        return self.tree.is_empty(self.path_info)
 
     def isdir(self):
-        return self.remote.isdir(self.path_info)
+        return self.tree.isdir(self.path_info)
 
     def isfile(self):
-        return self.remote.isfile(self.path_info)
+        return self.tree.isfile(self.path_info)
+
+    # pylint: disable=no-member
+
+    def ignore(self):
+        if not self.use_scm_ignore:
+            return
+
+        if self.repo.scm.is_tracked(self.fspath):
+            raise OutputAlreadyTrackedError(self)
+
+        self.repo.scm.ignore(self.fspath)
+
+    def ignore_remove(self):
+        if not self.use_scm_ignore:
+            return
+
+        self.repo.scm.ignore_remove(self.fspath)
+
+    # pylint: enable=no-member
 
     def save(self):
         if not self.exists:
@@ -206,39 +256,32 @@ class OutputBase(object):
             raise self.IsNotFileOrDirError(self)
 
         if self.is_empty:
-            logger.warning("'{}' is empty.".format(self))
+            logger.warning(f"'{self}' is empty.")
 
-        if self.use_scm_ignore:
-            if self.repo.scm.is_tracked(self.fspath):
-                raise OutputAlreadyTrackedError(self)
+        self.ignore()
 
-            self.repo.scm.ignore(self.fspath)
+        if self.metric or self.plot:
+            self.verify_metric()
 
         if not self.use_cache:
-            self.info = self.remote.save_info(self.path_info)
-            if self.metric:
-                self.verify_metric()
+            self.info = self.save_info()
             if not self.IS_DEPENDENCY:
-                logger.info(
-                    "Output '{}' doesn't use cache. Skipping saving.".format(
-                        self
-                    )
+                logger.debug(
+                    "Output '%s' doesn't use cache. Skipping saving.", self
                 )
             return
 
         assert not self.IS_DEPENDENCY
 
         if not self.changed():
-            logger.info(
-                "Output '{}' didn't change. Skipping saving.".format(self)
-            )
+            logger.debug("Output '%s' didn't change. Skipping saving.", self)
             return
 
-        self.info = self.remote.save_info(self.path_info)
+        self.info = self.save_info()
 
     def commit(self):
         if self.use_cache:
-            self.cache.save(self.path_info, self.info)
+            self.cache.save(self.path_info, self.cache.tree, self.info)
 
     def dumpd(self):
         ret = copy(self.info)
@@ -247,7 +290,8 @@ class OutputBase(object):
         if self.IS_DEPENDENCY:
             return ret
 
-        ret[self.PARAM_CACHE] = self.use_cache
+        if not self.use_cache:
+            ret[self.PARAM_CACHE] = self.use_cache
 
         if isinstance(self.metric, dict):
             if (
@@ -256,27 +300,27 @@ class OutputBase(object):
             ):
                 del self.metric[self.PARAM_METRIC_XPATH]
 
-        ret[self.PARAM_METRIC] = self.metric
-        ret[self.PARAM_PERSIST] = self.persist
+        if self.metric:
+            ret[self.PARAM_METRIC] = self.metric
 
-        if self.tags:
-            ret[self.PARAM_TAGS] = self.tags
+        if self.plot:
+            ret[self.PARAM_PLOT] = self.plot
+
+        if self.persist:
+            ret[self.PARAM_PERSIST] = self.persist
 
         return ret
 
     def verify_metric(self):
-        raise DvcException(
-            "verify metric is not supported for {}".format(self.scheme)
-        )
+        raise DvcException(f"verify metric is not supported for {self.scheme}")
 
     def download(self, to):
-        self.remote.download(self.path_info, to.path_info)
+        self.tree.download(self.path_info, to.path_info)
 
     def checkout(
         self,
         force=False,
         progress_callback=None,
-        tag=None,
         relink=False,
         filter_info=None,
     ):
@@ -287,14 +331,9 @@ class OutputBase(object):
                 )
             return None
 
