epoll-exp.c

#include <unistd.h>
#include <sys/epoll.h>

#include "lib.h"

#define DEPTH 6
#define FANOUT 1000

void add_many(int parent, int child) {
    int i;
    int fds[FANOUT];
    struct epoll_event evt = { .events = EPOLLIN };
    for (i = 0; i < FANOUT; i++) {
        if ((fds[i] = dup(child)) < 0)
            die_errno("dup");
        if (epoll_ctl(parent, EPOLL_CTL_ADD, fds[i], &evt) < 0)
            die_errno("add");
    }
    for (i = 0; i < FANOUT; i++)
        close(fds[i]);
}

int main(void) {
    int fds[DEPTH];
    int i;
    int p[2];
    struct epoll_event evt = { .events = EPOLLIN };

    for (i = 0; i < DEPTH; i++) {
        if ((fds[i] = epoll_create(1)) < 0)
            die_errno("create");
    }
    for (i = 1; i < DEPTH; i++) {
        add_many(fds[i-1], fds[i]);
    }
    if (pipe(p) < 0)
        die_errno("pipe");

    epoll_ctl(fds[DEPTH-1], EPOLL_CTL_ADD, p[0], &evt);
    write(p[1], p, sizeof(int));

    return 0;
}