RFR: 6983726: Reimplement MethodHandleProxies.asInterfaceInstance [v24]

[Mandy Chung]

On Tue, 11 Jul 2023 15:15:51 GMT, Chen Liang <liach at openjdk.org> wrote:

>> As John Rose has pointed out in this issue, the current j.l.r.Proxy based implementation of MethodHandleProxies.asInterface has a few issues:
>> 1. Exposes too much information via Proxy supertype (and WrapperInstance interface)
>> 2. Does not allow future expansion to support SAM[^1] abstract classes
>> 3. Slow (in fact, very slow)
>> 
>> This patch addresses all 3 problems:
>> 1. It updates the WrapperInstance methods to take an `Empty` to avoid method clashes
>> 2. This patch obtains already generated classes from a ClassValue by the requested interface type; the ClassValue can later be updated to compute implementation generation for abstract classes as well.
>> 3. This patch's faster than old implementation in general.
>> 
>> Benchmark for revision 17:
>> 
>> Benchmark                                                          Mode  Cnt      Score       Error  Units
>> MethodHandleProxiesAsIFInstance.baselineAllocCompute               avgt   15      1.503 ±     0.021  ns/op
>> MethodHandleProxiesAsIFInstance.baselineCompute                    avgt   15      0.269 ±     0.005  ns/op
>> MethodHandleProxiesAsIFInstance.testCall                           avgt   15      1.806 ±     0.018  ns/op
>> MethodHandleProxiesAsIFInstance.testCreate                         avgt   15     17.332 ±     0.210  ns/op
>> MethodHandleProxiesAsIFInstance.testCreateCall                     avgt   15     19.296 ±     1.371  ns/op
>> MethodHandleProxiesAsIFInstanceCall.callDoable                     avgt    5      0.419 ±     0.004  ns/op
>> MethodHandleProxiesAsIFInstanceCall.callHandle                     avgt    5      0.421 ±     0.004  ns/op
>> MethodHandleProxiesAsIFInstanceCall.callInterfaceInstance          avgt    5      1.731 ±     0.018  ns/op
>> MethodHandleProxiesAsIFInstanceCall.callLambda                     avgt    5      0.418 ±     0.003  ns/op
>> MethodHandleProxiesAsIFInstanceCall.constantDoable                 avgt    5      0.263 ±     0.003  ns/op
>> MethodHandleProxiesAsIFInstanceCall.constantHandle                 avgt    5      0.262 ±     0.002  ns/op
>> MethodHandleProxiesAsIFInstanceCall.constantInterfaceInstance      avgt    5      0.262 ±     0.002  ns/op
>> MethodHandleProxiesAsIFInstanceCall.constantLambda                 avgt    5      0.267 ±     0.019  ns/op
>> MethodHandleProxiesAsIFInstanceCall.direct                         avgt    5      0.266 ±     0.013  ns/op
>> MethodHandleProxiesAsIFInstanceCreate.createCallInterfaceInstance  avgt    5     18.057 ±     0.182 ...
>
> Chen Liang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix the lazy test, thanks Jorn Vernee!

I missed to comment on `getProxyClassLookup` - we agree to change this to synchronize on the holder object to avoid spinning multiple hidden classes when multiple threads are in the race of creating the wrapper class for the same interface.  Can you make the change?

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PR Comment: https://git.openjdk.org/jdk/pull/13197#issuecomment-1631116279