|
Andy Niu Help
1.0.0.0
|
变量 | |
| IO多路复用__总结 | |
| IO多路复用__select | |
| IO多路复用__poll | |
| IO多路复用__epoll | |
详细描述
变量说明
| IO多路复用__epoll |
1、server.cpp
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/epoll.h>
#include <unistd.h>
#include <sys/types.h>
#define IPADDRESS "127.0.0.1"
#define PORT 8787
#define MAXSIZE 1024
#define LISTENQ 5
#define FDSIZE 1000
#define EPOLLEVENTS 100
//函数声明
//创建套接字并进行绑定
static int socket_bind(const char* ip,int port);
//IO多路复用epoll
static void do_epoll(int listenfd);
//事件处理函数
static void
handle_events(int epollfd,struct epoll_event *events,int num,int listenfd,char *buf);
//处理接收到的连接
static void handle_accpet(int epollfd,int listenfd);
//读处理
static void do_read(int epollfd,int fd,char *buf);
//写处理
static void do_write(int epollfd,int fd,char *buf);
//添加事件
static void add_event(int epollfd,int fd,int state);
//修改事件
static void modify_event(int epollfd,int fd,int state);
//删除事件
static void delete_event(int epollfd,int fd,int state);
int main(int argc,char *argv[])
{
int listenfd;
listenfd = socket_bind(IPADDRESS,PORT);
listen(listenfd,LISTENQ);
do_epoll(listenfd);
return 0;
}
static int socket_bind(const char* ip,int port)
{
int listenfd;
struct sockaddr_in servaddr;
listenfd = socket(AF_INET,SOCK_STREAM,0);
if (listenfd == -1)
{
perror("socket error:");
exit(1);
}
bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
inet_pton(AF_INET,ip,&servaddr.sin_addr);
servaddr.sin_port = htons(port);
if (bind(listenfd,(struct sockaddr*)&servaddr,sizeof(servaddr)) == -1)
{
perror("bind error: ");
exit(1);
}
return listenfd;
}
static void do_epoll(int listenfd)
{
int epollfd;
struct epoll_event events[EPOLLEVENTS];
int ret;
char buf[MAXSIZE];
memset(buf,0,MAXSIZE);
//创建一个描述符
epollfd = epoll_create(FDSIZE);
//添加监听描述符事件
add_event(epollfd,listenfd,EPOLLIN);
for ( ; ; )
{
//获取已经准备好的描述符事件
ret = epoll_wait(epollfd,events,EPOLLEVENTS,-1);
handle_events(epollfd,events,ret,listenfd,buf);
}
close(epollfd);
}
static void
handle_events(int epollfd,struct epoll_event *events,int num,int listenfd,char *buf)
{
int i;
int fd;
//进行选好遍历
for (i = 0;i < num;i++)
{
fd = events[i].data.fd;
//根据描述符的类型和事件类型进行处理
if ((fd == listenfd) &&(events[i].events & EPOLLIN))
handle_accpet(epollfd,listenfd);
else if (events[i].events & EPOLLIN)
do_read(epollfd,fd,buf);
else if (events[i].events & EPOLLOUT)
do_write(epollfd,fd,buf);
}
}
static void handle_accpet(int epollfd,int listenfd)
{
int clifd;
struct sockaddr_in cliaddr;
socklen_t cliaddrlen;
clifd = accept(listenfd,(struct sockaddr*)&cliaddr,&cliaddrlen);
if (clifd == -1)
perror("accpet error:");
else
{
// 注意：cliaddr.sin_port的字节逆序，需要转换一下ntohs(cliaddr.sin_port)
printf("accept a new client: %s:%d\n",
inet_ntoa(cliaddr.sin_addr),
ntohs(cliaddr.sin_port));
//添加一个客户描述符和事件
add_event(epollfd,clifd,EPOLLIN);
}
}
static void do_read(int epollfd,int fd,char *buf)
{
int nread;
nread = read(fd,buf,MAXSIZE);
if (nread == -1)
{
perror("read error:");
close(fd);
delete_event(epollfd,fd,EPOLLIN);
}
else if (nread == 0)
{
fprintf(stderr,"client close.\n");
close(fd);
delete_event(epollfd,fd,EPOLLIN);
}
else
{
printf("read message is : %s",buf);
//修改描述符对应的事件，由读改为写
modify_event(epollfd,fd,EPOLLOUT);
}
}
static void do_write(int epollfd,int fd,char *buf)
{
int nwrite;
