On Thursday 15 December 2005 16:07, David Seikel wrote: > While I was investigating the best way to go about adding line > buffering to ecore_exe, I stumbled upon a little problem. The return > value from fd handlers is not documented anywhere, and it is in fact > used differently under different circumstances. > > If there is a buf_func defined for this handler, then a return of non > zero more or less means "there is more to do, keep calling all handlers > with a buf_func in a tight loop". The tight loop allows exiting from the > loop if buf_func or the handler returns zero. > > If there is no buf_func defined, then returning zero means "delete this > fd handler". The Ecore_Fd_Handler structure has a delete_me member > that means "delete this fd handler". There is also an > ecore_main_fd_handler_del() function. > > At the moment only ecore_x defines a buf_func for it's fd_handler. > It's handler always returns one, so there is no chance for it to > accidentally get deleted. It's buf_func returns zero sometimes, thus > exiting from the tight loop. > > I have not untangled the logic enough yet to see if returning zero from > your fd handler can cause accidental deletion if used with a buf_func. > Since none of this behaviour is documented, someone is likely to do > that one day, and it will likely drive them crazy trying to figure out > why their fd handler suddenly stops working. > > Since there are other ways to delete your fd handler, I suggest that we > don't delete it on the return of zero from the handler, and document > that returning zero means "there is more to do, call me back soon > without bothering with a select()". On the other hand, some users of > fd handlers may be relying on the delete on zero return behaviour, I > haven't checked them all yet. If we go ahead with this, these will > need to be changed to do an explicit delete using the del function.
I haven't looked at ecore_exe / fd handlers / etc. However, in most ecore handlers the return values are 0 - this handler is done, don't call it again / delete it !0 - this handler is not done, call it again next time the event comes up From your email, it sounds like that is how things work. However, you are a little unclear about whether you are talking about return values from the handler or return values from the buf_func, so I may be misreading. Also, in your last paragraph, you suggest documenting that a 0 return means "keep calling me", when earlier you state that it is a *non-zero* return that means "keep calling me"... Having 0 do this would be contrary to the rest of ecore. I'd suggest 'untangling the logic' a bit more before making suggestions on how to fix things. (Another approach would be "hey, this isn't making sense to me. can someone who understands it explain so we can document it for everyone else?"). -- rephorm ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://ads.osdn.com/?ad_idv37&alloc_id865&op=click _______________________________________________ enlightenment-devel mailing list enlightenment-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/enlightenment-devel
