- **status**: open --> pending-needsinfo

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** [bugs:#1353] curl_multi_socket_action in edge-triggered mode**
**Status:** pending-needsinfo
**Labels:** multi_socket 
**Created:** Wed Apr 02, 2014 07:36 AM UTC by Constantin Baranov
**Last Updated:** Sat May 17, 2014 06:44 PM UTC
**Owner:** Daniel Stenberg
An edge-triggered reactor like epoll with EPOLLET flag enabled supposes that at every iteration user (I/O handler) has to drain/fill all buffers to be able to receive next event on the same socket. If you're notified that a socket is writable, you keep writing to it until you get EAGAIN, same for reading.
curl_multi_socket_action() performs single iteration around given socket. To fit in the above mentioned model either one modification is needed:
* curl_multi_socket_action() shall perform as much I/O on given socket as possible without blocking. Easier to implement, but may lead to a starvation of other sockets in the same multi set.
* curl_multi_socket_action() shall return special value (CURLM_CALL_MULTI_PERFORM? or return the 'remaining' (not completely drained) events mask) if it hasn't received EAGAIN yet and thus could be called again without waiting.
The later approach seems better to me, but most likely will require many changes in multi implementation and, even worse, in some protocol implementation like SSL.
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