synchronization.py 文件源码

def do_acquire_write_lock(self, wait=True):
        self.condition.acquire()
        try:
            # here, we are not a synchronous reader, and after returning,
            # assuming waiting or immediate availability, we will be.

            if wait:
                # if another sync is working, wait
                while self.current_sync_operation is not None:
                    self.condition.wait()
            else:
                # if another sync is working,
                # we dont want to wait, so forget it
                if self.current_sync_operation is not None:
                    return False

            # establish ourselves as the current sync
            # this indicates to other read/write operations
            # that they should wait until this is None again
            self.current_sync_operation = _threading.currentThread()

            # now wait again for asyncs to finish
            if self.async > 0:
                if wait:
                    # wait
                    self.condition.wait()
                else:
                    # we dont want to wait, so forget it
                    self.current_sync_operation = None
                    return False