IO多路复用之poll全面总结(必看篇)

struct pollfd {

int fd;     /* 文件描述符 */
short events;     /* 等待的事件 */
short revents;    /* 实际发生了的事件 */
} ; 

#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>

#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);
  }
  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),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 "read msg is: ");
      write(STDOUT_FILENO,buf,n);
      //向客户端发送buf
      write(connfds[i].fd,buf,n);
    }
  }
}

#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>

#define MAXLINE   1024
#define IPADDRESS  "127.0.0.1"
#define SERV_PORT  8787

#define max(a,b) (a > b) "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);
    }
  }
}