RFR: 8316681: Rewrite URLEncoder.encode to use small reusable buffers [v2]

[Claes Redestad]

On Thu, 21 Sep 2023 16:16:42 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

>> Claes Redestad has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Minor refactoring, drop unnecessary double cast
>
> src/java.base/share/classes/java/net/URLEncoder.java line 245:
> 
>> 243:         CharsetEncoder ce = charset.newEncoder();
>> 244:         CharBuffer cb = CharBuffer.allocate(ENCODING_CHUNK_SIZE);
>> 245:         ByteBuffer bb = ByteBuffer.allocate((int)(ENCODING_CHUNK_SIZE * (double)ce.maxBytesPerChar()));
> 
> The cast to (double) is curious

It's copied from `String::scale`: 

    private static int scale(int len, float expansionFactor) {
        // We need to perform double, not float, arithmetic; otherwise
        // we lose low order bits when len is larger than 2**24.
        return (int)(len * (double)expansionFactor);
    }

... though admittedly this caveat doesn't apply since `len` in our case is a small constant value.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15865#discussion_r1333461724