epoll|linux下多路复用实现之Epoll c语言|服务器|linux

【epoll|linux下多路复用实现之Epoll】Epoll相关的API：

int epoll_create(int size); epoll在内核中维护一个事件表，将用户关心的文件描述符都放进去，因此无需像select和poll那样每次调用都要重复传入文件描述符或事件集，但epoll需要一个额外的文件描述符来唯一标识内核中的这个事件表。

int epoll_ctl(int epfd, int op, int fd, struct epoll_event* event); op: EPOLL_CTL_ADD：往事件表中注册fd上的事件 EPOLL_CTL_MOD：修改fd上注册的事件 EPOLL_CTL_DEL：删除fd上注册的事件event:该参数指定要传入的文件描述符上关注的事件，它是epoll_event结构体指针类型，epoll_event定义如下struct epoll_event{ __uint32_t events; //epoll事件 epoll_data_t data; //用户数据 }; 其中data用于存储用户数据，它是一个共用体，如下是data定义: typedef union epoll_data { void *ptr; int fd; uint32_t u32; uint64_t u64; }epoll_data_t;

int epoll_wait(int epfd, struct_event* events, int maxevents, int timeout); - epfd：内核事件表 - events：用户指定的写入就绪事件的结构体数组，由内核来修改 - maxevents：最大监听事件个数 - timeout：阻塞时间，含义与poll中相同 - 返回值：就绪文件描述符个数

如下是用epoll实现的服务端代码：

#include #include #include #include #include #include #include #include #include #include /* 出错处理 */ void err_exit(char *msg) { perror(msg); exit(1); }/* 创建socket */ int create_socket(const char *ip, int port) { struct sockaddr_in server_addr; int sockfd, reuse = 1; memset(&server_addr, 0, sizeof(server_addr)); server_addr.sin_family = AF_INET; server_addr.sin_port = htons(port); if (inet_pton(PF_INET, ip, &server_addr.sin_addr) == -1) err_exit("inet_pton() error"); if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1) err_exit("socket() error"); /* 设置复用socket地址 */ if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) == -1) err_exit("setsockopt() error"); if (bind(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) err_exit("bind() error"); if (listen(sockfd, 5) == -1) err_exit("listen() error"); return sockfd; }int main() { int listenFd = create_socket("127.0.0.1", 9977); printf("create listen fd:%d\n", listenFd); int epfd = epoll_create(10); printf("create epoll fd:%d\n", epfd); struct epoll_event event; event.events = EPOLLIN; event.data.fd = listenFd; epoll_ctl(epfd, EPOLL_CTL_ADD, listenFd, &event); while(1) { struct epoll_event events[100]; int num = epoll_wait(epfd, events, 100, -1); printf("epoll wait fd num:%d\n", num); int i = 0; for(i = 0; i < num; i++) { if(events[i].events & EPOLLRDHUP) { int fd = events[i].data.fd; printf("%d closed\n", fd); epoll_ctl(epfd, EPOLL_CTL_DEL, fd, NULL); } else if(events[i].events & EPOLLIN) { int fd = events[i].data.fd; if(listenFd == events[i].data.fd) { struct sockaddr_in cli; socklen_t len = sizeof(cli); int clientFd = accept(listenFd, (struct sockaddr*)&cli, &len); char ip[16]; memset(ip,0,sizeof(ip)); inet_ntop(AF_INET,&cli.sin_addr.s_addr,ip,sizeof(ip)); printf("client[%s:%d] has connected to server!\n", ip, ntohs(cli.sin_port)); struct epoll_event event; event.events = EPOLLIN|EPOLLRDHUP; event.data.fd = clientFd; epoll_ctl(epfd, EPOLL_CTL_ADD, clientFd, &event); }else { char buff[128] = {0}; int ret = recv(fd, buff, 127, 0); printf("%d: %s\n", fd, buff); send(fd, "OK", 2, 0); }} } } return 0; }

tcp实现的客户端:

#include #include #include #include #include #include #include #include #include #includeint main() { int sockfd = socket(PF_INET, SOCK_STREAM, 0); if(sockfd < 0) { perror("create socket failed\n"); exit(-1); } printf("tcp client fd:%d\n", sockfd); struct sockaddr_in ser; ser.sin_family = AF_INET; ser.sin_port = htons(9977); ser.sin_addr.s_addr = inet_addr("127.0.0.1"); if(connect(sockfd, (struct sockaddr*)&ser, sizeof(ser)) < 0) { perror("connect error"); exit(-1); } while(1) { char buf[128] = {0x00}; int i = 0; sprintf(buf, "tcp client send msg count:%d", ++i); if(send(sockfd, buf, strlen(buf), 0) < 0) printf("tcp client send failed.\n"); memset(buf, 0, sizeof(buf)); ssize_t recvLen = recv(sockfd, buf, sizeof(buf)-1, 0); if(recvLen < 0) printf("tcp client recv failed, ret value:%d\n",recvLen); printf("tcp client recv data:[%s]\n", buf); sleep(5); } return 0; }