RFR: 8361018: Re-examine buffering and encoding conversion in BufferedWriter [v6]
Chen Liang
liach at openjdk.org
Wed Jul 2 15:03:41 UTC 2025
On Tue, 1 Jul 2025 00:01:21 GMT, Shaojin Wen <swen at openjdk.org> wrote:
>> BufferedWriter -> OutputStreamWriter -> StreamEncoder
>>
>> In this call chain, BufferedWriter has a char[] buffer, and StreamEncoder has a ByteBuffer. There are two layers of cache here, or the BufferedWriter layer can be removed. And when charset is UTF8, if the content of write(String) is LATIN1, a conversion from LATIN1 to UTF16 and then to LATIN1 will occur here.
>>
>> LATIN1 -> UTF16 -> UTF8
>>
>> We can improve BufferedWriter. When the parameter Writer instanceof OutputStreamWriter is passed in, remove the cache and call it directly. In addition, improve write(String) in StreamEncoder to avoid unnecessary encoding conversion.
>
> Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:
>
> Revert "BufferedWriter buffer use StringBuilder"
>
> This reverts commit da902ca0b0bd6acc003deb8ad1ca0d6485a29a27.
It is not about exposing the implementation details of StringBuilder: it is just exporting a method for StringBuilder to encode itself with an ArrayEncoder (which has LATIN1/UTF16 entrypoints) to general JDK audiences.
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PR Comment: https://git.openjdk.org/jdk/pull/26022#issuecomment-3028212631
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