dvc.data: save and try loading raw dir objects

When staging a directory, always save a "raw dir object" to the odb.
If the corresponding ".dir" object has not been added to the odb,
`stage()` calls can load the tree from the raw dir object instead of
rebuilding it by walking the directory.

This can lead to significant speed improvements when calling
`dvc status` for modified directories.

Fixes #7390

dvc/data/stage.py

@@ -1,3 +1,4 @@
+import errno
 import hashlib
 import logging
 import os
@@ -19,6 +20,9 @@
     from dvc.fs.base import AnyFSPath, FileSystem
     from dvc.objects.db import ObjectDB
 
+    from .tree import Tree
+
+
 logger = logging.getLogger(__name__)
 
 
@@ -233,7 +237,7 @@ def _make_staging_url(
     return url
 
 
-def _get_staging(odb: "ObjectDB") -> "ObjectDB":
+def _get_staging(odb: "ObjectDB") -> "ReferenceObjectDB":
     """Return an ODB that can be used for staging objects.
 
     Staging will be a reference ODB stored in the the global memfs.
@@ -247,27 +251,90 @@ def _get_staging(odb: "ObjectDB") -> "ObjectDB":
     return ReferenceObjectDB(fs, fs_path, state=state)
 
 
-def _load_from_state(odb, staging, fs_path, fs, name):
+def _load_raw_dir_obj(odb: "ObjectDB", hash_info: "HashInfo") -> "Tree":
+    from dvc.objects.errors import ObjectFormatError
+
+    from .tree import Tree
+
+    try:
+        tree = Tree.load(odb, hash_info.as_raw())
+        tree.check(odb)
+        tree.hash_info = hash_info
+    except ObjectFormatError as exc:
+        raise FileNotFoundError(
+            errno.ENOENT,
+            "No such object",
+            odb.hash_to_path(hash_info.as_raw().value),
+        ) from exc
+
+    return tree
+
+
+def _load_from_state(
+    odb: "ObjectDB",
+    staging: "ReferenceObjectDB",
+    fs_path: "AnyFSPath",
+    fs: "FileSystem",
+    name: str,
+    dry_run: bool,
+) -> Tuple["ObjectDB", "Meta", "HashFile"]:
     from dvc.objects.errors import ObjectFormatError
 
     from . import check, load
     from .tree import Tree
 
     state = odb.state
     meta, hash_info = state.get(fs_path, fs)
-    if hash_info:
-        for odb_ in (odb, staging):
-            if odb_.exists(hash_info):
-                try:
-                    obj = load(odb_, hash_info)
-                    check(odb_, obj, check_hash=False)
-                    if isinstance(obj, Tree):
-                        meta.nfiles = len(obj)
-                    assert obj.hash_info.name == name
-                    return odb_, meta, obj
-                except (ObjectFormatError, FileNotFoundError):
-                    pass
-    raise FileNotFoundError
+    if not hash_info:
+        raise FileNotFoundError
+
+    for odb_ in (odb, staging):
+        if not odb_.exists(hash_info):
+            continue
+
+        try:
+            obj = load(odb, hash_info)
+            check(odb, obj, check_hash=False)
+        except (ObjectFormatError, FileNotFoundError):
+            continue
+
+        if isinstance(obj, Tree):
+            meta.nfiles = len(obj)
+        assert obj.hash_info.name == name
+        return odb_, meta, obj
+
+    if not hash_info.isdir:
+        raise FileNotFoundError
+
+    # Try loading the raw dir object saved by `stage`, see below and #7390
+    tree = _load_raw_dir_obj(odb, hash_info)
+    meta.nfiles = len(tree)
+    assert tree.hash_info.name == name
+
+    if not dry_run:
+        assert tree.fs
+        for key, _, oid in tree:
+            staging.add(
+                fs.path.join(fs_path, *key),
+                fs,
+                oid,
+                hardlink=False,
+                verify=False,
+            )
+
+        staging.add(
+            tree.fs_path,
+            tree.fs,
+            hash_info,
+            hardlink=False,
+        )
+
+        raw = staging.get(hash_info)
+        tree.fs = raw.fs
+        tree.fs_path = raw.fs_path
+
+    logger.debug("loaded tree '%s' from raw dir obj", tree)
+    return staging, meta, tree
 
 
 def _stage_external_tree_info(odb, tree, name):
@@ -318,7 +385,7 @@ def stage(
     staging = _get_staging(odb)
     if odb:
         try:
-            return _load_from_state(odb, staging, fs_path, fs, name)
+            return _load_from_state(odb, staging, fs_path, fs, name, dry_run)
         except FileNotFoundError:
             pass
 
