dvc: use DirInfo instead of dicts/lists (#4851)

Currently we are converting dir_info to/from lists all the time.
The reason is that dir_info is stored as list of dicts in *.dir files,
but that makes it hard to work with. In addition to that, we will likely
be changing .dir file format in the near future #829, so we need to
abstract away dir_info into something that we won't care how it will be
stored on disk.

Related #3256
Related #4847

dvc/cache/base.py

@@ -1,21 +1,18 @@
 import json
 import logging
 from copy import copy
-from operator import itemgetter
 
 from funcy import decorator
 from shortuuid import uuid
 
 import dvc.prompt as prompt
+from dvc.dir_info import DirInfo
 from dvc.exceptions import (
     CacheLinkError,
     CheckoutError,
     ConfirmRemoveError,
     DvcException,
-    MergeError,
 )
-from dvc.hash_info import HashInfo
-from dvc.path_info import WindowsPathInfo
 from dvc.progress import Tqdm
 from dvc.remote.slow_link_detection import slow_link_guard
 
@@ -77,7 +74,7 @@ class CloudCache:
         try:
             dir_info = self.load_dir_cache(hash_info)
         except DirCacheError:
-            dir_info = []
+            dir_info = DirInfo()
 
         self._dir_info[hash_info.value] = dir_info
         return dir_info
@@ -96,18 +93,9 @@ class CloudCache:
                 "dir cache file format error '%s' [skipping the file]",
                 path_info,
             )
-            return []
+            d = []
 
-        if self.tree.PATH_CLS == WindowsPathInfo:
+        return DirInfo.from_list(d)
-            # 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.
@@ -271,14 +259,9 @@ class CloudCache:
         from dvc.path_info import PathInfo
         from dvc.utils import tmp_fname
 
-        # Sorting the list by path to ensure reproducibility
-        if isinstance(dir_info, dict):
-            dir_info = self._from_dict(dir_info)
-        dir_info = sorted(dir_info, key=itemgetter(self.tree.PARAM_RELPATH))
-
         tmp = tempfile.NamedTemporaryFile(delete=False).name
         with open(tmp, "w+") as fobj:
-            json.dump(dir_info, fobj, sort_keys=True)
+            json.dump(dir_info.to_list(), fobj, sort_keys=True)
 
         from_info = PathInfo(tmp)
         to_info = self.tree.path_info / tmp_fname("")
@@ -286,8 +269,8 @@ class CloudCache:
 
         hash_info = self.tree.get_file_hash(to_info)
         hash_info.value += self.tree.CHECKSUM_DIR_SUFFIX
-        hash_info.dir_info = self._to_dict(dir_info)
+        hash_info.dir_info = dir_info
-        hash_info.nfiles = len(dir_info)
+        hash_info.nfiles = dir_info.nfiles
 
         return hash_info, to_info
 
@@ -312,14 +295,13 @@ class CloudCache:
 
     def _save_dir(self, path_info, tree, hash_info, save_link=True, **kwargs):
         if not hash_info.dir_info:
-            hash_info.dir_info = self._to_dict(
+            hash_info.dir_info = tree.cache.get_dir_cache(hash_info)
-                tree.cache.get_dir_cache(hash_info)
-            )
         hi = self.save_dir_info(hash_info.dir_info, hash_info)
-        for relpath, entry_hash in Tqdm(
+        for entry_info, entry_hash in Tqdm(
-            hi.dir_info.items(), desc="Saving " + path_info.name, unit="file"
+            hi.dir_info.items(path_info),
+            desc="Saving " + path_info.name,
+            unit="file",
         ):
-            entry_info = path_info / relpath
             self._save_file(
                 entry_info, tree, entry_hash, save_link=False, **kwargs
             )
@@ -404,13 +386,9 @@ class CloudCache:
         if self.changed_cache_file(hash_info):
             return True
 
-        for entry in self.get_dir_cache(hash_info):
+        dir_info = self.get_dir_cache(hash_info)
-            entry_hash = HashInfo(
+        for entry_info, entry_hash in dir_info.items(path_info):
-                self.tree.PARAM_CHECKSUM, 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
 
@@ -488,16 +466,14 @@ class CloudCache:
 
         logger.debug("Linking directory '%s'.", path_info)
 
