RFR: 8310994: Add JFR event for selection operations [v6]

[Erik Gahlin]

On Wed, 10 Apr 2024 23:51:34 GMT, Tim Prinzing <tprinzing at openjdk.org> wrote:

>> Added mirror event with static methods: jdk.internal.event.SelectionEvent that provides the duration of select calls and the count of how many keys are available.
>> 
>> Emit the event from SelectorImpl::lockAndDoSelect
>> 
>> Test at jdk.jfr.event.io.TestSelectionEvents
>
> Tim Prinzing has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove selector spin event attempt and associated test.

src/jdk.jfr/share/classes/jdk/jfr/events/SelectorSelectEvent.java line 44:

> 42: 
> 43:     @Label("Timeout Value")
> 44:     @Description("Milliseconds to block, or zero to block indefinitely")

The unit should not be mentioned. A GUI will typically convert it from the TimeSpan information and it will just look confusing if the descriptions says milliseconds when it's, for instance, displayed as 1 s.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16710#discussion_r1560583317