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 
#include 
#include 
#include 

#include 
#include 
#include 
#include 
#include 

#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  maxi &＃63; 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);
    }
  }
}

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

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

#define max(a,b) (a > b) &＃63; 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);
    }
  }
}