StructuredTaskScope.ShutdownOnSuccess (Java SE 23 & JDK 23)
Description: declaration: module: java.base, package: java.util.concurrent, class: StructuredTaskScope, class: ShutdownOnSuccess
Keywords: java.util.concurrent.StructuredTaskScope.ShutdownOnSuccess class

# Class StructuredTaskScope.ShutdownOnSuccess<T>

java.lang.Object
java.util.concurrent.StructuredTaskScopePREVIEW<T>
java.util.concurrent.StructuredTaskScope.ShutdownOnSuccess<T>

Type Parameters:
  `T` - the result type

All Implemented Interfaces:
  `AutoCloseable`

Enclosing class:
  `StructuredTaskScopePREVIEW<T>`

public static final class StructuredTaskScope.ShutdownOnSuccess<T> extends StructuredTaskScopePREVIEW<T>
`ShutdownOnSuccess` is a preview API of the Java platform.
Programs can only use `ShutdownOnSuccess` when preview features are enabled.
Preview features may be removed in a future release, or upgraded to permanent features of the Java platform.
A `StructuredTaskScope` that captures the result of the first subtask to complete successfullyPREVIEW. Once captured, it shuts downPREVIEW the task scope to interrupt unfinished threads and wakeup the task scope owner. The policy implemented by this class is intended for cases where the result of any subtask will do ("invoke any") and where the results of other unfinished subtasks are no longer needed.

Unless otherwise specified, passing a `null` argument to a method in this class will cause a `NullPointerException` to be thrown.

API Note:
  This class implements a policy to shut down the task scope when a subtask completes successfully. There shouldn't be any need to directly shut down the task scope with the `shutdown`PREVIEW method.
Since:
  21

- ## Nested Class Summary

  ### Nested classes/interfaces declared in class java.util.concurrent.StructuredTaskScopePREVIEW

  `StructuredTaskScope.ShutdownOnFailurePREVIEW, StructuredTaskScope.ShutdownOnSuccessPREVIEW<T>, StructuredTaskScope.SubtaskPREVIEW<T>`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `ShutdownOnSuccess()`
  Constructs a new unnamed `ShutdownOnSuccess` that creates virtual threads.
  `ShutdownOnSuccess(String name, ThreadFactory factory)`
  Constructs a new `ShutdownOnSuccess` with the given name and thread factory.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `StructuredTaskScope.ShutdownOnSuccessPREVIEW<T>`
  `join()`
  Wait for a subtask started in this task scope to complete successfullyPREVIEW or all subtasks to complete.
  `StructuredTaskScope.ShutdownOnSuccessPREVIEW<T>`
  `joinUntil(Instant deadline)`
  Wait for a subtask started in this task scope to complete successfullyPREVIEW or all subtasks to complete, up to the given deadline.
  `T`
  `result()`
  Returns the result of the first subtask that completed successfullyPREVIEW.
  `<X extends Throwable>
  T`
  `result(Function<Throwable,? extends X> esf)`
  Returns the result of the first subtask that completed successfullyPREVIEW, otherwise throws an exception produced by the given exception supplying function.

  ### Methods declared in class java.util.concurrent.StructuredTaskScopePREVIEW

  `close, ensureOwnerAndJoined, fork, handleComplete, isShutdown, shutdown`

  ### Methods declared in class java.lang.Object

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

- ## Constructor Details

  - ### ShutdownOnSuccess

    public ShutdownOnSuccess(String name, ThreadFactory factory)
    Constructs a new `ShutdownOnSuccess` with the given name and thread factory. The task scope is optionally named for the purposes of monitoring and management. The thread factory is used to `create` threads when subtasks are forkedPREVIEW. The task scope is owned by the current thread.

    Construction captures the current thread's scoped valuePREVIEW bindings for inheritance by threads started in the task scope. The Tree Structure section in the class description details how parent-child relations are established implicitly for the purpose of inheritance of scoped value bindings.

    Parameters:
      `name` - the name of the task scope, can be null
      `factory` - the thread factory

  - ### ShutdownOnSuccess

    public ShutdownOnSuccess()
    Constructs a new unnamed `ShutdownOnSuccess` that creates virtual threads.
    Implementation Requirements:
      This constructor is equivalent to invoking the 2-arg constructor with a name of `null` and a thread factory that creates virtual threads.

- ## Method Details

  - ### join

    public StructuredTaskScope.ShutdownOnSuccessPREVIEW<T> join() throws InterruptedException
    Wait for a subtask started in this task scope to complete successfullyPREVIEW or all subtasks to complete.

    This method waits for all subtasks by waiting for all threads startedPREVIEW in this task scope to finish execution. It stops waiting when all threads finish, a subtask completes successfully, or the current thread is interrupted. It also stops waiting if the `shutdown`PREVIEW method is invoked directly to shut down this task scope.

    This method may only be invoked by the task scope owner.

    Overrides:
      `join` in class `StructuredTaskScopePREVIEW<T>`
    Returns:
      this task scope
    Throws:
      `IllegalStateException` - if this task scope is closed
      `WrongThreadException` - if the current thread is not the task scope owner
      `InterruptedException` - if interrupted while waiting

  - ### joinUntil

    public StructuredTaskScope.ShutdownOnSuccessPREVIEW<T> joinUntil(Instant deadline) throws InterruptedException, TimeoutException
    Wait for a subtask started in this task scope to complete successfullyPREVIEW or all subtasks to complete, up to the given deadline.

    This method waits for all subtasks by waiting for all threads startedPREVIEW in this task scope to finish execution. It stops waiting when all threads finish, a subtask completes successfully, the deadline is reached, or the current thread is interrupted. It also stops waiting if the `shutdown`PREVIEW method is invoked directly to shut down this task scope.

    This method may only be invoked by the task scope owner.

    Overrides:
      `joinUntil` in class `StructuredTaskScopePREVIEW<T>`
    Parameters:
      `deadline` - the deadline
    Returns:
      this task scope
    Throws:
      `IllegalStateException` - if this task scope is closed
      `WrongThreadException` - if the current thread is not the task scope owner
      `InterruptedException` - if interrupted while waiting
      `TimeoutException` - if the deadline is reached while waiting

  - ### result

    public T result() throws ExecutionException
    Returns the result of the first subtask that completed successfullyPREVIEW.

    When no subtask completed successfully, but a subtask failedPREVIEW then `ExecutionException` is thrown with the subtask's exception as the cause.

    Returns:
      the result of the first subtask that completed successfullyPREVIEW
    Throws:
      `ExecutionException` - if no subtasks completed successfully but at least one subtask failed
      `IllegalStateException` - if no subtasks completed or the task scope owner did not join after forking
      `WrongThreadException` - if the current thread is not the task scope owner

  - ### result

    public <X extends Throwable> T result(Function<Throwable,? extends X> esf) throws X
    Returns the result of the first subtask that completed successfullyPREVIEW, otherwise throws an exception produced by the given exception supplying function.

    When no subtask completed successfully, but a subtask failedPREVIEW, then the exception supplying function is invoked with subtask's exception.

    Type Parameters:
      `X` - type of the exception to be thrown
    Parameters:
      `esf` - the exception supplying function
    Returns:
      the result of the first subtask that completed with a result
    Throws:
      `X` - if no subtasks completed successfully but at least one subtask failed
      `IllegalStateException` - if no subtasks completed or the task scope owner did not join after forking
      `WrongThreadException` - if the current thread is not the task scope owner