linux epoll系列3 利用epoll_wait设置timeout时间长度

epoll_wait函数的第四个参数可以设置，epoll_wait函数的等待时间（timeout时间长度）。

例子1,接收端

#include <stdio.h> #include <string.h> #include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <sys/epoll.h> #include <arpa/inet.h>  #define events 12  int main(){   int sock1, sock2;   sockaddr_in addr1, addr2;   int epfd;   epoll_event ev, ev_ret[events];   char buf[2048];   int i;   int nfds;   int n;    //创建2个接受消息的socket   sock1 = socket(af_inet, sock_dgram, 0);   sock2 = socket(af_inet, sock_dgram, 0);   addr1.sin_family = af_inet;   addr2.sin_family = af_inet;    inet_pton(af_inet, "127.0.0.1", &addr1.sin_addr.s_addr);   inet_pton(af_inet, "127.0.0.1", &addr2.sin_addr.s_addr);    addr1.sin_port = htons(11111);   addr2.sin_port = htons(22222);    bind(sock1, (sockaddr*)&addr1, sizeof(addr1));   bind(sock2, (sockaddr*)&addr2, sizeof(addr2));    //参数不小于0就行   epfd = epoll_create(1);   if(epfd < 0){     perror("epoll_create");     return 1;   }    memset(&ev, 0, sizeof(ev));   ev.events = epollin;//只读   ev.data.fd = sock1;//把sock1加到epoll   if(epoll_ctl(epfd, epoll_ctl_add, sock1, &ev) != 0){     perror("epoll_ctl");     return 1;   }    memset(&ev, 0, sizeof(ev));   ev.events = epollin;//只读   ev.data.fd = sock2;//把sock2加到epoll   if(epoll_ctl(epfd, epoll_ctl_add, sock2, &ev) != 0){     perror("epoll_ctl");     return 1;   }    while(1){     printf("before epoll_waitn");     //在这里会阻塞，只等待10秒，超过10秒，epoll_wait函数结束，返回0给nfds.     nfds = epoll_wait(epfd, ev_ret, events, 10*1000);     if(nfds < 0){       perror("epoll_wait");       return 1;     }      printf("after epoll_waitn");     if(nfds == 0){       printf("timeoutn");       break;     }      for(i = 0; i < nfds; ++i){       //判断进来的socket是哪个socket       if(ev_ret[i].data.fd == sock1){     //从sock1读取数据，并写入到标准输出     n = recv(sock1, buf, sizeof(buf), 0);     write(fileno(stdout), buf, n);       }       //判断进来的socket是哪个socket       else if(ev_ret[i].data.fd == sock2){     //从sock1读取数据，并写入到标准输出     n = recv(sock2, buf, sizeof(buf), 0);     write(fileno(stdout), buf, n);       }     }   }    close(sock1);   close(sock2);   return 0; } 

例子2， 是发送端。

#include <stdio.h> #include <string.h> #include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <sys/epoll.h> #include <arpa/inet.h>  int main(){   int sock;   sockaddr_in dest1, dest2;   char buf[1024];    sock = socket(af_inet, sock_dgram, 0);    dest1.sin_family = af_inet;   dest2.sin_family = af_inet;    inet_pton(af_inet, "127.0.0.1", &dest1.sin_addr.s_addr);   inet_pton(af_inet, "127.0.0.1", &dest2.sin_addr.s_addr);    dest1.sin_port = htons(11111);   dest2.sin_port = htons(22222);    strcpy(buf, "data to port 11111n");   //给地址1(dest1)送信   sendto(sock, buf, strlen(buf), 0, (sockaddr*)&dest1, sizeof(dest1));      strcpy(buf, "data to port 22222n");   //给地址2(dest2)送信   sendto(sock, buf, strlen(buf), 0, (sockaddr*)&dest2, sizeof(dest1));    close(sock);    return 0; } 

运行方法：先运行接收端，再运行发送端。