RFR: 8326099: GZIPOutputStream should use Deflater.getBytesRead() instead of Deflater.getTotalIn()

[Jaikiran Pai]

On Sat, 17 Feb 2024 12:08:38 GMT, Eirik Bjørsnøs <eirbjo at openjdk.org> wrote:

> Please review this cleanup PR in preparation for deprecating `Deflater.getTotalIn()` in JDK-8326096. 
> 
> This PR replaces `GZIPOutputStream.writeTrailer`'s call to `Deflater.getTotalIn()` with a call to `Deflater.getBytesRead()` followed by an explicit conversion to "modulo 2^32" (a cast to int) as described in RFC 1952:
> 
> 
>  ISIZE (Input SIZE)
>   This contains the size of the original (uncompressed) input
>   data modulo 2^32.
> 
> 
> Testing and verification: This should be trivially verifiable by code inspection. Nevertheless, I wrote a test which writes Integer.MAX_VALUE +1 bytes of uncompressed data and verified that the last four bytes written to the file was indeed as expected. (This test is not included in this PR because of its runtime and resource requirements).

Hello Eirik, the change looks OK to me. 

For context, the `getTotalIn()` and `getTotalOut()` methods are being proposed for deprecation https://mail.openjdk.org/pipermail/core-libs-dev/2024-February/119321.html. `getTotalIn()` was doing the same `(int) getBytesRead()` internally, so this change should be OK.

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Marked as reviewed by jpai (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/17900#pullrequestreview-1887705275