@@ -336,6 +403,12 @@ def stage(
         logger.debug("staged tree '%s'", obj)
         if name != "md5":
             obj = _stage_external_tree_info(odb, obj, name)
+
+        # In order to avoid re-building the tree when it is not committed to
+        # the local odb (e.g. for a status call), we save it as a raw object.
+        # Loading this instead of building the tree can speed up `dvc status`
+        # for modified directories, see #7390
+        odb.add(obj.fs_path, obj.fs, obj.hash_info.as_raw())
     else:
         _, meta, obj = _stage_file(
             fs_path,

dvc/data/tree.py

@@ -140,7 +140,7 @@ def from_list(cls, lst):
         return tree
 
     @classmethod
-    def load(cls, odb, hash_info):
+    def load(cls, odb, hash_info) -> "Tree":
         obj = odb.get(hash_info)
 
         try:

dvc/objects/hash_info.py

@@ -41,3 +41,9 @@ def isdir(self):
         if not self:
             return False
         return self.value.endswith(HASH_DIR_SUFFIX)
+
+    def as_raw(self) -> "HashInfo":
+        assert self.value
+        return HashInfo(
+            self.name, self.value.rsplit(HASH_DIR_SUFFIX)[0], self.obj_name
+        )

tests/func/test_commit.py

@@ -177,17 +177,22 @@ def test_commit_granular_dir(tmp_dir, dvc):
 
     cache = tmp_dir / ".dvc" / "cache"
 
-    assert set(cache.glob("*/*")) == set()
+    assert set(cache.glob("*/*")) == {
+        cache / "1a" / "ca2c799df82929bbdd976557975546",
+    }
 
     dvc.commit(os.path.join("data", "foo"))
     assert set(cache.glob("*/*")) == {
+        cache / "1a" / "ca2c799df82929bbdd976557975546",
         cache / "1a" / "ca2c799df82929bbdd976557975546.dir",
         cache / "ac" / "bd18db4cc2f85cedef654fccc4a4d8",
     }
     clean_staging()
 
     dvc.commit(os.path.join("data", "subdir"))
     assert set(cache.glob("*/*")) == {
+        cache / "26" / "d6b64d96a660707412f523e8184b5f",
+        cache / "1a" / "ca2c799df82929bbdd976557975546",
         cache / "1a" / "ca2c799df82929bbdd976557975546.dir",
         cache / "ac" / "bd18db4cc2f85cedef654fccc4a4d8",
         cache / "4c" / "e8d2a2cf314a52fa7f315ca37ca445",
@@ -197,6 +202,8 @@ def test_commit_granular_dir(tmp_dir, dvc):
 
     dvc.commit(os.path.join("data"))
     assert set(cache.glob("*/*")) == {
+        cache / "26" / "d6b64d96a660707412f523e8184b5f",
+        cache / "1a" / "ca2c799df82929bbdd976557975546",
         cache / "1a" / "ca2c799df82929bbdd976557975546.dir",
         cache / "ac" / "bd18db4cc2f85cedef654fccc4a4d8",
         cache / "4c" / "e8d2a2cf314a52fa7f315ca37ca445",

tests/func/test_external_repo.py

@@ -219,6 +219,7 @@ def test_subrepos_are_ignored(tmp_dir, erepo_dir):
             hardlink=True,
         )
         assert set(cache_dir.glob("??/*")) == {
+            cache_dir / "e1" / "d9e8eae5374860ae025ec84cfd85c7",
             cache_dir / "e1" / "d9e8eae5374860ae025ec84cfd85c7.dir",
             cache_dir / "37" / "b51d194a7513e45b56f6524f2d51f2",
             cache_dir / "94" / "7d2b84e5aa88170e80dff467a5bfb6",

tests/func/test_gc.py

@@ -20,13 +20,16 @@ def setUp(self):
         super().setUp()
 
         self.dvc.add(self.FOO)
-        self.dvc.add(self.DATA_DIR)
+        stages = self.dvc.add(self.DATA_DIR)
+        raw_dir_hash = stages[0].outs[0].hash_info.as_raw().value
+
         self.good_cache = [
             self.dvc.odb.local.hash_to_path(md5)
             for md5 in self.dvc.odb.local.all()
+            if md5 != raw_dir_hash
         ]
 
-        self.bad_cache = []
+        self.bad_cache = [self.dvc.odb.local.hash_to_path(raw_dir_hash)]
         for i in ["123", "234", "345"]:
             path = os.path.join(self.dvc.odb.local.cache_dir, i[0:2], i[2:])
             self.create(path, i)
@@ -203,7 +206,7 @@ def test_gc_no_dir_cache(tmp_dir, dvc):
     with pytest.raises(CollectCacheError):
         dvc.gc(workspace=True)
 
