RFR: 8259947: (fs) Optimize UnixPath.encode implementation [v3]

[Alan Bateman]

On Tue, 19 Jan 2021 12:26:08 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> This patch improves `UnixPath.encode` by reusing `JLA.getBytesNoRepl` (which has fast-paths for common encoding) and avoiding a `toCharArray` call on the input by refactoring the `normalizeNativePath` code to operate on `String`. This might have a cost on files on Mac that need additional native normalization.
>> 
>> This removes another `ThreadLocal` and a source of `SoftReference`s. Together with the UTF-8 fast-path my UTF-8 encoded file system see substantial speed-ups in a trivial `new File(str).toPath()` microbenchmark.
>
> Claes Redestad has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Move JLA to top, add imports

Marked as reviewed by alanb (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/2135