Package com.couchbase.client.core.util

Class CompositeStateful<T,IN,OUT>

java.lang.Object
com.couchbase.client.core.util.CompositeStateful<T,IN,OUT>
All Implemented Interfaces:
Stateful<OUT>
public class CompositeStateful<T,IN,OUT> extends Object implements Stateful<OUT>
Represents a stateful component of one or more individual stateful elements.

Every change to the composite state is serialized by this object's monitor, whether it is caused by registering or deregistering an element, or by an element changing state.

Elements usually notify the composite while holding their own SingleStateful monitor, so the lock order is: element, then composite, then the composite's own state. Code holding this composite's monitor must therefore never wait for an element's monitor.

An element's state change may instead be delivered by the thread registering that element (see SingleStateful). That thread already holds this composite's monitor, and does not hold the element's monitor, so this does not violate the lock order.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    close()
    Closes the composite permanently and deregisters all elements.
    static <T, IN, OUT>
    CompositeStateful<T,IN,OUT>
    create(OUT initialState, Function<Collection<IN>,OUT> transformer)
    Creates a new transformer with an initial state and the transform function that should be applied.
    static <T, IN, OUT>
    CompositeStateful<T,IN,OUT>
    create(OUT initialState, Function<Collection<IN>,OUT> transformer, BiConsumer<OUT,OUT> beforeTransitionCallback)
    Creates a new transformer with an initial state and the transform function that should be applied.
    void
    deregister(T identifier)
    Deregisters a stateful element from the composite.
    void
    register(T identifier, Stateful<IN> upstream)
    Registers a stateful element with the composite.
    OUT
    state()
    Returns the current state of the stateful component.
    reactor.core.publisher.Flux<OUT>
    states()
    Returns a stream of states for this component as they change.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Method Details

    • create

      public static <T, IN, OUT> CompositeStateful<T,IN,OUT> create(OUT initialState, Function<Collection<IN>,OUT> transformer, BiConsumer<OUT,OUT> beforeTransitionCallback)
      Creates a new transformer with an initial state and the transform function that should be applied.
      Parameters:
      initialState - the initial state.
      transformer - the custom transformer for the states.
      Returns:
      a created stateful composite.

    • create

      public static <T, IN, OUT> CompositeStateful<T,IN,OUT> create(OUT initialState, Function<Collection<IN>,OUT> transformer)
      Creates a new transformer with an initial state and the transform function that should be applied.
      Parameters:
      initialState - the initial state.
      transformer - the custom transformer for the states.
      Returns:
      a created stateful composite.

    • register

      public void register(T identifier, Stateful<IN> upstream)
      Registers a stateful element with the composite.

      If an element is already registered with the same identifier, it is replaced. Does nothing if the composite is closed.

      The element is deregistered automatically when its state stream terminates.

      Parameters:
      identifier - the unique identifier to use.
      upstream - the upstream flux with the state stream.

    • deregister

      public void deregister(T identifier)
      Deregisters a stateful element from the composite.

      Note that it might be possible that the passed in identifier is already deregistered (for example if the upstream flux already completed or failed). In this case, this is essentially a "noop" since the target state, the identifier not being part of the stateful component, is already reached.

      Parameters:
      identifier - the unique identifier to use.

    • close

      public void close()
      Closes the composite permanently and deregisters all elements.

      Transitions to the initial state (if not already in it), then completes the states() stream. Subsequent calls to register(T, com.couchbase.client.core.util.Stateful<IN>) and deregister(T) have no effect.

    • state

      public OUT state()
      Description copied from interface: Stateful
      Returns the current state of the stateful component.
      Specified by:
      state in interface Stateful<T>

    • states

      public reactor.core.publisher.Flux<OUT> states()
      Description copied from interface: Stateful
      Returns a stream of states for this component as they change.

      Subscribers may be notified synchronously while the component holds internal locks, so they must not block or do non-trivial work on the notifying thread. See SingleStateful for details.

      Specified by:
      states in interface Stateful<T>