sync.py 文件源码

def __init__(self, lock=None):
        # the lock actually used by .acquire() and .release()
        if lock is None:
            self.mutex = thread.allocate_lock()
        else:
            if hasattr(lock, 'acquire') and \
               hasattr(lock, 'release'):
                self.mutex = lock
            else:
                raise TypeError, 'condition constructor requires ' \
                                 'a lock argument'

        # lock used to block threads until a signal
        self.checkout = thread.allocate_lock()
        self.checkout.acquire()

        # internal critical-section lock, & the data it protects
        self.idlock = thread.allocate_lock()
        self.id = 0
        self.waiting = 0  # num waiters subject to current release
        self.pending = 0  # num waiters awaiting next signal
        self.torelease = 0      # num waiters to release
        self.releasing = 0      # 1 iff release is in progress