-        if tag:
-            info = self.tags[tag]
-        else:
-            info = self.info
-
         return self.cache.checkout(
             self.path_info,
-            info,
+            self.info,
             force=force,
             progress_callback=progress_callback,
             relink=relink,
@@ -302,18 +341,19 @@ class OutputBase(object):
         )
 
     def remove(self, ignore_remove=False):
-        self.remote.remove(self.path_info)
+        self.tree.remove(self.path_info)
         if self.scheme != "local":
             return
 
-        if ignore_remove and self.use_scm_ignore:
-            self.repo.scm.ignore_remove(self.fspath)
+        if ignore_remove:
+            self.ignore_remove()
 
     def move(self, out):
+        # pylint: disable=no-member
         if self.scheme == "local" and self.use_scm_ignore:
             self.repo.scm.ignore_remove(self.fspath)
 
-        self.remote.move(self.path_info, out.path_info)
+        self.tree.move(self.path_info, out.path_info)
         self.def_path = out.def_path
         self.path_info = out.path_info
         self.save()
@@ -332,9 +372,20 @@ class OutputBase(object):
 
     def unprotect(self):
         if self.exists:
-            self.remote.unprotect(self.path_info)
+            self.tree.unprotect(self.path_info)
 
-    def _collect_used_dir_cache(
+    def get_dir_cache(self, **kwargs):
+        if not self.is_dir_checksum:
+            raise DvcException("cannot get dir cache for file checksum")
+        if self.cache.changed_cache_file(self.checksum):
+            self.repo.cloud.pull(
+                NamedCache.make("local", self.checksum, str(self)),
+                show_checksums=False,
+                **kwargs,
+            )
+        return self.dir_cache
+
+    def collect_used_dir_cache(
         self, remote=None, force=False, jobs=None, filter_info=None
     ):
         """Get a list of `info`s related to the given directory.
@@ -358,16 +409,10 @@ class OutputBase(object):
 
         cache = NamedCache()
 
-        if self.cache.changed_cache_file(self.checksum):
-            try:
-                self.repo.cloud.pull(
-                    NamedCache.make("local", self.checksum, str(self)),
-                    jobs=jobs,
-                    remote=remote,
-                    show_checksums=False,
-                )
-            except DvcException:
-                logger.debug("failed to pull cache for '{}'".format(self))
+        try:
+            self.get_dir_cache(jobs=jobs, remote=remote)
+        except DvcException:
+            logger.debug(f"failed to pull cache for '{self}'")
 
         if self.cache.changed_cache_file(self.checksum):
             msg = (
@@ -383,11 +428,21 @@ class OutputBase(object):
             else:
                 return cache
 
+        path = str(self.path_info)
+        filter_path = str(filter_info) if filter_info else None
+        is_win = os.name == "nt"
         for entry in self.dir_cache:
-            checksum = entry[self.remote.PARAM_CHECKSUM]
-            info = self.path_info / entry[self.remote.PARAM_RELPATH]
-            if not filter_info or info.isin_or_eq(filter_info):
-                cache.add(self.scheme, checksum, str(info))
+            checksum = entry[self.tree.PARAM_CHECKSUM]
+            entry_relpath = entry[self.tree.PARAM_RELPATH]
+            if is_win:
+                entry_relpath = entry_relpath.replace("/", os.sep)
+            entry_path = os.path.join(path, entry_relpath)
+            if (
+                not filter_path
+                or entry_path == filter_path
+                or entry_path.startswith(filter_path + os.sep)
+            ):
+                cache.add(self.scheme, checksum, entry_path)
 
         return cache
 
@@ -420,9 +475,9 @@ class OutputBase(object):
             if self.exists:
                 msg += (
                     "\n"
-                    "You can also use `dvc commit {stage}` to associate "
-                    "existing '{out}' with '{stage}'.".format(
-                        out=self, stage=self.stage.relpath
+                    "You can also use `dvc commit {stage.addressing}` "
+                    "to associate existing '{out}' with {stage}.".format(
+                        out=self, stage=self.stage
                     )
                 )
             logger.warning(msg)
@@ -433,13 +488,15 @@ class OutputBase(object):
         if not self.is_dir_checksum:
             return ret
 
