Package org.apache.flink.runtime.state.internal

Interface InternalKvState.StateIncrementalVisitor<K,N,V>

Enclosing interface:
InternalKvState<K,N,V>
public static interface InternalKvState.StateIncrementalVisitor<K,N,V>
The state entry visitor which supports remove and update of the last returned entries.

The visitor should tolerate concurrent modifications. It might trade this tolerance for consistency and return duplicates or not all values (created while visiting) but always state values which exist and up-to-date at the moment of calling nextEntries().

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    hasNext()
    Whether the visitor potentially has some next entries to return from nextEntries().
    Collection<StateEntry<K,N,V>>
    nextEntries()
    Return some next entries which are available at the moment.
    void
    remove(StateEntry<K,N,V> stateEntry)
     
    void
    update(StateEntry<K,N,V> stateEntry, V newValue)
    Update the value of the last returned entry from the next() method.

  • Method Details

    • hasNext

      boolean hasNext()
      Whether the visitor potentially has some next entries to return from nextEntries().

    • nextEntries

      Collection<StateEntry<K,N,V>> nextEntries()
      Return some next entries which are available at the moment.

      If empty collection is returned, it does not mean that the visitor is exhausted but it means that the visitor has done some incremental work advancing and checking internal data structures. The finished state of the visitor has to be checked by hasNext() method.

      The returned collection and state values must not be changed internally (there might be no defensive copies in nextEntries() for performance). It has to be deeply copied if it is to modify, e.g. with the update() method.

    • remove

      void remove(StateEntry<K,N,V> stateEntry)

    • update

      void update(StateEntry<K,N,V> stateEntry, V newValue)
      Update the value of the last returned entry from the next() method.
      Throws:
      IllegalStateException - if next() has never been called yet or iteration is over.