<i18n dev> RFR: 8368172: Make java.time.format.DateTimePrintContext immutable [v6]

[Shaojin Wen]

On Thu, 2 Oct 2025 03:08:32 GMT, Shaojin Wen <swen at openjdk.org> wrote:

>> I propose to make j.t.f.DateTimePrintContext immutable.
>> 
>> Currently, DateTimePrintContext has only one mutable field, optional. This can be replaced by adding an optional parameter to the DateTimeFormatter.formatTo method.
>> 
>> Immutable DateTimePrintContext can be optimized by escape analysis, such as immutable object optimization.
>
> Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Improve javadoc for optional parameter in DateTimePrinterParser#format method

Creating a DateTimePrintContext during the formatting process also has a disadvantage: it is difficult to perform manual unrolling performance optimizations like the draft PR #26807 I submitted, and it also makes automatic unrolling by the C2 JIT more difficult.

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PR Comment: https://git.openjdk.org/jdk/pull/26913#issuecomment-3361498045