-        for entry in dir_info:
+        for entry_info, entry_hash_info in dir_info.items(path_info):
-            relative_path = entry[self.tree.PARAM_RELPATH]
+            entry_cache_info = self.tree.hash_to_path_info(
-            entry_hash = entry[self.tree.PARAM_CHECKSUM]
+                entry_hash_info.value
-            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 = HashInfo(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)
@@ -520,9 +496,7 @@ class CloudCache:
     def _remove_redundant_files(self, path_info, dir_info, force):
         existing_files = set(self.tree.walk_files(path_info))
 
-        needed_files = {
+        needed_files = {info for info, _ in dir_info.items(path_info)}
-            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)
@@ -623,77 +597,19 @@ class CloudCache:
             return 1
 
         if not filter_info:
-            return len(self.get_dir_cache(hash_info))
+            return self.get_dir_cache(hash_info).nfiles
 
         return ilen(
-            filter_info.isin_or_eq(path_info / entry[self.tree.PARAM_CHECKSUM])
+            filter_info.isin_or_eq(path_info / relpath)
-            for entry in self.get_dir_cache(hash_info)
+            for relpath, _ in self.get_dir_cache(hash_info).items()
-        )
-
-    def _to_dict(self, dir_info):
-        info = {}
-        for _entry in dir_info:
-            entry = _entry.copy()
-            relpath = entry.pop(self.tree.PARAM_RELPATH)
-            info[relpath] = HashInfo.from_dict(entry)
-        return info
-
-    def _from_dict(self, dir_dict):
-        return [
-            {self.tree.PARAM_RELPATH: relpath, **hash_info.to_dict()}
-            for relpath, hash_info in dir_dict.items()
-        ]
-
-    @staticmethod
-    def _diff(ancestor, other, allow_removed=False):
-        from dictdiffer import diff
-
-        allowed = ["add"]
-        if allow_removed:
-            allowed.append("remove")
-
-        result = list(diff(ancestor, other))
-        for typ, _, _ in result:
-            if typ not in allowed:
-                raise MergeError(
-                    "unable to auto-merge directories with diff that contains "
-                    f"'{typ}'ed files"
-                )
-        return result
-
-    def _merge_dirs(self, ancestor_info, our_info, their_info):
-        from dictdiffer import patch
-
-        ancestor = self._to_dict(ancestor_info)
-        our = self._to_dict(our_info)
-        their = self._to_dict(their_info)
-
-        our_diff = self._diff(ancestor, our)
-        if not our_diff:
-            return self._from_dict(their)
-
-        their_diff = self._diff(ancestor, their)
-        if not their_diff:
-            return self._from_dict(our)
-
-        # make sure there are no conflicting files
-        self._diff(our, their, allow_removed=True)
-
-        merged = patch(our_diff + their_diff, ancestor, in_place=True)
-
-        # Sorting the list by path to ensure reproducibility
-        return sorted(
-            self._from_dict(merged), key=itemgetter(self.tree.PARAM_RELPATH),
         )
 
     def _get_dir_size(self, dir_info):
-        def _getsize(entry):
-            return self.tree.getsize(
-                self.tree.hash_to_path_info(entry[self.tree.PARAM_CHECKSUM])
-            )
-
         try:
-            return sum(_getsize(entry) for entry in dir_info)
+            return sum(
+                self.tree.getsize(self.tree.hash_to_path_info(hi.value))
+                for _, hi in dir_info.items()
+            )
         except FileNotFoundError:
             return None
 
@@ -704,12 +620,12 @@ class CloudCache:
         if ancestor_info:
             ancestor = self.get_dir_cache(ancestor_info)
         else:
-            ancestor = []
+            ancestor = DirInfo()
 
         our = self.get_dir_cache(our_info)
         their = self.get_dir_cache(their_info)
 
-        merged = self._merge_dirs(ancestor, our, their)
+        merged = our.merge(ancestor, their)
         hash_info = self.save_dir_info(merged)
         hash_info.size = self._get_dir_size(merged)
         return hash_info
@@ -728,5 +644,5 @@ class CloudCache:
     def set_dir_info(self, hash_info):
         assert hash_info.isdir
 
