Integrated: 8342486: Implement JEP 505: Structured Concurrency (Fifth Preview)

[Alan Bateman]

On Wed, 6 Nov 2024 15:47:55 GMT, Alan Bateman <alanb at openjdk.org> wrote:

> Changes for [JEP 505: Structured Concurrency (Fifth Preview)](https://openjdk.org/jeps/8340343). The proposal is to re-preview the API with some changes, specifically:
> 
> - A [StructuredTaskScope](https://download.java.net/java/early_access/loom/docs/api/java.base/java/util/concurrent/StructuredTaskScope.html) is now opened with a static factory method instead of a constructor.  Once opened, the API usage is unchanged: fork subtasks individually, join them as a unit, process outcome, and close.
> - In conjunction with moving to using a static open method, policy and desired outcome is now selected by specifying a Joiner to the open method rather than extending STS. A Joiner handles subtask completion and produces the result for join to return. Joiner.onComplete is the equivalent of overriding handleComplete previously. This change means that the subclasses ShutdownOnFailure and ShutdownOnSuccess are removed, replaced by factory methods on Joiner to get an equivalent Joiner.
> - The join method is changed to return the result or throw STS.FailedException, replacing the need for an API in subclasses to obtain the outcome. This removes the hazard that was forgetting to call throwIfFailed to propagate exceptions.
> - Configuration that was provided with parameters for the constructor is changed so that can be provided by a configuration function.
> - joinUntil is replaced by allowing a timeout be configured by the configuration function. This allows the timeout to apply the scope rather than the join method.
>  
> The underlying implementation is unchanged except that ThreadFlock.shutdown and wakeup methods are no longer confined. The STS API implementation moves to non-public StructuedTaskScopeImpl because STS is now an interface. A non-public Joiners class is added with the built-in Joiner implementations.

This pull request has now been integrated.

Changeset: 132a890a
Author:    Alan Bateman <alanb at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/132a890a9b3b70f2358237ebd9242b6747ba03dd
Stats:     4036 lines in 14 files changed: 1818 ins; 1438 del; 780 mod

8342486: Implement JEP 505: Structured Concurrency (Fifth Preview)

Co-authored-by: Alan Bateman <alanb at openjdk.org>
Co-authored-by: Viktor Klang <vklang at openjdk.org>
Reviewed-by: vklang

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PR: https://git.openjdk.org/jdk/pull/21934