Pass digest to avoid processing Markdown at all if issue title did not changeadam-issue-title-vue

4 files changed, 23 insertions, 6 deletions

diff --git a/app/assets/javascripts/vue_issue_show/index.js.es6 b/app/assets/javascripts/vue_issue_show/index.js.es6
index f6f62d2c791..40fb251245d 100644
--- a/app/assets/javascripts/vue_issue_show/index.js.es6
+++ b/app/assets/javascripts/vue_issue_show/index.js.es6
@@ -40,6 +40,7 @@
       return {
         initialTitle: vueData.initialTitle,
         endpoint: vueData.endpoint,
+        initialTitleDigest: vueData.initialTitleDigest,
         user,
         token,
       };
@@ -50,6 +51,7 @@
           :initialTitle='initialTitle'
           :endpoint='endpoint'
           :user='user'
+          :initialTitleDigest='initialTitleDigest'
         >
         </vue-title>
       </div>
diff --git a/app/assets/javascripts/vue_issue_show/issue_title.js.es6 b/app/assets/javascripts/vue_issue_show/issue_title.js.es6
index 4562b229f73..14b1868745e 100644
--- a/app/assets/javascripts/vue_issue_show/issue_title.js.es6
+++ b/app/assets/javascripts/vue_issue_show/issue_title.js.es6
@@ -4,12 +4,14 @@
   gl.VueIssueTitle = Vue.extend({
     props: [
       'initialTitle',
-      'endpoint'
+      'endpoint',
+      'initialTitleDigest',
     ],
     data() {
       return {
         intervalId: '',
         title: this.initialTitle,
+        titleDigest: this.initialTitleDigest,
         failedCount: 0,
         pageRequest: false,
       };
@@ -22,16 +24,17 @@
         Vue.activeResources = 1;
         this.intervalId = setInterval(() => {
           if (!this.pageRequest) {
-            this.$http.get(this.endpoint)
+            this.$http.get(this.endpoint, { params: { digest: this.titleDigest } })
               .then((res) => {
                 Vue.activeResources = 0;
-                let title = JSON.parse(res.body).title;
-                if (this.title === title) {
+                let body = JSON.parse(res.body);
+                if (!body.changed) {
                   return;
                 }
+                this.titleDigest = body.digest;
                 this.$el.style.opacity = 0;
                 setTimeout(() => {
-                  this.title = title;
+                  this.title = body.title;
                   this.$el.style.transition = 'opacity 0.2s ease';
                   this.$el.style.opacity = 1;
                 }, 100);
diff --git a/app/controllers/projects/issues_controller.rb b/app/controllers/projects/issues_controller.rb
index 0f0c7f377f8..53cb0e70d90 100644
--- a/app/controllers/projects/issues_controller.rb
+++ b/app/controllers/projects/issues_controller.rb
@@ -165,9 +165,20 @@ class Projects::IssuesController < Projects::ApplicationController
   end
 
   def rendered_title
+    digest = hexdigest(@issue.title)
+    if digest == params.fetch(:digest)
+      response = { changed: false }
+    else
+      response = {
+        changed: true,
+        digest: digest,
+        title: view_context.markdown_field(@issue, :title)
+      }
+    end
+
     respond_to do |format|
       format.json do
-        render json: { title: view_context.markdown_field(@issue, :title) }
+        render json: response
       end
     end
   end
diff --git a/app/views/projects/issues/show.html.haml b/app/views/projects/issues/show.html.haml
index e37502aba93..cd669d7890e 100644
--- a/app/views/projects/issues/show.html.haml
+++ b/app/views/projects/issues/show.html.haml
@@ -57,6 +57,7 @@
     .vue-data.hidden{ "data" => { "initial-title" => markdown_field(@issue, :title),
       "endpoint" => rendered_title_namespace_project_issue_path(@project.namespace, @project, @issue),
       "user" => "#{current_user.nil?}",
+      "initial-title-digest" => hexdigest(@issue.title),
     } }
     .issue-title-vue
     - if @issue.description.present?