tree: get rid of explicit tree arguments (#4310)

* cache: don't make save() compute the hash

This is incorrect and leads to weird bugs like #4305

* tree: get rid of explicit tree arguments

dvc/cache/base.py

@@ -276,8 +276,6 @@ class CloudCache:
                 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)
 

dvc/external_repo.py

@@ -90,15 +90,26 @@ class BaseExternalRepo:
         """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
+        has_cache = hasattr(self, "cache")
+
+        if has_cache:
+            save_cache = self.cache.local  # pylint: disable=E0203
+            self.cache.local = cache  # pylint: disable=E0203
+        else:
+            from collections import namedtuple
+
+            mock_cache = namedtuple("MockCache", ["local"])(local=cache)
+            self.cache = mock_cache  # pylint: disable=W0201
+
         self._local_cache = cache
 
         yield
 
-        if hasattr(self, "cache"):
+        if has_cache:
             self.cache.local = save_cache
+        else:
+            del self.cache
+
         self._local_cache = None
 
     @cached_property
@@ -130,14 +141,17 @@ class BaseExternalRepo:
         for path in paths:
             if not self.repo_tree.exists(path):
                 raise PathMissingError(path, self.url)
-            save_info = self.local_cache.save(
+            hash_info = self.repo_tree.save_info(
+                path, download_callback=download_update
+            )
+            self.local_cache.save(
                 path,
                 self.repo_tree,
-                None,
+                hash_info,
                 save_link=False,
                 download_callback=download_update,
             )
-            save_infos.append(save_info)
+            save_infos.append(hash_info)
 
         return sum(download_results), failed, save_infos
 

dvc/repo/tree.py

@@ -245,6 +245,9 @@ class RepoTree(BaseTree):  # pylint:disable=abstract-method
     Any kwargs will be passed to `DvcTree()`.
     """
 
+    scheme = "local"
+    PARAM_CHECKSUM = "md5"
+
     def __init__(self, repo, **kwargs):
         super().__init__(repo, {"url": repo.root_dir})
         if hasattr(repo, "dvc_dir"):

dvc/tree/base.py

@@ -236,22 +236,17 @@ class BaseTree:
             return False
         return hash_.endswith(cls.CHECKSUM_DIR_SUFFIX)
 
-    def get_hash(self, path_info, tree=None, **kwargs):
+    def get_hash(self, path_info, **kwargs):
         assert path_info and (
             isinstance(path_info, str) or path_info.scheme == self.scheme
         )
 
-        if not tree:
-            tree = self
-
-        if not tree.exists(path_info):
+        if not self.exists(path_info):
             return None
 
-        if tree == self:
-            # pylint: disable=assignment-from-none
-            hash_ = self.state.get(path_info)
-        else:
-            hash_ = None
+        # pylint: disable=assignment-from-none
+        hash_ = self.state.get(path_info)
+
         # If we have dir hash in state db, but dir cache file is lost,
         # then we need to recollect the dir via .get_dir_hash() call below,
         # see https://github.com/iterative/dvc/issues/2219 for context
@@ -267,10 +262,10 @@ class BaseTree:
         if hash_:
             return hash_
 
-        if tree.isdir(path_info):
-            hash_ = self.get_dir_hash(path_info, tree, **kwargs)
+        if self.isdir(path_info):
+            hash_ = self.get_dir_hash(path_info, **kwargs)
         else:
-            hash_ = tree.get_file_hash(path_info)
+            hash_ = self.get_file_hash(path_info)
 
         if hash_ and self.exists(path_info):
             self.state.save(path_info, hash_)
@@ -280,11 +275,11 @@ class BaseTree:
     def get_file_hash(self, path_info):
         raise NotImplementedError
 
-    def get_dir_hash(self, path_info, tree, **kwargs):
+    def get_dir_hash(self, path_info, **kwargs):
         if not self.cache:
             raise RemoteCacheRequiredError(path_info)
 
-        dir_info = self._collect_dir(path_info, tree, **kwargs)
+        dir_info = self._collect_dir(path_info, **kwargs)
         return self._save_dir_info(dir_info, path_info)
 
     def hash_to_path_info(self, hash_):
@@ -298,29 +293,26 @@ class BaseTree:
 
         return "".join(parts)
 
-    def save_info(self, path_info, tree=None, **kwargs):
-        return {
-            self.PARAM_CHECKSUM: self.get_hash(path_info, tree=tree, **kwargs)
-        }
+    def save_info(self, path_info, **kwargs):
+        return {self.PARAM_CHECKSUM: self.get_hash(path_info, **kwargs)}
 
-    @staticmethod
-    def _calculate_hashes(file_infos, tree):
+    def _calculate_hashes(self, file_infos):
         file_infos = list(file_infos)
         with Tqdm(
             total=len(file_infos),
             unit="md5",
             desc="Computing file/dir hashes (only done once)",
         ) as pbar:
-            worker = pbar.wrap_fn(tree.get_file_hash)
-            with ThreadPoolExecutor(max_workers=tree.hash_jobs) as executor:
+            worker = pbar.wrap_fn(self.get_file_hash)
+            with ThreadPoolExecutor(max_workers=self.hash_jobs) as executor:
                 tasks = executor.map(worker, file_infos)
                 hashes = dict(zip(file_infos, tasks))
         return hashes
 
-    def _collect_dir(self, path_info, tree, **kwargs):
+    def _collect_dir(self, path_info, **kwargs):
         file_infos = set()
 
-        for fname in tree.walk_files(path_info, **kwargs):
+        for fname in self.walk_files(path_info, **kwargs):
             if DvcIgnore.DVCIGNORE_FILE == fname.name:
                 raise DvcIgnoreInCollectedDirError(fname.parent)
 
@@ -329,7 +321,7 @@ class BaseTree:
         hashes = {fi: self.state.get(fi) for fi in file_infos}
         not_in_state = {fi for fi, hash_ in hashes.items() if hash_ is None}
 
-        new_hashes = self._calculate_hashes(not_in_state, tree)
+        new_hashes = self._calculate_hashes(not_in_state)
         hashes.update(new_hashes)
 
         result = [

tests/func/test_tree.py

@@ -217,7 +217,10 @@ def test_repotree_cache_save(tmp_dir, dvc, scm, erepo_dir, local_cloud):
     with erepo_dir.dvc.state:
         cache = dvc.cache.local
         with cache.tree.state:
-            cache.save(PathInfo(erepo_dir / "dir"), tree, None)
+            path_info = PathInfo(erepo_dir / "dir")
+            hash_info = cache.tree.save_info(path_info)
+            cache.save(path_info, tree, hash_info)
+
     for hash_ in expected:
         assert os.path.exists(cache.tree.hash_to_path_info(hash_))