# Wednesday, 04 June 2014
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New Development Snapshot

More progress on the OpenJDK 8 integration and a couple of unrelated fixes.

I fixed an incompatibility with Mono (and other ECMA compliant tools that parse custom attributes). When I changed package manifest handling in 7.4 to handle reading the manifest from the right jar I unknowingly chose a custom attribute encoding that works on the CLR, but isn't actually ECMA compliant. Mono has since added support for this encoding.

Another somewhat interesting change is that I added an (internal only) feature to make it easier to replace sun.misc.Unsafe.compareAndSet() with Interlocked.CompareExchange. The trigger was the new reflection data caching in java.lang.Class. Here's an example of what it looks like:

@ikvm.internal.InterlockedCompareAndSet("reflectionData")
static native boolean casReflectionData(Class<?> clazz,
                                        SoftReference<ReflectionData<T>> oldData,
                                        SoftReference<ReflectionData<T>> newData);

The ikvmc compiler will generate a method body that uses Interlocked.CompareExchange<T>() to update the reflectionData field in Class. In other places where I previously used Interlocked methods (e.g. java.util.concurrent.AtomicReferenceArray) I implemented the method body in map.xml using MSIL instructions, but here the generic version of CompareExchange is needed and I didn't want to invent a syntax for instantiating a generic method in map.xml.

Oracle is working on adding atomic operations to Java and I suggested this annotation based approach, but it was rejected because "we don't add language semantics through annotations".

Changes:

  • Implemented method parameter reflection.
  • Compile class library with javac -parameters option to get parameter names for abstract and native methods.
  • Added (undocumented) -noparameterreflection option ikvmc to disable emitting method parameter reflection metadata
  • Enabled MethodParameter attribute in runtime stub generator.
  • Support round tripping malformed MethodParameter attribute in stub generator.
  • Fixed PackageListAttribute to be ECMA compliant.
  • Added support for defining abstract methods in remap file.
  • Implemented sun.nio.ch.Net.poll() native method.
  • Replaced sun.misc.Unsafe cas operations in java.lang.Class with Interlocked.CompareExchange().
  • Replaced AtomicReference[Array].getAndSet() implementations with Interlocked.Exchange() based implementations.
  • Fixed Linux build. Thanks to Joan Karadimov for reporting this.
  • Prevent unfocable windows from being activated by mouse click. (Based on patch by Maria Papendieck of pure-systems.)
  • Fixed clipboard access to use the right thread. (Based on patch by Maria Papendieck of pure-systems.)
  • IKVM.Reflection: Added UniverseOptions.DecodeVersionInfoAttributeBlobs to support decoding CustomAttributeBuilder with blob to extract version info fields.

Binaries available here: ikvmbin-8.0.5268.zip
Sources: ikvmsrc-8.0.5268.zip and openjdk-8-b132-stripped.zip

Wednesday, 04 June 2014 09:30:36 (W. Europe Daylight Time, UTC+02:00)  #    Comments [4]