From 7ebf518c028088d1932262649c1042fb76f9d013 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Tue, 2 May 2017 10:43:34 +0100
Subject: [PATCH 1/3] Make get_joined_users faster

---
 synapse/storage/roommember.py | 54 ++++++++++++++++++++++++-----------
 1 file changed, 38 insertions(+), 16 deletions(-)

diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index 7ad2198d96c2..46efdfb3e212 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -417,25 +417,47 @@ def _get_joined_users_from_context(self, room_id, state_group, current_state_ids
             if key[0] == EventTypes.Member
         ]
 
-        rows = yield self._simple_select_many_batch(
-            table="room_memberships",
-            column="event_id",
-            iterable=member_event_ids,
-            retcols=['user_id', 'display_name', 'avatar_url'],
-            keyvalues={
-                "membership": Membership.JOIN,
-            },
-            batch_size=500,
-            desc="_get_joined_users_from_context",
+        event_map = self._get_events_from_cache(
+            member_event_ids,
+            allow_rejected=False,
         )
 
-        users_in_room = {
-            to_ascii(row["user_id"]): ProfileInfo(
-                avatar_url=to_ascii(row["avatar_url"]),
-                display_name=to_ascii(row["display_name"]),
+        missing_member_event_ids = []
+        users_in_room = {}
+        for event_id, ev_entry in event_map.iteritems():
+            if event_id:
+                if ev_entry.event.membership == Membership.JOIN:
+                    users_in_room[to_ascii(ev_entry.event.state_key)] = ProfileInfo(
+                        display_name=to_ascii(
+                            ev_entry.event.content.get("displayname", None)
+                        ),
+                        avatar_url=to_ascii(
+                            ev_entry.event.content.get("avatar_url", None)
+                        ),
+                    )
+            else:
+                missing_member_event_ids.append(event_id)
+
+        if missing_member_event_ids:
+            rows = yield self._simple_select_many_batch(
+                table="room_memberships",
+                column="event_id",
+                iterable=member_event_ids,
+                retcols=('user_id', 'display_name', 'avatar_url',),
+                keyvalues={
+                    "membership": Membership.JOIN,
+                },
+                batch_size=500,
+                desc="_get_joined_users_from_context",
             )
-            for row in rows
-        }
+
+            users_in_room.update({
+                to_ascii(row["user_id"]): ProfileInfo(
+                    avatar_url=to_ascii(row["avatar_url"]),
+                    display_name=to_ascii(row["display_name"]),
+                )
+                for row in rows
+            })
 
         if event is not None and event.type == EventTypes.Member:
             if event.membership == Membership.JOIN:

From aa93cb9f442019dde1704a0c12b47e5b664e192a Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Thu, 4 May 2017 14:59:28 +0100
Subject: [PATCH 2/3] Add comment

---
 synapse/storage/roommember.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index 46efdfb3e212..dcb95b924a38 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -417,6 +417,9 @@ def _get_joined_users_from_context(self, room_id, state_group, current_state_ids
             if key[0] == EventTypes.Member
         ]
 
+        # We check if we have any of the member event ids in the event cache
+        # before we ask the DB
+
         event_map = self._get_events_from_cache(
             member_event_ids,
             allow_rejected=False,

From cf589f2c1e68b71db80cbc2cf56f88118faf545b Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Fri, 5 May 2017 10:17:56 +0100
Subject: [PATCH 3/3] Fixes

---
 synapse/storage/roommember.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index dcb95b924a38..c63c0622dd61 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -427,8 +427,9 @@ def _get_joined_users_from_context(self, room_id, state_group, current_state_ids
 
         missing_member_event_ids = []
         users_in_room = {}
-        for event_id, ev_entry in event_map.iteritems():
-            if event_id:
+        for event_id in member_event_ids:
+            ev_entry = event_map.get(event_id)
+            if ev_entry:
                 if ev_entry.event.membership == Membership.JOIN:
                     users_in_room[to_ascii(ev_entry.event.state_key)] = ProfileInfo(
                         display_name=to_ascii(
@@ -445,7 +446,7 @@ def _get_joined_users_from_context(self, room_id, state_group, current_state_ids
             rows = yield self._simple_select_many_batch(
                 table="room_memberships",
                 column="event_id",
-                iterable=member_event_ids,
+                iterable=missing_member_event_ids,
                 retcols=('user_id', 'display_name', 'avatar_url',),
                 keyvalues={
                     "membership": Membership.JOIN,