/* epoll 系統(tǒng)調(diào)用函數(shù) */ #include <sys/epoll.h> /* * 函數(shù)功能：創(chuàng)建epoll文件描寫(xiě)符； * 返回值：若成功則返回新創(chuàng)建的文件描寫(xiě)符； * 函數(shù)原型： */ int epoll_create(int size); /* * 參數(shù)size是epoll的最大文件描寫(xiě)符個(gè)數(shù)； * 在新的系統(tǒng)內(nèi)核中size已不被使用； */

/* * 函數(shù)功能：操作某個(gè)epoll文件描寫(xiě)符； * 返回值：若成功則返回0，否則出錯(cuò)返回⑴； * 函數(shù)原型： */ int epoll_ctl(int epfd, int op, int fd, struct epoll_event *event); /* * 參數(shù)： * epfd：由epoll_create創(chuàng)建的epoll文件描寫(xiě)符； * fd：是關(guān)聯(lián)的文件描寫(xiě)符； * op：是操作方式，有以下3種操作方式： * EPOLL_CTL_ADD 將fd注冊(cè)到epfd中； * EPOLL_CTL_MOD 修改已在epfd中注冊(cè)的fd事件； * EPOLL_CTL_DEL 將fd從epfd中刪除； * * event：指向struct epoll_event 結(jié)構(gòu)，表示需要監(jiān)聽(tīng)fd的某種事件； */ /* struct epoll_event 結(jié)構(gòu)體定義以下 */ typedef union epoll_data { void *ptr; int fd; uint32_t u32; uint64_t u64; } epoll_data_t; struct epoll_event { uint32_t events; /* Epoll events */ epoll_data_t data; /* User data variable */ }; /* * 其中events有以下的取值： * EPOLLIN 表示對(duì)應(yīng)的文件描寫(xiě)符可讀； * EPOLLOUT 表示對(duì)應(yīng)的文件描寫(xiě)符可寫(xiě)； * EPOLLPRI 表示對(duì)應(yīng)的文件描寫(xiě)符有緊急數(shù)據(jù)可讀； * EPOLLERR 表示對(duì)應(yīng)的文件描寫(xiě)符產(chǎn)生毛病； * EPOLLHUP 表示對(duì)應(yīng)的文件描寫(xiě)符被掛載； * EPOLLET 表示將EPOLL設(shè)置為邊沿觸發(fā)模式(Edge Triggered)； * EPOLLONESHOT 表示只監(jiān)聽(tīng)1次事件，當(dāng)監(jiān)聽(tīng)此次事件完成，若想繼續(xù)監(jiān)聽(tīng)，則需再次把該套接字描寫(xiě)符加入到EPOLL隊(duì)列中； */

struct epoll_event ev; /* 設(shè)置與要處理的事件相干的文件描寫(xiě)符 */ ev.data.fd=listenfd; /* 設(shè)置要處理的事件類型 */ ev.events=EPOLLIN|EPOLLET; /* 注冊(cè)epoll事件 */ epoll_ctl(epfd,EPOLL_CTL_ADD,listenfd,&ev);

/* * 函數(shù)功能：搜集在epoll監(jiān)聽(tīng)事件中已產(chǎn)生的事件； * 返回值：若成功則返回所產(chǎn)生的事件數(shù)，否則出錯(cuò)返回⑴； * 函數(shù)原型： */ int epoll_wait(int epfd, struct epoll_event *events, int maxevents, int timeout); /* * 參數(shù)： * epfd：由epoll_create創(chuàng)建的epoll文件描寫(xiě)符； * events：指向epoll_event結(jié)構(gòu)體，用于保存已產(chǎn)生的事件； * maxevents：每次能處理的最大事件數(shù)； * timeout：等待IO 事件產(chǎn)生的超時(shí)時(shí)間：⑴相當(dāng)于阻塞，即不會(huì)立即返回；0相當(dāng)于非阻塞，即立即返回； */

