Revert "FEATURE: Better thread reply counter cache (#21108)" (#21192)

This reverts commit 180e3e11d1.

Per internal discussions, this is a temporary revert, to investigate if this is causing a performance regression.

plugins/chat/app/models/chat/thread.rb

@@ -4,8 +4,6 @@ module Chat
   class Thread < ActiveRecord::Base
     EXCERPT_LENGTH = 150
 
-    include Chat::ThreadCache
-
     self.table_name = "chat_threads"
 
     belongs_to :channel, foreign_key: "channel_id", class_name: "Chat::Channel"
@@ -13,11 +11,7 @@ module Chat
     belongs_to :original_message, foreign_key: "original_message_id", class_name: "Chat::Message"
 
     has_many :chat_messages,
-             -> {
-               where("deleted_at IS NULL").order(
-                 "chat_messages.created_at ASC, chat_messages.id ASC",
-               )
-             },
+             -> { order("chat_messages.created_at ASC, chat_messages.id ASC") },
              foreign_key: :thread_id,
              primary_key: :id,
              class_name: "Chat::Message"
@@ -67,7 +61,7 @@ module Chat
       #
       # It is updated eventually via Jobs::Chat::PeriodicalUpdates. In
       # future we may want to update this more frequently.
-      updated_thread_ids = DB.query_single <<~SQL
+      DB.exec <<~SQL
         UPDATE chat_threads threads
         SET replies_count = subquery.replies_count
         FROM (
@@ -78,9 +72,7 @@ module Chat
         ) subquery
         WHERE threads.id = subquery.thread_id
         AND subquery.replies_count != threads.replies_count
-        RETURNING threads.id AS thread_id;
       SQL
-      self.clear_caches!(updated_thread_ids)
     end
   end
 end

plugins/chat/app/models/concerns/chat/thread_cache.rb

@@ -1,69 +0,0 @@
-# frozen_string_literal: true
-
-module Chat
-  module ThreadCache
-    extend ActiveSupport::Concern
-
-    class_methods do
-      def replies_count_cache_updated_at_redis_key(id)
-        "chat_thread:replies_count_cache_updated_at:#{id}"
-      end
-
-      def replies_count_cache_redis_key(id)
-        "chat_thread:replies_count_cache:#{id}"
-      end
-
-      def clear_caches!(ids = nil)
-        return Discourse.redis.delete_prefixed("chat_thread:") if ids.blank?
-        ids = Array.wrap(ids)
-
-        keys_to_delete =
-          ids
-            .map do |id|
-              [replies_count_cache_redis_key(id), replies_count_cache_updated_at_redis_key(id)]
-            end
-            .flatten
-        Discourse.redis.del(keys_to_delete)
-      end
-    end
-
-    def replies_count_cache_recently_updated?
-      replies_count_cache_updated_at.after?(5.minutes.ago)
-    end
-
-    def replies_count_cache_updated_at
-      Time.at(
-        Discourse.redis.get(Chat::Thread.replies_count_cache_updated_at_redis_key(self.id)).to_i,
-        in: Time.zone,
-      )
-    end
-
-    def replies_count_cache
-      redis_cache = Discourse.redis.get(Chat::Thread.replies_count_cache_redis_key(self.id))&.to_i
-      if redis_cache.present? && redis_cache != self.replies_count
-        redis_cache
-      else
-        self.replies_count
-      end
-    end
-
-    def set_replies_count_cache(value, update_db: false)
-      self.update!(replies_count: value) if update_db
-      Discourse.redis.setex(
-        Chat::Thread.replies_count_cache_redis_key(self.id),
-        5.minutes.from_now.to_i,
-        value,
-      )
-      Jobs.enqueue_in(5.seconds, Jobs::Chat::UpdateThreadReplyCount, thread_id: self.id)
-      ::Chat::Publisher.publish_thread_original_message_metadata!(self)
-    end
-
-    def increment_replies_count_cache
-      self.set_replies_count_cache(self.replies_count_cache + 1)
-    end
-
-    def decrement_replies_count_cache
-      self.set_replies_count_cache(self.replies_count_cache - 1)
-    end
-  end
-end