Interface ORSet<T>

  • Type Parameters:
    T - The type of elements.
    All Superinterfaces:
    java.util.Collection<T>, Crdt, java.lang.Iterable<T>, java.util.Set<T>

    public interface ORSet<T>
    extends Crdt, java.util.Set<T>
    An Observed-Removed Set.

    An Observed-Removed Set allows both the addition and removal of elements in a set. A removal can only be done if all of the additions that added the key have been seen by this node. This means that, for example if node 1 adds element A, and node 2 also adds element A, then node 1's addition is replicated to node 3, and node 3 deletes it before node 2's addition is replicated, then the element will still be in the map because node 2's addition had not yet been observed by node 3, and will cause the element to be re-added when node 3 receives it. However, if both additions had been replicated to node 3, then the element will be removed.

    Care needs to be taken to ensure that the serialized value of elements in the set is stable. For example, if using protobufs, the serialized value of any maps contained in the protobuf is not stable, and can yield a different set of bytes for the same logically equal element. Hence maps should be avoided. Additionally, some changes in protobuf schemas which are backwards compatible from a protobuf perspective, such as changing from sint32 to int32, do result in different serialized bytes, and so must be avoided.

    • Method Summary

      • Methods inherited from interface java.util.Collection

        parallelStream, removeIf, stream, toArray
      • Methods inherited from interface java.lang.Iterable

        forEach
      • Methods inherited from interface java.util.Set

        add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, spliterator, toArray, toArray