RFR: 8361209: (bf) Use CharSequence::getChars for StringCharBuffer bulk get methods [v2]

[Brett Okken]

On Mon, 14 Jul 2025 21:43:25 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> For `CharBuffer`s created from a `CharSequence`, use `CharSequence.getChars` to perform bulk gets instead of successively copying single characters.
>
> Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8361209: Fix problems due to ignoring slice offset

I think all 3 of those methods are implemented in the template to call through to a private `getArray` method in the template. Would it be simpler to make that method package scope and override it in StringCharBuffer?
https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/java/nio/X-Buffer.java.template#L953

In the X-Buffer template, there is a bulk putBuffer, with special handling for when the source is a `StringCharBuffer` to copy one byte at time.
https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/java/nio/X-Buffer.java.template#L1150-L1157
If the source is a `StringCharBuffer` and the instance we are putting into has a `char[]`, we should be able to use bulk transfer.

Maybe something like:


        } else { // src.isAddressable() == false
            assert StringCharBuffer.class.isInstance(src);
            if (this.hb != null) {
                ((StringCharBuffer) src).getArray(srcPos, this.hb, pos, n);
            } else {
                int posMax = pos + n;
                for (int i = pos, j = srcPos; i < posMax; i++, j++)
                    put(i, src.get(j));
            }
        }

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PR Comment: https://git.openjdk.org/jdk/pull/26251#issuecomment-3073206634
PR Comment: https://git.openjdk.org/jdk/pull/26251#issuecomment-3073229159