nwrite = write(fd,buf,strlen(buf));
if (nwrite == -1)
{
perror("write error:");
close(fd);
delete_event(epollfd,fd,EPOLLOUT);
}
else
modify_event(epollfd,fd,EPOLLIN);
memset(buf,0,MAXSIZE);
}
static void add_event(int epollfd,int fd,int state)
{
struct epoll_event ev;
ev.events = state;
ev.data.fd = fd;
epoll_ctl(epollfd,EPOLL_CTL_ADD,fd,&ev);
}
static void delete_event(int epollfd,int fd,int state)
{
struct epoll_event ev;
ev.events = state;
ev.data.fd = fd;
epoll_ctl(epollfd,EPOLL_CTL_DEL,fd,&ev);
}
static void modify_event(int epollfd,int fd,int state)
{
struct epoll_event ev;
ev.events = state;
ev.data.fd = fd;
epoll_ctl(epollfd,EPOLL_CTL_MOD,fd,&ev);
}
2、client.cpp
#include <netinet/in.h>
#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/epoll.h>
#include <time.h>
#include <unistd.h>
#include <sys/types.h>
#include <arpa/inet.h>
#define MAXSIZE 1024
#define IPADDRESS "127.0.0.1"
#define SERV_PORT 8787
#define FDSIZE 1024
#define EPOLLEVENTS 20
static void handle_connection(int sockfd);
static void
handle_events(int epollfd,struct epoll_event *events,int num,int sockfd,char *buf);
static void do_read(int epollfd,int fd,int sockfd,char *buf);
static void do_read(int epollfd,int fd,int sockfd,char *buf);
static void do_write(int epollfd,int fd,int sockfd,char *buf);
static void add_event(int epollfd,int fd,int state);
static void delete_event(int epollfd,int fd,int state);
static void modify_event(int epollfd,int fd,int state);
int main(int argc,char *argv[])
{
int sockfd;
struct sockaddr_in servaddr;
sockfd = socket(AF_INET,SOCK_STREAM,0);
bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(SERV_PORT);
inet_pton(AF_INET,IPADDRESS,&servaddr.sin_addr);
connect(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr));
//处理连接
handle_connection(sockfd);
close(sockfd);
return 0;
}
static void handle_connection(int sockfd)
{
int epollfd;
struct epoll_event events[EPOLLEVENTS];
char buf[MAXSIZE];
int ret;
epollfd = epoll_create(FDSIZE);
add_event(epollfd,STDIN_FILENO,EPOLLIN);
for ( ; ; )
{
ret = epoll_wait(epollfd,events,EPOLLEVENTS,-1);
handle_events(epollfd,events,ret,sockfd,buf);
}
close(epollfd);
}
static void
handle_events(int epollfd,struct epoll_event *events,int num,int sockfd,char *buf)
{
int fd;
int i;
for (i = 0;i < num;i++)
{
fd = events[i].data.fd;
if (events[i].events & EPOLLIN)
do_read(epollfd,fd,sockfd,buf);
else if (events[i].events & EPOLLOUT)
do_write(epollfd,fd,sockfd,buf);
}
}
static void do_read(int epollfd,int fd,int sockfd,char *buf)
{
int nread;
nread = read(fd,buf,MAXSIZE);
if (nread == -1)
{
perror("read error:");
close(fd);
}
else if (nread == 0)
{
fprintf(stderr,"server close.\n");
close(fd);
}
else
{
if (fd == STDIN_FILENO)
add_event(epollfd,sockfd,EPOLLOUT);
else
{
delete_event(epollfd,sockfd,EPOLLIN);
add_event(epollfd,STDOUT_FILENO,EPOLLOUT);
}
}
}
static void do_write(int epollfd,int fd,int sockfd,char *buf)
{
int nwrite;
nwrite = write(fd,buf,strlen(buf));
if (nwrite == -1)
{
perror("write error:");
close(fd);
}
else
{
if (fd == STDOUT_FILENO)
delete_event(epollfd,fd,EPOLLOUT);
else
modify_event(epollfd,fd,EPOLLIN);
}
memset(buf,0,MAXSIZE);
}
static void add_event(int epollfd,int fd,int state)
{
struct epoll_event ev;
ev.events = state;
