RFR: 8271308: (fc) FileChannel.transferTo() transfers no more than Integer.MAX_VALUE bytes in one call [v2]

[Brian Burkhalter]

On Tue, 3 Aug 2021 09:42:29 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>> In the updated code, the direct transfer case no longer loops and just maps to one syscall. The previously introduced private `transferTo()` method is removed. `transferToArbitraryChannel()` is modified to have a `long`-valued count. `transferToTrustedChannel()` works out of the box as-is and is not changed.
>
> The update mostly looks okay, just wondering if could case maxDirectTransferSize to avoid the JNI call every time.

I think it could be a constant equal to either the Linux or Windows value, not `Integer.MAX_VALUE`, as that would force `TransmiteFile()` to fail for the `MAX_VALUE` case. Or the JNI call could be made just once when setting up.

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PR: https://git.openjdk.java.net/jdk/pull/4940