RFR: 8196334: Optimize UUID#fromString

[Ivan Gerasimov]

Hi Claes and Andriy!

It looks good overall.

I wonder if it'll be even faster if the fast path were implemented in 
StringLatin1 (for compact strings only) and was called via 
SharedSecrets/JavaLangAccess?

Then, you could operate directly on bytes and avoid dealing with longs.

With kind regards,

Ivan


On 2/28/20 6:22 AM, Claes Redestad wrote:
> Hi all,
>
> please review this patch to optimize UUID#fromString.
>
> Jon Chambers originally proposed a patch that used a strict parser to
> get a similar speed-up, but I failed to adapt it in a way that
> could fall back to the less strict behavior while maintaining a
> reasonable speed-up in the fast-path case. Sorry, Jon!
>
> The patch proposed here was recently contributed by Andriy Plokhotnyuk
> (OCA signed), and manages to get more than a 3x speed-up on the new
> fromString microbenchmark, while falling back gently to the current,
> less strict implementation if ever needed. I've done some light edits,
> and added a simple microbenchmark.
>
> Bug:    https://bugs.openjdk.java.net/browse/JDK-8196334
> Webrev: http://cr.openjdk.java.net/~redestad/8196334/open.00/
>
> Testing: tier1-3
>
> Thanks!
>
> /Claes

-- 
With kind regards,
Ivan Gerasimov