ev.data.fd = fd;
epoll_ctl(epollfd,EPOLL_CTL_ADD,fd,&ev);
}
static void delete_event(int epollfd,int fd,int state)
{
struct epoll_event ev;
ev.events = state;
ev.data.fd = fd;
epoll_ctl(epollfd,EPOLL_CTL_DEL,fd,&ev);
}
static void modify_event(int epollfd,int fd,int state)
{
struct epoll_event ev;
ev.events = state;
ev.data.fd = fd;
epoll_ctl(epollfd,EPOLL_CTL_MOD,fd,&ev);
}
3、运行服务端
[root@localhost Epoll]# g++ -o server server.cpp
server.cpp:190:2: warning: no newline at end of file
[root@localhost Epoll]# ./server
accept a new client: 127.0.0.1:51619
read message is : 123
4、运行客户端
[root@localhost Epoll]# g++ -o client client.cpp
client.cpp:143:2: warning: no newline at end of file
[root@localhost Epoll]# ./client
123
123
| IO多路复用__poll |
1、server.cpp
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <poll.h>
#include <unistd.h>
#include <sys/types.h>
#include <arpa/inet.h>
#define IPADDRESS "127.0.0.1"
#define PORT 8787
#define MAXLINE 1024
#define LISTENQ 5
#define OPEN_MAX 1000
#define INFTIM -1
//函数声明
//创建套接字并进行绑定
static int socket_bind(const char* ip,int port);
//IO多路复用poll
static void do_poll(int listenfd);
//处理多个连接
static void handle_connection(struct pollfd *connfds,int num);
int main(int argc,char *argv[])
{
int listenfd,connfd,sockfd;
struct sockaddr_in cliaddr;
socklen_t cliaddrlen;
listenfd = socket_bind(IPADDRESS,PORT);
listen(listenfd,LISTENQ);
do_poll(listenfd);
return 0;
}
static int socket_bind(const char* ip,int port)
{
int listenfd;
struct sockaddr_in servaddr;
listenfd = socket(AF_INET,SOCK_STREAM,0);
if (listenfd == -1)
{
perror("socket error:");
exit(1);
}
int reuse = 1;
if (setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) == -1) {
return -1;
}
bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
inet_pton(AF_INET,ip,&servaddr.sin_addr);
servaddr.sin_port = htons(port);
if (bind(listenfd,(struct sockaddr*)&servaddr,sizeof(servaddr)) == -1)
{
perror("bind error: ");
exit(1);
}
return listenfd;
}
static void do_poll(int listenfd)
{
int connfd,sockfd;
struct sockaddr_in cliaddr;
socklen_t cliaddrlen;
struct pollfd clientfds[OPEN_MAX];
int maxi;
int i;
int nready;
//添加监听描述符
clientfds[0].fd = listenfd;
clientfds[0].events = POLLIN;
//初始化客户连接描述符
for (i = 1;i < OPEN_MAX;i++)
clientfds[i].fd = -1;
maxi = 0;
//循环处理
for ( ; ; )
{
//获取可用描述符的个数
nready = poll(clientfds,maxi+1,INFTIM);
if (nready == -1)
{
perror("poll error:");
exit(1);
}
//测试监听描述符是否准备好
if (clientfds[0].revents & POLLIN)
{
cliaddrlen = sizeof(cliaddr);
//接受新的连接
if ((connfd = accept(listenfd,(struct sockaddr*)&cliaddr,&cliaddrlen)) == -1)
{
if (errno == EINTR)
continue;
else
{
perror("accept error:");
exit(1);
}
}
fprintf(stdout,"accept a new client: %s:%d\n",
inet_ntoa(cliaddr.sin_addr),
ntohs(cliaddr.sin_port));
//将新的连接描述符添加到数组中
for (i = 1;i < OPEN_MAX;i++)
{
if (clientfds[i].fd < 0)
{
clientfds[i].fd = connfd;
break;
}
}
if (i == OPEN_MAX)
{
fprintf(stderr,"too many clients.\n");
exit(1);
}
//将新的描述符添加到读描述符集合中
clientfds[i].events = POLLIN;
//记录客户连接套接字的个数
maxi = (i > maxi ? i : maxi);
if (--nready <= 0)
continue;
}
//处理客户连接
handle_connection(clientfds,maxi);
}
}
static void handle_connection(struct pollfd *connfds,int num)
{
int i,n;
char buf[MAXLINE];
memset(buf,0,MAXLINE);
for (i = 1;i <= num;i++)
{
