Merge pull request #836 from matrix-org/erikj/change_event_cache

Change the way we cache events

synapse/storage/events.py

@@ -139,6 +139,9 @@ def _get_drainining_queue(self, room_id):
             pass
 
 
+_EventCacheEntry = namedtuple("_EventCacheEntry", ("event", "redacted_event"))
+
+
 class EventsStore(SQLBaseStore):
     EVENT_ORIGIN_SERVER_TS_NAME = "event_origin_server_ts"
 
@@ -738,53 +741,65 @@ def _get_events(self, event_ids, check_redacted=True,
         event_id_list = event_ids
         event_ids = set(event_ids)
 
-        event_map = self._get_events_from_cache(
+        event_entry_map = self._get_events_from_cache(
             event_ids,
-            check_redacted=check_redacted,
-            get_prev_content=get_prev_content,
             allow_rejected=allow_rejected,
         )
 
-        missing_events_ids = [e for e in event_ids if e not in event_map]
+        missing_events_ids = [e for e in event_ids if e not in event_entry_map]
 
         if missing_events_ids:
             missing_events = yield self._enqueue_events(
                 missing_events_ids,
                 check_redacted=check_redacted,
-                get_prev_content=get_prev_content,
                 allow_rejected=allow_rejected,
             )
 
-            event_map.update(missing_events)
+            event_entry_map.update(missing_events)
 
-        defer.returnValue([
-            event_map[e_id] for e_id in event_id_list
-            if e_id in event_map and event_map[e_id]
-        ])
+        events = []
+        for event_id in event_id_list:
+            entry = event_entry_map.get(event_id, None)
+            if not entry:
+                continue
+
+            if allow_rejected or not entry.event.rejected_reason:
+                if check_redacted and entry.redacted_event:
+                    event = entry.redacted_event
+                else:
+                    event = entry.event
+
+                events.append(event)
+
+                if get_prev_content:
+                    if "replaces_state" in event.unsigned:
+                        prev = yield self.get_event(
+                            event.unsigned["replaces_state"],
+                            get_prev_content=False,
+                            allow_none=True,
+                        )
+                        if prev:
+                            event.unsigned = dict(event.unsigned)
+                            event.unsigned["prev_content"] = prev.content
+                            event.unsigned["prev_sender"] = prev.sender
+
+        defer.returnValue(events)
 
     def _invalidate_get_event_cache(self, event_id):
-        for check_redacted in (False, True):
-            for get_prev_content in (False, True):
-                self._get_event_cache.invalidate(
-                    (event_id, check_redacted, get_prev_content)
-                )
+            self._get_event_cache.invalidate((event_id,))
 
-    def _get_events_from_cache(self, events, check_redacted, get_prev_content,
-                               allow_rejected):
+    def _get_events_from_cache(self, events, allow_rejected):
         event_map = {}
 
         for event_id in events:
-            try:
-                ret = self._get_event_cache.get(
-                    (event_id, check_redacted, get_prev_content,)
-                )
+            ret = self._get_event_cache.get((event_id,), None)
+            if not ret:
+                continue
 
-                if allow_rejected or not ret.rejected_reason:
-                    event_map[event_id] = ret
-                else:
-                    event_map[event_id] = None
-            except KeyError:
-                pass
+            if allow_rejected or not ret.event.rejected_reason:
+                event_map[event_id] = ret
+            else:
+                event_map[event_id] = None
 
         return event_map
 
@@ -855,8 +870,7 @@ def fire(evs):
                         reactor.callFromThread(fire, event_list)
 
     @defer.inlineCallbacks
-    def _enqueue_events(self, events, check_redacted=True,
-                        get_prev_content=False, allow_rejected=False):
+    def _enqueue_events(self, events, check_redacted=True, allow_rejected=False):
         """Fetches events from the database using the _event_fetch_list. This
         allows batch and bulk fetching of events - it allows us to fetch events
         without having to create a new transaction for each request for events.
@@ -894,8 +908,6 @@ def _enqueue_events(self, events, check_redacted=True,
             [
                 preserve_fn(self._get_event_from_row)(
                     row["internal_metadata"], row["json"], row["redacts"],
-                    check_redacted=check_redacted,
-                    get_prev_content=get_prev_content,
                     rejected_reason=row["rejects"],
                 )
                 for row in rows
@@ -904,7 +916,7 @@ def _enqueue_events(self, events, check_redacted=True,
         )
 
         defer.returnValue({
-            e.event_id: e
+            e.event.event_id: e
             for e in res if e
         })
 
@@ -936,7 +948,6 @@ def _fetch_event_rows(self, txn, events):
 
     @defer.inlineCallbacks
     def _get_event_from_row(self, internal_metadata, js, redacted,
-                            check_redacted=True, get_prev_content=False,
                             rejected_reason=None):
         d = json.loads(js)
         internal_metadata = json.loads(internal_metadata)
@@ -946,26 +957,27 @@ def _get_event_from_row(self, internal_metadata, js, redacted,
                 table="rejections",
                 keyvalues={"event_id": rejected_reason},
                 retcol="reason",
-                desc="_get_event_from_row",
+                desc="_get_event_from_row_rejected_reason",
             )
 
-        ev = FrozenEvent(
+        original_ev = FrozenEvent(
             d,
             internal_metadata_dict=internal_metadata,
             rejected_reason=rejected_reason,
         )
 
-        if check_redacted and redacted:
-            ev = prune_event(ev)
+        redacted_event = None
+        if redacted:
+            redacted_event = prune_event(original_ev)
 
             redaction_id = yield self._simple_select_one_onecol(
                 table="redactions",
-                keyvalues={"redacts": ev.event_id},
+                keyvalues={"redacts": redacted_event.event_id},
                 retcol="event_id",
-                desc="_get_event_from_row",
+                desc="_get_event_from_row_redactions",
             )
 
-            ev.unsigned["redacted_by"] = redaction_id
+            redacted_event.unsigned["redacted_by"] = redaction_id
             # Get the redaction event.
 
             because = yield self.get_event(
@@ -977,23 +989,16 @@ def _get_event_from_row(self, internal_metadata, js, redacted,
             if because:
                 # It's fine to do add the event directly, since get_pdu_json
                 # will serialise this field correctly
-                ev.unsigned["redacted_because"] = because
+                redacted_event.unsigned["redacted_because"] = because
 
-        if get_prev_content and "replaces_state" in ev.unsigned:
-            prev = yield self.get_event(
-                ev.unsigned["replaces_state"],
-                get_prev_content=False,
-                allow_none=True,
-            )
-            if prev:
-                ev.unsigned["prev_content"] = prev.content
-                ev.unsigned["prev_sender"] = prev.sender
-
-        self._get_event_cache.prefill(
-            (ev.event_id, check_redacted, get_prev_content), ev
+        cache_entry = _EventCacheEntry(
+            event=original_ev,
+            redacted_event=redacted_event,
         )
 
-        defer.returnValue(ev)
+        self._get_event_cache.prefill((original_ev.event_id,), cache_entry)
+
+        defer.returnValue(cache_entry)
 
     @defer.inlineCallbacks
     def count_daily_messages(self):