refactor requirement preparer to remove duplicated code paths for metadata-only dists

news/12863.trivial.rst

@@ -0,0 +1 @@
+Cache "concrete" dists by ``Distribution`` instead of ``InstallRequirement``.

news/12871.trivial.rst

@@ -0,0 +1 @@
+Refactor much of ``RequirementPreparer`` to avoid duplicated code paths for metadata-only requirements.

src/pip/_internal/distributions/__init__.py

@@ -1,4 +1,5 @@
 from pip._internal.distributions.base import AbstractDistribution
+from pip._internal.distributions.installed import InstalledDistribution
 from pip._internal.distributions.sdist import SourceDistribution
 from pip._internal.distributions.wheel import WheelDistribution
 from pip._internal.req.req_install import InstallRequirement
@@ -7,7 +8,18 @@
 def make_distribution_for_install_requirement(
     install_req: InstallRequirement,
 ) -> AbstractDistribution:
-    """Returns a Distribution for the given InstallRequirement"""
+    """Returns an AbstractDistribution for the given InstallRequirement.
+
+    As AbstractDistribution only covers installable artifacts, this method may only be
+    invoked at the conclusion of a resolve, when the RequirementPreparer has downloaded
+    the file corresponding to the resolved dist. Commands which intend to consume
+    metadata-only resolves without downloading should not call this method or
+    consume AbstractDistribution objects.
+    """
+    # Only pre-installed requirements will have a .satisfied_by dist.
+    if install_req.satisfied_by:
+        return InstalledDistribution(install_req)
+
     # Editable requirements will always be source distributions. They use the
     # legacy logic until we create a modern standard for them.
     if install_req.editable:

src/pip/_internal/distributions/base.py

@@ -37,11 +37,17 @@ def build_tracker_id(self) -> Optional[str]:
 
         If None, then this dist has no work to do in the build tracker, and
         ``.prepare_distribution_metadata()`` will not be called."""
-        raise NotImplementedError()
+        ...
 
     @abc.abstractmethod
     def get_metadata_distribution(self) -> BaseDistribution:
-        raise NotImplementedError()
+        """Generate a concrete ``BaseDistribution`` instance for this artifact.
+
+        The implementation should also cache the result with
+        ``self.req.cache_concrete_dist()`` so the distribution is available to other
+        users of the ``InstallRequirement``. This method is not called within the build
+        tracker context, so it should not identify any new setup requirements."""
+        ...
 
     @abc.abstractmethod
     def prepare_distribution_metadata(
@@ -50,4 +56,11 @@ def prepare_distribution_metadata(
         build_isolation: bool,
         check_build_deps: bool,
     ) -> None:
-        raise NotImplementedError()
+        """Generate the information necessary to extract metadata from the artifact.
+
+        This method will be executed within the context of ``BuildTracker#track()``, so
+        it needs to fully identify any setup requirements so they can be added to the
+        same active set of tracked builds, while ``.get_metadata_distribution()`` takes
+        care of generating and caching the ``BaseDistribution`` to expose to the rest of
+        the resolve."""
+        ...

src/pip/_internal/distributions/installed.py

@@ -1,9 +1,11 @@
-from typing import Optional
+from typing import TYPE_CHECKING, Optional
 
 from pip._internal.distributions.base import AbstractDistribution
-from pip._internal.index.package_finder import PackageFinder
 from pip._internal.metadata import BaseDistribution
 
+if TYPE_CHECKING:
+    from pip._internal.index.package_finder import PackageFinder
+
 
 class InstalledDistribution(AbstractDistribution):
     """Represents an installed package.
@@ -17,12 +19,14 @@ def build_tracker_id(self) -> Optional[str]:
         return None
 
     def get_metadata_distribution(self) -> BaseDistribution:
-        assert self.req.satisfied_by is not None, "not actually installed"
-        return self.req.satisfied_by
+        dist = self.req.satisfied_by
+        assert dist is not None, "not actually installed"
+        self.req.cache_concrete_dist(dist)
+        return dist
 
     def prepare_distribution_metadata(
         self,
-        finder: PackageFinder,
+        finder: "PackageFinder",
         build_isolation: bool,
         check_build_deps: bool,
     ) -> None:

src/pip/_internal/distributions/sdist.py

@@ -1,10 +1,10 @@
 import logging
-from typing import TYPE_CHECKING, Iterable, Optional, Set, Tuple
+from typing import TYPE_CHECKING, Iterable, Set, Tuple
 
 from pip._internal.build_env import BuildEnvironment
 from pip._internal.distributions.base import AbstractDistribution
 from pip._internal.exceptions import InstallationError
-from pip._internal.metadata import BaseDistribution
+from pip._internal.metadata import BaseDistribution, get_directory_distribution
 from pip._internal.utils.subprocess import runner_with_spinner_message
 
 if TYPE_CHECKING:
@@ -21,13 +21,19 @@ class SourceDistribution(AbstractDistribution):
     """
 
     @property
-    def build_tracker_id(self) -> Optional[str]:
+    def build_tracker_id(self) -> str:
         """Identify this requirement uniquely by its link."""
         assert self.req.link
         return self.req.link.url_without_fragment
 
     def get_metadata_distribution(self) -> BaseDistribution:
-        return self.req.get_dist()
+        assert (
+            self.req.metadata_directory
+        ), "Set as part of .prepare_distribution_metadata()"
+        dist = get_directory_distribution(self.req.metadata_directory)
+        self.req.cache_concrete_dist(dist)
+        self.req.validate_sdist_metadata()
+        return dist
 
     def prepare_distribution_metadata(
         self,
@@ -66,7 +72,11 @@ def prepare_distribution_metadata(
                 self._raise_conflicts("the backend dependencies", conflicting)
             if missing:
                 self._raise_missing_reqs(missing)
-        self.req.prepare_metadata()
+
+        # NB: we must still call .cache_concrete_dist() and .validate_sdist_metadata()
+        # before the InstallRequirement itself has been updated with the metadata from
+        # this directory!
+        self.req.prepare_metadata_directory()
 
     def _prepare_build_backend(self, finder: "PackageFinder") -> None:
         # Isolate in a BuildEnvironment and install the build-time

src/pip/_internal/distributions/wheel.py

@@ -31,7 +31,9 @@ def get_metadata_distribution(self) -> BaseDistribution:
         assert self.req.local_file_path, "Set as part of preparation during download"
         assert self.req.name, "Wheels are never unnamed"
         wheel = FilesystemWheel(self.req.local_file_path)
-        return get_wheel_distribution(wheel, canonicalize_name(self.req.name))
+        dist = get_wheel_distribution(wheel, canonicalize_name(self.req.name))
+        self.req.cache_concrete_dist(dist)
+        return dist
 
     def prepare_distribution_metadata(
         self,

src/pip/_internal/metadata/base.py

@@ -97,6 +97,15 @@ class RequiresEntry(NamedTuple):
 
 
 class BaseDistribution(Protocol):
+    @property
+    def is_concrete(self) -> bool:
+        """Whether the distribution really exists somewhere on disk.
+
+        If this is false, it has been synthesized from metadata, e.g. via
+        ``.from_metadata_file_contents()``, or ``.from_wheel()`` against
+        a ``MemoryWheel``."""
+        raise NotImplementedError()
+
     @classmethod
     def from_directory(cls, directory: str) -> "BaseDistribution":
         """Load the distribution from a metadata directory.
@@ -667,6 +676,10 @@ def iter_installed_distributions(
 class Wheel(Protocol):
     location: str
 
+    @property
+    def is_concrete(self) -> bool:
+        raise NotImplementedError()
+
     def as_zipfile(self) -> zipfile.ZipFile:
         raise NotImplementedError()
 
@@ -675,6 +688,10 @@ class FilesystemWheel(Wheel):
     def __init__(self, location: str) -> None:
         self.location = location
 
+    @property
+    def is_concrete(self) -> bool:
+        return True
+
     def as_zipfile(self) -> zipfile.ZipFile:
         return zipfile.ZipFile(self.location, allowZip64=True)
 
@@ -684,5 +701,9 @@ def __init__(self, location: str, stream: IO[bytes]) -> None:
         self.location = location
         self.stream = stream
 
+    @property
+    def is_concrete(self) -> bool:
+        return False
+
     def as_zipfile(self) -> zipfile.ZipFile:
         return zipfile.ZipFile(self.stream, allowZip64=True)

src/pip/_internal/metadata/importlib/_dists.py

@@ -102,16 +102,22 @@ def __init__(
         dist: importlib.metadata.Distribution,
         info_location: Optional[BasePath],
         installed_location: Optional[BasePath],
+        concrete: bool,
     ) -> None:
         self._dist = dist
         self._info_location = info_location
         self._installed_location = installed_location
+        self._concrete = concrete
+
+    @property
+    def is_concrete(self) -> bool:
+        return self._concrete
 
     @classmethod
     def from_directory(cls, directory: str) -> BaseDistribution:
         info_location = pathlib.Path(directory)
         dist = importlib.metadata.Distribution.at(info_location)
-        return cls(dist, info_location, info_location.parent)
+        return cls(dist, info_location, info_location.parent, concrete=True)
 
     @classmethod
     def from_metadata_file_contents(
@@ -128,7 +134,7 @@ def from_metadata_file_contents(
         metadata_path.write_bytes(metadata_contents)
         # Construct dist pointing to the newly created directory.
         dist = importlib.metadata.Distribution.at(metadata_path.parent)
-        return cls(dist, metadata_path.parent, None)
+        return cls(dist, metadata_path.parent, None, concrete=False)
 
