Module: MessageCommand

Includes:
DefaultLogging
Included in:
MessageProbe, MessagePusher, MessageSink
Defined in:
lib/pipeline_toolkit/message_command.rb

Defined Under Namespace

Modules: ProcessLine

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#sys_pipe ⇒ Object (readonly)

Returns the value of attribute sys_pipe.



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# File 'lib/pipeline_toolkit/message_command.rb', line 7

def sys_pipe
  @sys_pipe
end

Instance Method Details

#ack_msg(msg) ⇒ Object 



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# File 'lib/pipeline_toolkit/message_command.rb', line 53

def ack_msg(msg)
  return unless @use_ack
  @sys_pipe.syswrite(msg.ack_id + "\n")
end

#init_loop ⇒ Object

Override in included class. Provides a chance to initialize any code that needs to take place once the EM loop has started.



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# File 'lib/pipeline_toolkit/message_command.rb', line 64

def init_loop
  # Implemented in class that includes me
end

#pass_on_msg(msg) ⇒ Object 



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# File 'lib/pipeline_toolkit/message_command.rb', line 58

def pass_on_msg(msg)
  $stdout.syswrite(MessageCoder.encode(msg) << "\n")
end

#process_line(line) ⇒ Object 



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# File 'lib/pipeline_toolkit/message_command.rb', line 35

def process_line(line)
  msg = MessageCoder.decode(line)
  
  case msg[:msg_type]
  when :system
    result = process_system(msg)
  else
    result = process_message(msg)
  end
  
  case result
  when :ack
    self.ack_msg(msg)
  else
    self.pass_on_msg(result)
  end
end

#process_message(msg) ⇒ Object

Override in included class. Processes a message. This method must return either a msg object – which may or may not have been modified – or the symbol :ack. Returning :ack mean that the message has been dealt with and can be acknowledged back to the queue server. All messages must be acknowledged by at least one message_command.



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# File 'lib/pipeline_toolkit/message_command.rb', line 72

def process_message(msg)
  # Implemented in class that includes me
  msg
end

#process_system(msg) ⇒ Object 



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# File 'lib/pipeline_toolkit/message_command.rb', line 77

def process_system(msg)
  @sys_pipe = File.open(msg.sys_pipe, "w")
  @use_ack = msg.use_ack
  @max_unackd = msg.max_unackd
  msg
end

#shutdown ⇒ Object 



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# File 'lib/pipeline_toolkit/message_command.rb', line 30

def shutdown
  log.info("shutting down")
  @sys_pipe && @sys_pipe.close
end

#start ⇒ Object 



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# File 'lib/pipeline_toolkit/message_command.rb', line 9

def start
  log.info("starting")

  Signal.trap('INT') { EM.stop }
  Signal.trap('TERM'){ EM.stop }

  @ack_buffer ||= ""

  begin
    EM.run do
      self.init_loop
      EM.attach($stdin, ProcessLine, self)
    end
  rescue StandardError => e
    log.info e
    raise e
  ensure
    self.shutdown
  end
end