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

[Aleksey Shipilev]

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

test/micro/org/openjdk/bench/java/io/FileOpen.java line 103:

> 101:     @Warmup(time=2, iterations=5)
> 102:     @Measurement(time=3, iterations=5)
> 103:     @Fork(value=2, jvmArgs="-Xmx1g")

I thought this can be inherited from the enclosing benchmark.

test/micro/org/openjdk/bench/java/io/FileOpen.java line 104:

> 102:     @Measurement(time=3, iterations=5)
> 103:     @Fork(value=2, jvmArgs="-Xmx1g")
> 104:     public static class ToPath {

Do we really have to nest this test? It seems to gain nothing per se: the annotations and fields are still pretty much duplicated.

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