Source Code for Module Products.ZenUtils.Timeout

 1  ############################################################################## 
 2  #  
 3  # Copyright (C) Zenoss, Inc. 2008, all rights reserved. 
 4  #  
 5  # This content is made available according to terms specified in 
 6  # License.zenoss under the directory where your Zenoss product is installed. 
 7  #  
 8  ############################################################################## 
 9   
10   
11  from twisted.internet import reactor 
12  from twisted.internet import defer 
13   
14 -class TimeoutDeferred(defer.Deferred): 
15      """A deferred that fires errback if the result doesn't come 
16      back in the given time period""" 
17   
18      timer = None 
19       
20 -    def __init__(self, other, timeout): 
21          """Wrap the passed deferred and return a new deferred that 
22          will timeout 
23   
24          @type other: a Deferred 
25          @param other: the deferred to wrap 
26          @type timeout: floating point number 
27          @param timeout: time, in seconds, to wait before failing the deferred 
28          """ 
29          defer.Deferred.__init__(self) 
30          self.timer = reactor.callLater(timeout, self._timeout) 
31          other.chainDeferred(self) 
32   
33 -    def _timeout(self): 
34          "The wrapped deferred was too slow: fire the errback" 
35          if not self.called: 
36              self.timer = None 
37              self.errback(defer.TimeoutError()) 
38   
39 -    def _startRunCallbacks(self, result): 
40          "We have a result, fire callbacks or cancel the timer" 
41          if self.timer: 
42              self.timer.cancel() 
43              self.timer = None 
44          if not self.called: 
45              defer.Deferred._startRunCallbacks(self, result) 
46   
47 -def timeout(deferred, timeInSeconds): 
48      "Utility method to wrap a deferred to timeout in timeInSeconds" 
49      return TimeoutDeferred(deferred, timeInSeconds) 
50