import socket
import errno
from time import time as now
def wait_net_service(server, port, timeout=None):
""" Wait for network service to appear
@param timeout: in seconds, if None or 0 wait forever
@return: True of False, if timeout is None may return only True or
throw unhandled network exception
"""
s = socket.socket()
# time module is needed to calc timeout shared between two exceptions
end = timeout and now() + timeout
while True:
try:
if timeout:
next_timeout = end - now()
if next_timeout < 0:
return False
else:
s.settimeout(next_timeout)
s.connect((server, port))
except socket.timeout, err:
# this exception occurs only if timeout is set
if timeout:
return False
except socket.error, err:
# catch timeout exception from underlying network library
# this one is different from socket.timeout
if type(err.args) != tuple or err[0] not in (errno.ETIMEDOUT, errno.ECONNREFUSED):
raise
else:
s.close()
return True
