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    SubjectRe: unexpected extra pollout events from epoll
    On Sun, 26 Oct 2008, Paul P wrote:

    > > You do that by writing data until it's finished, or you
    > > get EAGAIN. If you
    > > get EAGAIN, you listen for EPOLLOUT.
    > > Reading is same, but you'd wait for EPOLLIN.
    > I've got a few questions about this approach. The most logical
    > way to do this seems to be:
    > 1) Leave the epoll_wait with the EPOLLIN|EPOLLOUT event flags and
    > use epoll_ctl to switch the interest mask for each fd between EPOLLIN
    > and EPOLLOUT on a per fd basis.

    Which version of epoll do you have? The epoll_wait() function does not
    accept an event mask (like you write above, EPOLLIN|EPOLLOUT). It never
    But yes, you'd switch interest with epoll_ctl().

    > 2) When I'm ready to write, I do a write and if it does not fully
    > write and I get the EAGAIN flag, I switch the fd with epoll_ctl(fd,MOD,EPOLLOUT).

    As optimization, if the EPOLLOUT bit is already set, you don't need to
    keep calling epoll_ctl(fd,MOD,EPOLLOUT).

    > However, I get strange behavior when I tried adding fd's with only the
    > EPOLLIN interest mask. If I use epoll_wait with both the EPOLLIN and
    > EPOLLOUT interest mask, but add fd's with only the EPOLLIN interest mask,
    > I still seem to get EPOLLOUT events on the fd.

    Again, how the heck do you "use epoll_wait with both the EPOLLIN and
    EPOLLOUT"?!? There is not such a thing.

    > So, I'm a little confused.

    From the wording above, that doesn't seem like a wrong guess.

    - Davide

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      Last update: 2008-10-27 02:21    [W:0.020 / U:55.724 seconds]
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