public Object execute(ReferenceMap map, Object keyReference, Object valueReference) {
Object existingValueReference;
Object existingValue;
do {
existingValueReference = map.delegate.putIfAbsent(keyReference, valueReference);
existingValue = map.dereferenceValue(existingValueReference);
} while (isExpired(existingValueReference, existingValue));
return existingValue;
}
public Object execute(ReferenceMap map, Object keyReference, Object valueReference) {
// ensure that the existing value is not collected
do {
Object existingValueReference;
Object existingValue;
do {
existingValueReference = map.delegate.get(keyReference);
existingValue = map.dereferenceValue(existingValueReference);
} while (isExpired(existingValueReference, existingValue));
if (existingValueReference == null) {
return Boolean.valueOf(false); // nothing to replace
}
if (map.delegate.replace(keyReference, existingValueReference, valueReference)) {
return existingValue; // existingValue did not expire since we still have a reference to
// it
}
} while (true);
}
public Object execute(ReferenceMap map, Object keyReference, Object valueReference) {
return map.dereferenceValue(map.delegate.put(keyReference, valueReference));
}