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    SubjectRe: epoll (was Re: [PATCH] async poll for 2.5)
    Date (John Myers) writes:

    > Close. What we would have is a modification of the epoll_addf()
    > semantics such that it would have an additional postcondition that if
    > the new_fd is in the ready state (has data available) then at least
    > one notification has been generated. In the code above, the three
    > lines comprising the if statement labeled "7*" would be removed.

    I see.

    I assume the kernel implementation is no big deal: epoll_addf() has to
    call the kernel internal equivalent to poll() with a zero timeout.

    This wouldn't break the first "solution" in my earlier post, but it
    would cause every new connection to experience one extra EAGAIN.

    I see three possibilities:

    1) keep the current epoll_addf()
    2) modify it as John suggests, posting the initial ready state in
    the next epoll_getevents()
    3) both: add an option to epoll_addf() that says which of 1 or 2 is desired.

    -- Buck

    How hard would it be to modify the current epoll code to work that
    way? I'd assume it's just a matter having epoll_addf call the legacy
    poll() code to check the condition (with a zero timeout).

    -- Buck

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