Use epoll in python to develop server programs

Python code: import socket, logging
Import select, errno

Logger = logging. getLogger ("network-server ")

Def InitLog ():
Logger. setLevel (logging. DEBUG)

Fh = logging. FileHandler ("network-server.log ")
Fh. setLevel (logging. DEBUG)
Ch = logging. StreamHandler ()
Ch. setLevel (logging. ERROR)

Formatter = logging. Formatter ("% (asctime) s-% (name) s-% (levelname) s-% (message) s ")
Ch. setFormatter (formatter)
Fh. setFormatter (formatter)

Logger. addHandler (fh)
Logger. addHandler (ch)


If _ name _ = "_ main __":
InitLog ()

Try:
Listen_fd = socket. socket (socket. AF_INET, socket. SOCK_STREAM, 0)
Failed t socket. error, msg:
Logger. error ("create a socket failed ")

Try:
Listen_fd.setsockopt (socket. SOL_SOCKET, socket. SO_REUSEADDR, 1)
Failed t socket. error, msg:
Logger. error ("setsocketopt error ")

Try:
Listen_fd.bind ('', 2003 ))
Failed t socket. error, msg:
Logger. error ("listen file id bind ip error ")

Try:
Listen_fd.listen (10)
Failed t socket. error, msg:
Logger. error (msg)

Try:
Epoll_fd = select. epoll ()
Epoll_fd.register (listen_fd.fileno (), select. EPOLLIN)
Before t select. error, msg:
Logger. error (msg)

Connections = {}
Addresses = {}
Datalist = {}
While True:
Epoll_list = epoll_fd.poll ()
For fd, events in epoll_list:
If fd = listen_fd.fileno ():
Conn, addr = listen_fd.accept ()
Logger. debug ("accept connection from % s, % d, fd = % d" % (addr [0], addr [1], conn. fileno ()))
Conn. setblocking (0)
Epoll_fd.register (conn. fileno (), select. EPOLLIN | select. EPOLLET)
Connections [conn. fileno ()] = conn
Addresses [conn. fileno ()] = addr
Elif select. EPOLLIN & events:
Datas =''
While True:
Try:
Data = connections [fd]. recv (10)
If not data and not datas:
Epoll_fd.unregister (fd)
Connections [fd]. close ()
Logger. debug ("% s, % d closed" % (addresses [fd] [0], addresses [fd] [1])
Break
Else:
Datas + = data
Failed t socket. error, msg:
If msg. errno = errno. EAGAIN:
Logger. debug ("% s receive % s" % (fd, datas ))
Datalist [fd] = datas
Epoll_fd.modify (fd, select. EPOLLET | select. EPOLLOUT)
Break
Else:
Epoll_fd.unregister (fd)
Connections [fd]. close ()
Logger. error (msg)
Break
Elif select. EPOLLHUP & events:
Epoll_fd.unregister (fd)
Connections [fd]. close ()
Logger. debug ("% s, % d closed" % (addresses [fd] [0], addresses [fd] [1])
Elif select. EPOLLOUT & events:
SendLen = 0
While True:
SendLen + = connections [fd]. send (datalist [fd] [sendLen:])
If sendLen = len (datalist [fd]):
Break
Epoll_fd.modify (fd, select. EPOLLIN | select. EPOLLET)
Else:
Continue

Client Program, Python code:

Import socket
Import time
Import logging

Logger = logging. getLogger ("network-client ")
Logger. setLevel (logging. DEBUG)

Fh = logging. FileHandler ("network-client.log ")
Fh. setLevel (logging. DEBUG)
Ch = logging. StreamHandler ()
Ch. setLevel (logging. ERROR)

Formatter = logging. Formatter ("% (asctime) s-% (name) s-% (levelname) s-% (message) s ")
Ch. setFormatter (formatter)
Fh. setFormatter (formatter)

Logger. addHandler (fh)
Logger. addHandler (ch)

If _ name _ = "_ main __":
Try:
ConnFd = socket. socket (socket. AF_INET, socket. SOCK_STREAM, 0)
Failed t socket. error, msg:
Logger. error (msg)

Try:
ConnFd. connect ("192.168.31.226", 2003 ))
Logger. debug ("connect to network server success ")
Failed t socket. error, msg:
Logger. error (msg)

For I in range (1, 11 ):
Data = "The Number is % d" % I
If connFd. send (data )! = Len (data ):
Logger. error ("send data to network server failed ")
Break
ReadData = connFd. recv (1024)
Print readData
Time. sleep (1)

ConnFd. close ()

This is a very simple C/S model program. In fact, the process is not much different from the C language, just to learn the basic syntax in python and the use of the logging, select, and socket modules. The client sends a string, and the server returns the string to the client, which is triggered by the edge used in epoll.

This is an authoritative article about this.
Http://scotdoyle.com/python-epoll-howto.html