-        hash_info.dir_info = self._to_dict(self.get_dir_cache(hash_info))
+        hash_info.dir_info = self.get_dir_cache(hash_info)
-        hash_info.nfiles = len(hash_info.dir_info)
+        hash_info.nfiles = hash_info.dir_info.nfiles

dvc/dir_info.py

@@ -0,0 +1,102 @@
+import posixpath
+from operator import itemgetter
+
+from pygtrie import Trie
+
+from .hash_info import HashInfo
+
+
+def _diff(ancestor, other, allow_removed=False):
+    from dictdiffer import diff
+
+    from dvc.exceptions import MergeError
+
+    allowed = ["add"]
+    if allow_removed:
+        allowed.append("remove")
+
+    result = list(diff(ancestor, other))
+    for typ, _, _ in result:
+        if typ not in allowed:
+            raise MergeError(
+                "unable to auto-merge directories with diff that contains "
+                f"'{typ}'ed files"
+            )
+    return result
+
+
+def _merge(ancestor, our, their):
+    import copy
+
+    from dictdiffer import patch
+
+    our_diff = _diff(ancestor, our)
+    if not our_diff:
+        return copy.deepcopy(their)
+
+    their_diff = _diff(ancestor, their)
+    if not their_diff:
+        return copy.deepcopy(our)
+
+    # make sure there are no conflicting files
+    _diff(our, their, allow_removed=True)
+
+    return patch(our_diff + their_diff, ancestor)
+
+
+class DirInfo:
+    PARAM_RELPATH = "relpath"
+
+    def __init__(self):
+        self.trie = Trie()
+
+    @property
+    def size(self):
+        try:
+            return sum(
+                hash_info.size
+                for _, hash_info in self.trie.iteritems()  # noqa: B301
+            )
+        except TypeError:
+            return None
+
+    @property
+    def nfiles(self):
+        return len(self.trie)
+
+    def items(self, path_info=None):
+        for key, hash_info in self.trie.iteritems():  # noqa: B301
+            path = posixpath.sep.join(key)
+            if path_info is not None:
+                path = path_info / path
+            yield path, hash_info
+
+    @classmethod
+    def from_list(cls, lst):
+        ret = DirInfo()
+        for _entry in lst:
+            entry = _entry.copy()
+            relpath = entry.pop(cls.PARAM_RELPATH)
+            parts = tuple(relpath.split(posixpath.sep))
+            ret.trie[parts] = HashInfo.from_dict(entry)
+        return ret
+
+    def to_list(self):
+        # Sorting the list by path to ensure reproducibility
+        return sorted(
+            (
+                {
+                    # NOTE: not using hash_info.to_dict() because we don't want
+                    # size/nfiles fields at this point.
+                    hash_info.name: hash_info.value,
+                    self.PARAM_RELPATH: posixpath.sep.join(parts),
+                }
+                for parts, hash_info in self.trie.iteritems()  # noqa: B301
+            ),
+            key=itemgetter(self.PARAM_RELPATH),
+        )
+
+    def merge(self, ancestor, their):
+        merged = DirInfo()
+        merged.trie = _merge(ancestor.trie, self.trie, their.trie)
+        return merged

dvc/output/base.py

@@ -454,9 +454,7 @@ class BaseOutput:
         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:
+        for entry_relpath, entry_hash_info in self.dir_cache.items():
-            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)
@@ -465,7 +463,7 @@ class BaseOutput:
                 or entry_path == filter_path
                 or entry_path.startswith(filter_path + os.sep)
             ):
-                cache.add(self.scheme, checksum, entry_path)
+                cache.add(self.scheme, entry_hash_info.value, entry_path)
 
         return cache
 

dvc/tree/base.py

@@ -7,6 +7,7 @@ from urllib.parse import urlparse
 
 from funcy import cached_property, decorator
 
+from dvc.dir_info import DirInfo
 from dvc.exceptions import DvcException, DvcIgnoreInCollectedDirError
 from dvc.ignore import DvcIgnore
 from dvc.path_info import URLInfo
@@ -50,7 +51,6 @@ class BaseTree:
     PATH_CLS = URLInfo
     JOBS = 4 * cpu_count()
 
-    PARAM_RELPATH = "relpath"
     CHECKSUM_DIR_SUFFIX = ".dir"
     HASH_JOBS = max(1, min(4, cpu_count() // 2))
     DEFAULT_VERIFY = False
@@ -318,35 +318,25 @@ class BaseTree:
         new_hash_infos = self._calculate_hashes(not_in_state)
         hash_infos.update(new_hash_infos)
 
