Source Code for Module ZenUtils.Timeout

 1  ########################################################################### 
 2  # 
 3  # This program is part of Zenoss Core, an open source monitoring platform. 
 4  # Copyright (C) 2008, Zenoss Inc. 
 5  # 
 6  # This program is free software; you can redistribute it and/or modify it 
 7  # under the terms of the GNU General Public License version 2 as published by 
 8  # the Free Software Foundation. 
 9  # 
10  # For complete information please visit: http://www.zenoss.com/oss/ 
11  # 
12  ########################################################################### 
13  from twisted.internet import reactor 
14  from twisted.internet import defer 
15   
16 -class TimeoutDeferred(defer.Deferred): 
17      """A deferred that fires errback if the result doesn't come 
18      back in the given time period""" 
19   
20      timer = None 
21       
22 -    def __init__(self, other, timeout): 
23          """Wrap the passed deferred and return a new deferred that 
24          will timeout 
25   
26          @type other: a Deferred 
27          @param other: the deferred to wrap 
28          @type timeout: floating point number 
29          @param timeout: time, in seconds, to wait before failing the deferred 
30          """ 
31          defer.Deferred.__init__(self) 
32          self.timer = reactor.callLater(timeout, self._timeout) 
33          other.chainDeferred(self) 
34   
35 -    def _timeout(self): 
36          "The wrapped deferred was too slow: fire the errback" 
37          if not self.called: 
38              self.timer = None 
39              self.errback(defer.TimeoutError()) 
40   
41 -    def _startRunCallbacks(self, result): 
42          "We have a result, fire callbacks or cancel the timer" 
43          if self.timer: 
44              self.timer.cancel() 
45              self.timer = None 
46          if not self.called: 
47              defer.Deferred._startRunCallbacks(self, result) 
48   
49 -def timeout(deferred, timeInSeconds): 
50      "Utility method to wrap a deferred to timeout in timeInSeconds" 
51      return TimeoutDeferred(deferred, timeInSeconds) 
52