git: use backend-provided trie in GitTree (#5044)

dvc/scm/git/backend/gitpython.py

@@ -1,3 +1,5 @@
+import io
+import locale
 import logging
 import os
 from functools import partial
@@ -7,9 +9,9 @@ from funcy import first
 
 from dvc.progress import Tqdm
 from dvc.scm.base import CloneError, RevError, SCMError
-from dvc.tree.base import BaseTree
 from dvc.utils import fix_env, is_binary
 
+from ..objects import GitObject
 from .base import BaseGitBackend
 
 logger = logging.getLogger(__name__)
@@ -47,6 +49,38 @@ class TqdmGit(Tqdm):
         return ops.get(op_code & OP.OP_MASK, "")
 
 
+class GitPythonObject(GitObject):
+    def __init__(self, obj):
+        self.obj = obj
+
+    def open(self, mode: str = "r", encoding: str = None):
+        if not encoding:
+            encoding = locale.getpreferredencoding(False)
+        # GitPython's obj.data_stream is a fragile thing, it is better to
+        # read it immediately, also it needs to be to decoded if we follow
+        # the `open()` behavior (since data_stream.read() returns bytes,
+        # and `open` with default "r" mode returns str)
+        data = self.obj.data_stream.read()
+        if mode == "rb":
+            return io.BytesIO(data)
+        return io.StringIO(data.decode(encoding))
+
+    @property
+    def name(self) -> str:
+        # NOTE: `obj.name` is not always a basename. See [1] for more details.
+        #
+        # [1] https://github.com/iterative/dvc/issues/3481
+        return os.path.basename(self.obj.path)
+
+    @property
+    def mode(self) -> int:
+        return self.obj.mode
+
+    def scandir(self) -> Iterable["GitPythonObject"]:
+        for obj in self.obj:
+            yield GitPythonObject(obj)
+
+
 class GitPythonBackend(BaseGitBackend):  # pylint:disable=abstract-method
     """git-python Git backend."""
 
@@ -227,10 +261,9 @@ class GitPythonBackend(BaseGitBackend):  # pylint:disable=abstract-method
             )
         ]
 
-    def get_tree(self, rev: str, **kwargs) -> BaseTree:
-        from dvc.tree.git import GitTree
-
-        return GitTree(self.repo, self.resolve_rev(rev), **kwargs)
+    def get_tree_obj(self, rev: str, **kwargs) -> GitPythonObject:
+        tree = self.repo.tree(rev)
+        return GitPythonObject(tree)
 
     def get_rev(self):
         return self.repo.rev_parse("HEAD").hexsha