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由 Daniel P. Berrange 提交于
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: NDaniel P. Berrange <berrange@redhat.com>
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