-        ret.update(self._collect_used_dir_cache(**kwargs))
+        ret.add_child_cache(
+            self.checksum, self.collect_used_dir_cache(**kwargs),
+        )
 
         return ret
 
     @classmethod
     def _validate_output_path(cls, path):
-        from dvc.stage import Stage
+        from dvc.dvcfile import is_valid_filename
 
-        if Stage.is_valid_filename(path):
+        if is_valid_filename(path):
             raise cls.IsStageFileError(path)

dvc/output/gs.py

@@ -1,6 +1,7 @@
-from dvc.output.s3 import OutputS3
-from dvc.remote.gs import RemoteGS
+from dvc.output.s3 import S3Output
+
+from ..tree.gs import GSTree
 
 
-class OutputGS(OutputS3):
-    REMOTE = RemoteGS
+class GSOutput(S3Output):
+    TREE_CLS = GSTree

dvc/output/hdfs.py

@@ -1,6 +1,7 @@
-from dvc.output.base import OutputBase
-from dvc.remote.hdfs import RemoteHDFS
+from dvc.output.base import BaseOutput
+
+from ..tree.hdfs import HDFSTree
 
 
-class OutputHDFS(OutputBase):
-    REMOTE = RemoteHDFS
+class HDFSOutput(BaseOutput):
+    TREE_CLS = HDFSTree

dvc/output/local.py

@@ -4,18 +4,17 @@ from urllib.parse import urlparse
 
 from dvc.exceptions import DvcException
 from dvc.istextfile import istextfile
-from dvc.output.base import OutputBase
-from dvc.remote.local import RemoteLOCAL
+from dvc.output.base import BaseOutput
 from dvc.utils import relpath
-from dvc.compat import fspath_py35
 from dvc.utils.fs import path_isin
 
+from ..tree.local import LocalTree
 
 logger = logging.getLogger(__name__)
 
 
-class OutputLOCAL(OutputBase):
-    REMOTE = RemoteLOCAL
+class LocalOutput(BaseOutput):
+    TREE_CLS = LocalTree
     sep = os.sep
 
     def __init__(self, stage, path, *args, **kwargs):
@@ -23,11 +22,17 @@ class OutputLOCAL(OutputBase):
             path = relpath(path, stage.wdir)
 
         super().__init__(stage, path, *args, **kwargs)
+        if (
+            self.is_in_repo
+            and self.repo
+            and isinstance(self.repo.tree, LocalTree)
+        ):
+            self.tree = self.repo.tree
 
-    def _parse_path(self, remote, path):
+    def _parse_path(self, tree, path):
         parsed = urlparse(path)
         if parsed.scheme == "remote":
-            p = remote.path_info / parsed.path.lstrip("/")
+            p = tree.path_info / parsed.path.lstrip("/")
         else:
             # NOTE: we can path either from command line or .dvc file,
             # so we should expect both posix and windows style paths.
@@ -35,15 +40,15 @@ class OutputLOCAL(OutputBase):
             #
             # FIXME: if we have Windows path containing / or posix one with \
             # then we have #2059 bug and can't really handle that.
-            p = self.REMOTE.path_cls(path)
-            if not p.is_absolute():
+            p = self.TREE_CLS.PATH_CLS(path)
+            if self.stage and not p.is_absolute():
                 p = self.stage.wdir / p
 
-        abs_p = os.path.abspath(os.path.normpath(fspath_py35(p)))
-        return self.REMOTE.path_cls(abs_p)
+        abs_p = os.path.abspath(os.path.normpath(p))
+        return self.TREE_CLS.PATH_CLS(abs_p)
 
     def __str__(self):
-        if not self.is_in_repo:
+        if not self.repo or not self.is_in_repo:
             return str(self.def_path)
 
         cur_dir = os.getcwd()
@@ -73,17 +78,18 @@ class OutputLOCAL(OutputBase):
         return ret
 
     def verify_metric(self):
-        if not self.metric:
+        if not self.metric or self.plot:
             return
 
