RFR (S) CR 8006627: Improving performance and reducing object allocations of java.util.UUID to/from string

[Steven Schlansker]

On Jan 30, 2013, at 11:42 AM, Mike Duigou <mike.duigou at oracle.com> wrote:

> Good work Steven! 

Thanks for the review :)
> 
> Some initial comments;
> 
> - The changes to Long should be in a separate issue. It's generally encouraged for changesets to focus on only one change. Sorry, yes, it's additional overhead.

That's unfortunate.  I don't have the ability / know how to file a second, separate issue, and I've already spent a lot more time trying to get this small change through than I'd expected on overhead.  Will it be preferable to have someone open a second issue, make two web revs, and code review both, or should I just abandon the attempt at code-sharing between UUID and Long?  In the original patch that Aleksey reviewed I had not attempted this; I did it on his suggestion.

> 
> - I would like to see if performed of toString() can be improved further by using String(char[] value, boolean share) constructor via a sun.miscSharedSecret.JavaLangAccesss method to construct the string directly from the character array. You could test to see if this has positive benefit by temporarily using a static char array.

I will incorporate this into my next revision

> 
> - public static String toString(long msb, long lsb) should be private. There's no compelling reason to add this to the API.
> 

I can remove this.  I added it on the theory that if you wish to ship UUIDs around as two longs, it may be useful to omit UUID object instantiation just to format as a string.  Maybe this is too far out there to make another public method acceptable.

> - Have you run this code against any of the existing regression tests?

Yes, I ran the jtreg UUID and Long tests, all pass.  I ran the Apache Harmony UUID test cases against the pre-integrated version of the code.  (There should only have been minor modifications since then, variable renamings, whatnot…)

> 
> Mike
> 
> On Jan 28 2013, at 19:23 , Steven Schlansker wrote:
> 
>> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8006627
>> 
>> I have created a patch that dramatically improves UUID to/from string performance.
>> Please find below a webrev with my proposed changes.
>> 
>> Thanks in advance for any feedback on the contents.
>> I do not believe I have a committer lined up yet.
>> My company has a signed OCA on file, "Ness Computing".
>> 
>> http://dl.dropbox.com/u/1422321/uuid_webrev/index.html
>> http://dl.dropbox.com/u/1422321/uuid_webrev.zip
>> 
>