# Twisted, the Framework of Your Internet # Copyright (C) 2001 Matthew W. Lefkowitz # # This library is free software; you can redistribute it and/or # modify it under the terms of version 2.1 of the GNU Lesser General Public # License as published by the Free Software Foundation. # # This library is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # Lesser General Public License for more details. # # You should have received a copy of the GNU Lesser General Public # License along with this library; if not, write to the Free Software # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA """A Queue subclass that supports timeouts.""" # System Imports import Queue, time _time = time.time _sleep = time.sleep class TimedOut(Exception): pass class TimeoutQueue(Queue.Queue): """A thread-safe queue that supports timeouts""" def __init__(self, max=0): Queue.Queue.__init__(self, max) def wait(self, timeout): """Wait until the queue isn't empty. Raises TimedOut if still empty.""" endtime = _time() + timeout delay = 0.0005 # 500 us -> initial delay of 1 ms while 1: gotit = not self.empty() if gotit: break remaining = endtime - _time() if remaining <= 0: raise TimedOut, "timed out." delay = min(delay * 2, remaining, .05) _sleep(delay) __all__ = ["TimeoutQueue", "TimedOut"]