libwebsockets

lws_raw_transaction_completed

This provides a way to defer closing if the output buflist has
unsent content for the wsi, until the buflist is drained.

It doesn't make any assumption about the content being related
to http, so you can use it on raw.

It follows the semantics of the http transaction completed, ie

     if (lws_raw_transaction_completed(wsi))
	return -1

     return 0;