Question

对于WSAECONNREFUSED（这意味着积压已满或端口不可用，Windows套接字有一些奇怪的行为，请参阅https://stackoverflow.com/a/10308338/851737）。如果Windows检测到这些条件之一，则重试（最多）两次，间隔为0.5秒。这意味着在套接字连接尝试（http://support.microsoft.com/kb/175523/en-us）上检测WSAECONNREFUSED至少需要1秒钟。

有没有办法在不弄乱注册表值的情况下加快检测速度？我需要在单元测试中模拟拒绝套接字连接。像模拟与原始套接字的拒绝连接一样的解决方法也是可以接受的。

这是一个简单的Python脚本，演示了这个问题：

import errno
import socket
import time

PORT = 50123


def main():
    s = socket.socket()
    s.bind(('127.0.0.1', PORT))
    s.listen(0)
    client = socket.socket()
    client.connect(('127.0.0.1', PORT))

    client2 = socket.socket()
    start = time.time()

    try:
        client2.connect(('127.0.0.1', PORT))
    except socket.error as e:
        assert e.errno == errno.WSAECONNREFUSED
        print 'connection attempt took', time.time() - start
    finally:
        client2.close()
        client.close()
        s.close()


if __name__ == '__main__':
    main()

Answer 1

这不完全是你问的问题。但如果您仅在单元测试中需要此功能，mock库将非常有用。

import errno
import socket
import time
import mock

PORT = 50123


def connect_mock(*agrs):
    raise socket.error(errno.WSAECONNREFUSED, "Testing")


def main():
    s = socket.socket()
    s.bind(('127.0.0.1', PORT))
    s.listen(0)
    client = socket.socket()
    client.connect(('127.0.0.1', PORT))

    client2 = socket.socket()
    start = time.time()

    with mock.patch('socket.socket.connect', connect_mock):
        try:
            client2.connect(('127.0.0.1', PORT))
            print "done"
        except socket.error as e:
            assert e.errno == errno.WSAECONNREFUSED
            print 'connection attempt took', time.time() - start
        finally:
            client2.close()
            client.close()
            s.close()


if __name__ == '__main__':
    main()

Answer 2

这是我的解决方案，基于dmitry-vakhrushev的answer，它正在修补连接方法更加智能化：

if sys.platform == 'win32':
    n_calls = [0]
    org_connect = socket.socket.connect

    def refusing_connect(*args):
        if n_calls[0] < 2:
            n_calls[0] += 1
            raise socket.error(errno.WSAECONNREFUSED, "Testing")
        return org_connect(*args)

    # patch socket.connect to speed up WSAECONNREFUSED detection
    patcher = mock.patch('socket.socket.connect', refusing_connect)
    patcher.start()
    self.addCleanup(patcher.stop)

快速检测或模拟WSAECONNREFUSED

2 个答案: