On Mon, 27 Feb 2023 09:14:56 GMT, Viktor Klang <d...@openjdk.org> wrote:
>> I noticed when looking at the code that there was no real need to use a CHM
>> to perform the tracking of activation in an ordered fashion on
>> ForEachOrderedTask, but instead a VarHandle can be used, reducing
>> allocations and indirection.
>
> Viktor Klang has updated the pull request with a new target base due to a
> merge or a rebase. The pull request now contains three commits:
>
> - Updating copyright header of ForEachOps.java and removing unnecessary
> suppression of an unchecked cast.
> - Write the initial value of the next reference without using the VarHandle
> - JDK-8302666: Replace CHM with VarHandle in ForeachOrderedTask
src/java.base/share/classes/java/util/stream/ForEachOps.java line 513:
> 511: // of right subtree (if any, which can be this task's right
> sibling)
> 512: //
> 513: var leftDescendant = (ForEachOrderedTask<S,
> T>)NEXT.getAndSet(this, null);
Casting the `null` is required for the resolved method descriptor to be
`(ForEachOrderedTask, ForEachOrderedTask)ForEachOrderedTask` instead of
`(ForEachOrderedTask, Object)ForEachOrderedTask`, which prevents unnecessary
type conversion `LambdaForm`s from being introduced and allows
[`VarHandle::withInvokeExactBehavior`] to be used:
Suggestion:
var leftDescendant = (ForEachOrderedTask<S, T>)
NEXT.getAndSet(this, (ForEachOrderedTask<S, T>) null);
[`VarHandle::withInvokeExactBehavior`]:
https://docs.oracle.com/en/java/javase/19/docs/api/java.base/java/lang/invoke/VarHandle.html#withInvokeExactBehavior()
-------------
PR: https://git.openjdk.org/jdk/pull/12320
