Send some ephemeral events to appservices (#8437)

Optionally sends typing, presence, and read receipt information to appservices.

synapse/handlers/typing.py

@@ -12,16 +12,16 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
 import logging
 import random
 from collections import namedtuple
 from typing import TYPE_CHECKING, List, Set, Tuple
 
 from synapse.api.errors import AuthError, ShadowBanError, SynapseError
+from synapse.appservice import ApplicationService
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.replication.tcp.streams import TypingStream
-from synapse.types import UserID, get_domain_from_id
+from synapse.types import JsonDict, UserID, get_domain_from_id
 from synapse.util.caches.stream_change_cache import StreamChangeCache
 from synapse.util.metrics import Measure
 from synapse.util.wheel_timer import WheelTimer
@@ -430,6 +430,33 @@ class TypingNotificationEventSource:
             "content": {"user_ids": list(typing)},
         }
 
+    async def get_new_events_as(
+        self, from_key: int, service: ApplicationService
+    ) -> Tuple[List[JsonDict], int]:
+        """Returns a set of new typing events that an appservice
+        may be interested in.
+
+        Args:
+            from_key: the stream position at which events should be fetched from
+            service: The appservice which may be interested
+        """
+        with Measure(self.clock, "typing.get_new_events_as"):
+            from_key = int(from_key)
+            handler = self.get_typing_handler()
+
+            events = []
+            for room_id in handler._room_serials.keys():
+                if handler._room_serials[room_id] <= from_key:
+                    continue
+                if not await service.matches_user_in_member_list(
+                    room_id, handler.store
+                ):
+                    continue
+
+                events.append(self._make_event_for(room_id))
+
+            return (events, handler._latest_room_serial)
+
     async def get_new_events(self, from_key, room_ids, **kwargs):
         with Measure(self.clock, "typing.get_new_events"):
             from_key = int(from_key)