Add button to load new replies in web UI (#35210)

app/models/worker_batch.rb

@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+class WorkerBatch
+  include Redisable
+
+  TTL = 3600
+
+  def initialize(id = nil)
+    @id = id || SecureRandom.hex(12)
+  end
+
+  attr_reader :id
+
+  # Connect the batch with an async refresh. When the number of processed jobs
+  # passes the given threshold, the async refresh will be marked as finished.
+  # @param [String] async_refresh_key
+  # @param [Float] threshold
+  def connect(async_refresh_key, threshold: 1.0)
+    redis.hset(key, { 'async_refresh_key' => async_refresh_key, 'threshold' => threshold })
+  end
+
+  # Add jobs to the batch. Usually when the batch is created.
+  # @param [Array<String>] jids
+  def add_jobs(jids)
+    if jids.blank?
+      async_refresh_key = redis.hget(key, 'async_refresh_key')
+
+      if async_refresh_key.present?
+        async_refresh = AsyncRefresh.new(async_refresh_key)
+        async_refresh.finish!
+      end
+
+      return
+    end
+
+    redis.multi do |pipeline|
+      pipeline.sadd(key('jobs'), jids)
+      pipeline.expire(key('jobs'), TTL)
+      pipeline.hincrby(key, 'pending', jids.size)
+      pipeline.expire(key, TTL)
+    end
+  end
+
+  # Remove a job from the batch, such as when it's been processed or it has failed.
+  # @param [String] jid
+  def remove_job(jid)
+    _, pending, processed, async_refresh_key, threshold = redis.multi do |pipeline|
+      pipeline.srem(key('jobs'), jid)
+      pipeline.hincrby(key, 'pending', -1)
+      pipeline.hincrby(key, 'processed', 1)
+      pipeline.hget(key, 'async_refresh_key')
+      pipeline.hget(key, 'threshold')
+    end
+
+    if async_refresh_key.present?
+      async_refresh = AsyncRefresh.new(async_refresh_key)
+      async_refresh.increment_result_count(by: 1)
+      async_refresh.finish! if pending.zero? || processed >= threshold.to_f * (processed + pending)
+    end
+  end
+
+  # Get pending jobs.
+  # @returns [Array<String>]
+  def jobs
+    redis.smembers(key('jobs'))
+  end
+
+  # Inspect the batch.
+  # @returns [Hash]
+  def info
+    redis.hgetall(key)
+  end
+
+  private
+
+  def key(suffix = nil)
+    "worker_batch:#{@id}#{":#{suffix}" if suffix}"
+  end
+end