Patent attributes
At least one read operation of at least one object of an object graph is initiated. For each corresponding read operation, a reference count of the root object is incremented (with the reference count 1 for the root object initially reflecting a single anchor pointer pointing to the root object). Subsequently, one or more of the objects are changed. Incompatible changes result in the root object, at least one changed object, and any intervening objects within the hierarchy of objects being cloned. The anchor pointer is then linked to the cloned root object. The root object is later dropped when the reference count for the root object is zero. In addition, the object graph is traversed starting at the root object and ending at the at least one changed object removing any edges for such objects. Each object having a reference count of zero is then dropped.
