Stub out GET presence requests in the frontend proxy (#7545)

We don't really make any promises about returning accurate presence data when
presence is disabled, so we may as well just return a static response, rather
than making the master handle a request.

changelog.d/7528.doc

@@ -0,0 +1 @@
+Change the systemd worker service to check that the worker config file exists instead of silently failing. Contributed by David Vo.

changelog.d/7545.misc

@@ -0,0 +1 @@
+Make worker processes return a stubbed-out response to `GET /presence` requests.

changelog.d/7548.bugfix

@@ -0,0 +1 @@
+Fix bug where a local user leaving a room could fail under rare circumstances.

docs/systemd-with-workers/system/matrix-synapse-worker@.service

@@ -1,6 +1,6 @@
 [Unit]
 Description=Synapse %i
-
+AssertPathExists=/etc/matrix-synapse/workers/%i.yaml
 # This service should be restarted when the synapse target is restarted.
 PartOf=matrix-synapse.target
 

synapse/app/generic_worker.py

@@ -26,7 +26,7 @@ from twisted.web.resource import NoResource
 
 import synapse
 import synapse.events
-from synapse.api.errors import HttpResponseException, SynapseError
+from synapse.api.errors import SynapseError
 from synapse.api.urls import (
     CLIENT_API_PREFIX,
     FEDERATION_PREFIX,
@@ -137,31 +137,18 @@ logger = logging.getLogger("synapse.app.generic_worker")
 
 class PresenceStatusStubServlet(RestServlet):
     """If presence is disabled this servlet can be used to stub out setting
-    presence status, while proxying the getters to the master instance.
+    presence status.
     """
 
     PATTERNS = client_patterns("/presence/(?P<user_id>[^/]*)/status")
 
     def __init__(self, hs):
         super(PresenceStatusStubServlet, self).__init__()
-        self.http_client = hs.get_simple_http_client()
         self.auth = hs.get_auth()
-        self.main_uri = hs.config.worker_main_http_uri
 
     async def on_GET(self, request, user_id):
-        # Pass through the auth headers, if any, in case the access token
-        # is there.
-        auth_headers = request.requestHeaders.getRawHeaders("Authorization", [])
-        headers = {"Authorization": auth_headers}
-
-        try:
-            result = await self.http_client.get_json(
-                self.main_uri + request.uri.decode("ascii"), headers=headers
-            )
-        except HttpResponseException as e:
-            raise e.to_synapse_error()
-
-        return 200, result
+        await self.auth.get_user_by_req(request)
+        return 200, {"presence": "offline"}
 
     async def on_PUT(self, request, user_id):
         await self.auth.get_user_by_req(request)

synapse/federation/sender/per_destination_queue.py

@@ -80,6 +80,9 @@ class PerDestinationQueue(object):
 
         # a list of tuples of (pending pdu, order)
         self._pending_pdus = []  # type: List[Tuple[EventBase, int]]
+
+        # XXX this is never actually used: see
+        # https://github.com/matrix-org/synapse/issues/7549
         self._pending_edus = []  # type: List[Edu]
 
         # Pending EDUs by their "key". Keyed EDUs are EDUs that get clobbered

synapse/storage/persist_events.py

@@ -740,8 +740,8 @@ class EventsPersistenceStorage(object):
         # whose state has changed as we've already their new state above.
         users_to_ignore = [
             state_key
-            for _, state_key in itertools.chain(delta.to_insert, delta.to_delete)
-            if self.is_mine_id(state_key)
+            for typ, state_key in itertools.chain(delta.to_insert, delta.to_delete)
+            if typ == EventTypes.Member and self.is_mine_id(state_key)
         ]
 
         if await self.main_store.is_local_host_in_room_ignoring_users(