RFR: 8293499: Provide jmod --compress option [v3]

[Mandy Chung]

On Mon, 12 Sep 2022 18:34:12 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> I have been looking into `make clean-images images` performance, and realized jmod keeps compressing files with default compression level. Tuning that toward lighter compression levels improves build performance considerably, without a heavy loss in *.jmod sizes. 
>> 
>> This PR allows JMOD to select the compression level. Follow-ups would use this in the build system, see #10214.
>> 
>> The interesting asymmetry against `jlink` is: `jlink` provides `--compress` option that only takes `2` for "ZIP compression". (Separately, we could argue if it would be beneficial to extend `--compress` to `jlink` as well, so to select the compression level there too.)
>
> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Adopt "--compress zip-[0-9]" as option format

I also like the new `--compress` option taking  `zip-0, zip-1,... zip-9` values.

src/jdk.jlink/share/classes/jdk/tools/jmod/JmodOutputStream.java line 58:

> 56:      * returning the output stream to write to the JMOD file.
> 57:      */
> 58:     static JmodOutputStream newOutputStream(Path file, LocalDateTime date, int compLevel) throws IOException {

Suggest to name this parameter  `compressLevel` to make it clear.

src/jdk.jlink/share/classes/jdk/tools/jmod/JmodTask.java line 171:

> 169:         Path extractDir;
> 170:         LocalDateTime date;
> 171:         int compLevel;

s/compLevel/compressLevel/

src/jdk.jlink/share/classes/jdk/tools/jmod/JmodTask.java line 1191:

> 1189:             if (idx != lastIdx) {
> 1190:                 throw new CommandException("err.compress.incorrect", value);
> 1191:             }

what about checking `value.substring(0, idx)` is "zip"?

test/jdk/tools/jmod/JmodTest.java line 807:

> 805:         jmod("create",
> 806:              "--class-path", cp,
> 807:              "--compress", "test",

good to have a test case verifying "test-0" value.

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PR: https://git.openjdk.org/jdk/pull/10213