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <netdb.h> #include <unistd.h> #include <fcntl.h> #include <sys/epoll.h> #include <errno.h> #define MAXEVENTS 64 static int make_socket_non_blocking (int sfd) { int flags, s; flags = fcntl (sfd, F_GETFL, 0); if (flags == ⑴) { perror ("fcntl"); return ⑴; } flags |= O_NONBLOCK; s = fcntl (sfd, F_SETFL, flags); if (s == ⑴) { perror ("fcntl"); return ⑴; } return 0; } static int create_and_bind (char *port) { struct addrinfo hints; struct addrinfo *result, *rp; int s, sfd; memset (&hints, 0, sizeof (struct addrinfo)); hints.ai_family = AF_UNSPEC; /* Return IPv4 and IPv6 choices */ hints.ai_socktype = SOCK_STREAM; /* We want a TCP socket */ hints.ai_flags = AI_PASSIVE; /* All interfaces */ s = getaddrinfo (NULL, port, &hints, &result); if (s != 0) { fprintf (stderr, "getaddrinfo: %s ", gai_strerror (s)); return ⑴; } for (rp = result; rp != NULL; rp = rp->ai_next) { sfd = socket (rp->ai_family, rp->ai_socktype, rp->ai_protocol); if (sfd == ⑴) continue; s = bind (sfd, rp->ai_addr, rp->ai_addrlen); if (s == 0) { /* We managed to bind successfully! */ break; } close (sfd); } if (rp == NULL) { fprintf (stderr, "Could not bind "); return ⑴; } freeaddrinfo (result); return sfd; } int main (int argc, char *argv[]) { int sfd, s; int efd; struct epoll_event event; struct epoll_event *events; if (argc != 2) { fprintf (stderr, "Usage: %s [port] ", argv[0]); exit (EXIT_FAILURE); } sfd = create_and_bind (argv[1]); if (sfd == ⑴) abort (); s = make_socket_non_blocking (sfd); if (s == ⑴) abort (); s = listen (sfd, SOMAXCONN); if (s == ⑴) { perror ("listen"); abort (); } efd = epoll_create1 (0); if (efd == ⑴) { perror ("epoll_create"); abort (); } event.data.fd = sfd; event.events = EPOLLIN | EPOLLET; s = epoll_ctl (efd, EPOLL_CTL_ADD, sfd, &event); if (s == ⑴) { perror ("epoll_ctl"); abort (); } /* Buffer where events are returned */ events = calloc (MAXEVENTS, sizeof event); /* The event loop */ while (1) { int n, i; n = epoll_wait (efd, events, MAXEVENTS, ⑴); for (i = 0; i < n; i++) { if ((events[i].events & EPOLLERR) || (events[i].events & EPOLLHUP) || (!(events[i].events & EPOLLIN))) { /* An error has occured on this fd, or the socket is not ready for reading (why were we notified then?) */ fprintf (stderr, "epoll error "); close (events[i].data.fd); continue; } else if (sfd == events[i].data.fd) { /* We have a notification on the listening socket, which means one or more incoming connections. */ while (1) { struct sockaddr in_addr; socklen_t in_len; int infd; char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV]; in_len = sizeof in_addr; infd = accept (sfd, &in_addr, &in_len); if (infd == ⑴) { if ((errno == EAGAIN) || (errno == EWOULDBLOCK)) { /* We have processed all incoming connections. */ break; } else { perror ("accept"); break; } } s = getnameinfo (&in_addr, in_len, hbuf, sizeof hbuf, sbuf, sizeof sbuf, NI_NUMERICHOST | NI_NUMERICSERV); if (s == 0) { printf("Accepted connection on descriptor %d " "(host=%s, port=%s) ", infd, hbuf, sbuf); } /* Make the incoming socket non-blocking and add it to the list of fds to monitor. */ s = make_socket_non_blocking (infd); if (s == ⑴) abort (); event.data.fd = infd; event.events = EPOLLIN | EPOLLET; s = epoll_ctl (efd, EPOLL_CTL_ADD, infd, &event); if (s == ⑴) { perror ("epoll_ctl"); abort (); } } continue; } else { /* We have data on the fd waiting to be read. Read and display it. We must read whatever data is available completely, as we are running in edge-triggered mode and won't get a notification again for the same data. */ int done = 0; while (1) { ssize_t count; char buf[512]; count = read (events[i].data.fd, buf, sizeof buf); if (count == ⑴) { /* If errno == EAGAIN, that means we have read all data. So go back to the main loop. */ if (errno != EAGAIN) { perror ("read"); done = 1; } break; } else if (count == 0) { /* End of file. The remote has closed the connection. */ done = 1; break; } /* Write the buffer to standard output */ s = write (1, buf, count); if (s == ⑴) { perror ("write"); abort (); } } if (done) { printf ("Closed connection on descriptor %d ", events[i].data.fd); /* Closing the descriptor will make epoll remove it from the set of descriptors which are monitored. */ close (events[i].data.fd); } } } } free (events); close (sfd); return EXIT_SUCCESS; }