I/O复用HTTP服务器

在这里总结几个实用的、起启发作用的网络编程实例。这些实例可能并不局限特定编程语言且不按难度排序。该文章会持续更新。目前包括的实例：

• 快速文件服务
• 使用epoll实现的I/O复用简易HTTP服务器

快速创建文件服务

快速创建一个文件服务，方便设备间共享文件。

• Golang版本

package main

import (
    "net/http"
)

func main() {
    h := http.FileServer(http.Dir("~"))
    http.ListenAndServe(":8080", h)
}

• Python版本

直接在命令行上写入

$python3 -m http.server 8080

对于Python2

python -m SocketServer 8080

如果非要写代码实现也不难。

import sys
from http.server import HTTPServer, BaseHTTPRequestHandler
from socketserver import ThreadingTCPServer

class ThreadingHTTPServer(ThreadingTCPServer, HTTPServer):
    pass

if __name__ == '__main__':
    httpd = ThreadingHTTPServer(('', 8080), BaseHTTPRequestHandler)
    try:
        httpd.serve_forever()
    except KeyboardInterrupt:
        print("\nKeyboard interrupt received, exiting.")
        sys.exit(0)

如果你喜欢，可以把代码中的ThreadingTCPServer改为ThreadingMixIn。根据socketserver源码不难理解，这也更符合编程规范。

使用epoll实现的I/O复用简易HTTP服务器

由于Windows并没有epoll，所以该代码只能在Linux OS下运行。该代码示例用于理解I/O多路复用编程。关于epoll参考Linux I/O模型

import time
import socket
import select


default = True

if default:
    EOL1 = b'\n\n'
    EOL2 = b'\n\r\n'
    response  = b'HTTP/1.0 200 OK\r\nDate: Mon, 1 Jan 2017 01:01:01 GMT\r\n'
    response += b'Content-Type: text/plain\r\nContent-Length: 13\r\n\r\n'
    response += b'Hello, world!'

server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1) #TCP_NODELAY
server.bind(('', 8080))
server.listen(1)
server.setblocking(0)

epoll = select.epoll()
epoll.register(server.fileno(), select.EPOLLIN) #select.EPOLLIN | select.EPOLLET

try:
    connections = {} #{fd: sock}
    requests = {} #{fd: requests}
    responses = {} #{fd: resposne}

while True:
        events = epoll.poll(timeout=10) #[(fd, event), ...]
        for fileno, event in events:
            if fileno == server.fileno():
                connection, address = server.accept()
                connection.setblocking(0)

epoll.register(connection.fileno(), select.EPOLLIN)
                connections[connection.fileno()] = connection
                requests[connection.fileno()] = b''
                responses[connection.fileno()] = response

elif event & select.POLLIN:
                requests[fileno] += connections[fileno].recv(1024)
                if EOL1 in requests[fileno] or EOL2 in requests[fileno]:
                    epoll.modify(fileno, select.EPOLLOUT) #修改监听文件描述符的方式，修改文件描述符的事件
                    print('-'*40, requests[fileno].decode()[:-2], sep='\n')

elif event & select.EPOLLOUT:
                byteswritten = connections[fileno].send(responses[fileno])
                responses[fileno] = responses[fileno][byteswritten:]

if len(responses[fileno]) == 0:
                    epoll.modify(fileno, 0) #
                    connections[fileno].shutdown(socket.SHUT_RDWR)

elif event & select.EPOLLHUP:
            #Hang up happened on the assoc. fd
                epoll.unregister(fileno)
                connections[fileno].close()
                del connections[fileno]

finally:
    epoll.unregister(server.fileno())
    epoll.close()
    server.close()

select模块中poll的用法类似，但底层原理是不一样的。

转载请包括本文地址：https://allenwind.github.io/blog/2622
更多文章请参考：https://allenwind.github.io/blog/archives/