Module java.base

Package java.util.concurrent

Class StructuredTaskScope.ShutdownOnSuccess<T>

java.lang.Object

java.util.concurrent.StructuredTaskScope^PREVIEW<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 successfully^PREVIEW. Once captured, it shuts down^PREVIEW 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.StructuredTaskScope^PREVIEW

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.StructuredTaskScope^PREVIEW

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 forked^PREVIEW. The task scope is owned by the current thread.

Construction captures the current thread's scoped value^PREVIEW 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 successfully^PREVIEW or all subtasks to complete.

This method waits for all subtasks by waiting for all threads started^PREVIEW 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 successfully^PREVIEW or all subtasks to complete, up to the given deadline.

This method waits for all subtasks by waiting for all threads started^PREVIEW 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 successfully^PREVIEW.

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

Returns:

the result of the first subtask that completed successfully^PREVIEW

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 successfully^PREVIEW, otherwise throws an exception produced by the given exception supplying function.

When no subtask completed successfully, but a subtask failed^PREVIEW, 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