threading.py 文件源码

def wait_for(self, predicate, timeout=None):
        """Wait until a condition evaluates to True.

        predicate should be a callable which result will be interpreted as a
        boolean value.  A timeout may be provided giving the maximum time to
        wait.

        """
        endtime = None
        waittime = timeout
        result = predicate()
        while not result:
            if waittime is not None:
                if endtime is None:
                    endtime = _time() + waittime
                else:
                    waittime = endtime - _time()
                    if waittime <= 0:
                        break
            self.wait(waittime)
            result = predicate()
        return result