-        path = fspath_py35(self.path_info)
+        path = os.fspath(self.path_info)
         if not os.path.exists(path):
             return
 
+        name = "metrics" if self.metric else "plot"
         if os.path.isdir(path):
-            msg = "directory '{}' cannot be used as metrics."
-            raise DvcException(msg.format(self.path_info))
+            msg = "directory '{}' cannot be used as {}."
+            raise IsADirectoryError(msg.format(self.path_info, name))
 
         if not istextfile(path):
-            msg = "binary file '{}' cannot be used as metrics."
-            raise DvcException(msg.format(self.path_info))
+            msg = "binary file '{}' cannot be used as {}."
+            raise DvcException(msg.format(self.path_info, name))

dvc/output/s3.py

@@ -1,6 +1,7 @@
-from dvc.output.base import OutputBase
-from dvc.remote.s3 import RemoteS3
+from dvc.output.base import BaseOutput
+
+from ..tree.s3 import S3Tree
 
 
-class OutputS3(OutputBase):
-    REMOTE = RemoteS3
+class S3Output(BaseOutput):
+    TREE_CLS = S3Tree

dvc/output/ssh.py

@@ -1,6 +1,7 @@
-from dvc.output.base import OutputBase
-from dvc.remote.ssh import RemoteSSH
+from dvc.output.base import BaseOutput
+
+from ..tree.ssh import SSHTree
 
 
-class OutputSSH(OutputBase):
-    REMOTE = RemoteSSH
+class SSHOutput(BaseOutput):
+    TREE_CLS = SSHTree

dvc/path_info.py

@@ -1,6 +1,7 @@
+# pylint: disable=protected-access
 import os
-import posixpath
 import pathlib
+import posixpath
 from urllib.parse import urlparse
 
 from funcy import cached_property
@@ -8,7 +9,7 @@ from funcy import cached_property
 from dvc.utils import relpath
 
 
-class _BasePath(object):
+class _BasePath:
     def overlaps(self, other):
         if isinstance(other, (str, bytes)):
             other = self.__class__(other)
@@ -17,7 +18,7 @@ class _BasePath(object):
         return self.isin_or_eq(other) or other.isin(self)
 
     def isin_or_eq(self, other):
-        return self == other or self.isin(other)
+        return self == other or self.isin(other)  # pylint: disable=no-member
 
 
 class PathInfo(pathlib.PurePath, _BasePath):
@@ -30,15 +31,14 @@ class PathInfo(pathlib.PurePath, _BasePath):
     def __new__(cls, *args):
         # Construct a proper subclass depending on current os
         if cls is PathInfo:
-            cls = WindowsPathInfo if os.name == "nt" else PosixPathInfo
+            cls = (  # pylint: disable=self-cls-assignment
+                WindowsPathInfo if os.name == "nt" else PosixPathInfo
+            )
+
         return cls._from_parts(args)
 
-    @classmethod
-    def from_posix(cls, s):
-        return cls(PosixPathInfo(s))
-
     def as_posix(self):
-        f = self._flavour
+        f = self._flavour  # pylint: disable=no-member
         # Unlike original implementation [1] that uses `str()` we actually need
         # to use `fspath`, because we've overridden `__str__` method to return
         # relative paths, which will break original `as_posix`.
@@ -54,7 +54,6 @@ class PathInfo(pathlib.PurePath, _BasePath):
         return "{}: '{}'".format(type(self).__name__, self)
 
     # This permits passing it to file utils directly in Python 3.6+
-    # With Python 2.7, Python 3.5+ we are stuck with path_info.fspath for now
     def __fspath__(self):
         return pathlib.PurePath.__str__(self)
 