if (connfds[i].fd < 0)
continue;
//测试客户描述符是否准备好
if (connfds[i].revents & POLLIN)
{
//接收客户端发送的信息
n = read(connfds[i].fd,buf,MAXLINE);
if (n == 0)
{
close(connfds[i].fd);
connfds[i].fd = -1;
continue;
}
// printf("read msg is: ");
write(STDOUT_FILENO,buf,n);
//向客户端发送buf
write(connfds[i].fd,buf,n);
}
}
}
2、client.cpp
#include <netinet/in.h>
#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <poll.h>
#include <time.h>
#include <unistd.h>
#include <sys/types.h>
#include <arpa/inet.h>
#define MAXLINE 1024
#define IPADDRESS "127.0.0.1"
#define SERV_PORT 8787
#define max(a,b) (a > b) ? a : b
static void handle_connection(int sockfd);
int main(int argc,char *argv[])
{
int sockfd;
struct sockaddr_in servaddr;
sockfd = socket(AF_INET,SOCK_STREAM,0);
bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(SERV_PORT);
inet_pton(AF_INET,IPADDRESS,&servaddr.sin_addr);
connect(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr));
//处理连接描述符
handle_connection(sockfd);
return 0;
}
static void handle_connection(int sockfd)
{
char sendline[MAXLINE],recvline[MAXLINE];
int maxfdp,stdineof;
struct pollfd pfds[2];
int n;
//添加连接描述符
pfds[0].fd = sockfd;
pfds[0].events = POLLIN;
//添加标准输入描述符
pfds[1].fd = STDIN_FILENO;
pfds[1].events = POLLIN;
for (; ;)
{
poll(pfds,2,-1);
if (pfds[0].revents & POLLIN)
{
n = read(sockfd,recvline,MAXLINE);
if (n == 0)
{
fprintf(stderr,"client: server is closed.\n");
close(sockfd);
}
write(STDOUT_FILENO,recvline,n);
}
//测试标准输入是否准备好
if (pfds[1].revents & POLLIN)
{
n = read(STDIN_FILENO,sendline,MAXLINE);
if (n == 0)
{
shutdown(sockfd,SHUT_WR);
continue;
}
write(sockfd,sendline,n);
}
}
}
3、运行服务端
[root@localhost poll]# ./server
accept a new client: 127.0.0.1:54849
abc
4、运行客户端
[root@localhost poll]# ./client
abc
abc
| IO多路复用__select |
1、server.cpp
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <sys/types.h>
#include <unistd.h>
#include <assert.h>
#define IPADDR "127.0.0.1"
#define PORT 8787
#define MAXLINE 1024
#define LISTENQ 5
#define SIZE 10
typedef struct server_context_st
{
int cli_cnt; /*客户端个数*/
int clifds[SIZE]; /*客户端的个数*/
fd_set allfds; /*句柄集合*/
int maxfd; /*句柄最大值*/
} server_context_st;
static server_context_st *s_srv_ctx = NULL;
/*===========================================================================
* ==========================================================================*/
static int create_server_proc(const char* ip,int port)
{
int fd;
struct sockaddr_in servaddr;
fd = socket(AF_INET, SOCK_STREAM,0);
if (fd == -1) {
fprintf(stderr, "create socket fail,erron:%d,reason:%s\n",
errno, strerror(errno));
return -1;
}
/*一个端口释放后会等待两分钟之后才能再被使用，SO_REUSEADDR是让端口释放后立即就可以被再次使用。*/
int reuse = 1;
if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) == -1) {
return -1;
}
bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
// ip和port进行转化
inet_pton(AF_INET,ip,&servaddr.sin_addr);
servaddr.sin_port = htons(port);
if (bind(fd,(struct sockaddr*)&servaddr,sizeof(servaddr)) == -1) {
perror("bind error: ");
return -1;
}
listen(fd,LISTENQ);
return fd;
}
static int accept_client_proc(int srvfd)
{
struct sockaddr_in cliaddr;
socklen_t cliaddrlen;
cliaddrlen = sizeof(cliaddr);
int clifd = -1;
printf("accpet clint proc is called.\n");
ACCEPT:
clifd = accept(srvfd,(struct sockaddr*)&cliaddr,&cliaddrlen);
