rebake based on version, not date

app/models/post.rb

@@ -15,9 +15,8 @@ class Post < ActiveRecord::Base
   include Trashable
   include HasCustomFields
 
-  # rebake all posts baked before this date
-  # in our periodical job
-  REBAKE_BEFORE = Time.new(2014,5,27)
+  # increase this number to force a system wide post rebake
+  BAKED_VERSION = 1
 
   rate_limit
   rate_limit :limit_posts_per_day
@@ -315,7 +314,7 @@ class Post < ActiveRecord::Base
   end
 
   def self.rebake_old(limit)
-    Post.where('baked_at IS NULL OR baked_at < ?', REBAKE_BEFORE)
+    Post.where('baked_version IS NULL OR baked_version < ?', BAKED_VERSION)
         .limit(limit).each do |p|
       begin
         p.rebake!
@@ -333,7 +332,7 @@ class Post < ActiveRecord::Base
     )
     old_cooked = cooked
 
-    update_columns(cooked: new_cooked, baked_at: Time.new)
+    update_columns(cooked: new_cooked, baked_at: Time.new, baked_version: BAKED_VERSION)
 
     # Extracts urls from the body
     TopicLink.extract_from self
@@ -391,6 +390,7 @@ class Post < ActiveRecord::Base
     self.last_editor_id ||= user_id
     self.cooked = cook(raw, topic_id: topic_id) unless new_record?
     self.baked_at = Time.new
+    self.baked_version = BAKED_VERSION
   end
 
   after_save do

db/migrate/20140530043913_add_baked_version_to_post.rb

@@ -0,0 +1,5 @@
+class AddBakedVersionToPost < ActiveRecord::Migration
+  def change
+    add_column :posts, :baked_version, :integer
+  end
+end

spec/models/post_spec.rb

@@ -834,11 +834,16 @@ describe Post do
   describe ".rebake_old" do
     it "will catch posts it needs to rebake" do
       post = create_post
-      post.update_column(:baked_at, Time.new(2000,1,1))
+      post.update_columns(baked_at: Time.new(2000,1,1), baked_version: -1)
       Post.rebake_old(100)
 
       post.reload
-      post.baked_at.should > 1.day.ago
+      post.baked_at.should be > 1.day.ago
+
+      baked = post.baked_at
+      Post.rebake_old(100)
+      post.reload
+      post.baked_at.should == baked
     end
   end