post regenerations: regenerate posts asynchronously.

Regenerate posts asynchronously using a delayed job.

Regenerating a post can be slow because it involves downloading the
original file, regenerating the thumbnails, and redistributing the new
thumbnails back to the image servers. It's better to run this in the
background, especially if a user is trying to regenerate posts in bulk.

The downside is there's no notification to the user when the regeneration
is complete. You have to check the modactions log to see when it's finished.

app/controllers/post_regenerations_controller.rb

@@ -1,9 +1,10 @@
 class PostRegenerationsController < ApplicationController
-  respond_to :xml, :json, :js
+  respond_to :xml, :json, :html
 
   def create
     @post = authorize Post.find(params[:post_id]), :regenerate?
-    @post.regenerate!(params[:category], CurrentUser.user)
+    @post.regenerate_later!(params[:category], CurrentUser.user)
+    flash[:notice] = "Post regeneration scheduled, press Ctrl+F5 in a few seconds to refresh the image"
 
     respond_with(@post)
   end

app/jobs/regenerate_post_job.rb

@@ -0,0 +1,8 @@
+class RegeneratePostJob < ApplicationJob
+  queue_as :default
+  queue_with_priority 20
+
+  def perform(post:, category:, user:)
+    post.regenerate!(category, user)
+  end
+end

app/models/post.rb

@@ -1326,6 +1326,10 @@ class Post < ApplicationRecord
   end
 
   concerning :RegenerationMethods do
+    def regenerate_later!(category, user)
+      RegeneratePostJob.perform_later(post: self, category: category, user: user)
+    end
+
     def regenerate!(category, user)
       if category == "iqdb"
         update_iqdb_async

app/views/post_regenerations/create.js.erb

@@ -1 +0,0 @@
-Danbooru.notice("Post regenerated");

app/views/posts/partials/show/_options.html.erb

@@ -88,6 +88,6 @@
     <% end %>
 
     <% if policy(post).regenerate? %>
-      <li id="post-option-regenerate-preview"><%= link_to "Regenerate image", post_regenerations_path(post_id: post.id, category: "resizes"), remote: true, method: :post, "data-confirm": "This will regenerate the posts's thumbnail images. Are you sure?" %></li>
+      <li id="post-option-regenerate-preview"><%= link_to "Regenerate image", post_regenerations_path(post_id: post.id, category: "resizes"), method: :post, "data-confirm": "This will regenerate the posts's thumbnail images. Are you sure?" %></li>
     <% end %>
 </ul>