Class: EventHub::ActorListener

Inherits:
Object
  • Object
show all
Includes:
Celluloid, Helper
Defined in:
lib/eventhub/actor_listener.rb

Overview

Listner Class

Instance Method Summary collapse

Methods included from Helper

#create_bunny_connection, #get_name_from_class, #now_stamp, #stringify_keys

Constructor Details

#initialize(processor_instance) ⇒ ActorListener

Returns a new instance of ActorListener.



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# File 'lib/eventhub/actor_listener.rb', line 9

def initialize(processor_instance)
  @actor_publisher = ActorPublisher.new_link
  @actor_watchdog = ActorWatchdog.new_link
  @connections = {}
  @processor_instance = processor_instance
  start
end

Instance Method Details

#cleanup ⇒ Object 



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# File 'lib/eventhub/actor_listener.rb', line 111

def cleanup
  EventHub.logger.info("Listener is cleaning up...")
  # close all open connections
  return unless @connections
  @connections.values.each do |connection|
    connection&.close
  end
end

#handle_payload(args = {}) ⇒ Object 



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# File 'lib/eventhub/actor_listener.rb', line 72

def handle_payload(args = {})
  response_messages = []
  connection = args[:connection]

  # convert to EventHub message
  message = EventHub::Message.from_json(args[:payload])

  # append to execution history
  message.append_to_execution_history(EventHub::Configuration.name)

  # return invalid messages to dispatcher
  if message.invalid?
    response_messages << message
    EventHub.logger.info("-> #{message} => return invalid to dispatcher")
  else
    begin
      response_messages = @processor_instance.send(:handle_message,
        message,
        pass_arguments(args))
    rescue => exception
      # this catches unexpected exceptions in handle message method
      # deadletter the message via dispatcher
      message.status_code = EventHub::STATUS_DEADLETTER
      message.status_message = exception.to_s
      EventHub.logger.info("-> #{message} => return exception to dispatcher")
      response_messages << message
    end
  end

  Array(response_messages).each do |message|
    publish(message: message.to_json, connection: connection)
  end
end

#listen(args = {}) ⇒ Object 



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# File 'lib/eventhub/actor_listener.rb', line 28

def listen(args = {})
  with_listen(args) do |connection, channel, consumer, queue, queue_name|
    EventHub.logger.info("Listening to queue [#{queue_name}]")
    consumer.on_delivery do |delivery_info, metadata, payload|
      EventHub.logger.info("#{queue_name}: [#{delivery_info.delivery_tag}]" \
                             " delivery")

      @processor_instance.statistics.measure(payload.size) do
        handle_payload(payload: payload,
          connection: connection,
          queue_name: queue_name,
          content_type: metadata[:content_type],
          priority: metadata[:priority],
          delivery_tag: delivery_info.delivery_tag)
        channel.acknowledge(delivery_info.delivery_tag, false)
      end

      EventHub.logger.info("#{queue_name}: [#{delivery_info.delivery_tag}]" \
                           " acknowledged")
    end
    queue.subscribe_with(consumer, block: false)
  end
rescue => error
  EventHub.logger.error("Unexpected exception: #{error}. It should restart now with this exception...")
  raise
end

#pass_arguments(args = {}) ⇒ Object 



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# File 'lib/eventhub/actor_listener.rb', line 106

def pass_arguments(args = {})
  keys_to_pass = [:queue_name, :content_type, :priority, :delivery_tag]
  args.select { |key| keys_to_pass.include?(key) }
end

#publish(args) ⇒ Object 



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# File 'lib/eventhub/actor_listener.rb', line 120

def publish(args)
  @actor_publisher.publish(args)
end

#restart ⇒ Object 



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# File 'lib/eventhub/actor_listener.rb', line 24

def restart
  raise "Listener is restarting..."
end

#start ⇒ Object 



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# File 'lib/eventhub/actor_listener.rb', line 17

def start
  EventHub.logger.info("Listener is starting...")
  EventHub::Configuration.processor[:listener_queues].each_with_index do |queue_name, index|
    async.listen(queue_name: queue_name, index: index)
  end
end

#with_listen(args = {}) {|connection, channel, consumer, queue, queue_name| ... } ⇒ Object

Yields:

  • (connection, channel, consumer, queue, queue_name) 


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# File 'lib/eventhub/actor_listener.rb', line 55

def with_listen(args = {}, &block)
  connection = create_bunny_connection
  connection.start
  queue_name = args[:queue_name]
  @connections[queue_name] = connection
  channel = connection.create_channel
  channel.prefetch(1)
  queue = channel.queue(queue_name, durable: true)
  consumer = EventHub::Consumer.new(channel,
    queue,
    EventHub::Configuration.name +
      "-" +
      args[:index].to_s,
    false)
  yield connection, channel, consumer, queue, queue_name
end