RFR: 8320971: Use BufferedInputStream.buf directly when param of implTransferTo() is trusted [v17]

[Markus KARG]

On Fri, 22 Dec 2023 09:55:15 GMT, Sergey Tsypanov <stsypanov at openjdk.org> wrote:

>> It looks like we can skip copying of `byte[]` in `BufferedInputStream.implTransferTo()` for `OutputStreams` residing in `java.io`.
>> 
>> See comment by @vlsi in https://github.com/openjdk/jdk/pull/10525/files#diff-e19c508d1bb6ee78697ecca66947c395adda0d9c49a85bf696e677ecbd977af1R612
>
> Sergey Tsypanov 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 22 additional commits since the last revision:
> 
>  - Merge branch 'master' into 8320971
>  - 8320971: Inline tests
>  - 8322292: Remove TransferToTrusted.checkedOutputStream()
>  - 8320971: Adjust JavaDoc
>  - Merge branch 'master' into 8320971
>  - 8320971: Revert irrelevant changes
>  - 8320971: Add more tests
>  - 8320971: Fix JavaDoc
>  - 8320971: Whitespaces
>  - 8320971: Fix build
>  - ... and 12 more: https://git.openjdk.org/jdk/compare/17ab55e8...ee035998

test/jdk/java/io/BufferedInputStream/TransferToTrusted.java line 68:

> 66: 
> 67:         var bis = new BufferedInputStream(new ByteArrayInputStream(dup));
> 68:         bis.mark(dup.length);

If you take a closer look into `BIS::transferTo()` then you will notice that in case you call `bis.mark()` then your optimization will effectively *not getting called at all*, due to this line: https://github.com/openjdk/jdk/pull/16879/files#diff-e19c508d1bb6ee78697ecca66947c395adda0d9c49a85bf696e677ecbd977af1L643. So Brian's comment still applies and you should fix your test before this PR can be accepted for a merge (hence: you MUST get rid of `mark()`).

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PR Review Comment: https://git.openjdk.org/jdk/pull/16879#discussion_r1435050559