Created
November 9, 2009 12:46
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#!/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' |
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