inscapist · September 7, 2024 14:59 · inscapist · Sep 7, 2024
diff --git a/about.md b/about.md
diff --git a/self_pipe.rb b/self_pipe.rb
 #!/usr/bin/env ruby

 # Contrived example of self-pipe preventing signal race condition prior to select()
 # @see http://cr.yp.to/docs/selfpipe.html
 # @author Paul Annesley

 SELF_READ, SELF_WRITE = IO.pipe
 @run = true

 trap :INT do
  @run = false
  SELF_WRITE.putc(0)
 end

 # send SIGINT mid-sleep
 Process.fork { sleep 1; Process.kill :INT, Process.ppid; exit }

 r,w = IO.pipe
 while @run do
  sleep 0.2 # .. amplify race-condition; exists until select()
  w.putc(".") if @run # .. nothing written if SIGINT handler has disabled @run
  selected = IO.select [r, SELF_READ]
  break if selected.first.include? SELF_READ
  print r.getc
 end

 puts 'without self-pipe, select() would have blocked'
	#!/usr/bin/env ruby

	# Contrived example of self-pipe preventing signal race condition prior to select()
	# @see http://cr.yp.to/docs/selfpipe.html
	# @author Paul Annesley

	SELF_READ, SELF_WRITE = IO.pipe
	@run = true

	trap :INT do
	@run = false
	SELF_WRITE.putc(0)
	end

	# send SIGINT mid-sleep
	Process.fork { sleep 1; Process.kill :INT, Process.ppid; exit }

	r,w = IO.pipe
	while @run do
	sleep 0.2 # .. amplify race-condition; exists until select()
	w.putc(".") if @run # .. nothing written if SIGINT handler has disabled @run
	selected = IO.select [r, SELF_READ]
	break if selected.first.include? SELF_READ
	print r.getc
	end

	puts 'without self-pipe, select() would have blocked'