Use stream id to live-update messages for name changes.

When we change a stream name, we now use the stream id as the
key to find messages we need to live update.  This eliminates
some possible race conditions from two users renaming a stream.

This commit introduces message_live_update.js.

The new call stack is this:

    subs.update_subscription_properties
    subs.update_stream_name
    message_live_update.update_stream_name
    message_list.update_stream_name

.eslintrc.json

@@ -34,6 +34,7 @@
         "compose_fade": false,
         "subs": false,
         "timerender": false,
+        "message_live_update": false,
         "message_edit": false,
         "reload": false,
         "composebox_typeahead": false,

static/js/message_list.js

@@ -555,13 +555,12 @@ exports.MessageList.prototype = {
         return item_list[cur_idx];
     },
 
-    change_display_recipient: function MessageList_change_display_recipient(old_recipient,
-                                                                            new_recipient) {
-        // This method only works for streams.
+    update_stream_name: function MessageList_update_stream_name(stream_id,
+                                                                new_stream_name) {
         _.each(this._items, function (item) {
-            if (item.display_recipient === old_recipient) {
-                item.display_recipient = new_recipient;
-                item.stream = new_recipient;
+            if (item.stream_id && (item.stream_id === stream_id)) {
+                item.display_recipient = new_stream_name;
+                item.stream = new_stream_name;
             }
         });
         this.view.rerender_the_whole_thing();

static/js/message_live_update.js

@@ -0,0 +1,17 @@
+var message_live_update = (function () {
+
+var exports = {};
+
+exports.update_stream_name = function (stream_id, new_name) {
+    _.each([home_msg_list, current_msg_list, message_list.all], function (list) {
+        list.update_stream_name(stream_id, new_name);
+    });
+};
+
+return exports;
+
+}());
+if (typeof module !== 'undefined') {
+    module.exports = message_live_update;
+}
+

static/js/subs.js

@@ -177,7 +177,7 @@ function update_stream_pin(sub, value) {
     sub.pin_to_top = value;
 }
 
-function update_stream_name(stream_id, old_name, new_name) {
+function update_stream_name(stream_id, new_name) {
     // Rename the stream internally.
     var sub = stream_data.rename_sub(stream_id, new_name);
 
@@ -195,9 +195,7 @@ function update_stream_name(stream_id, old_name, new_name) {
     sub_row.attr("data-stream-name", new_name);
 
     // Update the message feed.
-    _.each([home_msg_list, current_msg_list, message_list.all], function (list) {
-        list.change_display_recipient(old_name, new_name);
-    });
+    message_live_update.update_stream_name(stream_id, new_name);
 }
 
 function update_stream_description(sub, description) {
@@ -659,7 +657,7 @@ exports.update_subscription_properties = function (stream_name, property, value)
         update_stream_audible_notifications(sub, value);
         break;
     case 'name':
-        update_stream_name(sub.stream_id, sub.name, value);
+        update_stream_name(sub.stream_id, value);
         break;
     case 'description':
         update_stream_description(sub, value);

zproject/settings.py

@@ -793,6 +793,7 @@ JS_SPECS = {
             'js/filter.js',
             'js/message_list_view.js',
             'js/message_list.js',
+            'js/message_live_update.js',
             'js/narrow.js',
             'js/reload.js',
             'js/compose_fade.js',