if (clifd == -1) {
if (errno == EINTR) {
goto ACCEPT;
} else {
fprintf(stderr, "accept fail,error:%s\n", strerror(errno));
return -1;
}
}
// ip和port进行转化
fprintf(stdout, "accept a new client: %s:%d\n",
inet_ntoa(cliaddr.sin_addr),ntohs(cliaddr.sin_port));
//将新的连接描述符添加到数组中
int i = 0;
for (i = 0; i < SIZE; i++) {
if (s_srv_ctx->clifds[i] < 0) {
s_srv_ctx->clifds[i] = clifd;
s_srv_ctx->cli_cnt++;
break;
}
}
if (i == SIZE) {
fprintf(stderr,"too many clients.\n");
return -1;
}
}
static int handle_client_msg(int fd, char *buf)
{
assert(buf);
printf("recv buf is :%s\n", buf);
write(fd, buf, strlen(buf) +1);
return 0;
}
static void recv_client_msg(fd_set *readfds)
{
int i = 0, n = 0;
int clifd;
char buf[MAXLINE] = {0};
for (i = 0;i <= s_srv_ctx->cli_cnt;i++) {
clifd = s_srv_ctx->clifds[i];
if (clifd < 0) {
continue;
}
/*判断客户端套接字是否有数据*/
if (FD_ISSET(clifd, readfds)) {
//接收客户端发送的信息
n = read(clifd, buf, MAXLINE);
if (n <= 0) {
/*n==0表示读取完成，客户都关闭套接字*/
FD_CLR(clifd, &s_srv_ctx->allfds);
close(clifd);
s_srv_ctx->clifds[i] = -1;
continue;
}
handle_client_msg(clifd, buf);
}
}
}
static void handle_client_proc(int srvfd)
{
int clifd = -1;
int retval = 0;
fd_set *readfds = &s_srv_ctx->allfds;
struct timeval tv;
int i = 0;
while (1) {
/*每次调用select前都要重新设置文件描述符和时间，因为事件发生后，文件描述符和时间都被内核修改啦*/
FD_ZERO(readfds);
/*添加监听套接字*/
FD_SET(srvfd, readfds);
s_srv_ctx->maxfd = srvfd;
tv.tv_sec = 30;
tv.tv_usec = 0;
/*添加客户端套接字*/
for (i = 0; i < s_srv_ctx->cli_cnt; i++) {
clifd = s_srv_ctx->clifds[i];
/*去除无效的客户端句柄*/
if (clifd != -1) {
FD_SET(clifd, readfds);
}
s_srv_ctx->maxfd = (clifd > s_srv_ctx->maxfd ? clifd : s_srv_ctx->maxfd);
}
/*开始轮询接收处理服务端和客户端套接字*/
retval = select(s_srv_ctx->maxfd + 1, readfds, NULL, NULL, &tv);
if (retval == -1) {
fprintf(stderr, "select error:%s.\n", strerror(errno));
return;
}
if (retval == 0) {
fprintf(stdout, "select is timeout.\n");
continue;
}
if (FD_ISSET(srvfd, readfds)) {
/*监听客户端请求*/
accept_client_proc(srvfd);
} else {
/*接受处理客户端消息*/
recv_client_msg(readfds);
}
}
}
static void server_uninit()
{
if (s_srv_ctx) {
free(s_srv_ctx);
s_srv_ctx = NULL;
}
}
static int server_init()
{
s_srv_ctx = (server_context_st *)malloc(sizeof(server_context_st));
if (s_srv_ctx == NULL) {
return -1;
}
memset(s_srv_ctx, 0, sizeof(server_context_st));
int i = 0;
for (;i < SIZE; i++) {
s_srv_ctx->clifds[i] = -1;
}
return 0;
}
int main(int argc,char *argv[])
{
int srvfd;
/*初始化服务端context*/
if (server_init() < 0) {
return -1;
}
/*创建服务,开始监听客户端请求*/
srvfd = create_server_proc(IPADDR, PORT);
if (srvfd < 0) {
fprintf(stderr, "socket create or bind fail.\n");
goto err;
}
/*开始接收并处理客户端请求*/
handle_client_proc(srvfd);
server_uninit();
return 0;
err:
server_uninit();
return -1;
}
2、client.cpp
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/select.h>
#include <time.h>
#include <unistd.h>
#include <sys/types.h>
#include <errno.h>
#define MAXLINE 1024
#define IPADDRESS "127.0.0.1"
#define SERV_PORT 8787
#define max(a,b) (a > b) ? a : b
static void handle_recv_msg(int sockfd, char *buf)
{
printf("client recv msg is:%s\n", buf);
sleep(5);
write(sockfd, buf, strlen(buf) +1);
}
static void handle_connection(int sockfd)
{
char sendline[MAXLINE],recvline[MAXLINE];
int maxfdp,stdineof;
fd_set readfds;
int n;