-        sizes = [hi.size for hi in hash_infos.values()]
+        dir_info = DirInfo()
-        if None in sizes:
+        for fi, hi in hash_infos.items():
-            size = None
+            # NOTE: this is lossy transformation:
-        else:
+            #   "hey\there" -> "hey/there"
-            size = sum(sizes)
+            #   "hey/there" -> "hey/there"
+            # The latter is fine filename on Windows, which
+            # will transform to dir/file on back transform.
+            #
+            # Yes, this is a BUG, as long as we permit "/" in
+            # filenames on Windows and "\" on Unix
+            dir_info.trie[fi.relative_to(path_info).parts] = hi
 
-        dir_info = [
+        return dir_info
-            {
-                self.PARAM_CHECKSUM: hash_infos[fi].value,
-                # NOTE: this is lossy transformation:
-                #   "hey\there" -> "hey/there"
-                #   "hey/there" -> "hey/there"
-                # The latter is fine filename on Windows, which
-                # will transform to dir/file on back transform.
-                #
-                # Yes, this is a BUG, as long as we permit "/" in
-                # filenames on Windows and "\" on Unix
-                self.PARAM_RELPATH: fi.relative_to(path_info).as_posix(),
-            }
-            for fi in file_infos
-        ]
-
-        return (dir_info, size)
 
     @use_state
     def get_dir_hash(self, path_info, **kwargs):
-        dir_info, size = self._collect_dir(path_info, **kwargs)
+        dir_info = self._collect_dir(path_info, **kwargs)
         hash_info = self.repo.cache.local.save_dir_info(dir_info)
-        hash_info.size = size
+        hash_info.size = dir_info.size
         return hash_info
 
     def upload(self, from_info, to_info, name=None, no_progress_bar=False):

dvc/tree/dvc.py

@@ -32,7 +32,6 @@ class DvcTree(BaseTree):  # pylint:disable=abstract-method
 
     scheme = "local"
     PARAM_CHECKSUM = "md5"
-    _cached_dir_cache = None
     _dir_entry_hashes = {}
 
     def __init__(self, repo, fetch=False, stream=False):
@@ -60,11 +59,9 @@ class DvcTree(BaseTree):  # pylint:disable=abstract-method
             raise FileNotFoundError
 
         # NOTE: use string paths here for performance reasons
-        path_str = relpath(path_info, out.path_info)
+        key = tuple(relpath(path_info, out.path_info).split(os.sep))
-        if os.name == "nt":
-            path_str = path_str.replace(os.sep, "/")
         out.get_dir_cache(remote=remote)
-        file_hash = out.hash_info.dir_info.get(path_str)
+        file_hash = out.hash_info.dir_info.trie.get(key)
         if file_hash:
             return file_hash
         raise FileNotFoundError
@@ -166,12 +163,9 @@ class DvcTree(BaseTree):  # pylint:disable=abstract-method
 
         self._fetch_dir(out, filter_info=top, **kwargs)
 
-        for entry in out.dir_cache:
+        base = out.path_info.parts
-            entry_relpath = entry[out.tree.PARAM_RELPATH]
+        for key in out.dir_cache.trie.iterkeys():  # noqa: B301
-            if os.name == "nt":
+            trie[base + key] = None
-                entry_relpath = entry_relpath.replace("/", os.sep)
-            path_info = out.path_info / entry_relpath
-            trie[path_info.parts] = None
 
     def _walk(self, root, trie, topdown=True, **kwargs):
         dirs = set()

tests/func/remote/test_index.py

@@ -32,14 +32,16 @@ def remote(tmp_dir, dvc, tmp_path_factory, mocker):
 def test_indexed_on_status(tmp_dir, dvc, tmp_path_factory, remote):
     foo = tmp_dir.dvc_gen({"foo": "foo content"})[0].outs[0]
     bar = tmp_dir.dvc_gen({"bar": {"baz": "baz content"}})[0].outs[0]
-    baz = bar.dir_cache[0]
+    baz_hash = bar.dir_cache.trie.get(("baz",))
     dvc.push()
     with remote.index:
         remote.index.clear()
 
     dvc.status(cloud=True)
     with remote.index:
-        assert {bar.hash_info.value, baz["md5"]} == set(remote.index.hashes())
+        assert {bar.hash_info.value, baz_hash.value} == set(
+            remote.index.hashes()
+        )
         assert [bar.hash_info.value] == list(remote.index.dir_hashes())
         assert foo.hash_info.value not in remote.index.hashes()
 
