January 19, 2016

epoll API

API函数及参数说明

digraph G { node [style=rounded, shape=record]; create [shape=box,style=rounded, label="int epoll_create(int size);", fontsize=16, fontcolor=red]; /* ctl [label="int epoll_ctl(int epfd, int op, int fd, struct epoll_event* events);"]; wait [label="int epoll_wait(int epfd, struct epoll_event* events, int maxevents, int timeout);"]; */ subgraph cluster_ctl { fontcolor=red node [shape=record]; label="int epoll_ctl(int epfd, int op, int fd, struct epoll_event* events);" ctl_params [label="{<f0> int epfd|<f1> int op|int fd|<f2>struct epoll_event* events}"]; } subgraph cluster_wait { node [shape=record]; fontcolor=red label="int epoll_wait(int epfd, struct epoll_event* events, int maxevents, int timeout);"; wait_params [label="{<f0> int epfd|<f1> struct epoll_event* events|int maxevents|<f3> int timeout}"]; } subgraph cluster_event { label="struct epoll_event" fontcolor=blue node [shape=record]; struct_event [label="{<f0> uint32_t events;|<f1> epoll_data_t data;}"]; } subgraph cluster_data { label="struct epoll_data" fontcolor=blue node [shape=record]; struct_data [label="{void* ptr;|int fd;|uint32_t u32;|uint64_t u64;}"]; } subgraph cluster_events { label="event values" fontcolor=green node [shape=record]; evs [label="{EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLER|EPOLLHUP|EPOLLET|EPOLLONESHOT|EPOLLWAKEUP}"]; } subgraph cluster_ops { label="ops" fontcolor=green node [shape=record]; ops [label="{EPOLL_CTL_ADD|EPOLL_CTL_MOD|EPOLL_CTL_DEL}"]; } subgraph cluster_timeout { label="timeout value" fontcolor=green node [shape=record]; timeout [label="{\>0, milliseconds|0, return immediately|-1, block infinitely}"]; } struct_event:f0 -> evs; struct_event:f1 -> struct_data; ctl_params:f1 -> ops; ctl_params:f2 -> struct_event; wait_params:f1 -> struct_event; wait_params:f3 -> timeout; create -> ctl_params:f0; create -> wait_params:f0; }

示例代码

#define MAX_EVENTS 10
struct epoll_event ev, events[MAX_EVENTS];
int listen_sock, conn_sock, nfds, epollfd;

/* Set up listening socket, 'listen_sock' (socket(),
   bind(), listen()) */

epollfd = epoll_create(10);
if (epollfd == -1) {
    perror("epoll_create");
    exit(EXIT_FAILURE);
}

ev.events = EPOLLIN;
ev.data.fd = listen_sock;
if (epoll_ctl(epollfd, EPOLL_CTL_ADD, listen_sock, &ev) == -1) {
    perror("epoll_ctl: listen_sock");
    exit(EXIT_FAILURE);
}

for (;;) {
    nfds = epoll_wait(epollfd, events, MAX_EVENTS, -1);
    if (nfds == -1) {
        perror("epoll_pwait");
        exit(EXIT_FAILURE);
    }

    for (n = 0; n < nfds; ++n) {
        if (events[n].data.fd == listen_sock) {
            conn_sock = accept(listen_sock,
                            (struct sockaddr *) &local, &addrlen);
            if (conn_sock == -1) {
                perror("accept");
                exit(EXIT_FAILURE);
            }
            setnonblocking(conn_sock);
            ev.events = EPOLLIN | EPOLLET;
            ev.data.fd = conn_sock;
            if (epoll_ctl(epollfd, EPOLL_CTL_ADD, conn_sock,
                        &ev) == -1) {
                perror("epoll_ctl: conn_sock");
                exit(EXIT_FAILURE);
            }
        } else {
            do_use_fd(events[n].data.fd);
        }
    }
}
Posted by LiuHui
Filed under: program, c/c++
Tags: c/c++