Automatic thread safety

[Connelly Barnes]

Another useful code snippet...

This allows you to take a non-threadsafe class, and
automatically generate a threadsafe class. When a
method is called for your class, it automatically
locks the object, then calls the method, then unlocks
the object. You will have to perform any further
locking/unlocking manually.

# -------------------------------------------------
# threadclass: Get a threadsafe copy of a class.
# -------------------------------------------------

import types, threading
def threadclass(C):
"""Returns a 'threadsafe' copy of class C.
All public methods are modified to lock the object when called."""
class D(C):
def __init__(self):
self.lock = threading.RLock()
C.__init__(self)

def ubthreadfunction(f):
def g(self, *args, **kwargs):
self.lock.acquire()
ans = f(self, *args, **kwargs)
self.lock.release()
return ans
return g

for a in dir(D):
f = getattr(D, a)
if isinstance(f, types.UnboundMethodType) and a[:2] != '__':
setattr(D, a, ubthreadfunction(f))
return D


Example:

class Counter:
def __init__(self):
self.val = 0
def increment(self):
self.val += 1

SafeCounter = threadclass(Counter)


Now SafeCounter is a threadsafe class. Try it out!

Enjoy,
Connelly Barnes

 

[Peter Hansen]

Another useful code snippet...

[snip]

The Python Cookbook at http://aspn.activestate.com/ASPN/Python/Cookbook/
would be a much more effective way to make these snippets available
to others.