<i18n dev> RFR: 8288723: Avoid redundant ConcurrentHashMap.get call in java.time [v2]

[Attila Szegedi]

On Tue, 28 Jun 2022 07:27:30 GMT, Andrey Turbanov <aturbanov at openjdk.org> wrote:

>> src/java.base/share/classes/java/time/temporal/WeekFields.java line 331:
>> 
>>> 329:         String key = firstDayOfWeek.toString() + minimalDaysInFirstWeek;
>>> 330:         WeekFields rules = CACHE.get(key);
>>> 331:         if (rules == null) {
>> 
>> Perhaps you don't even need this `if` block and the preceding `CACHE.get(key)` and maybe it can be replaced with:
>> 
>> 
>> return CACHE.computeIfAbsent(key, ignore -> new WeekFields(firstDayOfWeek, minimalDaysInFirstWeek));
>
> But it will generate garbage: non-static lambda.

It already generates some garbage as it does string concatenation for the key. Here's an idea: declare a record class for the key, `record CacheKey(DayOfWeek firstDayOfWeek, int minimalDaysInFirstWeek)`. It will be more efficient than using strings for keys, and then you can have a static lambda.

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PR: https://git.openjdk.org/jdk/pull/9208