Improve opentracing support for ResponseCache

synapse/handlers/room.py

@@ -172,7 +172,7 @@ async def upgrade_room(
         user_id = requester.user.to_string()
 
         # Check if this room is already being upgraded by another person
-        for key in self._upgrade_response_cache.pending_result_cache:
+        for key in self._upgrade_response_cache.keys():
             if key[0] == old_room_id and key[1] != user_id:
                 # Two different people are trying to upgrade the same room.
                 # Send the second an error.

synapse/util/caches/response_cache.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-from typing import Any, Awaitable, Callable, Dict, Generic, Optional, TypeVar
+from typing import Any, Awaitable, Callable, Dict, Generic, Iterable, Optional, TypeVar
 
 import attr
 
@@ -80,6 +80,17 @@ def size(self) -> int:
     def __len__(self) -> int:
         return self.size()
 
+    def keys(self) -> Iterable[KV]:
+        """Get the keys currently in the result cache
+
+        Returns both incomplete entries, and (if the timeout on this cache is non-zero),
+        complete entries which are still in the cache.
+
+        Note that the returned iterator is not safe in the face of concurrent execution:
+        behaviour is undefined if `wrap` is called during iteration.
+        """
+        return self.pending_result_cache.keys()
+
     def get(self, key: KV) -> Optional[defer.Deferred]:
         """Look up the given key.