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,是接收端。
例子2,是发送端。
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。
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