Fix not sending events over federation when using sharded event persisters (#8536)

* Fix outbound federaion with multiple event persisters.

We incorrectly notified federation senders that the minimum persisted
stream position had advanced when we got an `RDATA` from an event
persister.

Notifying of federation senders already correctly happens in the
notifier, so we just delete the offending line.

* Change some interfaces to use RoomStreamToken.

By enforcing use of `RoomStreamTokens` we make it less likely that
people pass in random ints that they got from somewhere random.

10 files changed, 51 insertions, 21 deletions

diff --git a/changelog.d/8536.bugfix b/changelog.d/8536.bugfix
new file mode 100644
index 0000000000..8d238cc008
--- /dev/null
+++ b/changelog.d/8536.bugfix
@@ -0,0 +1 @@
+Fix not sending events over federation when using sharded event writers.
diff --git a/synapse/app/generic_worker.py b/synapse/app/generic_worker.py
index d53181deb1..1b511890aa 100644
--- a/synapse/app/generic_worker.py
+++ b/synapse/app/generic_worker.py
@@ -790,10 +790,6 @@ class FederationSenderHandler:
             send_queue.process_rows_for_federation(self.federation_sender, rows)
             await self.update_token(token)
 
-        # We also need to poke the federation sender when new events happen
-        elif stream_name == "events":
-            self.federation_sender.notify_new_events(token)
-
         # ... and when new receipts happen
         elif stream_name == ReceiptsStream.NAME:
             await self._on_new_receipts(rows)
diff --git a/synapse/federation/send_queue.py b/synapse/federation/send_queue.py
index 8e46957d15..5f1bf492c1 100644
--- a/synapse/federation/send_queue.py
+++ b/synapse/federation/send_queue.py
@@ -188,7 +188,7 @@ class FederationRemoteSendQueue:
             for key in keys[:i]:
                 del self.edus[key]
 
-    def notify_new_events(self, current_id):
+    def notify_new_events(self, max_token):
         """As per FederationSender"""
         # We don't need to replicate this as it gets sent down a different
         # stream.
diff --git a/synapse/federation/sender/__init__.py b/synapse/federation/sender/__init__.py
index e33b29a42c..604cfd1935 100644
--- a/synapse/federation/sender/__init__.py
+++ b/synapse/federation/sender/__init__.py
@@ -40,7 +40,7 @@ from synapse.metrics import (
     events_processed_counter,
 )
 from synapse.metrics.background_process_metrics import run_as_background_process
-from synapse.types import ReadReceipt
+from synapse.types import ReadReceipt, RoomStreamToken
 from synapse.util.metrics import Measure, measure_func
 
 logger = logging.getLogger(__name__)
@@ -154,10 +154,15 @@ class FederationSender:
             self._per_destination_queues[destination] = queue
         return queue
 
-    def notify_new_events(self, current_id: int) -> None:
+    def notify_new_events(self, max_token: RoomStreamToken) -> None:
         """This gets called when we have some new events we might want to
         send out to other servers.
         """
+        # We just use the minimum stream ordering and ignore the vector clock
+        # component. This is safe to do as long as we *always* ignore the vector
+        # clock components.
+        current_id = max_token.stream
+
         self._last_poked_id = max(current_id, self._last_poked_id)
 
         if self._is_processing:
diff --git a/synapse/handlers/appservice.py b/synapse/handlers/appservice.py
index 9d4e87dad6..c8d5e58035 100644
--- a/synapse/handlers/appservice.py
+++ b/synapse/handlers/appservice.py
@@ -27,6 +27,7 @@ from synapse.metrics import (
     event_processing_loop_room_count,
 )
 from synapse.metrics.background_process_metrics import run_as_background_process
+from synapse.types import RoomStreamToken
 from synapse.util.metrics import Measure
 
 logger = logging.getLogger(__name__)
@@ -47,15 +48,17 @@ class ApplicationServicesHandler:
         self.current_max = 0
         self.is_processing = False
 
-    async def notify_interested_services(self, current_id):
+    async def notify_interested_services(self, max_token: RoomStreamToken):
         """Notifies (pushes) all application services interested in this event.
 
         Pushing is done asynchronously, so this method won't block for any
         prolonged length of time.
-
-        Args:
-            current_id(int): The current maximum ID.
         """
+        # We just use the minimum stream ordering and ignore the vector clock
+        # component. This is safe to do as long as we *always* ignore the vector
+        # clock components.
+        current_id = max_token.stream
+
         services = self.store.get_app_services()
         if not services or not self.notify_appservices:
             return
diff --git a/synapse/notifier.py b/synapse/notifier.py
index 13adeed01e..51c830c91e 100644
--- a/synapse/notifier.py
+++ b/synapse/notifier.py
@@ -319,19 +319,19 @@ class Notifier:
         )
 
         if self.federation_sender:
-            self.federation_sender.notify_new_events(max_room_stream_token.stream)
+            self.federation_sender.notify_new_events(max_room_stream_token)
 
     async def _notify_app_services(self, max_room_stream_token: RoomStreamToken):
         try:
             await self.appservice_handler.notify_interested_services(
-                max_room_stream_token.stream
+                max_room_stream_token
             )
         except Exception:
             logger.exception("Error notifying application services of event")
 
     async def _notify_pusher_pool(self, max_room_stream_token: RoomStreamToken):
         try:
-            await self._pusher_pool.on_new_notifications(max_room_stream_token.stream)
+            await self._pusher_pool.on_new_notifications(max_room_stream_token)
         except Exception:
             logger.exception("Error pusher pool of event")
 
diff --git a/synapse/push/emailpusher.py b/synapse/push/emailpusher.py
index 28bd8ab748..c6763971ee 100644
--- a/synapse/push/emailpusher.py
+++ b/synapse/push/emailpusher.py
@@ -18,6 +18,7 @@ import logging
 from twisted.internet.error import AlreadyCalled, AlreadyCancelled
 
 from synapse.metrics.background_process_metrics import run_as_background_process
+from synapse.types import RoomStreamToken
 
 logger = logging.getLogger(__name__)
 
