Class: Preforker::SignalProcessor

Inherits:
Object
  • Object
show all
Defined in:
lib/preforker/signal_processor.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(master) ⇒ SignalProcessor

Returns a new instance of SignalProcessor.



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# File 'lib/preforker/signal_processor.rb', line 4

def initialize(master)
  @read_pipe, @write_pipe = IO.pipe
  @master = master
  @signal_queue = []
  @interesting_signals = [:WINCH, :QUIT, :INT, :TERM, :USR1, :USR2, :HUP, :TTIN, :TTOU]
  @interesting_signals.each { |sig| trap_deferred(sig) }
end

Instance Attribute Details

#interesting_signals ⇒ Object (readonly)

Returns the value of attribute interesting_signals.



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# File 'lib/preforker/signal_processor.rb', line 3

def interesting_signals
  @interesting_signals
end

#signal_queue ⇒ Object (readonly)

Returns the value of attribute signal_queue.



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# File 'lib/preforker/signal_processor.rb', line 3

def signal_queue
  @signal_queue
end

Instance Method Details

#reset ⇒ Object 



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# File 'lib/preforker/signal_processor.rb', line 82

def reset
  @interesting_signals.each { |sig| trap(sig, nil) }
  @signal_queue.clear
end

#sleep_master ⇒ Object

wait for a signal hander to wake us up and then consume the pipe Wake up every second anyways to run murder_lazy_workers



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# File 'lib/preforker/signal_processor.rb', line 62

def sleep_master
  begin
    maximum_sleep = @master.timeout > 1 ? 1 : @master.timeout / 2
    ready = IO.select([@read_pipe], nil, nil, maximum_sleep) or return
    ready.first && ready.first.first or return
    chunk_size = 16 * 1024
    loop { @read_pipe.read_nonblock(chunk_size) }
  rescue Errno::EAGAIN, Errno::EINTR
  end
end

#start_signal_loop ⇒ Object 



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# File 'lib/preforker/signal_processor.rb', line 23

def start_signal_loop
  last_check = Time.now
  begin
    loop do
      @master.reap_all_workers
      case @signal_queue.shift
        when nil
          # avoid murdering workers after our master process (or the
          # machine) comes out of suspend/hibernation
          @master.murder_lazy_workers if (last_check + @master.timeout) >= (last_check = Time.now)
          @master.maintain_worker_count
          sleep_master
        when :WINCH
          @master.logger.info "Gracefully stopping all workers"
          @master.number_of_workers = 0
        when :TTIN
          @master.number_of_workers += 1
        when :TTOU
          @master.number_of_workers -= 1 if @master.number_of_workers > 0
        when :QUIT # graceful shutdown
          break
        when :TERM, :INT # immediate shutdown
          @master.stop(false)
          break
      end
    end
  rescue Errno::EINTR
    retry
  rescue => e
    @master.logger.error "Unhandled master loop exception #{e.inspect}.\n#{e.backtrace.join("\n")}"
    retry
  ensure
    @master.logger.info "Master quitting"
    @master.quit
  end
end

#trap_deferred(signal) ⇒ Object 



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# File 'lib/preforker/signal_processor.rb', line 12

def trap_deferred(signal)
  trap(signal) do
    if @signal_queue.size < 5
      @signal_queue << signal
      wake_up_master
    else
      @master.logger.error "ignoring SIG#{signal}, queue=#{@signal_queue.inspect}"
    end
  end
end

#wake_up_master ⇒ Object 



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# File 'lib/preforker/signal_processor.rb', line 73

def wake_up_master
  begin
    @write_pipe.write_nonblock('.') # wakeup master process from select
  rescue Errno::EAGAIN, Errno::EINTR
    # pipe is full, master should wake up anyways
    retry
  end
end