On 01/11/2013 05:13 AM, Daniel P. Berrange wrote:
> From: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
>
> A great many virObject instances require a mutex, so introduce
> a convenient class for this which provides a mutex. This avoids
> repeating the tedious init/destroy code
> ---
> src/libvirt_private.syms | 4 +++
> src/util/virobject.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++--
> src/util/virobject.h | 20 +++++++++++
> 3 files changed, 109 insertions(+), 2 deletions(-)
> +void *virObjectLockableNew(virClassPtr klass)
> +{
> + virObjectLockablePtr obj;
> +
> + if (!virClassIsDerivedFrom(klass, virClassForObjectLockable())) {
> + virReportInvalidArg(klass,
> + _("Class %s must derive from virObjectLockable"),
> + virClassName(klass));
> + return NULL;
> + }
> +
> + if (!(obj = virObjectNew(klass)))
> + return NULL;
> +
> + if (virMutexInit(&obj->lock) < 0) {
> + virReportSystemError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("Unable to initialize mutex"));
> + virObjectUnref(obj);
> + return NULL;
> + }
This creates the new object locked...
> +
> + return obj;
> +}
> +
> +
> +static void virObjectLockableDispose(void *anyobj)
> +{
> + virObjectLockablePtr obj = anyobj;
> +
> + virMutexDestroy(&obj->lock);
...but this doesn't unlock anything. You may want to document that the
user is required to unlock the object before losing the last reference.
> + * virObjectLock:
> + * @anyobj: any instance of virObjectLockablePtr
> + *
> + * Acquire a lock on @anyobj. The lock must be
> + * released by virObjectUnlock.
> + */
> +void virObjectLock(void *anyobj)
> +{
> + virObjectLockablePtr obj = anyobj;
Is it worth a sanity check that anyobj is actually an object of the
right class, before we blindly dereference something wrong due to a
coding error?
> +void virObjectUnlock(void *anyobj)
> +{
> + virObjectLockablePtr obj = anyobj;
> +
And again, would a sanity check help?
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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