FIX: Don't allow a user to stage a post while another is being staged.

app/assets/javascripts/discourse/models/composer.js

@@ -461,7 +461,12 @@ Discourse.Composer = Discourse.Model.extend({
       if (post) {
         post.set('reply_count', (post.get('reply_count') || 0) + 1);
       }
-      postStream.stagePost(createdPost, currentUser);
+      if (!postStream.stagePost(createdPost, currentUser)) {
+
+        // If we can't stage the post, return and don't save. We're likely currently
+        // staging a post.
+        return;
+      }
     }
 
     // Save callback

app/assets/javascripts/discourse/models/post_stream.js

@@ -323,15 +323,19 @@ Discourse.PostStream = Em.Object.extend({
     @param {Discourse.User} the user creating the post
   **/
   stagePost: function(post, user) {
-    var topic = this.get('topic');
 
+    // We can't stage two posts simultaneously
+    if (this.get('stagingPost')) { return false; }
+
+    this.set('stagingPost', true);
+
+    var topic = this.get('topic');
     topic.setProperties({
       posts_count: (topic.get('posts_count') || 0) + 1,
       last_posted_at: new Date(),
       'details.last_poster': user,
       highest_post_number: (topic.get('highest_post_number') || 0) + 1
     });
-    this.set('stagingPost', true);
 
     post.setProperties({
       post_number: topic.get('highest_post_number'),
@@ -343,6 +347,8 @@ Discourse.PostStream = Em.Object.extend({
     if (this.get('lastPostLoaded')) {
       this.appendPost(post);
     }
+
+    return true;
   },
 
   /**

test/javascripts/models/post_stream_test.js

@@ -255,7 +255,8 @@ test("staging and undoing a new post", function() {
   });
 
   // Stage the new post in the stream
-  postStream.stagePost(stagedPost, user);
+  var result = postStream.stagePost(stagedPost, user);
+  equal(result, true, "it returns true");
   equal(topic.get('highest_post_number'), 2, "it updates the highest_post_number");
   ok(postStream.get('loading'), "it is loading while the post is being staged");
 
@@ -290,11 +291,15 @@ test("staging and committing a post", function() {
   topic.set('posts_count', 1);
 
   // Stage the new post in the stream
-  postStream.stagePost(stagedPost, user);
+  var result = postStream.stagePost(stagedPost, user);
+  equal(result, true, "it returns true");
   ok(postStream.get('loading'), "it is loading while the post is being staged");
   stagedPost.setProperties({ id: 1234, raw: "different raw value" });
   equal(postStream.get('filteredPostsCount'), 1, "it retains the filteredPostsCount");
 
+  result = postStream.stagePost(stagedPost, user);
+  equal(result, false, "you can't stage a post while it is currently staging");
+
   postStream.commitPost(stagedPost);
   ok(postStream.get('posts').contains(stagedPost), "the post is still in the stream");
   ok(!postStream.get('loading'), "it is no longer loading");