In MC's Deployers I found a couple of usages where I would need two+ steps on a Collection/Map to be atomic in this next sense: Collection<T> addAllAndClear() { Collection<T> target = new HashSet<T>(); synchronize(delegate) { target.addAll(delegate); delegate.clear(); } return target; } Does it make sense to introduce something like this in jboss-common or should this just be handled locally in the project via some helper methods? Or is AtomicCollection in order? e.g. public interface AtomicCollection<E> extends Collection<E> { /** * Add all and clear. * * @return new copy */ Collection<E> addAllAndClear(); // TODO - add more 'atomic' ops here }