RE: read/write locks

[Ross Johnson <rpj@ise.canberra.edu.au>]

Hi,

Re the read/write lock routines, I'll see if I can get them into the
next snapshot, but it may be the one after so that I don't delay
too long in getting recent bug fixes into the DLL.

Ross

On Thu, 9 Sep 1999, Medina, Aurelio wrote:

> To all,
> 
> Speaking of read/write locks, does anyone know if the POSIX read/write lock
> routines (e.g. pthread_rwlock_init()) that I submitted will eventually
> become part of the Pthreads-Win32 library?  Seems like someone is already
> working on another implementation.  The routines that I submitted were
> introduced in UNIX98 and are currently a X/Open standard.  These routines
> are portable and are currently available on HP-UX 11.0.
> 
> Thanks,
> Aurelio Medina
> 
> 	-----Original Message-----
> 	From:	Mikael.Ambrus@elema.siemens.se
> [SMTP:Mikael.Ambrus@elema.siemens.se]
> 	Sent:	Thursday, September 09, 1999 10:47 AM
> 	To:	pthreads-win32@sourceware.cygnus.com
> 	Subject:	pthread_cond_timedwait
> 
> 		[Ambrus Mikael]  Dear pthreads colleagues, 
> 
> 		I'm writing a program that uses pthread_cond_timedwait. In
> the book
> 	that I'm using (Pthreads Programming by Nicols, Buttlar & Proulux
> Farell )
> 	it says that this function should suspend the thread until some
> other thread
> 	calls  pthread_cond_signal, pthread_cond_broadcast OR the system
> timer is
> 	greater than or equal to the third argument (abstime). 
> 
> 		Since clock_gettime is not implemented and I cant find some
> other
> 	function that tells me the system time, I've tried to implement my
> own
> 	version of clock_gettime by using the ansi function clock(). This
> function
> 	returns the number of ticks that has elapsed since the program was
> started.
> 
> 		But it seams that this is not the same absolute time that
> 	pthread_cond_timedwait requires since the thread won't awaken.
> 
> 		Is there another way to acquire the relevant system time?
> 
> 		Another thing that has bothered me is that I recently
> downloaded the
> 	latest snip of phtreads and now my read/write locks won't work.
> Since the
> 	precompiled lib isn't recognised by the linker (neither with gcc
> v20.1 nor
> 	MSVC 6.0) for some reason, I built the libs using the buildlib.bat
> provided.
> 	Here's a snip of the code that fails:
> 
> 		int pthread_rdwr_wunlock_np (
> 		   pthread_rdwr_t *rdwrp
> 		){
> 		   assert( pthread_mutex_lock(&(rdwrp->mutex)) == 0 );
> 		   if (rdwrp->writers_writing == 0) {
> 		      assert( pthread_mutex_unlock(&(rdwrp->mutex)) == 0 );
> 		      return(-1);            
> 		   }else{
> 		      rdwrp->writers_writing = 0;
> 		      assert(pthread_cond_broadcast(&(rdwrp->lock_free)) ==
> 0);
> 
> 		   };
> 
> 		   assert( pthread_mutex_unlock(&(rdwrp->mutex)) == 0 );
> 		   return(0);
> 		};
> 
> 		pthread_cond_broadcast returns EINVAL. Does anyone recognise
> this
> 	problem?
> 
> 		Wkr
> 		Michael Ambrus
> 		Siemens Elema
> 	>  
> 

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