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

[Tim Blechmann]

> Ah. pthread_mutex_lock() / unlock(), as EXTERNAL functions, will never
> be optimized away or inlined. Now, being all sequence points, if you
> simply do
> 
> pthread_mutex_lock();
> xval = x;
> pthread_mutex_unlock();
> 
> the compiler is not allowed to move statements out the locked section
> or reorder them in any way (without need for any volatile qualifiers).

the hardware would be allowed to reorder them ... this is the reason why mutex 
implementations involve memory barriers ...

the main problem is the lack of a memory model for multi-threaded applications 
at the level of the language (c or c++). fortunately this is about to change 
with c++0x and probably c1x.

tim