test_defer.py 文件源码

def test_cancelSemaphoreAfterAcquired(self):
        """
        When canceling a L{Deferred} from a L{DeferredSemaphore} that
        already has the semaphore, the cancel should have no effect.
        """
        def _failOnErrback(_):
            self.fail("Unexpected errback call!")

        sem = defer.DeferredSemaphore(1)
        d = sem.acquire()
        d.addErrback(_failOnErrback)
        d.cancel()