@@ -91,7 +92,12 @@ class EmailPusher:
                 pass
             self.timed_call = None
 
-    def on_new_notifications(self, max_stream_ordering):
+    def on_new_notifications(self, max_token: RoomStreamToken):
+        # We just use the minimum stream ordering and ignore the vector clock
+        # component. This is safe to do as long as we *always* ignore the vector
+        # clock components.
+        max_stream_ordering = max_token.stream
+
         if self.max_stream_ordering:
             self.max_stream_ordering = max(
                 max_stream_ordering, self.max_stream_ordering
diff --git a/synapse/push/httppusher.py b/synapse/push/httppusher.py
index 26706bf3e1..793d0db2d9 100644
--- a/synapse/push/httppusher.py
+++ b/synapse/push/httppusher.py
@@ -23,6 +23,7 @@ from synapse.api.constants import EventTypes
 from synapse.logging import opentracing
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.push import PusherConfigException
+from synapse.types import RoomStreamToken
 
 from . import push_rule_evaluator, push_tools
 
@@ -114,7 +115,12 @@ class HttpPusher:
         if should_check_for_notifs:
             self._start_processing()
 
-    def on_new_notifications(self, max_stream_ordering):
+    def on_new_notifications(self, max_token: RoomStreamToken):
+        # We just use the minimum stream ordering and ignore the vector clock
+        # component. This is safe to do as long as we *always* ignore the vector
+        # clock components.
+        max_stream_ordering = max_token.stream
+
         self.max_stream_ordering = max(
             max_stream_ordering, self.max_stream_ordering or 0
         )
diff --git a/synapse/push/pusherpool.py b/synapse/push/pusherpool.py
index 76150e117b..0080c68ce2 100644
--- a/synapse/push/pusherpool.py
+++ b/synapse/push/pusherpool.py
@@ -24,6 +24,7 @@ from synapse.push import PusherConfigException
 from synapse.push.emailpusher import EmailPusher
 from synapse.push.httppusher import HttpPusher
 from synapse.push.pusher import PusherFactory
+from synapse.types import RoomStreamToken
 from synapse.util.async_helpers import concurrently_execute
 
 if TYPE_CHECKING:
@@ -186,11 +187,16 @@ class PusherPool:
                 )
                 await self.remove_pusher(p["app_id"], p["pushkey"], p["user_name"])
 
-    async def on_new_notifications(self, max_stream_id: int):
+    async def on_new_notifications(self, max_token: RoomStreamToken):
         if not self.pushers:
             # nothing to do here.
             return
 
+        # We just use the minimum stream ordering and ignore the vector clock
+        # component. This is safe to do as long as we *always* ignore the vector
+        # clock components.
+        max_stream_id = max_token.stream
+
         if max_stream_id < self._last_room_stream_id_seen:
             # Nothing to do
             return
@@ -214,7 +220,7 @@ class PusherPool:
 
                 if u in self.pushers:
                     for p in self.pushers[u].values():
-                        p.on_new_notifications(max_stream_id)
+                        p.on_new_notifications(max_token)
 
         except Exception:
             logger.exception("Exception in pusher on_new_notifications")
diff --git a/tests/handlers/test_appservice.py b/tests/handlers/test_appservice.py
index 2a0b7c1b56..ee4f3da31c 100644
--- a/tests/handlers/test_appservice.py
+++ b/tests/handlers/test_appservice.py
@@ -18,6 +18,7 @@ from mock import Mock
 from twisted.internet import defer
 
 from synapse.handlers.appservice import ApplicationServicesHandler
+from synapse.types import RoomStreamToken
 
 from tests.test_utils import make_awaitable
 from tests.utils import MockClock
@@ -61,7 +62,9 @@ class AppServiceHandlerTestCase(unittest.TestCase):
             defer.succeed((0, [event])),
             defer.succeed((0, [])),
         ]
-        yield defer.ensureDeferred(self.handler.notify_interested_services(0))
+        yield defer.ensureDeferred(
+            self.handler.notify_interested_services(RoomStreamToken(None, 0))
+        )
         self.mock_scheduler.submit_event_for_as.assert_called_once_with(
             interested_service, event
         )
@@ -80,7 +83,9 @@ class AppServiceHandlerTestCase(unittest.TestCase):
             defer.succeed((0, [event])),
             defer.succeed((0, [])),
         ]
-        yield defer.ensureDeferred(self.handler.notify_interested_services(0))
+        yield defer.ensureDeferred(
+            self.handler.notify_interested_services(RoomStreamToken(None, 0))
+        )
         self.mock_as_api.query_user.assert_called_once_with(services[0], user_id)
 
     @defer.inlineCallbacks
@@ -97,7 +102,9 @@ class AppServiceHandlerTestCase(unittest.TestCase):
             defer.succeed((0, [event])),
             defer.succeed((0, [])),
         ]
-        yield defer.ensureDeferred(self.handler.notify_interested_services(0))
+        yield defer.ensureDeferred(
+            self.handler.notify_interested_services(RoomStreamToken(None, 0))
+        )
         self.assertFalse(
             self.mock_as_api.query_user.called,
             "query_user called when it shouldn't have been.",