RFR: 8278268 - (ch) InputStream returned by Channels.newInputStream should have fast path for FileChannel targets [v21]

[Brian Burkhalter]

On Sat, 18 Mar 2023 16:35:15 GMT, Markus KARG <duke at openjdk.org> wrote:

>> This sub-issue defines the work to be done to implement JDK-8265891 solely for the particular case of FileChannel.transferFrom(ReadableByteChannel), including special treatment of SelectableByteChannel.
>
> Markus KARG has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Abstracted testMoreThanTwoGB

test/jdk/java/nio/channels/Channels/TransferToBase.java line 222:

> 220:                         byte[] rndBytes = createRandomBytes(BYTES_PER_WRITE, 0);
> 221:                         ByteBuffer src = ByteBuffer.wrap(rndBytes);
> 222:                         fc.write(src);

Should this code perhaps allow for a short write, i.e., `FileChannel::write` returning a value less than `rndBytes.length`? For example, something like this:

                    long pos = initPos;
                    while (pos < BYTES_WRITTEN) {
                        int len = Math.toIntExact(BYTES_WRITTEN - pos);
                        if (len > BYTES_PER_WRITE)
                            len = BYTES_PER_WRITE;
                        byte[] rndBytes = createRandomBytes(len, 0);
                        ByteBuffer src = ByteBuffer.wrap(rndBytes);
                        pos += fc.write(src);
                    }

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PR Review Comment: https://git.openjdk.org/jdk/pull/6711#discussion_r1142672553