@@ -47,11 +49,13 @@ def test_indexed_on_status(tmp_dir, dvc, tmp_path_factory, remote):
 def test_indexed_on_push(tmp_dir, dvc, tmp_path_factory, remote):
     foo = tmp_dir.dvc_gen({"foo": "foo content"})[0].outs[0]
     bar = tmp_dir.dvc_gen({"bar": {"baz": "baz content"}})[0].outs[0]
-    baz = bar.dir_cache[0]
+    baz_hash = bar.dir_cache.trie.get(("baz",))
 
     dvc.push()
     with remote.index:
-        assert {bar.hash_info.value, baz["md5"]} == set(remote.index.hashes())
+        assert {bar.hash_info.value, baz_hash.value} == set(
+            remote.index.hashes()
+        )
         assert [bar.hash_info.value] == list(remote.index.dir_hashes())
         assert foo.hash_info.value not in remote.index.hashes()
 

tests/func/test_add.py

@@ -80,8 +80,8 @@ def test_add_directory(tmp_dir, dvc):
     hash_info = stage.outs[0].hash_info
 
     dir_info = dvc.cache.local.load_dir_cache(hash_info)
-    for info in dir_info:
+    for path, _ in dir_info.trie.items():
-        assert "\\" not in info["relpath"]
+        assert "\\" not in path
 
 
 class TestAddDirectoryRecursive(TestDvc):

tests/func/test_cache.py

@@ -6,6 +6,7 @@ import pytest
 
 from dvc.cache import Cache
 from dvc.cache.base import DirCacheError
+from dvc.dir_info import DirInfo
 from dvc.hash_info import HashInfo
 from dvc.main import main
 from dvc.utils import relpath
@@ -60,9 +61,11 @@ class TestCacheLoadBadDirCache(TestDvc):
             self.dvc.cache.local.tree.hash_to_path_info(dir_hash)
         )
         self.create(fname, '{"a": "b"}')
-        self._do_test(
+        dir_info = self.dvc.cache.local.load_dir_cache(
-            self.dvc.cache.local.load_dir_cache(HashInfo("md5", dir_hash))
+            HashInfo("md5", dir_hash)
         )
+        self.assertTrue(isinstance(dir_info, DirInfo))
+        self.assertEqual(dir_info.nfiles, 0)
 
 
 class TestExternalCacheDir(TestDvc):

tests/func/test_checkout.py

@@ -100,10 +100,11 @@ class TestCheckoutCorruptedCacheDir(TestDvc):
 
         # NOTE: modifying cache file for one of the files inside the directory
         # to check if dvc will detect that the cache is corrupted.
-        entry = self.dvc.cache.local.load_dir_cache(out.hash_info)[0]
+        _, entry_hash = next(
-        entry_hash = entry[self.dvc.cache.local.tree.PARAM_CHECKSUM]
+            self.dvc.cache.local.load_dir_cache(out.hash_info).items()
+        )
         cache = os.fspath(
-            self.dvc.cache.local.tree.hash_to_path_info(entry_hash)
+            self.dvc.cache.local.tree.hash_to_path_info(entry_hash.value)
         )
 
         os.chmod(cache, 0o644)

tests/func/test_remote.py

@@ -7,6 +7,7 @@ import pytest
 from mock import patch
 
 from dvc.config import Config
+from dvc.dir_info import DirInfo
 from dvc.exceptions import DownloadError, RemoteCacheRequiredError, UploadError
 from dvc.main import main
 from dvc.path_info import PathInfo
@@ -149,23 +150,20 @@ def test_dir_hash_should_be_key_order_agnostic(tmp_dir, dvc):
     tmp_dir.gen({"data": {"1": "1 content", "2": "2 content"}})
 
     path_info = PathInfo("data")
+
+    dir_info = DirInfo.from_list(
+        [{"relpath": "1", "md5": "1"}, {"relpath": "2", "md5": "2"}]
+    )
     with patch.object(
-        BaseTree,
+        BaseTree, "_collect_dir", return_value=dir_info,
-        "_collect_dir",
-        return_value=(
-            [{"relpath": "1", "md5": "1"}, {"relpath": "2", "md5": "2"}],
-            None,
-        ),
     ):
         hash1 = dvc.cache.local.tree.get_hash(path_info)
 
