Clean up discussion list retaining mechanism

js/forum/src/components/discussion-list.js

@@ -17,24 +17,15 @@ export default class DiscussionList extends Component {
     this.loading = m.prop(true);
     this.moreResults = m.prop(false);
     this.discussions = m.prop([]);
+    this.subtrees = [];
 
-    this.willRedraw();
     this.refresh();
 
     app.session.on('loggedIn', this.loggedInHandler = this.refresh.bind(this))
   }
 
-  willRedraw() {
-    this.subtrees = [];
-    this.addSubtrees(this.discussions());
-  }
-
   addSubtrees(discussions) {
-    discussions.forEach(discussion => {
+
-      this.subtrees[discussion.id()] = new SubtreeRetainer(
-        () => discussion.freshness
-      )
-    });
   }
 
   params() {
@@ -90,7 +81,9 @@ export default class DiscussionList extends Component {
   parseResults(results) {
     m.startComputation();
     this.loading(false);
-    this.addSubtrees(results);
+
+    results.forEach(discussion => this.subtrees[discussion.id()] = new SubtreeRetainer(() => discussion.freshness));
+
     [].push.apply(this.discussions(), results);
     this.moreResults(!!results.payload.links.next);
     m.endComputation();

js/forum/src/components/discussion-page.js

@@ -36,6 +36,9 @@ export default class DiscussionPage extends Component {
     app.store.find('discussions', m.route.param('id'), this.params()).then(this.setupDiscussion.bind(this));
 
     if (app.cache.discussionList) {
+      if (!(app.current instanceof DiscussionPage)) {
+        app.cache.discussionList.subtrees.map(subtree => subtree.invalidate());
+      }
       app.pane.enable();
       app.pane.hide();
       m.redraw.strategy('diff'); // otherwise pane redraws and mouseenter even is triggered so it doesn't hide

js/forum/src/components/index-page.js

@@ -22,7 +22,7 @@ export default class IndexPage extends Component {
 
     var params = this.params();
     if (app.cache.discussionList) {
-      app.cache.discussionList.willRedraw();
+      app.cache.discussionList.subtrees.map(subtree => subtree.invalidate());
       Object.keys(params).some(key => {
         if (app.cache.discussionList.props.params[key] !== params[key]) {
           app.cache.discussionList = null;

js/forum/src/components/post-comment.js

@@ -17,7 +17,7 @@ export default class PostComment extends Post {
     super(props);
 
     this.postHeaderUser = new PostHeaderUser({post: this.props.post});
-    this.subtree.add(this.postHeaderUser.showCard);
+    this.subtree.check(this.postHeaderUser.showCard);
   }
 
   view() {

js/lib/utils/subtree-retainer.js

@@ -4,14 +4,14 @@
     () => this.props.post.freshness,
     () => this.showing
   );
-  this.subtree.add(() => this.props.user.freshness);
+  this.subtree.check(() => this.props.user.freshness);
 
   // view
   this.subtree.retain() || 'expensive expression'
  */
 export default class SubtreeRetainer {
   constructor() {
-    this.clear();
+    this.invalidate();
     this.callbacks = [].slice.call(arguments);
   }
 
@@ -27,11 +27,11 @@ export default class SubtreeRetainer {
     return needsRebuild ? false : {subtree: 'retain'};
   }
 
-  add() {
+  check() {
     this.callbacks = this.callbacks.concat([].slice.call(arguments));
   }
 
-  clear() {
+  invalidate() {
     this.old = [];
   }
 }