#!/usr/bin/env python
     # encoding: utf-8
     #
     # Copyright (c) 2008 Doug Hellmann All rights reserved.
     #
     """Controlling access to a resource using a Lock
     """
     #end_pymotw_header
     
     import logging
     import random
     import threading
     import time
     
     logging.basicConfig(level=logging.DEBUG,
                         format='(%(threadName)-10s) %(message)s',
                         )
                         
     class Counter(object):
         def __init__(self, start=0):
             self.lock = threading.Lock()
             self.value = start
         def increment(self):
             logging.debug('Waiting for lock')
             self.lock.acquire()
             try:
                 logging.debug('Acquired lock')
                 self.value = self.value + 1
             finally:
                 self.lock.release()
     
     def worker(c):
         for i in range(2):
             pause = random.random()
             logging.debug('Sleeping %0.02f', pause)
             time.sleep(pause)
             c.increment()
         logging.debug('Done')
     
     counter = Counter()
     for i in range(2):
         t = threading.Thread(target=worker, args=(counter,))
         t.start()
     
     logging.debug('Waiting for worker threads')
     main_thread = threading.currentThread()
     for t in threading.enumerate():
         if t is not main_thread:
             t.join()
     logging.debug('Counter: %d', counter.value)