RFR: 8303891: Speed up Zip64SizeTest using a small ZIP64 file [v5]

[Eirik Bjørsnøs]

On Fri, 9 Feb 2024 06:39:31 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

>> Eirik Bjørsnøs has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 13 additional commits since the last revision:
>> 
>>  - Use a small ZIP64 file to reproduce the issue. Convert test to JUnit
>>  - Update copyright year for 2024
>>  - Use ENTRY instead of FILE when refering to names and sizes of file entries in the ZIP file
>>  - Merge branch 'master' into zip64-size-test-sparse
>>  - Merge branch 'master' into zip64-size-test-sparse
>>  - Sparse files must be created explicitly on NTFS
>>  - Merge branch 'master' into zip64-size-test-sparse
>>  - Merge branch 'master' into zip64-size-test-sparse
>>  - Make test method public
>>  - Add a missing "when" in Javadocs for SparseOutputStream
>>  - ... and 3 more: https://git.openjdk.org/jdk/compare/1bff6cd8...41b2ba5e
>
> test/jdk/java/util/zip/ZipFile/Zip64SizeTest.java line 53:
> 
>> 51:     // ZIP file to create
>> 52:     private static final Path ZIP_FILE = Path.of("Zip64SizeTest.zip");
>> 53:     // ontents to write to ZIP entries
> 
> Typo - should have been "contents"

Thanks, fixed.

> Hello Eirik, I couldn't understand why we first add a opaque extra field first and then update it to be a zip64 extra field. Why do we do this?

`ZipEntry.setExtra` processes the byte array argument, looking for Zip64 extended fields which it can extract the size fields from. To prevent this parsing from happening, we temporarily use the `unknown` tag.

In this particular case, `ZipExtra.setExtra` actually ends up skipping this processing (because `isLOC == true` and it has a guard for the block size being `>= 16`).

However, I prefer the test to not depend too much on the details of `setExtra` Zip64 processing. This trick is used in other tests as well and may be copied over to a test where the conditions are not the same.

I have refactored a bit and added some code comments to help explain the use of the 'unknown' tag.

Do you think this makes sense?

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

PR Review Comment: https://git.openjdk.org/jdk/pull/12948#discussion_r1484148941
PR Review Comment: https://git.openjdk.org/jdk/pull/12948#discussion_r1484148034