Merge pull request #84 from matrix-org/rav/fix_refs_npes

Fix some races due to promises completing after we've switched rooms

src/components/structures/RoomView.js

@@ -118,6 +118,12 @@ module.exports = React.createClass({
     },
 
     componentWillUnmount: function() {
+        // set a boolean to say we've been unmounted, which any pending
+        // promises can use to throw away their results.
+        //
+        // (We could use isMounted, but facebook have deprecated that.)
+        this.unmounted = true;
+
         if (this.refs.messagePanel) {
             // disconnect the D&D event listeners from the message panel. This
             // is really just for hygiene - the messagePanel is going to be
@@ -214,7 +220,7 @@ module.exports = React.createClass({
     },*/
 
     onRoomTimeline: function(ev, room, toStartOfTimeline) {
-        if (!this.isMounted()) return;
+        if (this.unmounted) return;
 
         // ignore anything that comes in whilst paginating: we get one
         // event for each new matrix event so this would cause a huge
@@ -371,11 +377,14 @@ module.exports = React.createClass({
     _paginateCompleted: function() {
         debuglog("paginate complete");
 
-        this.setState({
+        // we might have switched rooms since the paginate started - just bin
-            room: MatrixClientPeg.get().getRoom(this.props.roomId)
+        // the results if so.
-        });
+        if (this.unmounted) return;
 
-        this.setState({paginating: false});
+        this.setState({
+            room: MatrixClientPeg.get().getRoom(this.props.roomId),
+            paginating: false,
+        });
     },
 
     onSearchResultsFillRequest: function(backwards) {
@@ -559,7 +568,7 @@ module.exports = React.createClass({
 
         return searchPromise.then(function(results) {
             debuglog("search complete");
-            if (!self.state.searching || self.searchId != localSearchId) {
+            if (self.unmounted || !self.state.searching || self.searchId != localSearchId) {
                 console.error("Discarding stale search results");
                 return;
             }

src/components/structures/ScrollPanel.js

@@ -112,6 +112,14 @@ module.exports = React.createClass({
         this.checkFillState();
     },
 
+    componentWillUnmount: function() {
+        // set a boolean to say we've been unmounted, which any pending
+        // promises can use to throw away their results.
+        //
+        // (We could use isMounted(), but facebook have deprecated that.)
+        this.unmounted = true;
+    },
+
     onScroll: function(ev) {
         var sn = this._getScrollNode();
         debuglog("Scroll event: offset now:", sn.scrollTop, "recentEventScroll:", this.recentEventScroll);
@@ -158,6 +166,10 @@ module.exports = React.createClass({
 
     // check the scroll state and send out backfill requests if necessary.
     checkFillState: function() {
+        if (this.unmounted) {
+            return;
+        }
+
         var sn = this._getScrollNode();
 
         // if there is less than a screenful of messages above or below the
@@ -346,6 +358,12 @@ module.exports = React.createClass({
      * message panel.
      */
     _getScrollNode: function() {
+        if (this.unmounted) {
+            // this shouldn't happen, but when it does, turn the NPE into
+            // something more meaningful.
+            throw new Error("ScrollPanel._getScrollNode called when unmounted");
+        }
+
         var panel = ReactDOM.findDOMNode(this.refs.geminiPanel);
 
         // If the gemini scrollbar is doing its thing, this will be a div within