<i18n dev> RFR: 8278642: Refactor java.util.Formatter

[Claes Redestad]

On Tue, 14 Dec 2021 00:14:32 GMT, Claes Redestad <redestad at openjdk.org> wrote:

> A few refactorings to how `java.util.Formatter` sets up `FormatString`s, aligning the implementation with changes explored by the TemplatedStrings JEP and ever so slightly improving performance:
> 
> - turn `Flags` into an `int` (fewer allocations in the complex case)
> - remove some superfluous varargs: `checkBadFlags(Flags.PARENTHESES, ...` -> `checkBadFlags(Flags.Parentheses | ...` - again less allocations in the complex cases since these varargs arrays were being allocated. Also improves error messages since all bad flags will be listed in the exception message.
> - make `FormatSpecifier` and `FixedString` static, reducing size of these objects slightly.
> 
> Baseline: 
> 
> Benchmark                                                           Mode  Cnt     Score     Error   Units
> StringFormat.complexFormat                                          avgt   25  8977.043 ± 246.810   ns/op
> StringFormat.complexFormat:·gc.alloc.rate.norm                      avgt   25  2144.170 ±   0.012    B/op
> StringFormat.stringFormat                                           avgt   25   252.109 ±   2.732   ns/op
> StringFormat.stringFormat:·gc.alloc.rate.norm                       avgt   25   256.019 ±   0.001    B/op
> StringFormat.stringIntFormat                                        avgt   25   576.423 ±   4.596   ns/op
> StringFormat.stringIntFormat:·gc.alloc.rate.norm                    avgt   25   432.034 ±   0.002    B/op
> StringFormat.widthStringFormat                                      avgt   25   999.835 ±  20.127   ns/op
> StringFormat.widthStringFormat:·gc.alloc.rate.norm                  avgt   25   525.509 ±  14.742    B/op
> StringFormat.widthStringIntFormat                                   avgt   25  1332.163 ±  30.901   ns/op
> StringFormat.widthStringIntFormat:·gc.alloc.rate.norm               avgt   25   720.715 ±   8.798    B/op
> 
> 
> Patch:
> 
> Benchmark                                                           Mode  Cnt     Score    Error   Units
> StringFormat.complexFormat                                          avgt   25  8840.089 ± 51.222   ns/op
> StringFormat.complexFormat:·gc.alloc.rate.norm                      avgt   25  1736.151 ±  0.009    B/op
> StringFormat.stringFormat                                           avgt   25   247.310 ±  2.091   ns/op
> StringFormat.stringFormat:·gc.alloc.rate.norm                       avgt   25   248.018 ±  0.001    B/op
> StringFormat.stringIntFormat                                        avgt   25   565.487 ±  6.572   ns/op
> StringFormat.stringIntFormat:·gc.alloc.rate.norm                    avgt   25   408.032 ±  0.002    B
> StringFormat.widthStringFormat                                      avgt   25   970.015 ± 32.915   ns/op
> StringFormat.widthStringFormat:·gc.alloc.rate.norm                  avgt   25   449.991 ± 25.716    B/op
> StringFormat.widthStringIntFormat                                   avgt   25  1284.572 ± 28.829   ns/op
> StringFormat.widthStringIntFormat:·gc.alloc.rate.norm               avgt   25   636.872 ±  7.331    B/op

Re-ran tier1+2 in our CI due to the mystery error in GHA testing. All passed.

-------------

PR: https://git.openjdk.java.net/jdk/pull/6821