python - 快速检测或模拟 WSAECONNREFUSED

Question

Windows 套接字在涉及 WSAECONNREFUSED 时有一些奇怪的行为(这意味着积压已满或端口不可用，请参阅 https://stackoverflow.com/a/10308338/851737)。如果 Windows 检测到其中一种情况，它会重试(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。

有没有什么方法可以在不扰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。像使用原始套接字模拟拒绝连接这样的解决方法也是可以接受的。

这是一个简单的 Python 脚本来演示这个问题:

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

这不是你问的。但是如果你只在unittests 中需要这个，mock图书馆会很有用。

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()