     @classmethod
     def from_wheel(cls, wheel: Wheel, name: str) -> BaseDistribution:
@@ -137,7 +143,14 @@ def from_wheel(cls, wheel: Wheel, name: str) -> BaseDistribution:
                 dist = WheelDistribution.from_zipfile(zf, name, wheel.location)
         except zipfile.BadZipFile as e:
             raise InvalidWheel(wheel.location, name) from e
-        return cls(dist, dist.info_location, pathlib.PurePosixPath(wheel.location))
+        except UnsupportedWheel as e:
+            raise UnsupportedWheel(f"{name} has an invalid wheel, {e}")
+        return cls(
+            dist,
+            dist.info_location,
+            pathlib.PurePosixPath(wheel.location),
+            concrete=wheel.is_concrete,
+        )
 
     @property
     def location(self) -> Optional[str]:

src/pip/_internal/metadata/importlib/_envs.py

@@ -80,7 +80,7 @@ def find(self, location: str) -> Iterator[BaseDistribution]:
                 installed_location: Optional[BasePath] = None
             else:
                 installed_location = info_location.parent
-            yield Distribution(dist, info_location, installed_location)
+            yield Distribution(dist, info_location, installed_location, concrete=True)
 
     def find_linked(self, location: str) -> Iterator[BaseDistribution]:
         """Read location in egg-link files and return distributions in there.
@@ -104,7 +104,7 @@ def find_linked(self, location: str) -> Iterator[BaseDistribution]:
                 continue
             target_location = str(path.joinpath(target_rel))
             for dist, info_location in self._find_impl(target_location):
-                yield Distribution(dist, info_location, path)
+                yield Distribution(dist, info_location, path, concrete=True)
 
     def _find_eggs_in_dir(self, location: str) -> Iterator[BaseDistribution]:
         from pip._vendor.pkg_resources import find_distributions
@@ -116,7 +116,7 @@ def _find_eggs_in_dir(self, location: str) -> Iterator[BaseDistribution]:
                 if not entry.name.endswith(".egg"):
                     continue
                 for dist in find_distributions(entry.path):
-                    yield legacy.Distribution(dist)
+                    yield legacy.Distribution(dist, concrete=True)
 
     def _find_eggs_in_zip(self, location: str) -> Iterator[BaseDistribution]:
         from pip._vendor.pkg_resources import find_eggs_in_zip
@@ -128,7 +128,7 @@ def _find_eggs_in_zip(self, location: str) -> Iterator[BaseDistribution]:
         except zipimport.ZipImportError:
             return
         for dist in find_eggs_in_zip(importer, location):
-            yield legacy.Distribution(dist)
+            yield legacy.Distribution(dist, concrete=True)
 
     def find_eggs(self, location: str) -> Iterator[BaseDistribution]:
         """Find eggs in a location.

src/pip/_internal/metadata/pkg_resources.py

@@ -81,8 +81,9 @@ def run_script(self, script_name: str, namespace: str) -> None:
 
 
 class Distribution(BaseDistribution):
-    def __init__(self, dist: pkg_resources.Distribution) -> None:
+    def __init__(self, dist: pkg_resources.Distribution, concrete: bool) -> None:
         self._dist = dist
+        self._concrete = concrete
         # This is populated lazily, to avoid loading metadata for all possible
         # distributions eagerly.
         self.__extra_mapping: Optional[Mapping[NormalizedName, str]] = None
@@ -96,6 +97,10 @@ def _extra_mapping(self) -> Mapping[NormalizedName, str]:
 
         return self.__extra_mapping
 
+    @property
+    def is_concrete(self) -> bool:
+        return self._concrete
+
     @classmethod
     def from_directory(cls, directory: str) -> BaseDistribution:
         dist_dir = directory.rstrip(os.sep)
@@ -114,7 +119,7 @@ def from_directory(cls, directory: str) -> BaseDistribution:
             dist_name = os.path.splitext(dist_dir_name)[0].split("-")[0]
 
         dist = dist_cls(base_dir, project_name=dist_name, metadata=metadata)
-        return cls(dist)
+        return cls(dist, concrete=True)
 
     @classmethod
     def from_metadata_file_contents(
@@ -131,7 +136,7 @@ def from_metadata_file_contents(
             metadata=InMemoryMetadata(metadata_dict, filename),
             project_name=project_name,
         )
-        return cls(dist)
+        return cls(dist, concrete=False)
 
     @classmethod
     def from_wheel(cls, wheel: Wheel, name: str) -> BaseDistribution:
@@ -152,7 +157,7 @@ def from_wheel(cls, wheel: Wheel, name: str) -> BaseDistribution:
             metadata=InMemoryMetadata(metadata_dict, wheel.location),
             project_name=name,
         )
-        return cls(dist)
+        return cls(dist, concrete=wheel.is_concrete)
 
     @property
     def location(self) -> Optional[str]:
@@ -264,7 +269,7 @@ def from_paths(cls, paths: Optional[List[str]]) -> BaseEnvironment:
 
     def _iter_distributions(self) -> Iterator[BaseDistribution]:
         for dist in self._ws:
-            yield Distribution(dist)
+            yield Distribution(dist, concrete=True)
 
     def _search_distribution(self, name: str) -> Optional[BaseDistribution]:
         """Find a distribution matching the ``name`` in the environment.