api: refactor to use metadata and RepoTree

dvc/api.py

@@ -2,16 +2,17 @@
 from contextlib import _GeneratorContextManager as GCM
 from contextlib import contextmanager
 
-from dvc.exceptions import DvcException, NotDvcRepoError
+from funcy import reraise
+
+from dvc.exceptions import (
+    NotDvcRepoError,
+    OutputNotFoundError,
+    PathMissingError,
+)
 from dvc.external_repo import external_repo
+from dvc.path_info import PathInfo
 from dvc.repo import Repo
-
-
-class UrlNotDvcRepoError(DvcException):
-    """Thrown if the given URL is not a DVC repository."""
-
-    def __init__(self, url):
-        super().__init__(f"'{url}' is not a DVC repository.")
+from dvc.tree.repo import RepoTree
 
 
 def get_url(path, repo=None, rev=None, remote=None):
@@ -20,17 +21,26 @@ def get_url(path, repo=None, rev=None, remote=None):
     in a DVC repo. For Git repos, HEAD is used unless a rev argument is
     supplied. The default remote is tried unless a remote argument is supplied.
 
-    Raises UrlNotDvcRepoError if repo is not a DVC project.
+    Raises OutputNotFoundError if the file is not a dvc-tracked file.
 
     NOTE: This function does not check for the actual existence of the file or
     directory in the remote storage.
     """
     with _make_repo(repo, rev=rev) as _repo:
-        if not isinstance(_repo, Repo):
-            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.tree.hash_to_path_info(out.checksum))
+        tree = RepoTree(_repo, fetch=True)
+        path_info = PathInfo(_repo.root_dir) / path
+
+        meta = tree.metadata(path_info)
+        exc = OutputNotFoundError(path)
+        if not meta.is_dvc:
+            raise exc
+
+        with reraise(FileNotFoundError, exc):
+            _, hash_ = tree.get_hash(PathInfo(_repo.root_dir) / path)
+
+        assert hash_ and meta.repo
+        cloud = meta.repo.cloud
+        return cloud.get_url_for(remote, checksum=hash_)
 
 
 def open(  # noqa, pylint: disable=redefined-builtin
@@ -74,10 +84,14 @@ def __getattr__(self, name):
 
 def _open(path, repo=None, rev=None, remote=None, mode="r", encoding=None):
     with _make_repo(repo, rev=rev) as _repo:
-        with _repo.open_by_relpath(
-            path, remote=remote, mode=mode, encoding=encoding
-        ) as fd:
-            yield fd
+        tree = RepoTree(_repo, stream=True, fetch=True)
+
+        path = PathInfo(_repo.root_dir) / path
+        with reraise(FileNotFoundError, PathMissingError(path, repo)):
+            with tree.open(
+                path, remote=remote, mode=mode, encoding=encoding
+            ) as fd:
+                yield fd
 
 
 def read(path, repo=None, rev=None, remote=None, mode="r", encoding=None):

dvc/data_cloud.py

@@ -116,3 +116,11 @@ def status(self, cache, jobs=None, remote=None, show_checksums=False):
         return self.repo.cache.local.status(
             cache, jobs=jobs, remote=remote, show_checksums=show_checksums
         )
+
+    def get_url_for(self, remote=None, checksum=None):
+        remote = self.get_remote(remote)
+        tree = remote.tree
+
+        if checksum:
+            return tree.hash_to_path_info(checksum).url
+        return tree.path_info.url

dvc/exceptions.py

@@ -291,19 +291,16 @@ def __init__(self, code, reason):
 
 
 class PathMissingError(DvcException):
-    default_msg = (
-        "The path '{}' does not exist in the target repository '{}'"
-        " neither as a DVC output nor as a Git-tracked file."
-    )
-    default_msg_dvc_only = (
-        "The path '{}' does not exist in the target repository '{}'"
-        " as an DVC output."
-    )
-
-    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))
+    def __init__(self, path, repo=None, dvc_only=False):
+        msg = f"The path '{path}' does not exist in the"
+        msg += " repository" if not repo else f" target repository '{repo}'"
+        msg += " as a DVC output"
+        msg = f"{msg}." if dvc_only else f"{msg} nor as a Git-tracked file."
+
         self.dvc_only = dvc_only
+        self.repo = repo
+        self.path = path
+        super().__init__(msg)
 
