Subject: Re: [linux-audio-dev] jack_ringbuffer_read_space() question
From: Tom Szilagyi (tszilagyi_AT_users.sourceforge.net)
Date: Mon Jul 12 2004 - 22:59:29 EEST
On Mon, Jul 12, 2004 at 08:20:08PM +0200, Florian Schmidt wrote:
> On Mon, 12 Jul 2004 16:52:40 +0200
> Tom Szilagyi <tszilagyi_AT_users.sourceforge.net> wrote:
> > [...]
> > I have a program with some (p)threads, and a jack ringbuffer. One
> > thread is writing to the ringbuffer, and another is reading from it.
> >
> > The question is: is it (thread-)safe to have a _third_ thread that
> > looks at the ringbuffer via jack_ringbuffer_read_space() at random
> > times to determine how much data is in the ringbuffer? This third
> > thread does not actually read nor write any data to/from the
> > ringbuffer, just wants to know the amount of data in it.
> > [...]
>
> As long as the third thread really never reads/writes any data from
> the ringbuffer it should be ok afaik.. But what is the purpose of
> that third thread? Do maybe the results of this third thread have
> side effects on the other two threads? Depending on what you do with
> the fill information of the ringbuffer you might get unexpected
> results..
Not really important, it's not even audio-related. (Just some private
play-around to learn new things...) I was just using the jack
ringbuffer interface, as it is a really appealing way of doing data
transfer between threads.
As Paul pointed out, the measurement is not very accurate, but that's
not a problem. I just need to make sure it never crashes/locks up.
So thanks for the answers,
Tom
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