Source Code for Module Products.ZenHub.services.Procrastinator

 1  ############################################################################## 
 2  #  
 3  # Copyright (C) Zenoss, Inc. 2007, 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  import logging 
12  from twisted.internet import reactor, defer 
13   
14   
15  log = logging.getLogger('zen.Procrastinator') 
16   
17   
18 -class Procrastinate(object): 
19      "A class to delay executing a change to a device" 
20   
21      _DO_LATER_DELAY = 5 
22      _DO_NOW_DELAY = 0.05 
23   
24 -    def __init__(self, cback): 
25          self.cback = cback 
26          self.devices = set() 
27          self.timer = None 
28          self._stopping = False 
29          self._stopping_deferred = defer.Deferred() 
30   
31 -    def clear(self): 
32          self.devices = set() 
33   
34 -    def stop(self): 
35          self._stopping = True 
36          if not self.devices: 
37              return defer.succeed(True) 
38          log.debug("Returning stopping deferred") 
39          d, self._stopping_deferred = self._stopping_deferred, None 
40          return d 
41   
42 -    def doLater(self, device = None): 
43          if not self._stopping: 
44              if self.timer and not self.timer.called: 
45                  self.timer.cancel() 
46              self.devices.add(device) 
47              self.timer = reactor.callLater(Procrastinate._DO_LATER_DELAY, self._doNow) 
48   
49 -    def _doNow(self, *unused): 
50          if self.devices: 
51              device = self.devices.pop() 
52              self.cback(device) 
53              if self.devices: 
54                  reactor.callLater(Procrastinate._DO_NOW_DELAY, self._doNow) 
55              elif self._stopping: 
56                  log.debug("Callback to _stopping_deferred") 
57                  self._stopping_deferred.callback(None) 
58