RFR: 8293839: Documentation memory consistency effects of runLater

[Jens Lidestrom]

On Tue, 6 Sep 2022 16:20:02 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> Prior to this change it was not clear from the documentation if callers of Platform#runLater must perform
>> any synchronisation to have writes of the calling thread be visible in the JavaFX Application
>> Thread. It is important to document either if callers can rely on runLater to do such synchronisation
>> internally, or to document is users CAN NOT rely on runLater for this.
>> 
>> This change documents that actions in a thread prior to submitting a runnable to
>> Platform#runLater happen-before actions performed by the runnable in the JavaFX
>> Application Thread.
>> 
>> runLater inherits the memory consistency effects of InvokeLaterDispatcher in most cases. 
>> InvokeLaterDispatcher uses BlockingDeque internally. This change documents this
>> in the same way as it is documented by BlockingDeque.
>> 
>> Other implementations of runLater should have similar memory consistency effects.
>
> @jensli I was going through the PRs that are not marked as `rfr` (ready for review), and spotted this one. There are two needed steps before this will be marked as ready:
> 
> 1. You need to file a bug report
> 2. You need to fix the whitespace error pointed out by `jcheck`  in the code diffs
> 
> See [CONTRIBUTING.md](https://github.com/openjdk/jfx/blob/master/CONTRIBUTING.md) for more information.

@kevinrushforth This is now finished. Can you review?

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PR: https://git.openjdk.org/jfx/pull/872