Re: condvar

Philippe Houdoin <[email protected]> wrote:
> > 3) (the clean version) add a new pair of system calls: switch_sem()
> > and switch_sem_etc() (other naming suggestions are welcome). 
> > Applications using these functions would not run on R5 or Zeta 
> > anymore.
> Cleaness was (most of the time) the BeOS way. IMHO, better to kept 
> Haiku on the
> same road. New syscalls is great. It's a > R1 feature, so it make 
> sense to
> expand the kernel API anyway... and still keep binary compatibility 
> with R5
> apps.

As it's already implemented, we might as well make it public for R1. 
Anyway, I'll add the functions to the public OS.h header, and add a 
syscall for them - we can then still decide what to do when we actually 
do release something; until then it's private anyway :-)

> François added:
> > Btw, there is a big issue with the current pthread implementation 
> > as
> > well as yours: it doesn't handle the STATIC initializers...
[...]
> > #define PTHREAD_MUTEX_INITIALIZER	NULL

Ours doesn't do that, although it doesn't work the way it's done now 
either :)
I am well aware of that, but thanks for the note anyway.

[...]
> It's a ticking bomb :-(, because it assert that we never destroy or 
> unlock a
> mutex without having locked *once* at least. Plus the performance 
> hit, also.

One could easily add the semaphore construction to all functions; but 
in any way, it's not very clean. However, since C does not know the 
concept of global initializers, there is little we can do about it; it 
will look similar to your solution.
BTW the POSIX specs only talk about pthread_mutex_lock() for lazy 
initialization of a static lock, and since mutexes are not like 
semaphores, this should be no problem.

> - Philippe, back online (have I mentioned that I hates my ISP?)
> with huge stack of pending emails...

Nice to have you back anyway :-)
Will you make it to BeGeistert this time? (I expect François to be 
there anyway :-))

Bye,
   Axel.



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