RFR: JDK-8054987: (reflect) Add sharing of annotations between instances of Executable

[Peter Levart]

Hi Joel,

If you make Executable.declaredAnnotations field volatile, 
synchronization is only necessary on the 'root' instance:


     private transient volatile Map<Class<? extends Annotation>, 
Annotation> declaredAnnotations;

     private Map<Class<? extends Annotation>, Annotation> 
declaredAnnotations() {
         Map<Class<? extends Annotation>, Annotation> anns = 
declaredAnnotations;
         if (anns == null) {
             Executable root = getRoot();
             if (root != null) {
                 declaredAnnotations = anns = root.declaredAnnotations();
             } else {
                 synchronized (this) {
                     declaredAnnotations = anns = 
AnnotationParser.parseAnnotations(
                         getAnnotationBytes(),
sun.misc.SharedSecrets.getJavaLangAccess().
getConstantPool(getDeclaringClass()),
                         getDeclaringClass());
                 }
             }
         }
         return anns;
     }


Regards, Peter

On 08/14/2014 06:54 PM, Peter Levart wrote:
> On 08/14/2014 08:47 AM, Joel Borggren-Franck wrote:
>> On 2014-08-13, Joe Darcy wrote:
>>> Hi Joel,
>>>
>>> Does your changeset alter the support (or non-support) of redefining
>>> an annotation?
>>>
>> Hi Joe,
>>
>> It does not interact with the current non-support and I am convinced it
>> wont hinder us in improving the situation.
>>
>> cheers
>> /Joel
> Hi Joel,
>
> Good to see this patch. It improves the efficiency of annotations 
> caching on methods/constructors. What about fields? They too are 
> AccessibleObject(s), contain annotations and are copied from root 
> instances when handed over to the user...
>
> The difference of behaviour in the presence of class redefinition 
> could be observed though, but I think this is not a problem. For example:
>
> Class c = ...;
>
> Method m1 = c.getDeclaredMethod("m");
> Method m2 = c.getDeclaredMethod("m");
>
> assert m1 != m2; // but they share the same root;
>
> Annotation[] anns1 = m1.getDeclaredAnnotations();
>
> // now class 'c' is redefined and annotations changes on method m()...
>
> Annotation[] anns2 = m2.getDeclaredAnnotations();
>
> // previously anns1 / anns2 would countain annotations pre / post 
> class redefinition, but with this patch, they would both contain the 
> pre class redefinition annotations.
>
>
> But as I see it this is not a big problem to hold the patch back.
>
>
> Regards, Peter
>