Module: Pgbus::Process::SignalHandler

Included in:
Outbox::Poller, Consumer, Dispatcher, Supervisor, Worker, Recurring::Scheduler
Defined in:
lib/pgbus/process/signal_handler.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(base) ⇒ Object 



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# File 'lib/pgbus/process/signal_handler.rb', line 6

def self.included(base)
  base.attr_reader :signal_queue
end

Instance Method Details

#graceful_shutdown ⇒ Object

Raises:

  • (NotImplementedError) 


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# File 'lib/pgbus/process/signal_handler.rb', line 60

def graceful_shutdown
  raise NotImplementedError
end

#handled_signals ⇒ Object

The signals setup_signals has installed handlers for (and will restore on restore_signals). Empty until setup_signals runs.



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# File 'lib/pgbus/process/signal_handler.rb', line 12

def handled_signals
  (@previous_handlers || {}).keys
end

#immediate_shutdown ⇒ Object

Raises:

  • (NotImplementedError) 


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# File 'lib/pgbus/process/signal_handler.rb', line 64

def immediate_shutdown
  raise NotImplementedError
end

#interruptible_sleep(seconds) ⇒ Object

Sleep that can be interrupted by signals. Use this instead of Kernel#sleep in any loop that needs to respond to INT/TERM/QUIT promptly.



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# File 'lib/pgbus/process/signal_handler.rb', line 55

def interruptible_sleep(seconds)
  @self_pipe_r.wait_readable(seconds)
  drain_self_pipe
end

#process_signals ⇒ Object 



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# File 'lib/pgbus/process/signal_handler.rb', line 38

def process_signals
  while (sig = begin
    @signal_queue.pop(true)
  rescue StandardError
    nil
  end)
    case sig
    when "INT", "TERM"
      graceful_shutdown
    when "QUIT"
      immediate_shutdown
    end
  end
end

#restore_signals ⇒ Object 



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# File 'lib/pgbus/process/signal_handler.rb', line 30

def restore_signals
  @previous_handlers&.each do |sig, handler|
    trap(sig, handler || "DEFAULT")
  end
  @self_pipe_r&.close unless @self_pipe_r&.closed?
  @self_pipe_w&.close unless @self_pipe_w&.closed?
end

#setup_signals ⇒ Object 



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# File 'lib/pgbus/process/signal_handler.rb', line 16

def setup_signals
  @signal_queue = Queue.new
  @previous_handlers = {}
  @self_pipe_r, @self_pipe_w = IO.pipe

  %w[INT TERM QUIT].each do |sig|
    @previous_handlers[sig] = trap(sig) do
      @signal_queue << sig
      # Wake any IO.select / interruptible_sleep call
      @self_pipe_w.write_nonblock(".", exception: false)
    end
  end
end