-    assert _count_files(dvc.odb.local.cache_dir) == 4
+    assert _count_files(dvc.odb.local.cache_dir) == 5
     dvc.gc(force=True, workspace=True)
     assert _count_files(dvc.odb.local.cache_dir) == 2
 

tests/func/test_odb.py

@@ -205,6 +205,9 @@ def test_shared_cache(tmp_dir, dvc, group):
 
     expected = {
         os.path.join(cache_dir, "17"): dir_mode,
+        os.path.join(
+            cache_dir, "17", "4eaa1dd94050255b7b98a7e1924b31"
+        ): file_mode,
         os.path.join(
             cache_dir, "17", "4eaa1dd94050255b7b98a7e1924b31.dir"
         ): file_mode,

tests/func/test_remote.py

@@ -154,6 +154,9 @@ def test_dir_hash_should_be_key_order_agnostic(tmp_dir, dvc):
         _, _, obj = stage(dvc.odb.local, path, dvc.odb.local.fs, "md5")
         hash1 = obj.hash_info
 
+    # remove the raw dir obj to force building the tree on the next stage call
+    dvc.odb.local.fs.remove(dvc.odb.local.hash_to_path(hash1.as_raw().value))
+
     tree = Tree.from_list(
         [{"md5": "1", "relpath": "1"}, {"md5": "2", "relpath": "2"}]
     )

tests/func/test_stage.py

@@ -13,6 +13,7 @@
 from dvc.utils.serialize import dump_yaml, load_yaml
 from dvc.utils.strictyaml import YAMLValidationError
 from tests.basic_env import TestDvc
+from tests.utils import clean_staging
 
 
 def test_cmd_obj():
@@ -321,3 +322,62 @@ def test_stage_run_checkpoint(tmp_dir, dvc, mocker, checkpoint):
     mock_cmd_run.assert_called_with(
         stage, checkpoint_func=callback, dry=False, run_env=None
     )
+
+
+@pytest.mark.parametrize(
+    "dry_run, expected_staging_contents",
+    [
+        (True, set()),
+        (
+            False,
+            {
+                "37b51d194a7513e45b56f6524f2d51f2",
+                "568f3dd88592a68ef99459a5491011cd",
+                "68dde2c3c4e7953c2290f176bbdc9a54",
+                "fd4034d9514d6e875538422c8b0dbeb2.dir",
+            },
+        ),
+    ],
+)
+def test_stage_dir_optimization(
+    tmp_dir, dvc, mocker, dry_run, expected_staging_contents
+):
+    from dvc.data import stage
+    from dvc.data.tree import Tree
+
+    tmp_dir.dvc_gen(
+        {
+            "data": {
+                "foo": "bar",
+                "subdir": {"subfoo": "subbar"},
+            }
+        }
+    )
+    odb = dvc.odb.local
+
+    objs = set(odb.all())
+    clean_staging()
+
+    tmp_dir.gen({"data": {"baz": "quz"}})
+
+    stage_spy = mocker.spy(stage, "_stage_tree")
+    _, _, tree = stage.stage(odb, "data", odb.fs, odb.fs.PARAM_CHECKSUM)
+
+    assert stage_spy.called
+    assert set(odb.all()) - objs == {tree.hash_info.as_raw().value}
+    stage_spy.reset_mock()
+    clean_staging()
+
+    load_spy = mocker.spy(Tree, "load")
+    build_tree_spy = mocker.spy(stage, "_build_tree")
+
+    staging, _, tree = stage.stage(
+        odb, "data", odb.fs, odb.fs.PARAM_CHECKSUM, dry_run=dry_run
+    )
+    assert not stage_spy.called
+    assert not build_tree_spy.called
+
+    load_args, _ = load_spy.call_args
+    assert load_args[1].value == tree.hash_info.as_raw().value
+
+    assert set(staging.all()) == expected_staging_contents

tests/unit/test_hashinfo.py

@@ -0,0 +1,17 @@
+from dvc.objects.hash_info import HashInfo
+
+
+def test_as_raw():
+    hash_info = HashInfo(
+        "md5", "a1d0c6e83f027327d8461063f4ac58a6.dir", "objname"
+    )
+
+    raw = hash_info.as_raw()
+
+    assert hash_info.name == "md5"
+    assert hash_info.value == "a1d0c6e83f027327d8461063f4ac58a6.dir"
+    assert hash_info.obj_name == "objname"
+
+    assert raw.name == "md5"
+    assert raw.value == "a1d0c6e83f027327d8461063f4ac58a6"
+    assert raw.obj_name == "objname"