Hello,
I've added a pipe file descriptor (fd1) to an epoll (fd3) with
EPOLLOUT in edge-triggered mode, and then added the fd3 to another
epoll (fd4) with EPOLLIN in edge-triggered too.
Next, waiting for fd4 without timeout. When fd1 to be writable, i
think epoll_wait(fd4, ...) only return once, because all file
descriptors are added in edge-triggered mode.
But, the actual result is returns many and many times until do once
eopll_wait(fd3, ...).
#include <stdio.h>
#include <unistd.h>
#include <sys/epoll.h>
int
main (int argc, char *argv[])
{
int efd[2];
struct epoll_event e;
efd[0] = epoll_create (1);
if (efd[0] < 0)
return -1;
efd[1] = epoll_create (1);
if (efd[1] < 0)
return -2;
e.events = EPOLLIN | EPOLLET;
e.data.u64 = 1;
if (epoll_ctl (efd[0], EPOLL_CTL_ADD, efd[1], &e) < 0)
return -3;
e.events = EPOLLOUT | EPOLLET;
e.data.u64 = 2;
if (epoll_ctl (efd[1], EPOLL_CTL_ADD, 1, &e) < 0)
return -4;
for (;;) {
struct epoll_event events[16];
int nfds;
nfds = epoll_wait (efd[0], events, 16, -1);
printf ("nfds: %d\n", nfds);
}
close (efd[1]);
close (efd[0]);
return 0;
}
--
Best regards!
Hev
https://hev.cc
