<i18n dev> RFR: 8304976: Optimize DateTimeFormatterBuilder.ZoneTextPrinterParser.getTree() [v2]

[Naoto Sato]

On Wed, 29 Mar 2023 08:16:32 GMT, Sergey Tsypanov <stsypanov at openjdk.org> wrote:

>> 1) When `DateTimeFormatter` is reused we don't need to copy `availableZoneIds` and allocate `nonRegionIds` as PrefixTree can be taken from cache. In the related benchmark allocation of `HashSet` takes ~93% of all time, so avoiding it should bring some improvement for cases when we reuse `DateTimeFormatter` to parse a string into `ZoneDateTime`
>> ![image](https://user-images.githubusercontent.com/10835776/219609028-af48eae4-d326-4719-8366-c215baa85835.png)
>> 
>> 2) `DateTimeFormatter` is mostly used with one locale, so `cachedTree` and `cachedTreeCI` can have predefined size.
>> 
>> 
>> @State(Scope.Thread)
>> @BenchmarkMode(Mode.AverageTime)
>> @OutputTimeUnit(TimeUnit.NANOSECONDS)
>> public class DateTimeFormatterBenchmark {
>> 
>>     private static final DateTimeFormatter df = new DateTimeFormatterBuilder().appendPattern("yyyy:MM:dd:HH:mm:v").toFormatter();
>>     private static final String TEXT = "2015:03:10:12:13:ECT";
>> 
>>     @Setup
>>     public void setUp() {
>>         ZonedDateTime.parse(TEXT, df);
>>     }
>> 
>>     @Benchmark
>>     public ZonedDateTime parse() {
>>         return ZonedDateTime.parse(TEXT, df);
>>     }
>> }
>
> Sergey Tsypanov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8304745: Fix package

LGTM

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Marked as reviewed by naoto (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/12612#pullrequestreview-1363506079