From 852d6a3be5a4bb2d9c3c6ee42fd4fafd64e08dc8 Mon Sep 17 00:00:00 2001
From: David Baker <dave@matrix.org>
Date: Wed, 22 Aug 2018 14:34:02 +0100
Subject: [PATCH 1/2] Fix CPU spin on joining large room

checkIfAlone() filters the whole member list, which is fine until
we do it once for every membership event, then we have an n^2
problem. Move it into the rate limited function.

Fixes https://github.com/vector-im/riot-web/issues/7163
---
 src/components/structures/RoomView.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/components/structures/RoomView.js b/src/components/structures/RoomView.js
index 855090873f..1ecd7dad2e 100644
--- a/src/components/structures/RoomView.js
+++ b/src/components/structures/RoomView.js
@@ -701,7 +701,6 @@ module.exports = React.createClass({
         }
 
         this._updateRoomMembers();
-        this._checkIfAlone(this.state.room);
     },
 
     onRoomMemberMembership: function(ev, member, oldMembership) {
@@ -717,6 +716,7 @@ module.exports = React.createClass({
         // refresh the conf call notification state
         this._updateConfCallNotification();
         this._updateDMState();
+        this._checkIfAlone(this.state.room);
     }, 500),
 
     _checkIfAlone: function(room) {

From a5f98b6a29675f1acc09f655e63230a6d366f499 Mon Sep 17 00:00:00 2001
From: David Baker <dave@matrix.org>
Date: Wed, 22 Aug 2018 17:05:36 +0100
Subject: [PATCH 2/2] Make the is-alone check use efficient methods

---
 src/components/structures/RoomView.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/components/structures/RoomView.js b/src/components/structures/RoomView.js
index 1ecd7dad2e..dd8fba3929 100644
--- a/src/components/structures/RoomView.js
+++ b/src/components/structures/RoomView.js
@@ -729,8 +729,8 @@ module.exports = React.createClass({
             return;
         }
 
-        const joinedMembers = room.currentState.getMembers().filter((m) => m.membership === "join" || m.membership === "invite");
-        this.setState({isAlone: joinedMembers.length === 1});
+        const joinedOrInvitedMemberCount = room.getJoinedMemberCount() + room.getInvitedMemberCount();
+        this.setState({isAlone: joinedOrInvitedMemberCount === 1});
     },
 
     _updateConfCallNotification: function() {