+    dir_info = DirInfo.from_list(
+        [{"md5": "1", "relpath": "1"}, {"md5": "2", "relpath": "2"}]
+    )
     with patch.object(
-        BaseTree,
+        BaseTree, "_collect_dir", return_value=dir_info,
-        "_collect_dir",
-        return_value=(
-            [{"md5": "1", "relpath": "1"}, {"md5": "2", "relpath": "2"}],
-            None,
-        ),
     ):
         hash2 = dvc.cache.local.tree.get_hash(path_info)
 
@@ -277,7 +275,7 @@ def test_push_order(tmp_dir, dvc, tmp_path_factory, mocker, local_remote):
     remote = dvc.cloud.get_remote("upstream")
     foo_path = remote.tree.hash_to_path_info(foo.hash_info.value)
     bar_path = remote.tree.hash_to_path_info(
-        foo.hash_info.dir_info["bar"].value
+        foo.hash_info.dir_info.trie[("bar",)].value
     )
     paths = [args[1] for args, _ in mocked_upload.call_args_list]
     assert paths.index(foo_path) > paths.index(bar_path)

tests/func/test_tree.py

@@ -198,9 +198,9 @@ def test_repotree_walk_fetch(tmp_dir, dvc, scm, local_remote):
         pass
 
     assert os.path.exists(out.cache_path)
-    for entry in out.dir_cache:
+    for _, hi in out.dir_cache.items():
-        hash_ = entry[out.tree.PARAM_CHECKSUM]
+        assert hi.name == out.tree.PARAM_CHECKSUM
-        assert os.path.exists(dvc.cache.local.tree.hash_to_path_info(hash_))
+        assert os.path.exists(dvc.cache.local.tree.hash_to_path_info(hi.value))
 
 
 def test_repotree_cache_save(tmp_dir, dvc, scm, erepo_dir, local_cloud):

tests/unit/output/test_local.py

@@ -3,6 +3,7 @@ import os
 from mock import patch
 
 from dvc.cache.local import LocalCache
+from dvc.dir_info import DirInfo
 from dvc.hash_info import HashInfo
 from dvc.output import LocalOutput
 from dvc.stage import Stage
@@ -81,7 +82,12 @@ class TestGetFilesNumber(TestDvc):
     @patch.object(
         LocalCache,
         "get_dir_cache",
-        return_value=[{"md5": "asdf"}, {"md5": "qwe"}],
+        return_value=DirInfo.from_list(
+            [
+                {"relpath": "foo", "md5": "asdf"},
+                {"relpath": "bar", "md5": "qwe"},
+            ]
+        ),
     )
     def test_return_multiple_for_dir(self, _mock_get_dir_cache):
         o = self._get_output()

