def __init__(self):
# Based on Zope async.py: http://svn.zope.org/zc.ngi/trunk/src/zc/ngi/async.py
self.writer = socket.socket()
# Disable buffering -- pulling the trigger sends 1 byte,
# and we want that sent immediately, to wake up ASAP.
self.writer.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
count = 0
while 1:
count += 1
# Bind to a local port; for efficiency, let the OS pick
# a free port for us.
# Unfortunately, stress tests showed that we may not
# be able to connect to that port ("Address already in
# use") despite that the OS picked it. This appears
# to be a race bug in the Windows socket implementation.
# So we loop until a connect() succeeds (almost always
# on the first try). See the long thread at
# http://mail.zope.org/pipermail/zope/2005-July/160433.html
# for hideous details.
a = socket.socket()
a.bind(("127.0.0.1", 0))
connect_address = a.getsockname() # assigned (host, port) pair
a.listen(1)
try:
self.writer.connect(connect_address)
break # success
except socket.error, detail:
if detail[0] != errno.WSAEADDRINUSE:
# "Address already in use" is the only error
# I've seen on two WinXP Pro SP2 boxes, under
# Pythons 2.3.5 and 2.4.1.
raise
# (10048, 'Address already in use')
# assert count <= 2 # never triggered in Tim's tests
if count >= 10: # I've never seen it go above 2
a.close()
self.writer.close()
raise socket.error("Cannot bind trigger!")
# Close `a` and try again. Note: I originally put a short
# sleep() here, but it didn't appear to help or hurt.
a.close()
self.reader, addr = a.accept()
self.reader.setblocking(0)
self.writer.setblocking(0)
a.close()
self.reader_fd = self.reader.fileno()
评论列表
文章目录