@@ -92,7 +91,7 @@ class _URLPathInfo(PosixPathInfo):
     __unicode__ = __str__
 
 
-class _URLPathParents(object):
+class _URLPathParents:
     def __init__(self, src):
         self.src = src
         self._parents = self.src._path.parents
@@ -104,7 +103,7 @@ class _URLPathParents(object):
         return self.src.replace(path=self._parents[idx])
 
     def __repr__(self):
-        return "<{}.parents>".format(self.src)
+        return f"<{self.src}.parents>"
 
 
 class URLInfo(_BasePath):
@@ -115,7 +114,7 @@ class URLInfo(_BasePath):
         assert not p.query and not p.params and not p.fragment
         assert p.password is None
 
-        self.fill_parts(p.scheme, p.hostname, p.username, p.port, p.path)
+        self._fill_parts(p.scheme, p.hostname, p.username, p.port, p.path)
 
     @classmethod
     def from_parts(
@@ -124,13 +123,13 @@ class URLInfo(_BasePath):
         assert bool(host) ^ bool(netloc)
 
         if netloc is not None:
-            return cls("{}://{}{}".format(scheme, netloc, path))
+            return cls(f"{scheme}://{netloc}{path}")
 
         obj = cls.__new__(cls)
-        obj.fill_parts(scheme, host, user, port, path)
+        obj._fill_parts(scheme, host, user, port, path)
         return obj
 
-    def fill_parts(self, scheme, host, user, port, path):
+    def _fill_parts(self, scheme, host, user, port, path):
         assert scheme != "remote"
         assert isinstance(path, (str, bytes, _URLPathInfo))
 
@@ -158,7 +157,7 @@ class URLInfo(_BasePath):
 
     @cached_property
     def url(self):
-        return "{}://{}{}".format(self.scheme, self.netloc, self._spath)
+        return f"{self.scheme}://{self.netloc}{self._spath}"
 
     def __str__(self):
         return self.url
@@ -220,10 +219,10 @@ class URLInfo(_BasePath):
         if isinstance(other, (str, bytes)):
             other = self.__class__(other)
         if self.__class__ != other.__class__:
-            msg = "'{}' has incompatible class with '{}'".format(self, other)
+            msg = f"'{self}' has incompatible class with '{other}'"
             raise ValueError(msg)
         if self._base_parts != other._base_parts:
-            msg = "'{}' does not start with '{}'".format(self, other)
+            msg = f"'{self}' does not start with '{other}'"
             raise ValueError(msg)
         return self._path.relative_to(other._path)
 
@@ -244,6 +243,8 @@ class CloudURLInfo(URLInfo):
 
 
 class HTTPURLInfo(URLInfo):
+    __hash__ = URLInfo.__hash__
+
     def __init__(self, url):
         p = urlparse(url)
         stripped = p._replace(params=None, query=None, fragment=None)
@@ -264,7 +265,7 @@ class HTTPURLInfo(URLInfo):
         params=None,
         query=None,
         fragment=None,
-    ):
+    ):  # pylint: disable=arguments-differ
         assert bool(host) ^ bool(netloc)
 
         if netloc is not None:
@@ -280,7 +281,7 @@ class HTTPURLInfo(URLInfo):
             )
 
         obj = cls.__new__(cls)
-        obj.fill_parts(scheme, host, user, port, path)
+        obj._fill_parts(scheme, host, user, port, path)
         obj.params = params
         obj.query = query
         obj.fragment = fragment
@@ -314,6 +315,3 @@ class HTTPURLInfo(URLInfo):
             and self._path == other._path
             and self._extra_parts == other._extra_parts
         )
-
-    def __hash__(self):
-        return hash(self.parts)

