Re: AMIGA will use Linux, but Linux has several "multimedia-deficiencies"
Jamie Lokier (lkd@tantalophile.demon.co.uk)
Wed, 14 Jul 1999 21:48:56 +0200
Gerard Roudier wrote:
> Using select() and une unique message queue for read is possible with
> conjunction of SIGIO/SIGALRM with the risk of the application to lose time
> if it has very bad luck.
>
> You can implement something like that:
>
> If you expect event(s) from fds (basically SIGIO will kick ass you)
>
> 1) set an alarm of a few seconds (<=2 seconds for example)
> also set the alarm from the alarm handler.
>
> 2) get next message in blocking mode
>
> 3) if interrupted go with poll/select the fds
> (can be either SIGIO or SIGALRM)
>
> If you are so unfortunate that the SIGIO occurs between 1 and 2, your
> program will only be stuck for less than 1..2 seconds.
> (The period between (1) and (2) that may let msgrcv block can be minimized
> by some additionnal code).
You can get rid of the possible 1..2 second delay by using sigsetjmp
before 2 and siglongjmp in the SIGIO handler.
It crashes some systems (cygwinb19.1) but is completely reliable on
others (Linux).
> By the way, this works for me since 10 years in some applications, and I
> never have been able to get the problem in my testings. Indeed it is not
> clean and not optimal at all, but when you haven't the choice such a
> band-aid is really helpfull.
Yes your solution is the one I use too. You can catch SIGCHLD and other
signals this way too -- everything becomes an event, innit great :-)
-- Jamie
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