pyre: correctly type functions passed to @contextlib.contextmanager.

Summary:
This seems to be a fairly common mistake: the `contextlib.contextmanager` decorator is applied to functions that return an `Iterator`, and turns them into ContextManagers. The decorated functions should *not* be typed to return ContextManager.

This changes typing so that it can be properly applied.

Test Plan: CI

Differential Revision: D50840616

fbshipit-source-id: 404f1d39b5bda77abd399006dac11f1e0111824c

antlir/rpm/storage/cli_object_storage.py

@@ -8,7 +8,7 @@
 import uuid
 from abc import abstractmethod
 from contextlib import contextmanager
-from typing import ContextManager, List, Mapping, NamedTuple
+from typing import Iterator, List, Mapping, NamedTuple
 
 from antlir.common import check_popen_returncode, get_logger
 
@@ -79,7 +79,7 @@ def _make_storage_id(cls) -> str:
         return str(uuid.uuid4()).replace("-", "")
 
     @contextmanager
-    def writer(self) -> ContextManager[StorageOutput]:
+    def writer(self) -> Iterator[StorageOutput]:
         sid = self._make_storage_id()
         path = self._path_for_storage_id(sid)
         log_prefix = f"{self.__class__.__name__}"
@@ -136,16 +136,12 @@ def get_id_and_release_resources():
             # pyre-fixme[6]: Expected `ContextManager[typing.Any]` for 2nd
             # param but got `() -> Any`.
             with _CommitCallback(self, get_id_and_release_resources) as commit:
-                # pyre-fixme[7]: Expected
-                # `ContextManager[antlir.rpm.storage.storage.StorageOutput]`
-                # but got `Generator[antlir.rpm.storage.storage.StorageOutput,
-                # None, None]`.
                 # pyre-fixme[6]: Expected `IO[typing.Any]` for 1st param but got
                 #  `Optional[typing.IO[typing.Any]]`.
                 yield StorageOutput(output=proc.stdin, commit_callback=commit)
 
     @contextmanager
-    def reader(self, sid: str) -> ContextManager[StorageInput]:
+    def reader(self, sid: str) -> Iterator[StorageInput]:
         # We currently waste significant time per read waiting for CLIs
         # to start, which is terrible for small reads (most system
         # RPMs are small).
@@ -157,9 +153,6 @@ def reader(self, sid: str) -> ContextManager[StorageInput]:
             stdout=subprocess.PIPE,
         ) as proc:
             log.debug(f"{log_prefix} - Started {path} GET proc")
-            # pyre-fixme[7]: Expected
-            #  `ContextManager[antlir.rpm.storage.storage.StorageInput]` but got
-            #  `Generator[antlir.rpm.storage.storage.StorageInput, None, None]`.
             # pyre-fixme[6]: Expected `IO[typing.Any]` for 1st param but got
             #  `Optional[typing.IO[typing.Any]]`.
             yield StorageInput(input=proc.stdout)
@@ -169,11 +162,9 @@ def reader(self, sid: str) -> ContextManager[StorageInput]:
         check_popen_returncode(proc)
 
     @contextmanager
-    def remover(self) -> ContextManager[_StorageRemover]:
+    def remover(self) -> Iterator[_StorageRemover]:
         rm = _StorageRemover(storage=self, procs=[])
         try:
-            # pyre-fixme[7]: Expected `ContextManager[_StorageRemover]` but got
-            #  `Generator[_StorageRemover, None, None]`.
             yield rm
         finally:
             last_ex = None  # We'll re-raise the last exception.

antlir/rpm/storage/filesystem_storage.py

@@ -8,7 +8,7 @@
 import stat
 import uuid
 from contextlib import contextmanager
-from typing import AnyStr, ContextManager
+from typing import AnyStr, Iterator
 
 from antlir.fs_utils import Path
 
@@ -43,7 +43,7 @@ def _path_for_storage_id(self, sid: str) -> str:
         return self.base_dir / sid[:3] / sid[3:6] / sid[6:9] / sid[9:]
 
     @contextmanager
-    def writer(self) -> ContextManager[StorageOutput]:
+    def writer(self) -> Iterator[StorageOutput]:
         sid = str(uuid.uuid4()).replace("-", "")
         sid_path = self._path_for_storage_id(sid)
         try:
@@ -75,15 +75,11 @@ def get_id_and_release_resources():
             # pyre-fixme[6]: Expected `ContextManager[typing.Any]` for 2nd
             # param but got `() -> Any`.
             with _CommitCallback(self, get_id_and_release_resources) as commit:
-                # pyre-fixme[7]: Expected `ContextManager[StorageOutput]` but
-                # got `Generator[StorageOutput, None, None]`.
                 yield StorageOutput(output=outfile, commit_callback=commit)
 
     @contextmanager
-    def reader(self, sid: str) -> ContextManager[StorageInput]:
+    def reader(self, sid: str) -> Iterator[StorageInput]:
         with open(self._path_for_storage_id(self.strip_key(sid)), "rb") as inp:
-            # pyre-fixme[7]: Expected `ContextManager[StorageInput]` but got
-            #  `Generator[StorageInput, None, None]`.
             yield StorageInput(input=inp)
 
     def remove(self, sid: str) -> None: