Add support for epoll

[andreas-bok-sociomantic]

Currently the poll and select is used for handling the asynchronous io.

epoll offers several advantages which allows for improved scalability and more flexibility on the client side of the api

[mathias-baumann-sociomantic]

Is that really required or even an issue with

libdrizzle-redux/libdrizzle-5.1/drizzle.h

Lines 171 to 188 in c07059b

	* Set a custom I/O event watcher function for a drizzle structure. Used to
	* integrate libdrizzle with a custom event loop. The callback will be invoked
	* to register or deregister interest in events for a connection. When the
	* events are triggered, drizzle_con_set_revents() should be called to
	* indicate which events are ready. The event loop should stop waiting for
	* these events, as libdrizzle will call the callback again if it is still
	* interested. To resume processing, the libdrizzle function that returned
	* DRIZZLE_RETURN_IO_WAIT should be called again. See drizzle_event_watch_fn().
	*
	* @param[in] drizzle Drizzle structure previously initialized with
	* drizzle_create() or drizzle_clone().
	* @param[in] function Function to call when there is an I/O event.
	* @param[in] context Argument to pass into the callback function.
	*/
	DRIZZLE_API
	void drizzle_set_event_watch_fn(drizzle_st *drizzle,
	drizzle_event_watch_fn *function,
	void *context);

existing?

[andreas-bok-sociomantic]

It is meant for "future work". For the current use cases it isn't necessary but given the advantages of epoll it might still be worth looking into.

[mathias-baumann-sociomantic]

But you can use epoll in every use case, that's what I mean ;)

[andreas-bok-sociomantic]

Well it isn't supported on all platform so poll and select should still be there

[mathias-baumann-sociomantic]

I feel so misunderstood