RFR: 4452735: Add GZIPOutputStream constructor to specify Deflater

[Archie Cobbs]

On Fri, 19 Jul 2024 15:16:01 GMT, Lance Andersen <lancea at openjdk.org> wrote:

>>> I understand the request here, but is there a current use case for needing a custom Deflater?
>> 
>> I think the primary use case is when you want to set a non-default compression level, e.g., "best" or "fast". This is a pretty normal thing to do and matches what people expect from the `gzip(1)` command line flags. Allowing a custom `Deflater` is the simplest way to accomplish this; it also solves some other less common use cases, e.g., you want to set "no compression" for an already compressed file, or you want to keep the `Deflater` open so you can gather stats or whatever.
>> 
>>> Before adding additional features, I think GZIP could benefit with more test coverage.
>> 
>> Agreed. `GZIPOutputStream` does get some coverage in some of the `GZIPInputStream` tests, and this PR adds more testing, but certainly more is better.
>
>> > I understand the request here, but is there a current use case for needing a custom Deflater?
>> 
>> I think the primary use case is when you want to set a non-default compression level, e.g., "best" or "fast". This is a pretty normal thing to do and matches what people expect from the `gzip(1)` command line flags. Allowing a custom `Deflater` is the simplest way to accomplish this; it also solves some other less common use cases, e.g., you want to set "no compression" for an already compressed file, or you want to keep the `Deflater` open so you can gather stats or whatever.
> 
> thank you Archie.  I don't have an issue with the feature request, but given this API has been around for since JDK 1.1 and there has not been a must have push for this enhancement, I would prefer to focus on JDK-8322256 closed out and adding more overall test coverage before tackling this.
>> 
>> > Before adding additional features, I think GZIP could benefit with more test coverage.
>> 
>> Agreed. `GZIPOutputStream` does get some coverage in some of the `GZIPInputStream` tests, and this PR adds more testing, but certainly more is better.
> 
> Yes which why we should look to add additional tests, including more coverage from gzip files created via the gzip command line tool.

@LanceAndersen, if you have time now I'd like to pick this one back up. A review for the CSR is also needed. Thanks for any comments.

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PR Comment: https://git.openjdk.org/jdk/pull/20226#issuecomment-2594091292