Initial commit

lib/daemons/amqp_daemon.rb

@@ -0,0 +1,96 @@
+# encoding: UTF-8
+# frozen_string_literal: true
+ROOT = File.expand_path('../../..', __FILE__)
+
+require File.join(ROOT, 'config', 'environment')
+
+raise "bindings must be provided." if ARGV.size == 0
+
+logger = Rails.logger
+
+conn = Bunny.new AMQP::Config.connect
+conn.start
+
+ch = conn.create_channel
+id = $0.split(':')[2]
+prefetch = AMQP::Config.channel(id)[:prefetch] || 0
+ch.prefetch(prefetch) if prefetch > 0
+logger.info { "Connected to AMQP broker (prefetch: #{prefetch > 0 ? prefetch : 'default'})" }
+
+terminate = proc do
+  # logger is forbidden in signal handling, just use puts here
+  puts "Terminating threads .."
+  ch.work_pool.kill
+  puts "Stopped."
+end
+
+at_exit { conn.close }
+
+Signal.trap("INT",  &terminate)
+Signal.trap("TERM", &terminate)
+
+workers = []
+ARGV.each do |id|
+  worker = AMQP::Config.binding_worker(id)
+  queue  = ch.queue *AMQP::Config.binding_queue(id)
+
+  if args = AMQP::Config.binding_exchange(id)
+    x = ch.send *args
+
+    case args.first
+    when 'direct'
+      queue.bind x, routing_key: AMQP::Config.routing_key(id)
+    when 'topic'
+      AMQP::Config.topics(id).each do |topic|
+        queue.bind x, routing_key: topic
+      end
+    else
+      queue.bind x
+    end
+  end
+
+  clean_start = AMQP::Config.data[:binding][id][:clean_start]
+  queue.purge if clean_start
+
+  # Enable manual acknowledge mode by setting manual_ack: true.
+  queue.subscribe manual_ack: true do |delivery_info, metadata, payload|
+    logger.info { "Received: #{payload}" }
+    begin
+
+      # Invoke Worker#process with floating number of arguments.
+      args          = [JSON.parse(payload), metadata, delivery_info]
+      arity         = worker.method(:process).arity
+      resized_args  = arity < 0 ? args : args[0...arity]
+      worker.process(*resized_args)
+
+      # Send confirmation to RabbitMQ that message has been successfully processed.
+      # See http://rubybunny.info/articles/queues.html
+      ch.ack(delivery_info.delivery_tag)
+
+    rescue StandardError => e
+
+      # Ask RabbitMQ to deliver message once again later.
+      # See http://rubybunny.info/articles/queues.html
+      ch.nack(delivery_info.delivery_tag, false, true)
+
+      if worker.is_db_connection_error?(e)
+        logger.error(db: :unhealthy, message: e.message)
+        exit(1)
+      end
+
+      report_exception(e)
+    end
+  end
+
+  workers << worker
+end
+
+%w(USR1 USR2).each do |signal|
+  Signal.trap(signal) do
+    puts "#{signal} received."
+    handler = "on_#{signal.downcase}"
+    workers.each {|w| w.send handler if w.respond_to?(handler) }
+  end
+end
+
+ch.work_pool.join