Merge pull request #283 from matrix-org/erikj/atomic_join_federation

Atomically persist events when joining a room over federation/

synapse/handlers/federation.py

@@ -125,8 +125,20 @@ class FederationHandler(BaseHandler):
         )
         if not is_in_room and not event.internal_metadata.is_outlier():
             logger.debug("Got event for room we're not in.")
-            current_state = state
 
+            try:
+                event_stream_id, max_stream_id = yield self._persist_auth_tree(
+                    auth_chain, state, event
+                )
+            except AuthError as e:
+                raise FederationError(
+                    "ERROR",
+                    e.code,
+                    e.msg,
+                    affected=event.event_id,
+                )
+
+        else:
             event_ids = set()
             if state:
                 event_ids |= {e.event_id for e in state}
@@ -649,35 +661,8 @@ class FederationHandler(BaseHandler):
                 # FIXME
                 pass
 
-            ev_infos = []
-            for e in itertools.chain(state, auth_chain):
-                if e.event_id == event.event_id:
-                    continue
-
-                e.internal_metadata.outlier = True
-                auth_ids = [e_id for e_id, _ in e.auth_events]
-                ev_infos.append({
-                    "event": e,
-                    "auth_events": {
-                        (e.type, e.state_key): e for e in auth_chain
-                        if e.event_id in auth_ids
-                    }
-                })
-
-            yield self._handle_new_events(origin, ev_infos, outliers=True)
-
-            auth_ids = [e_id for e_id, _ in event.auth_events]
-            auth_events = {
-                (e.type, e.state_key): e for e in auth_chain
-                if e.event_id in auth_ids
-            }
-
-            _, event_stream_id, max_stream_id = yield self._handle_new_event(
-                origin,
-                new_event,
-                state=state,
-                current_state=state,
-                auth_events=auth_events,
+            event_stream_id, max_stream_id = yield self._persist_auth_tree(
+                auth_chain, state, event
             )
 
             with PreserveLoggingContext():
@@ -1026,6 +1011,76 @@ class FederationHandler(BaseHandler):
             is_new_state=(not outliers and not backfilled),
         )
 
+    @defer.inlineCallbacks
+    def _persist_auth_tree(self, auth_events, state, event):
+        """Checks the auth chain is valid (and passes auth checks) for the
+        state and event. Then persists the auth chain and state atomically.
+        Persists the event seperately.
+
+        Returns:
+            2-tuple of (event_stream_id, max_stream_id) from the persist_event
+            call for `event`
+        """
+        events_to_context = {}
+        for e in itertools.chain(auth_events, state):
+            ctx = yield self.state_handler.compute_event_context(
+                e, outlier=True,
+            )
+            events_to_context[e.event_id] = ctx
+            e.internal_metadata.outlier = True
+
+        event_map = {
+            e.event_id: e
+            for e in auth_events
+        }
+
+        create_event = None
+        for e in auth_events:
+            if (e.type, e.state_key) == (EventTypes.Create, ""):
+                create_event = e
+                break
+
+        for e in itertools.chain(auth_events, state, [event]):
+            auth_for_e = {
+                (event_map[e_id].type, event_map[e_id].state_key): event_map[e_id]
+                for e_id, _ in e.auth_events
+            }
+            if create_event:
+                auth_for_e[(EventTypes.Create, "")] = create_event
+
+            try:
+                self.auth.check(e, auth_events=auth_for_e)
+            except AuthError as err:
+                logger.warn(
+                    "Rejecting %s because %s",
+                    e.event_id, err.msg
+                )
+
+                if e == event:
+                    raise
+                events_to_context[e.event_id].rejected = RejectedReason.AUTH_ERROR
+
+        yield self.store.persist_events(
+            [
+                (e, events_to_context[e.event_id])
+                for e in itertools.chain(auth_events, state)
+            ],
+            is_new_state=False,
+        )
+
+        new_event_context = yield self.state_handler.compute_event_context(
+            event, old_state=state, outlier=False,
+        )
+
+        event_stream_id, max_stream_id = yield self.store.persist_event(
+            event, new_event_context,
+            backfilled=False,
+            is_new_state=True,
+            current_state=state,
+        )
+
+        defer.returnValue((event_stream_id, max_stream_id))
+
     @defer.inlineCallbacks
     def _prep_event(self, origin, event, state=None, backfilled=False,
                     current_state=None, auth_events=None):