RFR (S) CR 8016236: Class.getGenericInterfaces performance improvement

[Aleksey Shipilev]

Hi,

This is the follow-up on the issue Doug identified:
  http://mail.openjdk.java.net/pipermail/core-libs-dev/2013-June/017798.html

I had reworked the patch, webrev is here:
  http://cr.openjdk.java.net/~shade/8016236/webrev.01/

Notable differences from Doug's version are:
  - handle non-generic cases as well
  - reuse ReflectionData to cache the interfaces and generic signatures
  - code style (chained ternary operators blown up)
  - fixes the race along the way
      http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6398355

Testing:
  - Linux x86_64/release: build OK
  - Linux x86_64/release: java/lang/reflect regression tests OK
  - Microbenchmarks show whooping increase in performance, see below

(If there are no stylistic and other comments, I would like to do the
JPRT submit and/or additional testing [which?]).

The benchmark is here (you need JMH to build and run):
  http://cr.openjdk.java.net/~shade/8016236/classbench.zip

Before:
> Benchmark                                       Mode Thr    Cnt  Sec         Mean   Mean error    Units
> o.b.ClassBench.generic_getGenericInterfaces     avgt   1      5    1      326.835        1.220  nsec/op
> o.b.ClassBench.generic_getGenericSuperclass     avgt   1      5    1      308.793        2.828  nsec/op
> o.b.ClassBench.generic_getTypeParameters        avgt   1      5    1      312.627        1.637  nsec/op
> o.b.ClassBench.raw_getGenericInterfaces         avgt   1      5    1      216.983        8.902  nsec/op
> o.b.ClassBench.raw_getGenericSuperclass         avgt   1      5    1       59.933        0.183  nsec/op
> o.b.ClassBench.raw_getTypeParameters            avgt   1      5    1       65.469        0.284  nsec/op

Doug's version:
> Benchmark                                       Mode Thr    Cnt  Sec         Mean   Mean error    Units
> o.b.ClassBench.generic_getGenericInterfaces     avgt   1      5    1       15.106        0.271  nsec/op
> o.b.ClassBench.generic_getGenericSuperclass     avgt   1      5    1        5.304        0.024  nsec/op
> o.b.ClassBench.generic_getTypeParameters        avgt   1      5    1       16.739        0.045  nsec/op
> o.b.ClassBench.raw_getGenericInterfaces         avgt   1      5    1      213.825        1.346  nsec/op
> o.b.ClassBench.raw_getGenericSuperclass         avgt   1      5    1       61.651        0.394  nsec/op
> o.b.ClassBench.raw_getTypeParameters            avgt   1      5    1       64.340        0.522  nsec/op

After:
> Benchmark                                       Mode Thr    Cnt  Sec         Mean   Mean error    Units
> o.b.ClassBench.generic_getGenericInterfaces     avgt   1      5    1       14.985        0.104  nsec/op
> o.b.ClassBench.generic_getGenericSuperclass     avgt   1      5    1        5.300        0.008  nsec/op
> o.b.ClassBench.generic_getTypeParameters        avgt   1      5    1       16.874        0.175  nsec/op
> o.b.ClassBench.raw_getGenericInterfaces         avgt   1      5    1       23.941        0.177  nsec/op
> o.b.ClassBench.raw_getGenericSuperclass         avgt   1      5    1        8.583        0.044  nsec/op
> o.b.ClassBench.raw_getTypeParameters            avgt   1      5    1       12.400        0.045  nsec/op

Thanks,
Aleksey.