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:

> Which platform was used to generate the performance data?

Ubuntu 20.04.5 LTS (x86_64)

> Also what was the source stream?

`Channels.newInputStream(Channels.newChannel(new ByteArrayInputStream(byte[size])))`

> 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.

Yes, but apparently `FileChannel.transferFrom` is doing such copy loop more efficient than `InputStream.transferTo`'s loop.

> 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.

Thanks. Please remember that the code was already reviewed and test-driven by Lance a year ago and just was held back due to the bug in Windows's Socket implementation, *discovered by* this PR's test.

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

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