import threading
import os
import select
import fcntl
import time
import errno
import random

POLLER_THREADS = 20
TOGGLER_THREADS = 1

def poller(pollobj, fd):
	global event
	p1 = random.random() * 0.001
	p2 = int(random.random() * 100)
	while True:
		time.sleep(p1)
		try:
			events = pollobj.poll(p2)
		except select.error, e:
			if e.args[0] != errno.EINTR:
				raise
		else:
			if not events:
				continue
			if events[0][0] != fd:
				if not event:
					print "poll returned %r, we were looking for fd %d" % (events, fd)
					event = True
				break
			if events[0][1] & ~(select.POLLIN | select.POLLHUP | select.POLLNVAL):
				print "fd correct but revents might be bogus; poll returned %r" % (events,)
				break
			if events[0][1] & select.POLLIN:
				continue
			if events[0][1] & (select.POLLHUP | select.POLLNVAL):
				break
			print "should not get here; poll returned %r" % (events,)

def toggler(r, w):
	p1 = random.random() * 0.001
	while True:
		time.sleep(p1)
		try:
			os.write(w, "!")
		except OSError, e:
			if e.errno == errno.EBADF:
				return
			if e.errno == errno.EPIPE:
				return
			raise
		try:
			n = os.read(r, 4096)
		except OSError, e:
			if e.errno == errno.EBADF:
				break
			if e.errno == errno.EAGAIN:
				continue
			raise

if __name__ == '__main__':
	events = 0
	for _ in xrange(30):
		event = False
		r, w = os.pipe()
		fcntl.fcntl(r, fcntl.F_SETFL, fcntl.fcntl(r, fcntl.F_GETFL) | os.O_NONBLOCK)
		pollobj = select.poll()
		pollobj.register(r, select.POLLIN)
		threads = (
			[threading.Thread(target=poller, args=(pollobj, r)) for _ in xrange(POLLER_THREADS)] +
			[threading.Thread(target=toggler, args=(r, w)) for _ in xrange(TOGGLER_THREADS)] +
		[])
		for t in threads:
			t.setDaemon(1)
			t.start()

		time.sleep(1.0)

		os.close(r)
		os.close(w)
		time.sleep(0.1)
		if event:
			events += 1
	print "%d events in 30 iterations" % (events,)