dvc/pathspec_math.py

@@ -0,0 +1,87 @@
+# Path Specification Pattern Math
+# Including changing base dir of path specification patterns and merging
+# of two path specification patterns with different base
+# All the operations follow the documents of `gitignore`
+import os
+
+from pathspec.util import normalize_file
+
+from dvc.utils import relpath
+
+
+def _not_ignore(rule):
+    return (True, rule[1:]) if rule.startswith("!") else (False, rule)
+
+
+def _is_comment(rule):
+    return rule.startswith("#")
+
+
+def _remove_slash(rule):
+    if rule.startswith("\\"):
+        return rule[1:]
+    return rule
+
+
+def _match_all_level(rule):
+    if rule[:-1].find("/") >= 0 and not rule.startswith("**/"):
+        if rule.startswith("/"):
+            rule = rule[1:]
+        return False, rule
+    if rule.startswith("**/"):
+        rule = rule[3:]
+    return True, rule
+
+
+def change_rule(rule, rel):
+    rule = rule.strip()
+    if _is_comment(rule):
+        return rule
+    not_ignore, rule = _not_ignore(rule)
+    match_all, rule = _match_all_level(rule)
+    rule = _remove_slash(rule)
+    if not match_all:
+        rule = f"/{rule}"
+    else:
+        rule = f"/**/{rule}"
+    if not_ignore:
+        rule = f"!/{rel}{rule}"
+    else:
+        rule = f"/{rel}{rule}"
+    rule = normalize_file(rule)
+    return rule
+
+
+def _change_dirname(dirname, pattern_list, new_dirname):
+    if new_dirname == dirname:
+        return pattern_list
+    rel = relpath(dirname, new_dirname)
+    if rel.startswith(".."):
+        raise ValueError("change dirname can only change to parent path")
+
+    return [change_rule(rule, rel) for rule in pattern_list]
+
+
+def merge_patterns(pattern_a, prefix_a, pattern_b, prefix_b):
+    """
+    Merge two path specification patterns.
+
+    This implementation merge two path specification patterns on different
+    bases. It returns the longest common parent directory, and the patterns
+    based on this new base directory.
+    """
+    if not pattern_a:
+        return pattern_b, prefix_b
+    elif not pattern_b:
+        return pattern_a, prefix_a
+
+    longest_common_dir = os.path.commonpath([prefix_a, prefix_b])
+    new_pattern_a = _change_dirname(prefix_a, pattern_a, longest_common_dir)
+    new_pattern_b = _change_dirname(prefix_b, pattern_b, longest_common_dir)
+
+    if len(prefix_a) <= len(prefix_b):
+        merged_pattern = new_pattern_a + new_pattern_b
+    else:
+        merged_pattern = new_pattern_b + new_pattern_a
+
+    return merged_pattern, longest_common_dir

dvc/progress.py

@@ -19,18 +19,17 @@ class Tqdm(tqdm):
 
     BAR_FMT_DEFAULT = (
         "{percentage:3.0f}% {desc}|{bar}|"
-        "{n_fmt}/{total_fmt}"
-        " [{elapsed}<{remaining}, {rate_fmt:>11}{postfix}]"
+        "{postfix[info]}{n_fmt}/{total_fmt}"
+        " [{elapsed}<{remaining}, {rate_fmt:>11}]"
     )
     # nested bars should have fixed bar widths to align nicely
     BAR_FMT_DEFAULT_NESTED = (
         "{percentage:3.0f}%|{bar:10}|{desc:{ncols_desc}.{ncols_desc}}"
-        "{n_fmt}/{total_fmt}"
-        " [{elapsed}<{remaining}, {rate_fmt:>11}{postfix}]"
+        "{postfix[info]}{n_fmt}/{total_fmt}"
+        " [{elapsed}<{remaining}, {rate_fmt:>11}]"
     )
     BAR_FMT_NOTOTAL = (
-        "{desc:{ncols_desc}.{ncols_desc}}{n_fmt}"
-        " [{elapsed}, {rate_fmt:>11}{postfix}]"
+        "{desc}{bar:b}|{postfix[info]}{n_fmt} [{elapsed}, {rate_fmt:>11}]"
     )
     BYTES_DEFAULTS = dict(
         unit="B", unit_scale=True, unit_divisor=1024, miniters=1
@@ -47,6 +46,7 @@ class Tqdm(tqdm):
         bytes=False,  # pylint: disable=W0622
         file=None,
         total=None,
+        postfix=None,
         **kwargs
     ):
         """
@@ -68,7 +68,6 @@ class Tqdm(tqdm):
             kwargs.setdefault("unit_scale", total > 999 if total else True)
         if file is None:
             file = sys.stderr
-        self.desc_persist = desc
         # auto-disable based on `logger.level`
         if not disable:
             disable = logger.getEffectiveLevel() > level
@@ -89,6 +88,7 @@ class Tqdm(tqdm):
             total=total,
             **kwargs
         )
+        self.postfix = postfix or {"info": ""}
         if bar_format is None:
             if self.__len__():
                 self.bar_format = (
@@ -102,11 +102,11 @@ class Tqdm(tqdm):
             self.bar_format = bar_format
         self.refresh()
 