struct timeval tv;
int retval = 0;
while (1) {
FD_ZERO(&readfds);
FD_SET(sockfd,&readfds);
maxfdp = sockfd;
tv.tv_sec = 5;
tv.tv_usec = 0;
retval = select(maxfdp+1,&readfds,NULL,NULL,&tv);
if (retval == -1) {
return ;
}
if (retval == 0) {
printf("client timeout.\n");
continue;
}
if (FD_ISSET(sockfd, &readfds)) {
n = read(sockfd,recvline,MAXLINE);
if (n <= 0) {
fprintf(stderr,"client: server is closed.\n");
close(sockfd);
FD_CLR(sockfd,&readfds);
return;
}
handle_recv_msg(sockfd, recvline);
}
}
}
int main(int argc,char *argv[])
{
int sockfd;
struct sockaddr_in servaddr;
sockfd = socket(AF_INET,SOCK_STREAM,0);
bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(SERV_PORT);
inet_pton(AF_INET,IPADDRESS,&servaddr.sin_addr);
int retval = 0;
retval = connect(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr));
if (retval < 0) {
fprintf(stderr, "connect fail,error:%s\n", strerror(errno));
return -1;
}
sockaddr_in clientAddr;
sockaddr_in serverAddr;
socklen_t addrLen = sizeof(sockaddr_in);
// 获取本地ip和port
getsockname(sockfd, (struct sockaddr*)&clientAddr, &addrLen);
// 获取对端ip和port
getpeername(sockfd, (struct sockaddr*)&serverAddr, &addrLen);
printf("client[%s:%d] connect server[%s:%d]\n",
inet_ntoa(clientAddr.sin_addr),
ntohs(clientAddr.sin_port),
inet_ntoa(serverAddr.sin_addr),
ntohs(serverAddr.sin_port));
printf("client send to server.\n");
char data[64] ={0};
sprintf(data,"hello server[%s:%d],this is client[%s:%d]",
inet_ntoa(serverAddr.sin_addr),
ntohs(serverAddr.sin_port),
inet_ntoa(clientAddr.sin_addr),
ntohs(clientAddr.sin_port));
write(sockfd, data, 64);
handle_connection(sockfd);
return 0;
}
3、运行服务端
[root@localhost Select]# g++ -o server server.cpp
[root@localhost Select]# ./server
accpet clint proc is called.
accept a new client: 127.0.0.1:42108
recv buf is :hello server[127.0.0.1:8787],this is client[127.0.0.1:42108]
accpet clint proc is called.
accept a new client: 127.0.0.1:42109
recv buf is :hello server[127.0.0.1:8787],this is client[127.0.0.1:42109]
recv buf is :hello server[127.0.0.1:8787],this is client[127.0.0.1:42108]
recv buf is :hello server[127.0.0.1:8787],this is client[127.0.0.1:42109]
recv buf is :hello server[127.0.0.1:8787],this is client[127.0.0.1:42108]
4、运行客户端
[root@localhost Select]# g++ -o client client.cpp
client[127.0.0.1:42108] connect server[127.0.0.1:8787]
client send to server.
client recv msg is:hello server[127.0.0.1:8787],this is client[127.0.0.1:42108]
client recv msg is:hello server[127.0.0.1:8787],this is client[127.0.0.1:42108]
5、注意：if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) == -1) 这段代码的意义。
没有这段代码，先关闭服务端，这时候连接处于 TIME_WAIT状态，在开启server报错：
[root@localhost poll]# ./server
bind error: : Address already in use
加上上面的这段代码，就不会有这个问题。
| IO多路复用__总结 |
1、IO多路复用解决什么问题？
一个连接创建一个线程，用于这个连接的交互，但是线程的开销比较大，当连接很多的时候，就会出现严重的性能问题。
2、怎么解决这个问题？
可以使用一个线程管理多个连接，一个连接对应一个socket句柄，在linux系统中就是文件描述符，这就是多路复用。
3、select特点
a、监视的FD（文件描述符）个数有限，1024个
b、对于FD集合，需要从用户态拷贝到内核态，同时进行线性扫描，存在性能问题
4、poll特点
a、poll可以认为是加强版的select，可以监视的FD个数不限，因为他是基于链表的
b、整体拷贝和线性扫描的问题，还是同样存在
5、epoll特点
a、epoll解决了上述问题，可以监视的FD个数不限
b、从用户态到内核态只拷贝一次
c、select、poll不断主动轮询，把就绪的FD设置一下，在应用程序检查是否就绪。
epoll也就是主动轮询，但是只把就绪的FD放入就绪链表中，把这个链表回调给应用程序。
Copyright (c) 2015~2016, Andy Niu @All rights reserved. By Andy Niu Edit.