epoll应用的一个例子

代码:

/*  *  PipeTest by Davide Libenzi ( Epoll performace tester )  *  Copyright (C) 1999,..,2003  Davide Libenzi  *  *  This program is free software; you can redistribute it and/or modify  *  it under the terms of the GNU General Public License as published by  *  the Free Software Foundation; either version 2 of the License, or  *  (at your option) any later version.  *  *  This program is distributed in the hope that it will be useful,  *  but WITHOUT ANY WARRANTY; without even the implied warranty of  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the  *  GNU General Public License for more details.  *  *  You should have received a copy of the GNU General Public License  *  along with this program; if not, write to the Free Software  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA  *  *  Davide Libenzi <[email protected]>  *  *  *  You need either a never glibc or the epoll library available here :  *  *  http://www.xmailserver.org/linux-patches/nio-improve.html#sys_epoll  *  *  to build this source file. To build :  *  *  gcc -o pipetest pipetest.c -lepoll  *  */ #include <sys/types.h> #include <sys/stat.h> #include <sys/time.h> #include <sys/socket.h> #include <sys/signal.h> #include <sys/resource.h> #include <fcntl.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <unistd.h> #include <errno.h> #include <sys/epoll.h> #define RUNTIMES 16 static int count, writes, fired; static int *pipes; static int num_pipes, num_active, num_writes; static int epfd; static struct epoll_event *events; unsigned long long getustime(void) {    struct timeval tm;    gettimeofday(&tm, NULL);    return (unsigned long long) tm.tv_sec * 1000000ULL + (unsigned long long) tm.tv_usec; } void read_cb(int fd, int idx) {    int widx = idx + num_active + 1;    u_char ch;    if (read(fd, &ch, sizeof(ch)))       count++;    else       fprintf(stderr, "false read event: fd=%d idx=%d/n", fd, idx);    if (writes) {       if (widx >= num_pipes)          widx -= num_pipes;       write(pipes[2 * widx + 1], "e", 1);       writes--;       fired++;    } } int run_once(long *work, unsigned long long *tr) {    int i, res;    unsigned long long ts, te;    fired = 0;    for (i = 0; i < num_active; i++, fired++)       write(pipes[i * 2 + 1], "e", 1);    count = 0;    writes = num_writes;    ts = getustime();    do {       res = epoll_wait(epfd, events, num_pipes, 0);       for (i = 0; i < res; i++)          read_cb(pipes[2 * events[i].data.u32], events[i].data.u32);    } while (count != fired);    te = getustime();    *tr = te - ts;    *work = count;    return (0); } int main (int argc, char **argv) {    struct rlimit rl;    int i, c;    long work;    unsigned long long tr;    int *cp;    struct epoll_event ev;    extern char *optarg;    num_pipes = 100;    num_active = 1;    num_writes = num_pipes;    while ((c = getopt(argc, argv, "n:a:w:")) != -1) {       switch (c) {       case 'n':          num_pipes = atoi(optarg);          break;       case 'a':          num_active = atoi(optarg);          break;       case 'w':          num_writes = atoi(optarg);          break;       default:          fprintf(stderr, "Illegal argument /"%c/"/n", c);          exit(1);       }    }    rl.rlim_cur = rl.rlim_max = num_pipes * 2 + 50;    if (setrlimit(RLIMIT_NOFILE, &rl) == -1) {       perror("setrlimit");       exit(1);    }    events = calloc(num_pipes, sizeof(struct epoll_event));    pipes = calloc(num_pipes * 2, sizeof(int));    if (events == NULL || pipes == NULL) {       perror("malloc");       exit(1);    }    if ((epfd = epoll_create(num_pipes)) == -1) {       perror("epoll_create");       exit(1);    }    for (cp = pipes, i = 0; i < num_pipes; i++, cp += 2) {       if (pipe(cp) == -1) {          perror("pipe");          exit(1);       }       fcntl(cp[0], F_SETFL, fcntl(cp[0], F_GETFL) | O_NONBLOCK);    }    for (cp = pipes, i = 0; i < num_pipes; i++, cp += 2) {       ev.events = EPOLLIN;       ev.data.u32 = i;       if (epoll_ctl(epfd, EPOLL_CTL_ADD, cp[0], &ev) < 0) {          perror("epoll_ctl");          exit(1);       }    }    for (i = 0; i < RUNTIMES; i++) {       run_once(&work, &tr);       if (!work)          exit(1);       fprintf(stdout, "%lf/n", (double) tr / (double) work);    }    exit(0); }