 
 class RemoteCacheRequiredError(DvcException):

dvc/tree/_metadata.py

@@ -1,9 +1,12 @@
 from dataclasses import dataclass, field
-from typing import List
+from typing import TYPE_CHECKING, List, Optional
 
 from dvc.output import BaseOutput
 from dvc.path_info import PathInfo
 
+if TYPE_CHECKING:
+    from dvc.repo import Repo
+
 
 @dataclass
 class Metadata:
@@ -30,6 +33,7 @@ class Metadata:
     isdir: bool = False  # is it a directory?
     is_exec: bool = False  # is it an executable?
     outs: List[BaseOutput] = field(default_factory=list)  # list of outputs
+    repo: Optional["Repo"] = None  # the repo path falls in
 
     def __post_init__(self):
         self.output_exists = bool(self.outs)

dvc/tree/dvc.py

@@ -45,7 +45,8 @@ def _get_granular_checksum(self, path, out, remote=None):
         assert isinstance(path, PathInfo)
         if not self.fetch and not self.stream:
             raise FileNotFoundError
-        dir_cache = out.get_dir_cache(remote=remote)
+        with self.repo.state:
+            dir_cache = out.get_dir_cache(remote=remote)
         for entry in dir_cache:
             entry_relpath = entry[out.tree.PARAM_RELPATH]
             if os.name == "nt":
@@ -240,6 +241,6 @@ def metadata(self, path_info):
         path_info = PathInfo(os.path.abspath(path_info))
         outs = self._find_outs(path_info, strict=False, recursive=True)
 
-        meta = Metadata(path_info=path_info, outs=outs)
+        meta = Metadata(path_info=path_info, outs=outs, repo=self.repo)
         meta.isdir = meta.isdir or self.check_isdir(meta.path_info, meta.outs)
         return meta

tests/func/test_api.py

@@ -3,8 +3,7 @@
 import pytest
 
 from dvc import api
-from dvc.api import UrlNotDvcRepoError
-from dvc.exceptions import FileMissingError
+from dvc.exceptions import OutputNotFoundError, PathMissingError
 from dvc.path_info import URLInfo
 from dvc.utils.fs import remove
 
@@ -47,10 +46,10 @@ def test_get_url_external(erepo_dir, cloud):
 def test_get_url_requires_dvc(tmp_dir, scm):
     tmp_dir.scm_gen({"foo": "foo"}, commit="initial")
 
-    with pytest.raises(UrlNotDvcRepoError, match="not a DVC repository"):
+    with pytest.raises(OutputNotFoundError, match="with output 'foo'"):
         api.get_url("foo", repo=os.fspath(tmp_dir))
 
-    with pytest.raises(UrlNotDvcRepoError):
+    with pytest.raises(OutputNotFoundError):
         api.get_url("foo", repo=f"file://{tmp_dir}")
 
 
@@ -144,7 +143,7 @@ def test_missing(tmp_dir, dvc, remote):
 
     remove("foo")
 
-    with pytest.raises(FileMissingError):
+    with pytest.raises(PathMissingError, match="path 'foo' does not exist"):
         api.read("foo")
 
 
@@ -164,12 +163,12 @@ def test_open_not_cached(dvc):
     dvc.run(
         single_stage=True,
         metrics_no_cache=[metric_file],
-        cmd=(f'python -c "{metric_code}"'),
+        cmd=f'python -c "{metric_code}"',
     )
 
     with api.open(metric_file) as fd:
         assert fd.read() == metric_content
 
     os.remove(metric_file)
-    with pytest.raises(FileMissingError):
+    with pytest.raises(PathMissingError):
         api.read(metric_file)