tests/unit/test_dir_info.py

@@ -0,0 +1,273 @@
+from operator import itemgetter
+
+import pytest
+from pygtrie import Trie
+
+from dvc.dir_info import DirInfo, _merge
+from dvc.hash_info import HashInfo
+from dvc.path_info import PosixPathInfo, WindowsPathInfo
+
+
+@pytest.mark.parametrize(
+    "lst, trie_dict",
+    [
+        ([], {}),
+        (
+            [
+                {"md5": "def", "relpath": "zzz"},
+                {"md5": "123", "relpath": "foo"},
+                {"md5": "abc", "relpath": "aaa"},
+                {"md5": "456", "relpath": "bar"},
+            ],
+            {
+                ("zzz",): HashInfo("md5", "def"),
+                ("foo",): HashInfo("md5", "123"),
+                ("bar",): HashInfo("md5", "456"),
+                ("aaa",): HashInfo("md5", "abc"),
+            },
+        ),
+        (
+            [
+                {"md5": "123", "relpath": "dir/b"},
+                {"md5": "456", "relpath": "dir/z"},
+                {"md5": "789", "relpath": "dir/a"},
+                {"md5": "abc", "relpath": "b"},
+                {"md5": "def", "relpath": "a"},
+                {"md5": "ghi", "relpath": "z"},
+                {"md5": "jkl", "relpath": "dir/subdir/b"},
+                {"md5": "mno", "relpath": "dir/subdir/z"},
+                {"md5": "pqr", "relpath": "dir/subdir/a"},
+            ],
+            {
+                ("dir", "b"): HashInfo("md5", "123"),
+                ("dir", "z"): HashInfo("md5", "456"),
+                ("dir", "a"): HashInfo("md5", "789"),
+                ("b",): HashInfo("md5", "abc"),
+                ("a",): HashInfo("md5", "def"),
+                ("z",): HashInfo("md5", "ghi"),
+                ("dir", "subdir", "b"): HashInfo("md5", "jkl"),
+                ("dir", "subdir", "z"): HashInfo("md5", "mno"),
+                ("dir", "subdir", "a"): HashInfo("md5", "pqr"),
+            },
+        ),
+    ],
+)
+def test_list(lst, trie_dict):
+    dir_info = DirInfo.from_list(lst)
+    assert dir_info.trie == Trie(trie_dict)
+    assert dir_info.to_list() == sorted(lst, key=itemgetter("relpath"))
+
+
+@pytest.mark.parametrize(
+    "trie_dict, size",
+    [
+        ({}, 0),
+        (
+            {
+                ("a",): HashInfo("md5", "abc", size=1),
+                ("b",): HashInfo("md5", "def", size=2),
+                ("c",): HashInfo("md5", "ghi", size=3),
+                ("dir", "foo"): HashInfo("md5", "jkl", size=4),
+                ("dir", "bar"): HashInfo("md5", "mno", size=5),
+                ("dir", "baz"): HashInfo("md5", "pqr", size=6),
+            },
+            21,
+        ),
+        (
+            {
+                ("a",): HashInfo("md5", "abc", size=1),
+                ("b",): HashInfo("md5", "def", size=None),
+            },
+            None,
+        ),
+    ],
+)
+def test_size(trie_dict, size):
+    dir_info = DirInfo()
+    dir_info.trie = Trie(trie_dict)
+    assert dir_info.size == size
+
+
+@pytest.mark.parametrize(
+    "trie_dict, nfiles",
+    [
+        ({}, 0),
+        (
+            {
+                ("a",): HashInfo("md5", "abc", size=1),
+                ("b",): HashInfo("md5", "def", size=2),
+                ("c",): HashInfo("md5", "ghi", size=3),
+                ("dir", "foo"): HashInfo("md5", "jkl", size=4),
+                ("dir", "bar"): HashInfo("md5", "mno", size=5),
+                ("dir", "baz"): HashInfo("md5", "pqr", size=6),
+            },
+            6,
+        ),
+        (
+            {
+                ("a",): HashInfo("md5", "abc", size=1),
+                ("b",): HashInfo("md5", "def", size=None),
+            },
+            2,
+        ),
+    ],
+)
+def test_nfiles(trie_dict, nfiles):
+    dir_info = DirInfo()
+    dir_info.trie = Trie(trie_dict)
+    assert dir_info.nfiles == nfiles
+
+
+@pytest.mark.parametrize(
+    "trie_dict, items",
+    [
+        ({}, []),
+        (
+            {
+                ("a",): HashInfo("md5", "abc"),
+                ("b",): HashInfo("md5", "def"),
+                ("c",): HashInfo("md5", "ghi"),
+                ("dir", "foo"): HashInfo("md5", "jkl"),
+                ("dir", "bar"): HashInfo("md5", "mno"),
+                ("dir", "baz"): HashInfo("md5", "pqr"),
+                ("dir", "subdir", "1"): HashInfo("md5", "stu"),
+                ("dir", "subdir", "2"): HashInfo("md5", "vwx"),
+                ("dir", "subdir", "3"): HashInfo("md5", "yz"),
+            },
+            [
+                ("a", HashInfo("md5", "abc")),
+                ("b", HashInfo("md5", "def")),
+                ("c", HashInfo("md5", "ghi")),
+                ("dir/foo", HashInfo("md5", "jkl")),
+                ("dir/bar", HashInfo("md5", "mno")),
