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/*
* virobject.c: libvirt reference counted object
*
* Copyright (C) 2012 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; If not, see
* <http://www.gnu.org/licenses/>.
*
*/
#include <config.h>
#include "virobject.h"
#include "threads.h"
#include "memory.h"
#include "viratomic.h"
#include "virterror_internal.h"
#include "logging.h"
#define VIR_FROM_THIS VIR_FROM_NONE
static unsigned int magicCounter = 0xCAFE0000;
struct _virClass {
unsigned int magic;
const char *name;
size_t objectSize;
virObjectDisposeCallback dispose;
};
/**
* virClassNew:
* @name: the class name
* @objectSize: total size of the object struct
* @dispose: callback to run to free object fields
*
* Register a new object class with @name. The @objectSize
* should give the total size of the object struct, which
* is expected to have a 'virObject object;' field as its
* first member. When the last reference on the object is
* released, the @dispose callback will be invoked to free
* memory of the object fields
*
* Returns a new class instance
*/
virClassPtr virClassNew(const char *name,
size_t objectSize,
virObjectDisposeCallback dispose)
{
virClassPtr klass;
if (VIR_ALLOC(klass) < 0)
goto no_memory;
if (!(klass->name = strdup(name)))
goto no_memory;
klass->magic = virAtomicIntInc(&magicCounter);
klass->objectSize = objectSize;
klass->dispose = dispose;
return klass;
no_memory:
VIR_FREE(klass);
virReportOOMError();
return NULL;
}
/**
* virObjectNew:
* @klass: the klass of object to create
*
* Allocates a new object of type @klass. The returned
* object will be an instance of "virObjectPtr", which
* can be cast to the struct associated with @klass.
*
* The initial reference count of the object will be 1.
*
* Returns the new object
*/
void *virObjectNew(virClassPtr klass)
{
virObjectPtr obj = NULL;
char *somebytes;
if (VIR_ALLOC_N(somebytes, klass->objectSize) < 0) {
virReportOOMError();
return NULL;
}
obj = (virObjectPtr)somebytes;
obj->magic = klass->magic;
obj->klass = klass;
virAtomicIntSet(&obj->refs, 1);
PROBE(OBJECT_NEW, "obj=%p classname=%s", obj, obj->klass->name);
return obj;
}
/**
* virObjectUnref:
* @anyobj: any instance of virObjectPtr
*
* Decrement the reference count on @anyobj and if
* it hits zero, runs the "dispose" callback associated
* with the object class and frees @anyobj.
*
* Returns true if the remaining reference count is
* non-zero, false if the object was disposed of
*/
bool virObjectUnref(void *anyobj)
{
virObjectPtr obj = anyobj;
if (!obj)
return false;
bool lastRef = virAtomicIntDecAndTest(&obj->refs);
PROBE(OBJECT_UNREF, "obj=%p", obj);
if (lastRef) {
PROBE(OBJECT_DISPOSE, "obj=%p", obj);
if (obj->klass->dispose)
obj->klass->dispose(obj);
/* Clear & poison object */
memset(obj, 0, obj->klass->objectSize);
obj->magic = 0xDEADBEEF;
obj->klass = (void*)0xDEADBEEF;
VIR_FREE(obj);
}
return !lastRef;
}
/**
* virObjectRef:
* @anyobj: any instance of virObjectPtr
*
* Increment the reference count on @anyobj and return
* the same pointer
*
* Returns @anyobj
*/
void *virObjectRef(void *anyobj)
{
virObjectPtr obj = anyobj;
if (!obj)
return NULL;
virAtomicIntInc(&obj->refs);
PROBE(OBJECT_REF, "obj=%p", obj);
return anyobj;
}
/**
* virObjectIsClass:
* @anyobj: any instance of virObjectPtr
* @klass: the class to check
*
* Checks whether @anyobj is an instance of
* @klass
*
* Returns true if @anyobj is an instance of @klass
*/
bool virObjectIsClass(void *anyobj,
virClassPtr klass)
{
virObjectPtr obj = anyobj;
return obj != NULL && (obj->magic == klass->magic) && (obj->klass == klass);
}
/**
* virClassName:
* @klass: the object class
*
* Returns the name of @klass
*/
const char *virClassName(virClassPtr klass)
{
return klass->name;
}
/**
* virObjectFreeCallback:
* @opaque: a pointer to a virObject instance
*
* Provides identical functionality to virObjectUnref,
* but with the signature matching the virFreeCallback
* typedef.
*/
void virObjectFreeCallback(void *opaque)
{
virObjectUnref(opaque);
}
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