Class: Spawner

Inherits:
Object
  • Object
show all
Defined in:
lib/tootsie/spawner.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Spawner

Returns a new instance of Spawner.



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# File 'lib/tootsie/spawner.rb', line 9

def initialize(options = {})
  @num_children = options[:num_children] || 1
  @pids = Set.new
  @logger = options[:logger]
  @terminating = false
  @parent = true
end

Instance Attribute Details

#logger ⇒ Object (readonly)

Returns the value of attribute logger.



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# File 'lib/tootsie/spawner.rb', line 97

def logger
  @logger
end

Instance Method Details

#on_spawn(&block) ⇒ Object 



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# File 'lib/tootsie/spawner.rb', line 17

def on_spawn(&block)
  @on_spawn = block
end

#run(&block) ⇒ Object 



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# File 'lib/tootsie/spawner.rb', line 21

def run(&block)
  loop do
    unless @terminating
      while @pids.length < @num_children
        pid = Process.fork
        if pid
          # In parent process
          @pids << pid
          logger.info("Child PID=#{pid} spawned")
        else
          # In child process 
          @parent = false
          @on_spawn.call
          exit(0)
        end
      end
    end
    wait_for_children
    break if @terminated and @pids.empty?
  end
end

#terminate ⇒ Object 



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# File 'lib/tootsie/spawner.rb', line 64

def terminate
  if @parent
    logger.info("Parent terminating, will terminate all child PIDs")
    @terminating = true
    @pids.each do |pid|
      logger.info("Terminating child PID=#{pid}")
      begin
        Process.kill("TERM", pid)
      rescue Errno::ESRCH
        # Ignore
      end
    end
    begin
      timeout(5) do
        while @pids.any?
          sleep(0.5)
          wait_for_children
        end
      end
    rescue Timeout::Error
      logger.error("Timed out waiting for children, killing them")
      @pids.each do |pid|
        logger.info("Killing child PID=#{pid}")
        begin
          Process.kill("KILL", pid)
        rescue Errno::ESRCH
          # Ignore
        end
      end
    end
  end
end

#wait_for_children ⇒ Object 



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# File 'lib/tootsie/spawner.rb', line 43

def wait_for_children
  pid = Process.waitpid(-1)
  if pid
    status = $?
    if status.exited? 
      if status.exitstatus == 0
        logger.info("Child PID=#{pid} exited normally")
      else
        logger.info("Child PID=#{pid} exited unexpectedly with exit code #{status.exitstatus}")
      end
    elsif status.stopped?
      logger.info("Child PID=#{pid} stopped unexpectedly with signal #{status.stopsig}")
    elsif status.signaled?
      logger.info("Child PID=#{pid} died unexpectedly by signal #{status.termsig}")
    else
      logger.info("Child PID=#{pid} died unexpectedly")
    end
    @pids.delete(pid)
  end
end