On Wed, Oct 28, 2009 at 05:15:05PM +0100, Daniel Veillard wrote:
> On Fri, Oct 23, 2009 at 02:05:31PM +0100, Daniel P. Berrange wrote:
> > This implements a thin wrapper around the pthread_rwlock
> > primitives. No impl is provided for Win32 at this time
> > since it is rather hard, and none of our code yet requires
> > it on Win32
> >
> > * src/util/threads.h: Add virRWLockInit, virRWLockDestroy,
> > virRWLockRead, virRWLockWrite, virRWLockUnlock APIs
> > * src/util/threads-pthread.h: define virRWLock struct
> > * src/util/threads-pthread.c: Implement RWLock APIs
> > ---
> > src/libvirt_private.syms | 6 ++++++
> > src/util/threads-pthread.c | 30 ++++++++++++++++++++++++++++++
> > src/util/threads-pthread.h | 4 ++++
> > src/util/threads.h | 10 ++++++++++
> > 4 files changed, 50 insertions(+), 0 deletions(-)
> >
> > diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> > index bd9d84a..6ed562d 100644
> > --- a/src/libvirt_private.syms
> > +++ b/src/libvirt_private.syms
> > @@ -426,6 +426,12 @@ virCondWait;
> > virCondSignal;
> > virCondBroadcast;
> >
> > +virRWLockInit;
> > +virRWLockDestroy;
> > +virRWLockRead;
> > +virRWLockWrite;
> > +virRWLockUnlock;
> > +
> > # util.h
> > virFileReadAll;
> > virFileWriteStr;
> > diff --git a/src/util/threads-pthread.c b/src/util/threads-pthread.c
> > index 4e00bc5..2052c0a 100644
> > --- a/src/util/threads-pthread.c
> > +++ b/src/util/threads-pthread.c
> > @@ -57,6 +57,36 @@ void virMutexUnlock(virMutexPtr m)
> > }
> >
> >
> > +int virRWLockInit(virRWLockPtr m)
> > +{
> > + if (pthread_rwlock_init(&m->lock, NULL) != 0) {
> > + errno = EINVAL;
> > + return -1;
> > + }
> > + return 0;
> > +}
> > +
> > +void virRWLockDestroy(virRWLockPtr m)
> > +{
> > + pthread_rwlock_destroy(&m->lock);
> > +}
> > +
> > +void virRWLockRead(virRWLockPtr m)
> > +{
> > + pthread_rwlock_rdlock(&m->lock);
> > +}
> > +
> > +void virRWLockWrite(virRWLockPtr m)
> > +{
> > + pthread_rwlock_wrlock(&m->lock);
> > +}
> > +
> > +void virRWLockUnlock(virRWLockPtr m)
> > +{
> > + pthread_rwlock_unlock(&m->lock);
> > +}
> > +
> > +
>
> Hum it's a small patch, but I would rather fix those function to not
> be void when the underlying pthread_ counterpart can actually fail.
> IMHO we should report errors coming from the thread library (whichever
> is used on a given platform).
I mis-understood the manpage for this - I read it to mean these calls
would actually deadlock upon error (as a mutex would), but in fact they
return error EDEADLOCK instead which is rather unhelpful.
I'm going to withdraw this entire patch.
Daniel
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