DEV: wrap find_missing_uploads method in distributed mutex

And skip posts with deleted topics.\ne8fafbc123170dd1f7d2a8adea4e7810585d3e76

app/models/post.rb

@@ -919,11 +919,15 @@ class Post < ActiveRecord::Base
   end
 
   def self.find_missing_uploads(include_local_upload: true)
-    PostCustomField.where(name: Post::MISSING_UPLOADS).delete_all
     missing_uploads = []
     missing_post_uploads = {}
+    count = 0
+
+    DistributedMutex.synchronize("find_missing_uploads") do
+      PostCustomField.where(name: Post::MISSING_UPLOADS).delete_all
       query = Post
         .have_uploads
+        .joins(:topic)
         .joins("LEFT JOIN post_custom_fields ON posts.id = post_custom_fields.post_id AND post_custom_fields.name = '#{Post::MISSING_UPLOADS_IGNORED}'")
         .where("post_custom_fields.id IS NULL")
         .select(:id, :cooked)
@@ -958,7 +962,6 @@ class Post < ActiveRecord::Base
         end
       end
 
-    count = 0
       missing_post_uploads = missing_post_uploads.reject do |post_id, uploads|
         if uploads.present?
           PostCustomField.create!(post_id: post_id, name: Post::MISSING_UPLOADS, value: uploads.to_json)
@@ -967,6 +970,7 @@ class Post < ActiveRecord::Base
 
         uploads.empty?
       end
+    end
 
     { uploads: missing_uploads, post_uploads: missing_post_uploads, count: count }
   end