fix race condition in S3 Express identity cache (closes #1072)

CHANGES.rst

@@ -1,6 +1,10 @@
 Changes
 -------
 
+2.9.1 (2024-01-16)
+^^^^^^^^^^^^^^^^^^
+* fix race condition in S3 Express identity cache #1072
+
 2.9.0 (2023-12-12)
 ^^^^^^^^^^^^^^^^^^
 * bump botocore dependency specification

aiobotocore/__init__.py

@@ -1 +1 @@
-__version__ = '2.9.0'
+__version__ = '2.9.1'

aiobotocore/utils.py

@@ -367,30 +367,16 @@ async def get_credentials(self, **kwargs):
 
 
 class AioS3ExpressIdentityCache(AioIdentityCache, S3ExpressIdentityCache):
-    @functools.cached_property
-    def _aio_credential_cache(self):
-        """Substitutes upstream credential cache."""
-        return {}
+    @functools.lru_cache(maxsize=100)
+    def _get_credentials(self, bucket):
+        return asyncio.create_task(super().get_credentials(bucket=bucket))
 
     async def get_credentials(self, bucket):
         # upstream uses `@functools.lru_cache(maxsize=100)` to cache credentials.
         # This is incompatible with async code.
         # We need to implement custom caching logic.
 
-        if (credentials := self._aio_credential_cache.get(bucket)) is None:
-            # cache miss -> get credentials asynchronously
-            credentials = await super().get_credentials(bucket=bucket)
-
-            # upstream cache is bounded at 100 entries
-            if len(self._aio_credential_cache) >= 100:
-                # drop oldest entry from cache (deviates from lru_cache logic)
-                self._aio_credential_cache.pop(
-                    next(iter(self._aio_credential_cache)),
-                )
-
-            self._aio_credential_cache[bucket] = credentials
-
-        return credentials
+        return await self._get_credentials(bucket=bucket)
 
     def build_refresh_callback(self, bucket):
         async def refresher():