RFR: 8278268 - (ch) InputStream returned by Channels.newInputStream should have fast path for FileChannel targets [v17]

[Markus KARG]

On Mon, 12 Dec 2022 20:04:40 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>> Markus KARG has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains one commit:
>> 
>>   Implementing 8278268
>>   
>>   Signed-off-by: Markus Karg <markus at headcrashing.eu>
>
> Which platform was used to generate the performance data? Also what was the source stream? Just asking as FileChannel.transferFrom uses copy_file_range for file-to-file (Linux), memory mapping for file-to-file, and a copy loop for other cases.
> 
> In any case, the changes to ChannelInputStream.transferTo does the right thing. Most of the change in the PR is the tests. I don't have time to look at those closely right now but Lance or Brian might have cycles.

@AlanBateman @LanceAndersen Kindly asking to resume this MR. Thanks! :-)

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PR: https://git.openjdk.org/jdk/pull/6711