RFR: 8365611: Use lookup table for JfrEventThrottler [v2]

[Markus Grönlund]

On Wed, 20 Aug 2025 16:47:44 GMT, Robert Toyonaga <duke at openjdk.org> wrote:

>> Thomas Stuefe has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Markus Feedback
>
> src/hotspot/share/jfr/recorder/service/jfrEventThrottler.cpp line 103:
> 
>> 101: JfrEventThrottler* JfrEventThrottler::for_event(JfrEventId event_id) {
>> 102:   JfrEventThrottler* const throttler = _throttler_table.at(event_id);
>> 103:   assert(throttler != nullptr, "Event type %d has an unconfigured throttler", (int)event_id);
> 
> The call to configure throttlers originates from up in the Java level JFR code.  Would it be possible to attempt sampling when a throttler is created, but not yet configured? 
> 
> If this is possible, then it was possible before this PR too (not introduced here).

The settings system prevents this situation, because configure -> !enabled

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PR Review Comment: https://git.openjdk.org/jdk/pull/26801#discussion_r2290535281