Messages in this thread | | | Date | Sat, 12 Jul 2003 16:55:10 -0700 (PDT) | From | Davide Libenzi <> | Subject | Re: [Patch][RFC] epoll and half closed TCP connections |
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On Sat, 12 Jul 2003, Eric Varsanyi wrote:
> > (Sorry, I missed this) > > You can work that out very easily. When your read/write returns a lower > > number of bytes, it means that it is time to stop processing this fd. If > > events happened meanwhile, you will get them at the next epoll_wait(). If > > not, the next time they'll happen. There's no blind spot if you follow > > this simple rule, and you do not even have the extra syscall with EAGAIN. > > The scenario that I think is still uncovered (edge trigger only): > > User Kernel > -------- ---------- > Read data added to socket > > Socket posts read event to epfd > > epoll_wait() Event cleared from epfd, EPOLLIN > returned to user > > more read data added to socket > > Socket posts a new read event to epfd > > read() until short read with EAGAIN all data read from socket > > epoll_wait() returns another EPOLLIN for socket and > clears it from epfd > > read(), returns 0 right away socket buffer is empty
read will return -1 with errno=EAGAIN in that case, not zero.
- Davide
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