Class: EventQ::Amazon::QueueWorker

Inherits:
Object
  • Object
show all
Includes:
WorkerId
Defined in:
lib/eventq_aws/aws_queue_worker.rb

Constant Summary collapse

APPROXIMATE_RECEIVE_COUNT = 
'ApproximateReceiveCount'.freeze
MESSAGE = 
'Message'.freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ QueueWorker

Returns a new instance of QueueWorker.



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# File 'lib/eventq_aws/aws_queue_worker.rb', line 11

def initialize
  @threads = []
  @forks = []
  @is_running = false

  @retry_exceeded_block = nil

  @hash_helper = HashKit::Helper.new
  @serialization_provider_manager = EventQ::SerializationProviders::Manager.new

  @last_gc_flush = Time.now
  @gc_flush_interval = 10

  @queue_poll_wait = 10
end

Instance Attribute Details

#is_running ⇒ Object

Returns the value of attribute is_running.



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# File 'lib/eventq_aws/aws_queue_worker.rb', line 9

def is_running
  @is_running
end

Instance Method Details

#deserialize_message(payload) ⇒ Object 



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# File 'lib/eventq_aws/aws_queue_worker.rb', line 175

def deserialize_message(payload)
  provider = @serialization_provider_manager.get_provider(EventQ::Configuration.serialization_provider)
  return provider.deserialize(payload)
end

#gc_flush ⇒ Object 



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# File 'lib/eventq_aws/aws_queue_worker.rb', line 114

def gc_flush
  if Time.now - last_gc_flush > @gc_flush_interval
    GC.start
    @last_gc_flush = Time.now
  end
end

#last_gc_flush ⇒ Object 



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# File 'lib/eventq_aws/aws_queue_worker.rb', line 121

def last_gc_flush
  @last_gc_flush
end

#on_retry_exceeded(&block) ⇒ Object 



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# File 'lib/eventq_aws/aws_queue_worker.rb', line 167

def on_retry_exceeded(&block)
  @retry_exceeded_block = block
end

#running? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/eventq_aws/aws_queue_worker.rb', line 171

def running?
  return @is_running
end

#start(queue, options = {}, &block) ⇒ Object 



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# File 'lib/eventq_aws/aws_queue_worker.rb', line 27

def start(queue, options = {}, &block)

  EventQ.log(:info, "[#{self.class}] - Preparing to start listening for messages.")

  configure(queue, options)

  if options[:client] == nil
    raise "[#{self.class}] - :client (QueueClient) must be specified."
  end

  raise "[#{self.class}] - Worker is already running." if running?

  EventQ.log(:info, "[#{self.class}] - Listening for messages.")

  @forks = []

  if @fork_count > 1
    @fork_count.times do
      pid = fork do
        start_process(options, queue, block)
      end
      @forks.push(pid)
    end

    if options.key?(:wait) && options[:wait] == true
      @forks.each { |pid| Process.wait(pid) }
    end

  else
    start_process(options, queue, block)
  end

  return true
end

#start_process(options, queue, block) ⇒ Object 



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# File 'lib/eventq_aws/aws_queue_worker.rb', line 62

def start_process(options, queue, block)

  %w'INT TERM'.each do |sig|
    Signal.trap(sig) {
      stop
      exit
    }
  end

  @is_running = true
  @threads = []

  #loop through each thread count
  @thread_count.times do
    thr = Thread.new do

      client = options[:client]
      manager = EventQ::Amazon::QueueManager.new({ client: client })

      #begin the queue loop for this thread
      while true do

        #check if the worker is still allowed to run and break out of thread loop if not
        if !@is_running
          break
        end

        has_message_received = thread_process_iteration(client, manager, queue, block)

        gc_flush

        if !has_message_received
          EventQ.log(:debug, "[#{self.class}] - No message received.")
          if @sleep > 0
            EventQ.log(:debug, "[#{self.class}] - Sleeping for #{@sleep} seconds")
            sleep(@sleep)
          end
        end

      end

    end
    @threads.push(thr)

  end

  if options.key?(:wait) && options[:wait] == true
    @threads.each { |thr| thr.join }
  end

end

#stop ⇒ Object 



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# File 'lib/eventq_aws/aws_queue_worker.rb', line 160

def stop
  EventQ.log(:info, "[#{self.class}] - Stopping.")
  @is_running = false
  @threads.each { |thr| thr.join }
  return true
end

#thread_process_iteration(client, manager, queue, block) ⇒ Object 



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# File 'lib/eventq_aws/aws_queue_worker.rb', line 125

def thread_process_iteration(client, manager, queue, block)
  #get the queue
  q = manager.get_queue(queue)

  received = false

  begin

    #request a message from the queue
    response = client.sqs.receive_message({
                                              queue_url: q,
                                              max_number_of_messages: 1,
                                              wait_time_seconds: @queue_poll_wait,
                                              attribute_names: [APPROXIMATE_RECEIVE_COUNT]
                                          })

    #check that a message was received
    if response.messages.length > 0
      received = true
      begin
        tag_processing_thread
        process_message(response, client, queue, q, block)
      ensure
        untag_processing_thread
      end

    end

  rescue => e
    EventQ.log(:error, "[#{self.class}] - An error occurred attempting to retrieve a message from the queue. Error: #{e.backtrace}")
  end

  return received
end