epoll_wait：让它永远等待

Question

As per to the man page of epoll_wait, following has been described.

int epoll_wait(int epfd, struct epoll_event *events,
                      int maxevents, int timeout);

In kernels before 2.6.37, a timeout value larger than approximately LONG_MAX / HZ milliseconds is treated as -1 (ie, infinity). Thus, for example, on a system where the sizeof(long) is 4 and the kernel HZ value is 1000, this means that timeouts greater than 35.79 minutes are treated as infinity.

In this sense, how would I set the timeout to for-ever without any kernel or hardware dependencies? would setting timeout to (-1) would result in such behavior?

Thank you.

Answer 1

As of man epoll_wait

Specifying a timeout of -1 causes epoll_wait() to block indefinitely, while specifying a timeout equal to zero cause epoll_wait() to return immediately, even if no events are available.

If you want an indefinite wait, then -1 is the right answer (no matter which system). But if you want to wait (on kernels before 2.6.37 and sizeof(long) is 4) more than 35.79 minutes but less than infinity, then you would have to split the calls, because of the specified bug.