Source Code for Module advene.util.synchronized

 1  """ 
 2  I provi to de mechanisms similar to the ``synchronized`` keyword in Java. 
 3   
 4  The idea is to associate a reentrant lock to each object, with the possibility 
 5  for a section of code to claim that lock. Functions `enter_cs` and `exit_cs` 
 6  can be used for synchronizing any section of code on any object, while the 
 7  `synchronized` decorator can be used to synchronize a whole method on its 
 8  ``self`` parameter. 
 9  """ 
10   
11  from threading import Lock, RLock 
12   
13  # the following global lock is used to prevent several locks being created 
14  # for the same object 
15  _sync_lock = Lock() 
16   
17 -def enter_cs(obj): 
18      """ 
19      Enter a critical section on `obj`. 
20      """ 
21      _sync_lock.acquire() 
22      try: 
23          L = obj.__rlock 
24      except AttributeError: 
25          L = obj.__rlock = RLock() 
26      finally: 
27          _sync_lock.release() 
28      L.acquire() 
29   
30 -def exit_cs(obj): 
31      """ 
32      Exit a critical section on `obj`. 
33      """ 
34      obj.__rlock.release() 
35   
36 -def synchronized(f): 
37      """ 
38      A decorator for synchronized methods (alla Java). 
39      """ 
40      def synchronized_f(self, *a, **kw): 
41          enter_cs(self) 
42          try: 
43              return f(self, *a, **kw) 
44          finally: 
45              exit_cs(self) 
46      synchronized_f.__name__ = f.__name__ 
47      synchronized_f.__doc__ = f.__doc__ 
48      return synchronized_f 
49