背景

关于tornado，我这里就不详细讲了，有兴趣的同学可以通过以下两篇博客了解一下：

  http://yunjianfei.iteye.com/blog/2185476

http://yunjianfei.iteye.com/blog/2185446

我们一般用tornado来编写web程序，但实际上，tornado底层的代码非常优秀，也可以用这些代码来编写TCP应用。

代码

tornado最突出的特点就是“异步”，所以，我这里编写了一个异步的TCPServer和一个异步的TCPClient来帮助大家理解，下面直接看代码：

文件：tcp_server.py

#!/usr/bin/env python2.7
# -*- coding: utf-8 -*-

from tornado import ioloop, httpclient, gen
from tornado.gen import Task
from tornado.tcpserver import TCPServer
import pdb, time, logging
from tornado import stack_context
from tornado.escape import native_str

#Init logging
def init_logging():
    logger = logging.getLogger()
    logger.setLevel(logging.DEBUG)

    sh = logging.StreamHandler()

    formatter = logging.Formatter('%(asctime)s -%(module)s:%(filename)s-L%(lineno)d-%(levelname)s: %(message)s')
    sh.setFormatter(formatter)

    logger.addHandler(sh)
    logging.info("Current log level is : %s", logging.getLevelName(logger.getEffectiveLevel()))


class MyServer(TCPServer):
    def __init__(self, io_loop=None, **kwargs):
        TCPServer.__init__(self, io_loop=io_loop, **kwargs)

    def handle_stream(self, stream, address):
        TCPConnection(stream, address, io_loop=self.io_loop)

class TCPConnection(object):
    def __init__(self, stream, address, io_loop):
        self.io_loop = io_loop
        self.stream = stream
        self.address = address
        self.address_family = stream.socket.family

        self.EOF = b' END'

        self._clear_request_state()

        self._message_callback = stack_context.wrap(self._on_message)

        self.stream.set_close_callback(self._on_connection_close)
        self.stream.read_until(self.EOF, self._message_callback)

    def _on_timeout(self):
        logging.info("Send message..")
        self.write("Hello client!" + self.EOF)

    def _on_message(self, data):
        try:
            timeout = 5
            data = native_str(data.decode('latin1'))
            logging.info("Received: %s", data)
            self.io_loop.add_timeout(self.io_loop.time() + timeout, self._on_timeout)
        except Exception, ex:
            logging.error("Exception: %s", str(ex))

    def _clear_request_state(self):
        """Clears the per-request state.
        """
        self._write_callback = None
        self._close_callback = None

    def set_close_callback(self, callback):
        """Sets a callback that will be run when the connection is closed.
        """
        self._close_callback = stack_context.wrap(callback)

    def _on_connection_close(self):
        if self._close_callback is not None:
            callback = self._close_callback
            self._close_callback = None
            callback()
        self._clear_request_state()

    def close(self):
        self.stream.close()
        # Remove this reference to self, which would otherwise cause a
        self._clear_request_state()

    def write(self, chunk, callback=None):
        """Writes a chunk of output to the stream."""
        if not self.stream.closed():
            self._write_callback = stack_context.wrap(callback)
            self.stream.write(chunk, self._on_write_complete)

    def _on_write_complete(self):
        if self._write_callback is not None:
            callback = self._write_callback
            self._write_callback = None
            callback()

def main():
    init_logging()

    server = MyServer()
    server.listen(8001)
    ioloop.IOLoop.instance().start()

if __name__ == "__main__":
    try:
        main()
    except Exception, ex:
        print "Ocurred Exception: %s" % str(ex)
        quit()

文件： tcp_client.py

#!/usr/bin/env python2.7
# -*- coding: utf-8 -*-

from tornado import ioloop, httpclient, gen
from tornado.gen import Task
import pdb, time, logging
import tornado.ioloop
import tornado.iostream
import socket

#Init logging
def init_logging():
    logger = logging.getLogger()
    logger.setLevel(logging.DEBUG)

    sh = logging.StreamHandler()

    formatter = logging.Formatter('%(asctime)s -%(module)s:%(filename)s-L%(lineno)d-%(levelname)s: %(message)s')
    sh.setFormatter(formatter)

    logger.addHandler(sh)
    logging.info("Current log level is : %s", logging.getLevelName(logger.getEffectiveLevel()))


class TCPClient(object):
    def __init__(self, host, port, io_loop=None):
        self.host = host
        self.port = port
        self.io_loop = io_loop

        self.shutdown = False
        self.stream = None
        self.sock_fd = None

        self.EOF = b' END'


    def get_stream(self):
        self.sock_fd = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)
        self.stream = tornado.iostream.IOStream(self.sock_fd)
        self.stream.set_close_callback(self.on_close)

    def connect(self):
        self.get_stream()
        self.stream.connect((self.host, self.port), self.send_message)

    def on_receive(self, data):
        logging.info("Received: %s", data)
        self.stream.close()

    def on_close(self):
        if self.shutdown:
            self.io_loop.stop()

    def send_message(self):
        logging.info("Send message....")
        self.stream.write(b"Hello Server!" + self.EOF)
        self.stream.read_until(self.EOF, self.on_receive)
        logging.info("After send....")

    def set_shutdown(self):
        self.shutdown = True

def main():
    init_logging()

    io_loop = tornado.ioloop.IOLoop.instance()
    c1 = TCPClient("127.0.0.1", 8001, io_loop)
    c2 = TCPClient("127.0.0.1", 8001, io_loop)

    c1.connect()
    c2.connect()

    c2.set_shutdown()

    logging.info("**********************start ioloop******************")
    io_loop.start()

if __name__ == "__main__":
    try:
        main()
    except Exception, ex:
        print "Ocurred Exception: %s" % str(ex)
        quit()

分别运行tcp_server.py和tcp_client.py，通过测试结果，可以非常明显的了解到tornado的“异步”，以及强大的性能。

测试结果如下：

tcp_server:

 tcp_client: