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authorErik Johnston <erikj@jki.re>2019-01-18 12:17:04 +0000
committerAmber Brown <hawkowl@atleastfornow.net>2019-01-18 23:17:04 +1100
commit25dd56ace36e9d3dbb717a34c9b9051b243f84ad (patch)
treee90eb41341272b569f9c4d2e74fa2f892f6bc981
parentTweak code coverage settings (#4400) (diff)
downloadsynapse-25dd56ace36e9d3dbb717a34c9b9051b243f84ad.tar.xz
Fix race when persisting create event (#4404)
* Fix race when persisting create event

When persisting a chunk of DAG it is sometimes requried to do a state
resolution, which requires knowledge of the room version. If this
happens while we're persisting the create event then we need to use that
event rather than attempting to look it up in the database.
Diffstat (limited to '')
-rw-r--r--changelog.d/4404.bugfix1
-rw-r--r--synapse/storage/events.py13
2 files changed, 13 insertions, 1 deletions
diff --git a/changelog.d/4404.bugfix b/changelog.d/4404.bugfix
new file mode 100644
index 0000000000..5d40a3a60b
--- /dev/null
+++ b/changelog.d/4404.bugfix
@@ -0,0 +1 @@
+Fix potential bug where creating or joining a room could fail
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index 2047110b1d..79e0276de6 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -739,7 +739,18 @@ class EventsStore(StateGroupWorkerStore, EventFederationStore, EventsWorkerStore
         }
 
         events_map = {ev.event_id: ev for ev, _ in events_context}
-        room_version = yield self.get_room_version(room_id)
+
+        # We need to get the room version, which is in the create event.
+        # Normally that'd be in the database, but its also possible that we're
+        # currently trying to persist it.
+        room_version = None
+        for ev, _ in events_context:
+            if ev.type == EventTypes.Create and ev.state_key == "":
+                room_version = ev.content.get("room_version", "1")
+                break
+
+        if not room_version:
+            room_version = yield self.get_room_version(room_id)
 
         logger.debug("calling resolve_state_groups from preserve_events")
         res = yield self._state_resolution_handler.resolve_state_groups(