python 中select，poll, epoll 使用例子

select_demo.py

# coding: utf-8
import select
import socket
import queue


def select_demo():
    server = socket.socket()
    server.bind(('127.0.0.1', 9000))
    server.listen(5)
    server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    server.setblocking(False)  # 设置为非阻塞

    msg_dict = {}  # 定义一个队列字典
    inputs = [server]
    outputs = []

    while True:
        readable, writeable, exceptional = select.select(inputs, outputs, inputs)
        for r in readable:
            if r is server:
                # 如果这个socket是server, 说明有新的客户端连接
                conn, addr = r.accept()
                print(f'new connection: {addr}')
                # 为了不阻塞整个程序， 不会立即在这里开始接收客户端发送的数据
                inputs.append(conn)
                # 初始化一个队列， 后面要存储返回该客户端的数据
                msg_dict[conn] = queue.Queue()
            else:
                # 如果不是server， 就说明是之前建立的客户端来数据了
                data = r.recv(1024)
                print(f'receive data: {data.decode()}')
                # 收到的数据先放到queue中， 一会返回给客户端
                msg_dict[r].put(data)
                outputs.append(r)
        for w in writeable:
            data_to_client = msg_dict[w].get()
            print(f'send data: {data_to_client.decode()}')
            w.send(data_to_client)
            outputs.remove(w)
        for e in exceptional:
            if e in outputs:
                outputs.remove(e)
            inputs.remove(e)
            del msg_dict[e]

def poll_demo():
    response = b'hello world'

    server = socket.socket()
    server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    server.bind(('127.0.0.1', 9008))
    server.listen(5)
    server.setblocking(0)

    poll = select.poll()
    poll.register(server.fileno(), select.POLLIN)

    connections = {}
    try:
        while True:
            for fd, event in poll.poll():
                if event & select.POLLIN:
                    if fd == server.fileno():
                        conn, addr = server.accept()
                        poll.register(conn, select.POLLIN)
                        connections[conn.fileno()] = conn
                    else:
                        conn = connections[fd]
                        data = conn.recv(1024)
                        if data:
                            poll.modify(fd, select.POLLOUT)
                elif event & select.POLLOUT:
                    conn = connections[fd]
                    conn.send(response)
                    poll.unregister(fd)
                    conn.close()
    finally:
        server.close()

def epoll_demo:
    EOL1 = b'\r\n'
    EOL2 = b'\n\r\n'

    response = b'HTTP/1.0 200 OK\r\nDate: Mon, 1 Jan 1996 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()
    server.bind(('127.0.0.1', 9000))
    server.listen(5)
    server.setblocking(0)

    epoll = select.epoll()
    epoll.register(server.fileno(), select.EPOLLIN)

    try:
        connections = {}
        requests = {}
        responses = {}
        while True:
            events = epoll.poll(1)
            for fd, event in events:
                if fd == server.fileno():
                    conn, addr = server.accept()
                    conn.setblocking(0)
                    epoll.register(conn.fileno(), select.EPOLLIN)
                    connections[conn.fileno()] = conn
                    requests[conn.fileno()] = b''
                    responses[conn.fileno()] = response
                elif event & select.EPOLLIN:
                    requests[fd] += connections[fd].recv(1024)
                    if EOL1 in requests[fd] or EOL2 in requests[fd]:
                        epoll.modify(fd, select.EPOLLOUT)
                        print('-'*40 + '\n' + requests[fd].decode()[:-2])
                elif event & select.EPOLLOUT:
                    byteswritten = connections[fd].send(responses[fd])
                    responses[fd] = responses[fd][byteswritten:]
                    if len(responses[fd]) == 0:
                        epoll.modify(fd, 0)
                        connections[fd].shutdown(socket.SHUT_RDWR)
                elif event & select.EPOLLHUP:
                    epoll.unregister(fd)
                    connections[fd].close()
                    del connections[fd]
    finally:
        epoll.unregister(server.fileno())
        epoll.close()
        server.close()