Source Code for Module elisa.core.utils.defer

  1  # -*- coding: utf-8 -*- 
  2  # Moovida - Home multimedia server 
  3  # Copyright (C) 2006-2009 Fluendo Embedded S.L. (www.fluendo.com). 
  4  # All rights reserved. 
  5  # 
  6  # This file is available under one of two license agreements. 
  7  # 
  8  # This file is licensed under the GPL version 3. 
  9  # See "LICENSE.GPL" in the root of this distribution including a special 
 10  # exception to use Moovida with Fluendo's plugins. 
 11  # 
 12  # The GPL part of Moovida is also available under a commercial licensing 
 13  # agreement from Fluendo. 
 14  # See "LICENSE.Moovida" in the root directory of this distribution package 
 15  # for details on that license. 
 16   
 17   
 18  from twisted.internet import defer 
 19  from twisted.python import failure 
 20  import cancellable_defer 
 21   
 22   
 23  if not hasattr(defer.Deferred(), 'cancel'): 
 24      Deferred = cancellable_defer.CancellableDeferred 
 25      CancelledError = cancellable_defer.CancelledError 
 26  else: 
 27      Deferred = defer.Deferred 
 28      CancelledError = defer.CancelledError 
 29   
 30   
 31 -def succeed(result): 
 32      """ 
 33      see L{twisted.internet.defer.succeed}. 
 34   
 35      @rtype: L{Deferred} 
 36      """ 
 37      d = Deferred() 
 38      d.callback(result) 
 39      return d 
 40   
 41 -def fail(result=None): 
 42      """ 
 43      see L{twisted.internet.defer.fail}. The biggest difference is that the 
 44      twisted API allows you to call this without any parameters, which leads to 
 45      an error. See http://twistedmatrix.com/trac/ticket/3145. 
 46   
 47      @rtype: L{Deferred} 
 48      """ 
 49      d = Deferred() 
 50      d.errback(result) 
 51      return d 
 52   
 53 -def execute(callable, *args, **kw): 
 54      """ 
 55      see L{twisted.internet.defer.execute}. 
 56   
 57      @rtype: L{Deferred} 
 58      """ 
 59      try: 
 60          result = callable(*args, **kw) 
 61      except Exception, exc: 
 62          return fail(exc) 
 63      else: 
 64          return succeed(result) 
 65   
 66   
 67 -def timeout(deferred): 
 68      # old and new API compatible 
 69      if hasattr(deferred, 'cancel'): 
 70          deferred.cancel() 
 71      else: 
 72          msg = 'Callback timed out' 
 73          deferred.errback(failure.Failure(defer.TimeoutError(msg))) 
 74   
 75 -def deferred_accumulator(invocation_hint, return_accu, handler_return): 
 76      """ 
 77      Accumulator to use with gobject signals where callbacks are supposed to 
 78      return a Deferred. With this, emit() will return a list of all the 
 79      Deferred returned by the connected callbacks. It ignores callback return 
 80      values that are not Deferreds. 
 81   
 82      @param invocation_hint: (signal_id, detail, run_type) (this parameter is 
 83      ignored) 
 84      @type invocation_hint: C{tuple} 
 85      @param return_accu: a list of Deferred (or possibly None) 
 86      @type return_accu: C{list} 
 87      @param handler_return: The return value of the signal handler 
 88      @type handler_return: C{elisa.core.utils.Deferred} 
 89   
 90      @return: a tuple containing True and a list of deferreds. 
 91      @rtype: C{tuple} 
 92      """ 
 93      accu = return_accu 
 94      if accu == None: 
 95          accu = [] 
 96      if not isinstance(handler_return, Deferred): 
 97          return True, accu 
 98      return True, accu + [handler_return] 
 99   
100  # for compability with twisted.internet.defer: 
101  DeferredList = defer.DeferredList 
102   
103  FAILURE = defer.FAILURE 
104  SUCCESS = defer.SUCCESS 
105  TimeoutError = defer.TimeoutError 
106  AlreadyCalledError = defer.AlreadyCalledError 
107   
108  gatherResults = defer.gatherResults 
109  maybeDeferred = defer.maybeDeferred 
110  waitForDeferred = defer.waitForDeferred 
111  deferredGenerator = defer.deferredGenerator 
112  inlineCallbacks = defer.inlineCallbacks 
113   
114  DeferredLock = defer.DeferredLock 
115  DeferredSemaphore = defer.DeferredSemaphore 
116  DeferredQueue = defer.DeferredQueue 
117   
118  # these classes are new since 8.1 
119  try: 
120      DeferredFilesystemLock = defer.DeferredFilesystemLock 
121      AlreadyTryingToLockError = defer.AlreadyTryingToLockError 
122  except AttributeError: 
123      pass 
124