Merge pull request #832 from matrix-org/erikj/presence_coount

Change def of small delta in presence stream. Add metrics.

synapse/handlers/presence.py

@@ -50,6 +50,8 @@ timers_fired_counter = metrics.register_counter("timers_fired")
 federation_presence_counter = metrics.register_counter("federation_presence")
 bump_active_time_counter = metrics.register_counter("bump_active_time")
 
+get_updates_counter = metrics.register_counter("get_updates", labels=["type"])
+
 
 # If a user was last active in the last LAST_ACTIVE_GRANULARITY, consider them
 # "currently_active"
@@ -974,13 +976,13 @@ class PresenceEventSource(object):
 
             user_ids_changed = set()
             changed = None
-            if from_key and max_token - from_key < 100:
-                # For small deltas, its quicker to get all changes and then
-                # work out if we share a room or they're in our presence list
+            if from_key:
                 changed = stream_change_cache.get_all_entities_changed(from_key)
 
-            # get_all_entities_changed can return None
-            if changed is not None:
+            if changed is not None and len(changed) < 500:
+                # For small deltas, its quicker to get all changes and then
+                # work out if we share a room or they're in our presence list
+                get_updates_counter.inc("stream")
                 for other_user_id in changed:
                     if other_user_id in friends:
                         user_ids_changed.add(other_user_id)
@@ -992,6 +994,8 @@ class PresenceEventSource(object):
             else:
                 # Too many possible updates. Find all users we can see and check
                 # if any of them have changed.
+                get_updates_counter.inc("full")
+
                 user_ids_to_check = set()
                 for room_id in room_ids:
                     users = yield self.store.get_users_in_room(room_id)