Messages in this thread | | | Date | Sat, 12 Jul 2003 20:44:32 +0100 | From | Jamie Lokier <> | Subject | Re: [Patch][RFC] epoll and half closed TCP connections |
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Eric Varsanyi wrote: > - epoll_wait() returns a single EPOLLIN event on the FD representing > both the 1/2 shutdown state and data available
Correct.
> At this point there is no way the app can tell if there is a half closed > connection so it may issue a close() back to the client after writing > results. Normally the server would distinguish these events by assuming > EOF if it got a read ready indication and the first read returned 0 bytes, > or would issue read calls until less data was returned than was asked for. > > In a level triggered world this all just works because the read ready > indication is driven back to the app as long as the socket state is half > closed. The event driven epoll mechanism folds these two indications > together and thus loses one 'edge'.
Well then, use epoll's level-triggered mode. It's quite easy - it's the default now. :)
If there's an EOF condition pending after you called read(), and then you call epoll_wait(), you _should_ see another EPOLLIN condition immediately.
If you aren't seeing epoll_wait() return with EPOLLIN when there's an EOF pending, *and* you haven't set EPOLLET in the event flags, that's a bug in epoll. Is that what you're seeing?
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