ClassValue perf?

[Remi Forax]

Hi Mickael, 
the experience has proven that the code of ClassValue is hard to get right, adding any optimization into such code will make it more complex, less readable, more error prone so any optimization introduced as to really worth it. 
I may have not correctly read the perf number, but IMO it's not enough. 

The other problem is that ClassValue is currently used by the implementations of method handles and var handles and may be used by several other classes in the future, so the optimization is/will not be very reliable. 

I've not seriously review your patch but the first two lines of removeSingleEntry seems rather mysterious. 

cheers, 
Rémi 

----- Mail original -----

> De: "Michael Haupt" <michael.haupt at oracle.com>
> À: "Da Vinci Machine Project" <mlvm-dev at openjdk.java.net>
> Envoyé: Vendredi 29 Avril 2016 13:19:32
> Objet: Re: ClassValue perf?

> Hi Jochen,

> > Am 29.04.2016 um 12:17 schrieb Jochen Theodorou < blackdrag at gmx.org >:
> 
> > my fear is a bit that having only a single value, will not be enough if you
> > have for example multiple dynamic languages running... let's say Nashorn,
> > JRuby, and Groovy. Also, if I ever get there, using multiple values would
> > become a normal case in Groovy.
> 

> > So any size depending optimization looks problematic for me
> 

> I may misunderstand you here - note the patch does not introduce a
> single-value *only* ClassValue. The patch is meant to introduce a special
> case for as long as there is only one value associated with a class. As soon
> as a second value comes in, the ClassValue will transition to the usual map
> storage.

> Please let me know if this is a response to your concern.

> Best,

> Michael

> --

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