BURs: lock posts when updating tags during bulk updates.

Fixes updates sometimes getting clobbered when multiple aliases or mass
updates tried to update the same post at the same time.

app/jobs/tag_batch_change_job.rb

@@ -28,9 +28,10 @@ class TagBatchChangeJob < ApplicationJob
 
   def migrate_posts(normalized_antecedent, normalized_consequent)
     ::Post.tag_match(normalized_antecedent.join(" ")).find_each do |post|
-      post.reload
-      tags = (post.tag_array - normalized_antecedent + normalized_consequent).join(" ")
-      post.update(tag_string: tags)
+      post.with_lock do
+        tags = (post.tag_array - normalized_antecedent + normalized_consequent).join(" ")
+        post.update(tag_string: tags)
+      end
     end
   end
 

app/models/tag_alias.rb

@@ -136,16 +136,6 @@ class TagAlias < TagRelationship
     end
   end
 
-  def update_posts
-    Post.without_timeout do
-      Post.raw_tag_match(antecedent_name).find_each do |post|
-        escaped_antecedent_name = Regexp.escape(antecedent_name)
-        fixed_tags = post.tag_string.sub(/(?:\A| )#{escaped_antecedent_name}(?:\Z| )/, " #{consequent_name} ").strip
-        post.update(tag_string: fixed_tags)
-      end
-    end
-  end
-
   def rename_wiki_and_artist
     antecedent_wiki = WikiPage.titled(antecedent_name).first
     if antecedent_wiki.present?

app/models/tag_implication.rb

@@ -155,15 +155,6 @@ class TagImplication < TagRelationship
       end
     end
 
-    def update_posts
-      Post.without_timeout do
-        Post.raw_tag_match(antecedent_name).where("true /* TagImplication#update_posts */").find_each do |post|
-          fixed_tags = "#{post.tag_string} #{descendant_names_string}".strip
-          post.update(tag_string: fixed_tags)
-        end
-      end
-    end
-
     def approve!(approver: CurrentUser.user, update_topic: true)
       update(approver: approver, status: "queued")
       ProcessTagImplicationJob.perform_later(self, update_topic: update_topic)

app/models/tag_relationship.rb

@@ -215,6 +215,16 @@ class TagRelationship < ApplicationRecord
     Post.fast_count(antecedent_name, skip_cache: true)
   end
 
+  def update_posts
+    Post.without_timeout do
+      Post.raw_tag_match(antecedent_name).find_each do |post|
+        post.with_lock do
+          post.save!
+        end
+      end
+    end
+  end
+
   def update_notice
     TagChangeNoticeService.update_cache(
       [antecedent_name, consequent_name],