网络编程基础【day09】：socketserver进阶（十）

本节内容

1、概述

2、多用户并发

3、socketserver.BaseServer

一、概述

　　之前上一篇写的 day8-socketserver使用 讲解了socketsever如何使用，但是在最后 简单代码实现 里面并没有实现多并发的效果，这个就郁闷了，其实不然，其实我们需要用多线程或者多线程的模块来实现

 　　友情提示：客户端代码就不用写了，这边主要写服务端的代码。

二、多用户并发

2.1、多线程

说明：主要在实例化TCPServer时，采用ThreadingTCPServer这种多线程方式

import  socketserver

class  MyTCPHandler(socketserver.BaseRequestHandler):
    """
    The request handler class for our server.

    It is instantiated once per connection to the server, and must
    override the handle() method to implement communication to the
    client.
    """
    def  handle( self ):
        # self.request is the TCP socket connected to the client
            while  True :
                try :
                    self .data  =  self .request.recv( 1024 )
                    print ( "{0} write:" . format ( self .client_address[ 0 ]))
                    print ( self .data)
                    self .request.send( self .data.upper())
                except  ConnectionResetError as e:
                    print ( "error:" ,e)
                    break

if  __name__  = =  "__main__" :
    HOST,PORT  =  "localhost" , 9999
    server  =  socketserver.ThreadingTCPServer((HOST,PORT),MyTCPHandler)   #采用ThreadingTCPServer多线程方式实例化
    server.serve_forever()
    server.server_close()

注：ThreadingTCPServer表示服务器每收到客户端一个请求，服务器就会开启一个线程，开启一个线程跟这个链接交互，这个新的线程就是独立的线程，如果你有10个线程，代表可以干10件事。

2.2、多进程

说明：主要在实例化TCPServer时，采用ForkingTCPServer这种多线程方式，但是这种方式在windows上不好使，需要在Linux上去执行，因为windows和linux处理多进程方式不一样。

import  socketserver

class  MyTCPHandler(socketserver.BaseRequestHandler):
    """
    The request handler class for our server.

    It is instantiated once per connection to the server, and must
    override the handle() method to implement communication to the
    client.
    """
    def  handle( self ):
        # self.request is the TCP socket connected to the client
            while  True :
                try :
                    self .data  =  self .request.recv( 1024 )
                    print ( "{0} write:" . format ( self .client_address[ 0 ]))
                    print ( self .data)
                    self .request.send( self .data.upper())
                except  ConnectionResetError as e:
                    print ( "error:" ,e)
                    break

if  __name__  = =  "__main__" :
    HOST,PORT  =  "localhost" , 9999
    server  =  socketserver.ForkingTCPServer((HOST,PORT),MyTCPHandler)  #采用ForkingTCPServer实现多进程
    server.serve_forever()
    server.server_close()

小结：让你的socketserver并发起来， 必须选择使用以下一个多并发的类

class socketserver.ForkingTCPServer

class socketserver.ForkingUDPServer

class socketserver.ThreadingTCPServer

class socketserver.ThreadingUDPServer

so 只需要把下面这句：

server  =  socketserver.TCPServer((HOST, PORT), MyTCPHandler)

 换成下面这个，就可以多并发了，这样，客户端每连进一个来，服务器端就会分配一个新的线程来处理这个客户端的请求

server  =  socketserver.ThreadingTCPServer((HOST, PORT), MyTCPHandler)

三、socketserver.BaseServer

class socketserver.BaseServer(server_address, RequestHandlerClass) 主要有以下方法：

class socketserver.BaseServer(server_address, RequestHandlerClass)
This is the superclass of all Server objects in the module. It defines the interface, given below, but does not implement most of the methods, which is done in subclasses. The two parameters are stored in the respective server_address and RequestHandlerClass attributes.

fileno()
Return an integer file descriptor for the socket on which the server is listening. This function is most commonly passed to selectors, to allow monitoring multiple servers in the same process.

handle_request()
Process a single request. This function calls the following methods in order: get_request(), verify_request(), and process_request(). If the user-provided handle() method of the handler class raises an exception, the server’s handle_error() method will be called. If no request is received within timeout seconds, handle_timeout() will be called and handle_request() will return.

serve_forever(poll_interval=0.5)
Handle requests until an explicit shutdown() request. Poll for shutdown every poll_interval seconds. Ignores the timeout attribute. It also calls service_actions(), which may be used by a subclass or mixin to provide actions specific to a given service. For example, the ForkingMixIn class uses service_actions() to clean up zombie child processes.

Changed in version 3.3: Added service_actions call to the serve_forever method.

service_actions()
This is called in the serve_forever() loop. This method can be overridden by subclasses or mixin classes to perform actions specific to a given service, such as cleanup actions.

New in version 3.3.

shutdown()
Tell the serve_forever() loop to stop and wait until it does.

server_close()
Clean up the server. May be overridden.

address_family
The family of protocols to which the server’s socket belongs. Common examples are socket.AF_INET and socket.AF_UNIX.

RequestHandlerClass
The user-provided request handler class; an instance of this class is created for each request.

server_address
The address on which the server is listening. The format of addresses varies depending on the protocol family; see the documentation for the socket module for details. For Internet protocols, this is a tuple containing a string giving the address, and an integer port number: ('127.0.0.1', 80), for example.

socket
The socket object on which the server will listen for incoming requests.

The server classes support the following class variables:

allow_reuse_address
Whether the server will allow the reuse of an address. This defaults to False, and can be set in subclasses to change the policy.

request_queue_size
The size of the request queue. If it takes a long time to process a single request, any requests that arrive while the server is busy are placed into a queue, up to request_queue_size requests. Once the queue is full, further requests from clients will get a “Connection denied” error. The default value is usually 5, but this can be overridden by subclasses.

socket_type
The type of socket used by the server; socket.SOCK_STREAM and socket.SOCK_DGRAM are two common values.

timeout
Timeout duration, measured in seconds, or None if no timeout is desired. If handle_request() receives no incoming requests within the timeout period, the handle_timeout() method is called.

There are various server methods that can be overridden by subclasses of base server classes like TCPServer; these methods aren’t useful to external users of the server object.

finish_request()
Actually processes the request by instantiating RequestHandlerClass and calling its handle() method.

get_request()
Must accept a request from the socket, and return a 2-tuple containing the new socket object to be used to communicate with the client, and the client’s address.

handle_error(request, client_address)
This function is called if the handle() method of a RequestHandlerClass instance raises an exception. The default action is to print the traceback to standard output and continue handling further requests.

handle_timeout()
This function is called when the timeout attribute has been set to a value other than None and the timeout period has passed with no requests being received. The default action for forking servers is to collect the status of any child processes that have exited, while in threading servers this method does nothing.

process_request(request, client_address)
Calls finish_request() to create an instance of the RequestHandlerClass. If desired, this function can create a new process or thread to handle the request; the ForkingMixIn and ThreadingMixIn classes do this.

server_activate()
Called by the server’s constructor to activate the server. The default behavior for a TCP server just invokes listen() on the server’s socket. May be overridden.

server_bind()
Called by the server’s constructor to bind the socket to the desired address. May be overridden.

verify_request(request, client_address)
Must return a Boolean value; if the value is True, the request will be processed, and if it’s False, the request will be denied. This function can be overridden to implement access controls for a server. The default implementation always returns True.