lio_listio fixes and adding kqueue notification patch

[John-Mark Gurney]

Doug Ambrisko wrote this message on Fri, Oct 22, 2004 at 08:42 -0700:
> BTW this could show my own ignorance since I don't think this exists.
> What would be nice is if a signal could be associated with kevents 
> happening.  The idea would be that instead of polling for kevents that 
> a signal handler could be setup to notify the process when a kevent 
> just happened.  The usage would be to set a tell kqueue to signal a 
> certain signal if any kevent events occur.  This would allow a program
> not to be just focused on I/O but allow a bunch of computation to 
> happen then deal with I/O without polling for it.  Not every app.
> is just a "bit pusher".

I'm looking at this problem now, but I thought I might as well respond
to this...

There is a problem with that in that you could have a kqueue (possibly
the same kq) that has an event when that signal is delivered.. this would
then attempt to deliver and end up recursing on the lock... I have
fixed this wrt kq in a kq, but I haven't investigated trying to make
signals delivery work..

You can look at the FIOASYNC code Alfred commited to use the signal on
fd ready a while back, but is if 0'd because of this issue...  It would
probably be easy enough to create another task that does the signal
delivery if you want...  so when a kq becomes ready, it init's a task
to deliver the signal...

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."