RFR: 8288723: Avoid redundant ConcurrentHashMap.get call in java.time [v2]

[Attila Szegedi]

On Sun, 3 Jul 2022 20:42:53 GMT, liach <duke at openjdk.org> wrote:

>> Andrey Turbanov has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8288723: Avoid redundant ConcurrentHashMap.get call in java.time
>>   use computeIfAbsent where lambda could be short and static
>
> src/java.base/share/classes/java/time/format/DateTimeTextProvider.java line 312:
> 
>> 310:     private Object findStore(TemporalField field, Locale locale) {
>> 311:         Entry<TemporalField, Locale> key = createEntry(field, locale);
>> 312:         return CACHE.computeIfAbsent(key, e -> createStore(e.getKey(), e.getValue()));
> 
> If `createStore` can be static, the call site will only have to construct a constant lambda than having to pass `this` to construct a new instance on every call

Well, if you _really_ want to noodle this for performance, you can also store a `this`-bound lambda in a `private final`  instance field, so then it's only created once too. I wouldn't put it past `javac` to do this, but I'd have to disassemble the bytecode of a little test program to see whether it's the case.

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