On Thu, 6 Apr 2023 03:44:07 GMT, Chen Liang <li...@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 implements proxies with one hidden class for each requested interface >> and replaced WrapperInstance inheritance with an annotation. This can avoid >> unexpected passing of `instanceof`, and avoids the nasty problem of >> exporting a JDK interface to a dynamic module to ensure access. >> 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 generated hidden classes has call performance on par with >> those of lambda expressions; the creation performance is slightly less than >> that of LambdaMetafactory: >> https://jmh.morethan.io/?gist=fcb946d83ee4ac7386901795ca49b224 >> >> Additionally, an obsolete `ProxyForMethodHandle` test was removed, for it's >> no longer applicable. Tests in `jdk/java/lang/invoke` and >> `jdk/java/lang/reflect` pass. >> >> In addition, I have a question: in >> [8161245](https://bugs.openjdk.org/browse/JDK-8161245) it seems some fields >> can be optimized as seen in >> [ciField.cpp](https://github.com/openjdk/jdk/blob/6aec6f3a842ead30b26cd31dc57a2ab268f67875/src/hotspot/share/ci/ciField.cpp#L219). >> Does it affect the execution performance of MethodHandle in hidden classes' >> Condy vs. MethodHandle in regular final field in hidden classes? >> >> [^1]: single abstract method > > Chen Liang has updated the pull request incrementally with one additional > commit since the last revision: > > Whitespace, cleanup, rename benchmarks to be informative src/java.base/share/classes/java/lang/invoke/MethodHandleProxies.java line 284: > 282: return > type.getDeclaredAnnotation(WrapperInstance.class); > 283: } > 284: }) : type.getDeclaredAnnotation(WrapperInstance.class); This may introduce a security vulnerability: @AnnotationTest.ClassHolder(sun.misc.Unsafe.class) public class AnnotationTest { @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @interface ClassHolder { Class<?> value(); } public static void main(String[] args) throws PrivilegedActionException { MethodHandleProxies.isWrapperInstance(new AnnotationTest()); System.out.println(AnnotationTest.class.getDeclaredAnnotation(ClassHolder.class).value()); } } Don't parse annotations in a privileged context. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/13197#discussion_r1159989152
