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This introduces a fairly basic reference counted virObject type
and an associated virClass type, that use atomic operations for
ref counting.
In a global initializer (recommended to be invoked using the
virOnceInit API), a virClass type must be allocated for each
object type. This requires a class name, a "dispose" callback
which will be invoked to free memory associated with the object's
fields, and the size in bytes of the object struct.
eg,
virClassPtr connclass = virClassNew("virConnect",
sizeof(virConnect),
virConnectDispose);
The struct for the object, must include 'virObject' as its
first member
eg
struct _virConnect {
virObject object;
virURIPtr uri;
};
The 'dispose' callback is only responsible for freeing
fields in the object, not the object itself. eg a suitable
impl for the above struct would be
void virConnectDispose(void *obj) {
virConnectPtr conn = obj;
virURIFree(conn->uri);
}
There is no need to reset fields to 'NULL' or '0' in the
dispose callback, since the entire object will be memset
to 0, and the klass pointer & magic integer fields will
be poisoned with 0xDEADBEEF before being free()d
When creating an instance of an object, one needs simply
pass the virClassPtr eg
virConnectPtr conn = virObjectNew(connclass);
if (!conn)
return NULL;
conn->uri = virURIParse("foo:///bar")
Object references can be manipulated with
virObjectRef(conn)
virObjectUnref(conn)
The latter returns a true value, if the object has been
freed (ie its ref count hit zero)
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>