-    def update_desc(self, desc, n=1):
+    def update_msg(self, msg, n=1):
         """
-        Calls `set_description_str(desc)` and `update(n)`
+        Sets `msg` as a postfix and calls `update(n)`.
         """
-        self.set_description_str(desc, refresh=False)
+        self.postfix["info"] = " %s |" % msg
         self.update(n)
 
     def update_to(self, current, total=None):
@@ -114,13 +114,27 @@ class Tqdm(tqdm):
             self.total = total  # pylint: disable=W0613,W0201
         self.update(current - self.n)
 
+    def wrap_fn(self, fn, callback=None):
+        """
+        Returns a wrapped `fn` which calls `callback()` on each call.
+        `callback` is `self.update` by default.
+        """
+        if callback is None:
+            callback = self.update
+
+        def wrapped(*args, **kwargs):
+            res = fn(*args, **kwargs)
+            callback()
+            return res
+
+        return wrapped
+
     def close(self):
-        if self.desc_persist is not None:
-            self.set_description_str(self.desc_persist, refresh=False)
-        # unknown/zero ETA
-        self.bar_format = self.bar_format.replace("<{remaining}", "")
-        # remove completed bar
-        self.bar_format = self.bar_format.replace("|{bar:10}|", " ")
+        self.postfix["info"] = ""
+        # remove ETA (either unknown or zero); remove completed bar
+        self.bar_format = self.bar_format.replace("<{remaining}", "").replace(
+            "|{bar:10}|", " "
+        )
         super().close()
 
     @property
@@ -128,12 +142,15 @@ class Tqdm(tqdm):
         """inject `ncols_desc` to fill the display width (`ncols`)"""
         d = super().format_dict
         ncols = d["ncols"] or 80
-        ncols_desc = ncols - len(self.format_meter(ncols_desc=1, **d)) + 1
-        ncols_desc = max(ncols_desc, 0)
-        if ncols_desc:
-            d["ncols_desc"] = ncols_desc
+        # assumes `bar_format` has max one of ("ncols_desc" & "ncols_info")
+        ncols_left = (
+            ncols - len(self.format_meter(ncols_desc=1, ncols_info=1, **d)) + 1
+        )
+        ncols_left = max(ncols_left, 0)
+        if ncols_left:
+            d["ncols_desc"] = d["ncols_info"] = ncols_left
         else:
             # work-around for zero-width description
-            d["ncols_desc"] = 1
+            d["ncols_desc"] = d["ncols_info"] = 1
             d["prefix"] = ""
         return d

dvc/prompt.py

@@ -38,7 +38,7 @@ def confirm(statement):
     Returns:
         bool: whether or not specified statement was confirmed.
     """
-    prompt = "{statement} [y/n]".format(statement=statement)
+    prompt = f"{statement} [y/n]"
     answer = _ask(prompt, limited_to=["yes", "no", "y", "n"])
     return answer and answer.startswith("y")
 
@@ -52,5 +52,5 @@ def password(statement):
     Returns:
         str: password entered by the user.
     """
-    logger.info("{statement}: ".format(statement=statement))
+    logger.info(f"{statement}: ")
     return getpass("")