+                ("dir/baz", HashInfo("md5", "pqr")),
+                ("dir/subdir/1", HashInfo("md5", "stu")),
+                ("dir/subdir/2", HashInfo("md5", "vwx")),
+                ("dir/subdir/3", HashInfo("md5", "yz")),
+            ],
+        ),
+    ],
+)
+def test_items(trie_dict, items):
+    dir_info = DirInfo()
+    dir_info.trie = Trie(trie_dict)
+    assert list(dir_info.items()) == items
+
+
+@pytest.mark.parametrize(
+    "path_info, trie_dict, items",
+    [
+        (PosixPathInfo(), {}, []),
+        (WindowsPathInfo(), {}, []),
+        (
+            PosixPathInfo("/some/path"),
+            {
+                ("a",): HashInfo("md5", "abc"),
+                ("dir", "foo"): HashInfo("md5", "jkl"),
+                ("dir", "sub", "1"): HashInfo("md5", "stu"),
+            },
+            [
+                (PosixPathInfo("/some/path/a"), HashInfo("md5", "abc")),
+                (PosixPathInfo("/some/path/dir/foo"), HashInfo("md5", "jkl")),
+                (
+                    PosixPathInfo("/some/path/dir/sub/1"),
+                    HashInfo("md5", "stu"),
+                ),
+            ],
+        ),
+        (
+            WindowsPathInfo("C:\\some\\path"),
+            {
+                ("a",): HashInfo("md5", "abc"),
+                ("dir", "foo"): HashInfo("md5", "jkl"),
+                ("dir", "sub", "1"): HashInfo("md5", "stu"),
+            },
+            [
+                (WindowsPathInfo("C:\\some\\path\\a"), HashInfo("md5", "abc")),
+                (
+                    WindowsPathInfo("C:\\some\\path\\dir\\foo"),
+                    HashInfo("md5", "jkl"),
+                ),
+                (
+                    WindowsPathInfo("C:\\some\\path\\dir\\sub\\1"),
+                    HashInfo("md5", "stu"),
+                ),
+            ],
+        ),
+    ],
+)
+def test_items_with_path(path_info, trie_dict, items):
+    dir_info = DirInfo()
+    dir_info.trie = Trie(trie_dict)
+    assert list(dir_info.items(path_info)) == items
+
+
+@pytest.mark.parametrize(
+    "ancestor_dict, our_dict, their_dict, merged_dict",
+    [
+        ({}, {}, {}, {}),
+        (
+            {("foo",): HashInfo("md5", "123")},
+            {
+                ("foo",): HashInfo("md5", "123"),
+                ("bar",): HashInfo("md5", "345"),
+            },
+            {
+                ("foo",): HashInfo("md5", "123"),
+                ("baz",): HashInfo("md5", "678"),
+            },
+            {
+                ("foo",): HashInfo("md5", "123"),
+                ("bar",): HashInfo("md5", "345"),
+                ("baz",): HashInfo("md5", "678"),
+            },
+        ),
+        (
+            {
+                ("common",): HashInfo("md5", "123"),
+                ("subdir", "foo"): HashInfo("md5", "345"),
+            },
+            {
+                ("common",): HashInfo("md5", "123"),
+                ("subdir", "foo"): HashInfo("md5", "345"),
+                ("subdir", "bar"): HashInfo("md5", "678"),
+            },
+            {
+                ("common",): HashInfo("md5", "123"),
+                ("subdir", "foo"): HashInfo("md5", "345"),
+                ("subdir", "baz"): HashInfo("md5", "91011"),
+            },
+            {
+                ("common",): HashInfo("md5", "123"),
+                ("subdir", "foo"): HashInfo("md5", "345"),
+                ("subdir", "bar"): HashInfo("md5", "678"),
+                ("subdir", "baz"): HashInfo("md5", "91011"),
+            },
+        ),
+        (
+            {},
+            {("foo",): HashInfo("md5", "123")},
+            {("bar",): HashInfo("md5", "456")},
+            {
+                ("foo",): HashInfo("md5", "123"),
+                ("bar",): HashInfo("md5", "456"),
+            },
+        ),
+        (
+            {},
+            {},
+            {("bar",): HashInfo("md5", "123")},
+            {("bar",): HashInfo("md5", "123")},
+        ),
+        (
+            {},
+            {("bar",): HashInfo("md5", "123")},
+            {},
+            {("bar",): HashInfo("md5", "123")},
+        ),
+    ],
+)
+def test_merge(ancestor_dict, our_dict, their_dict, merged_dict):
+    actual = _merge(Trie(ancestor_dict), Trie(our_dict), Trie(their_dict))
+    expected = Trie(merged_dict)
+    assert actual == expected

tests/unit/tree/test_repo.py

@@ -560,7 +560,7 @@ def test_get_hash_dirty_dir(tmp_dir, dvc):
     actual = tree.get_hash(PathInfo(tmp_dir) / "dir")
     expected = HashInfo("md5", "ba75a2162ca9c29acecb7957105a0bc2.dir")
     assert actual == expected
-    assert len(actual.dir_info) == 3
+    assert actual.dir_info.nfiles == 3
 
 
 @pytest.mark.parametrize("traverse_subrepos", [True, False])