RFR: 8029019: (ann) Optimize annotation handling in core reflection

[Peter Levart]

On 10/13/2017 08:55 AM, Christoph Dreis wrote:
> Hi Peter,
>
> Thanks for your feedback!
>
>> Method.getName() returns an interned String and String literals are interned strings. Reference comparison is therefore possible
> Good point.
>
>> The pair (declaringClass, methodName) uniquely identifies the method for a bunch of interesting methods when declaringClass is either java.lang.Object or java.lang.annotation.Annotation, so we don't need to obtain method's parameterTypes even for equals().
> Forgive me the maybe stupid question, but isn't your proposed code changing semantics because it doesn't check for the first parameter in equals() to be of type java.lang.Object anymore? E.g. like "method.getParameterTypes()[0] == Object.class". Am I missing something? Personally, I find this a bit too "magic" overall. I don't know what Claes thinks about that.

There's only one method named "equals" declared in either Object or 
Annotation (currently :-). So it's enough to check for declaringClass 
and name to identify the correct method.

Regards, Peter

>
> I would settle on this, if I include the reference comparison change of yours.
>
> For example:
>
>     public Object invoke(Object proxy, Method method, Object[] args) {
>          String memberName = method.getName(); // guaranteed interned String
>          int parameterCount = method.getParameterCount();
>
>          // Handle Object and Annotation methods
>          if (parameterCount == 1 && memberName == "equals" &&
>              method.getParameterTypes()[0] == Object.class)
>              return equalsImpl(proxy, args[0]);
>          if (parameterCount != 0)
>              throw new AssertionError("Too many parameters for an annotation method");
>
>          if (memberName == "hashCode") return hashCodeImpl();
>          if (memberName == "annotationType") return type;
>          if (memberName == "toString") return toStringImpl();
>
>          // Handle annotation member accessors
>          Object result = memberValues.get(memberName);
>
>          if (result == null)
>              throw new IncompleteAnnotationException(type, memberName);
>
>          if (result instanceof ExceptionProxy)
>              throw ((ExceptionProxy) result).generateException();
>
>          if (result.getClass().isArray() && Array.getLength(result) != 0)
>              result = cloneArray(result);
>
>          return result;
>      }
>
> What do you think?
>
> Cheers,
> Christoph
>