l8-d15 IO多路复用select函数

一、IO多路复用select函数

1.select函数

int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout);

        nfds:         是三个集合中编号最高的文件描述符，加上 1

        readfds/writefds/exceptfds:         可读集合/可写集合/异常集合

        timeout:        NULL: 永久阻塞

                                0：  非阻塞模式

                        

                        struct timeval {

                            long    tv_sec;         /* 秒 */

                            long    tv_usec;        /* 微秒 */

                        };

fd_set结构体

二、多路复用select实现

服务端

头文件

#ifndef _NET_H_
#define _NET_H_
 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
 
typedef struct sockaddr Addr;
typedef struct sockaddr_in Addr_in;
#define BACKLOG 5
#define ErrExit(msg) do { perror(msg); exit(EXIT_FAILURE); } while(0)
 
void Argment(int argc, char *argv[]);
int CreateSocket(char *argv[]);
int DataHandle(int fd);
 
 
#endif
 

select函数

#include "net.h"
#include 
#define MAX_SOCK_FD 1024
 
int main(int argc, char *argv[])
{
	int i, ret, fd, newfd;
	fd_set set, tmpset;
	Addr_in clientaddr;
	socklen_t clientlen = sizeof(Addr_in);
	/*检查参数，小于3个 直接退出进程*/
	Argment(argc, argv);
	/*创建已设置监听模式的套接字*/
	fd = CreateSocket(argv);
 
	FD_ZERO(&set);
	FD_ZERO(&tmpset);
	FD_SET(fd, &set);
	while(1){
		tmpset = set;
		if( (ret = select(MAX_SOCK_FD, &tmpset, NULL, NULL, NULL)) < 0)
			ErrExit("select");
		if(FD_ISSET(fd, &tmpset) ){
			/*接收客户端连接，并生成新的文件描述符*/
			if( (newfd = accept(fd, (Addr *)&clientaddr, &clientlen) ) < 0)
				perror("accept");
			printf("[%s:%d]已建立连接\n", 
					inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));
			FD_SET(newfd, &set);
		}else{ //处理客户端数据
			for(i = fd + 1; i < MAX_SOCK_FD; i++){
				if(FD_ISSET(i, &tmpset)){
					if( DataHandle(i) <= 0){
						if( getpeername(i, (Addr *)&clientaddr, &clientlen) )
							perror("getpeername");
						printf("[%s:%d]断开连接\n", 
								inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));
						FD_CLR(i, &set);
					}
				}
			}
		}
	}
	return 0;
}
 

封装函数 

#include "net.h"
 
void Argment(int argc, char *argv[]){
	if(argc < 3){
		fprintf(stderr, "%s\n", argv[0]);
		exit(0);
	}
}
int CreateSocket(char *argv[]){
	/*创建套接字*/
	int fd = socket(AF_INET, SOCK_STREAM, 0);
	if(fd < 0)
		ErrExit("socket");
	/*允许地址快速重用*/
	int flag = 1;
	if( setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &flag, sizeof(flag) ) )
		perror("setsockopt");
	/*设置通信结构体*/
	Addr_in addr;
	bzero(&addr, sizeof(addr) );
	addr.sin_family = AF_INET;
	addr.sin_port = htons( atoi(argv[2]) );
	/*绑定通信结构体*/
	if( bind(fd, (Addr *)&addr, sizeof(Addr_in) ) )
		ErrExit("bind");
	/*设置套接字为监听模式*/
	if( listen(fd, BACKLOG) )
		ErrExit("listen");
	return fd;
}
int DataHandle(int fd){
	char buf[BUFSIZ] = {};
	Addr_in peeraddr;
	socklen_t peerlen = sizeof(Addr_in);
	if( getpeername(fd, (Addr *)&peeraddr, &peerlen) )
		perror("getpeername");
	int ret = recv(fd, buf, BUFSIZ, 0);
	if(ret < 0)
		perror("recv");
	if(ret > 0){
		printf("[%s:%d]data: %s\n", 
				inet_ntoa(peeraddr.sin_addr), ntohs(peeraddr.sin_port), buf);
	}
	return ret;
}