how to use linux epoll with python

#!/usr/bin/python
# -*- coding:utf-8 -*-

import socket, select

EOL1 = b'\n\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!'

serversocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
serversocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
serversocket.bind(('0.0.0.0', 8080))
serversocket.listen(1)
serversocket.setblocking(0)

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

try:
  connections = {}; requests = {}; responses = {}

  while True:
     events = epoll.poll(1)

     for fileno, event in events:
        if fileno == serversocket.fileno():
           connection, address = serversocket.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.EPOLLIN:
           requests[fileno] += connections[fileno].recv(1024)

           if EOL1 in requests[fileno] or EOL2 in requests[fileno]:
              epoll.modify(fileno, select.EPOLLOUT)
              print('-'*40 + '\n' + requests[fileno].decode()[:-2])

        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:
           epoll.unregister(fileno)
           connections[fileno].close()
           del connections[fileno]

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

轉載自：http://scotdoyle.com/python-epoll-howto.html.  python epoll編程基本上都是從這篇文章開始。

 

epoll流程：

創建socket

  -->綁定socket並監聽

      -->創建epoll對象

          -->註冊socket到epoll對象，使用epoll的註冊函數對socket進行管理

              -->服務器進入循環

                -->epoll對象輪詢註冊的socket隊列（即：已經就緒的socket隊列）

                  -->判斷socket是否是新加入的

                     ->新加入socket：創建socket對象，並調用accept()，然後把socket註冊到epoll

                     ->非新socket，且socket狀態爲可讀，調用recv()。如果接收到的消息包含中斷或exit等字符，修改socket狀態

                     ->非新socket，且狀態爲可寫，調用send函數。

                     ->非新socket，且狀態爲HUP，從註冊函數中刪除socket，並調用close()