postpone loading the members until the user joined the room

when peeking, the members weren't being loaded at all because
the room wasn't available yet,
and the need for loading the members was never re-evaluated after that.

This only loads the members once the user has joined the room,
which also helps to avoid load all the members before an invite
is accepted.

src/components/structures/RoomView.js

@@ -314,16 +314,6 @@ module.exports = React.createClass({
                 // Stop peeking because we have joined this room previously
                 MatrixClientPeg.get().stopPeeking();
                 this.setState({isPeeking: false});
-
-                // lazy load members if enabled
-                if (SettingsStore.isFeatureEnabled('feature_lazyloading')) {
-                    room.loadMembersIfNeeded().catch((err) => {
-                        const errorMessage = `Fetching room members for ${room.roomId} failed.` +
-                            " Room members will appear incomplete.";
-                        console.error(errorMessage);
-                        console.error(err);
-                    });
-                }
             }
         }
     },
@@ -592,6 +582,23 @@ module.exports = React.createClass({
         this._warnAboutEncryption(room);
         this._calculatePeekRules(room);
         this._updatePreviewUrlVisibility(room);
+        this._loadMembersIfJoined();
+    },
+
+    _loadMembersIfJoined: function() {
+        // lazy load members if enabled
+        if (SettingsStore.isFeatureEnabled('feature_lazyloading')) {
+            const cli = MatrixClientPeg.get();
+            const room = cli.getRoom(this.state.roomId);
+            if (room && room.getMyMembership() === 'join') {
+                room.loadMembersIfNeeded().catch((err) => {
+                    const errorMessage = `Fetching room members for ${room.roomId} failed.` +
+                        " Room members will appear incomplete.";
+                    console.error(errorMessage);
+                    console.error(err);
+                });
+            }
+        }
     },
 
     _warnAboutEncryption: function(room) {
@@ -705,6 +712,7 @@ module.exports = React.createClass({
 
     onRoomMemberMembership: function(ev, member, oldMembership) {
         if (member.userId == MatrixClientPeg.get().credentials.userId) {
+            this._loadMembersIfJoined();
             this.forceUpdate();
         }
     },

src/components/views/rooms/MemberList.js

@@ -46,6 +46,8 @@ module.exports = React.createClass({
         if (!cli.hasLazyLoadMembersEnabled()) {
             this._listenForMembersChanges();
         }
+        cli.on("Room", this.onRoom); // invites & joining after peek
+        cli.on("RoomMember.membership", this.onRoomMembership); // update when accepting an invite
         const enablePresenceByHsUrl = SdkConfig.get()["enable_presence_by_hs_url"];
         const hsUrl = MatrixClientPeg.get().baseUrl;
         this._showPresence = true;
@@ -59,7 +61,6 @@ module.exports = React.createClass({
         cli.on("RoomState.members", this.onRoomStateMember);
         cli.on("RoomMember.name", this.onRoomMemberName);
         cli.on("RoomState.events", this.onRoomStateEvent);
-        cli.on("Room", this.onRoom); // invites
         // We listen for changes to the lastPresenceTs which is essentially
         // listening for all presence events (we display most of not all of
         // the information contained in presence events).
@@ -69,14 +70,7 @@ module.exports = React.createClass({
 
     componentDidMount: async function() {
         this._mounted = true;
-        const cli = MatrixClientPeg.get();
+        this._loadMembersIfNeeded(true);
-        if (cli.hasLazyLoadMembersEnabled()) {
-            await this._waitForMembersToLoad();
-            if (this._mounted) {
-                this.setState(this._getMembersState());
-                this._listenForMembersChanges();
-            }
-        }
     },
 
     componentWillUnmount: function() {
@@ -85,6 +79,7 @@ module.exports = React.createClass({
         if (cli) {
             cli.removeListener("RoomState.members", this.onRoomStateMember);
             cli.removeListener("RoomMember.name", this.onRoomMemberName);
+            cli.removeListener("RoomMember.membership", this.onRoomMembership);
             cli.removeListener("RoomState.events", this.onRoomStateEvent);
             cli.removeListener("Room", this.onRoom);
             cli.removeListener("User.lastPresenceTs", this.onUserLastPresenceTs);
@@ -95,14 +90,24 @@ module.exports = React.createClass({
         this._updateList.cancelPendingCall();
     },
 
-    _waitForMembersToLoad: async function() {
+    _loadMembersIfNeeded: async function(initial) {
-        if (!this.props.roomId) return {};
         const cli = MatrixClientPeg.get();
-        const room = cli.getRoom(this.props.roomId);
+        if (cli.hasLazyLoadMembersEnabled()) {
-        if (room) {
+            const cli = MatrixClientPeg.get();
-            try {
+            const room = cli.getRoom(this.props.roomId);
-                await room.loadMembersIfNeeded();
+            if (room && room.getMyMembership() === 'join') {
-            } catch(ex) {/* already logged in RoomView */}
+                this.setState({loading: true});
+                try {
+                    await room.loadMembersIfNeeded();
+                } catch(ex) {/* already logged in RoomView */}
+                if (this._mounted) {
+                    this.setState(this._getMembersState());
+                    this._listenForMembersChanges();
+                }
+            } else if(initial) {
+                // show the members we've got
+                this.setState(this._getMembersState());
+            }
         }
     },
 
@@ -163,14 +168,28 @@ module.exports = React.createClass({
         }
     },
 
-    onRoom: function(room) {
+    onRoom: async function(room) {
         if (room.roomId !== this.props.roomId) {
             return;
         }
         // We listen for room events because when we accept an invite
         // we need to wait till the room is fully populated with state
         // before refreshing the member list else we get a stale list.
-        this._updateList();
+
+        // also when peeking, we need to await the members being loaded
+        // before showing them.
+
+        this._loadMembersIfNeeded();
+    },
+
+    onRoomMembership: async function(ev, member, oldMembership) {
+        const cli = MatrixClientPeg.get();
+        const myId = cli.getUserId();
+        if (member.userId === myId && oldMembership !== "join" && member.membership === "join") {
+            // once we've joined, no need to listen for membership anymore
+            cli.removeListener("RoomMember.membership", this.onRoomMembership);
+            this._loadMembersIfNeeded();
+        }
     },
 
     onRoomStateMember: function(ev, state, member) {
@@ -197,6 +216,7 @@ module.exports = React.createClass({
     _updateList: new rate_limited_func(function() {
         // console.log("Updating memberlist");
         const newState = {
+            loading: false,
             members: this.roomMembers(),
         };
         newState.filteredJoinedMembers = this._filterMembers(newState.members, 'join', this.state.searchQuery);