PERF: only subscribe to a topic once for polls

in the past as views were created and destroyed poll subscriptions would change

this caused a lot of load on messaging bus and uneeded traffic

plugins/poll/assets/javascripts/controllers/poll.js.es6

@@ -15,7 +15,7 @@ export default Ember.Controller.extend({
   showResultsDisabled: Em.computed.equal("poll.voters", 0),
   hideResultsDisabled: Em.computed.or("isClosed", "post.topic.closed", "post.topic.archived"),
 
-  @computed("model", "vote")
+  @computed("model", "vote", "model.voters", "model.options", "model.status")
   poll(poll, vote) {
     if (poll) {
       const options = _.map(poll.get("options"), o => Em.Object.create(o));

plugins/poll/assets/javascripts/initializers/extend-for-poll.js.es6

@@ -1,4 +1,7 @@
 import PostView from "discourse/views/post";
+import TopicController from "discourse/controllers/topic";
+import Post from "discourse/models/post";
+
 import { on } from "ember-addons/ember-computed-decorators";
 
 function createPollView(container, post, poll, vote) {
@@ -6,7 +9,7 @@ function createPollView(container, post, poll, vote) {
         view = container.lookup("view:poll");
 
   controller.set("vote", vote);
-  controller.setProperties({ model: Em.Object.create(poll), post });
+  controller.setProperties({ model: poll, post });
   view.set("controller", controller);
 
   return view;
@@ -17,13 +20,39 @@ export default {
 
   initialize(container) {
 
-    const messageBus = container.lookup("message-bus:main");
+    Post.reopen({
+      // we need a proper ember object so it is bindable
+      pollsChanged: function(){
+        const polls  = this.get("polls");
+        if (polls) {
+          this._polls = this._polls || {};
+          _.map(polls, (v,k) => {
+            const existing = this._polls[k];
+            if (existing) {
+              this._polls[k].setProperties(v);
+            } else {
+              this._polls[k] = Em.Object.create(v);
+            }
+          });
+          this.set("pollsObject", this._polls);
+        }
+      }.observes("polls")
+    });
 
-    // listen for back-end to tell us when a post has a poll
-    messageBus.subscribe("/polls", data => {
-      const post = container.lookup("controller:topic").get('model.postStream').findLoadedPost(data.post_id);
-      // HACK to trigger the "postViewUpdated" event
-      Em.run.next(() => post.set("cooked", post.get("cooked") + " "));
+    TopicController.reopen({
+      subscribe(){
+          this._super();
+          this.messageBus.subscribe("/polls/" + this.get("model.id"), msg => {
+            const post = this.get('model.postStream').findLoadedPost(msg.post_id);
+            if (post) {
+              post.set('polls', msg.polls);
+            }
+        });
+      },
+      unsubscribe(){
+        this.messageBus.unsubscribe('/polls/*');
+        this._super();
+      }
     });
 
     // overwrite polls
@@ -32,12 +61,16 @@ export default {
       @on("postViewInserted", "postViewUpdated")
       _createPollViews($post) {
         const post = this.get("post"),
-              polls = post.get("polls"),
               votes = post.get("polls_votes") || {};
 
+        post.pollsChanged();
+        const polls = post.get("pollsObject");
+
         // don't even bother when there's no poll
         if (!polls) { return; }
 
+        // TODO inject cleanly into 
+
         // clean-up if needed
         this._cleanUpPollViews();
 
@@ -55,23 +88,11 @@ export default {
           pollViews[pollName] = pollView;
         });
 
-        messageBus.subscribe(`/polls/${this.get("post.id")}`, results => {
-          if (results && results.polls) {
-            _.forEach(results.polls, poll => {
-              if (pollViews[poll.name]) {
-                pollViews[poll.name].get("controller").set("model", Em.Object.create(poll));
-              }
-            });
-          }
-        });
-
         this.set("pollViews", pollViews);
       },
 
       @on("willClearRender")
       _cleanUpPollViews() {
-        messageBus.unsubscribe(`/polls/${this.get("post.id")}`);
-
         if (this.get("pollViews")) {
           _.forEach(this.get("pollViews"), v => v.destroy());
         }

plugins/poll/plugin.rb

@@ -81,7 +81,7 @@ after_initialize do
           post.custom_fields[VOTES_CUSTOM_FIELD]["#{user_id}"] ||= {}
           post.custom_fields[VOTES_CUSTOM_FIELD]["#{user_id}"][poll_name] = options
 
-          post.custom_fields[VOTES_CUSTOM_FIELD].each do |user_id, user_votes|
+          post.custom_fields[VOTES_CUSTOM_FIELD].each do |_, user_votes|
             next unless votes = user_votes[poll_name]
             votes.each { |option| all_options[option] += 1 }
             poll["voters"] += 1 if (available_options & votes.to_set).size > 0
@@ -92,7 +92,7 @@ after_initialize do
           post.custom_fields[POLLS_CUSTOM_FIELD] = polls
           post.save_custom_fields(true)
 
-          MessageBus.publish("/polls/#{post_id}", { polls: polls })
+          MessageBus.publish("/polls/#{post.topic_id}", { post_id: post_id, polls: polls })
 
           return [poll, options]
         end
@@ -128,7 +128,7 @@ after_initialize do
 
           post.save_custom_fields(true)
 
-          MessageBus.publish("/polls/#{post_id}", { polls: polls })
+          MessageBus.publish("/polls/#{post.topic_id}", {post_id: post.id, polls: polls })
 
           polls[poll_name]
         end
@@ -350,7 +350,7 @@ after_initialize do
           post.save_custom_fields(true)
 
           # publish the changes
-          MessageBus.publish("/polls/#{post.id}", { polls: polls })
+          MessageBus.publish("/polls/#{post.topic_id}", { post_id: post.id, polls: polls })
         end
       end
     else
@@ -370,7 +370,9 @@ after_initialize do
   # tells the front-end we have a poll for that post
   on(:post_created) do |post|
     next if post.is_first_post? || post.custom_fields[POLLS_CUSTOM_FIELD].blank?
-    MessageBus.publish("/polls", { post_id: post.id })
+    MessageBus.publish("/polls/#{post.topic_id}", {
+                         post_id: post.id,
+                         polls: post.custom_fields[POLLS_CUSTOM_FIELD]})
   end
 
   add_to_serializer(:post, :polls, false) { post_custom_fields[POLLS_CUSTOM_FIELD] }