[LAD] a *simple* ring buffer, comments pls?

[Chris Cannam]

On 12 July 2011 21:36, Paul Davis <paul at linuxaudiosystems.com> wrote:
>   2) do you need memory barriers to ensure correct synchronization
>         for this kind of data structure in the face of possible hardware level
>         instruction reordering?

The transactional metaphor for this kind of thing seems useful -- the
idea that "we've written everything, now we commit for our readers"
feels like a helpful way to picture the points where barriers might be
necessary.

Since transactional integrity is not provided for us, the commit needs
to be either

 * protected with a memory barrier, if it doesn't matter that the data
is available before it has been announced but does matter if the data
is announced before being available
 * an atomic swap, if the new data must not be available before it has
been announced and also there is only a single point of reference to
the new data
 * mutex protected, if the references to any changes may be
significant or we are not confident of either of the previous cases

...?


Chris