Hi Joe,
The code below is more optimal only in AnnotatedElement implementations
that don't override getDeclaredAnnotation(Class) with more optimal
implementation based on a HashMap lookup. Your implementation avoids
calling getDeclaredAnnotations() in common cases (where only directly
present or only in-directly present annotations exist), but as this is a
default method, it must be assumed that it will be invoked on
AnnotatedElement implementations that don't override it and those
presumably also don't override default getDeclaredAnnotation(Class)
which is based on getDeclaredAnnotations() and interation over returned
elements. In this situation, your code does 2 (or in uncommon case 3)
calls to getDeclaredAnnotations() with iteration over elements, while
the below code only does 1...
On 10/25/2013 05:03 PM, Peter Levart wrote:
Hi Joe,
I propose some "premature" optimization for
AnnotatedElement.getDeclaredAnnotationsByType(). This implementation
calls either getDeclaredAnnotatios() once or
getDeclaredAnnotation(Class) once, depending on whether the annotation
type is repeatable or not respectively (this check also requires a
getDeclaredAnnotation() call, but I propose to extend AnnotationType
in the future to provide with cached containerClass directly). Also,
it is about 7x faster to use annotationClass.isInstance(ann) to check
for the type of annotation instead of ann.annotationType() ==
annotationClass which goes through annotation Proxy, etc...
Here it is:
default <T extends Annotation> T[]
getDeclaredAnnotationsByType(Class<T> annotationClass) {
Objects.requireNonNull(annotationClass);
Repeatable repeatable =
annotationClass.getDeclaredAnnotation(Repeatable.class);
// non-repeatable: just delegate to getDeclaredAnnotation and
return wrapped result
if (repeatable == null) {
T ann = getDeclaredAnnotation(annotationClass);
@SuppressWarnings("unchecked")
T[] result = (T[]) Array.newInstance(annotationClass, ann
== null ? 0 : 1);
if (ann != null) result[0] = ann;
return result;
}
// repeatable: iterate all declared annotations, find directly
and indirectly present
// and also determine the order (directlyPresentFirst)...
Class<? extends Annotation> containerClass = repeatable.value();
T directlyPresent = null;
T[] indirectlyPresent = null;
boolean directlyPresentFirst = false;
for (Annotation ann : getDeclaredAnnotations()) {
if (directlyPresent == null &&
annotationClass.isInstance(ann)) {
directlyPresent = annotationClass.cast(ann);
if (indirectlyPresent != null) {
break;
}
} else if (indirectlyPresent == null &&
containerClass.isInstance(ann)) {
indirectlyPresent = AnnotationSupport.getValueArray(ann);
if (directlyPresent != null) {
directlyPresentFirst = true;
break;
}
}
}
// concatenate directlyPresent and indirectlyPresent annotations
@SuppressWarnings("unchecked")
T[] result = (directlyPresent == null && indirectlyPresent !=
null)
? indirectlyPresent
: (T[]) Array.newInstance(annotationClass,
(directlyPresent == null ? 0 : 1) +
(indirectlyPresent == null ? 0 :
indirectlyPresent.length));
if (directlyPresent != null) {
if (indirectlyPresent == null || indirectlyPresent.length
== 0) {
result[0] = directlyPresent;
} else {
result[directlyPresentFirst ? 0 :
indirectlyPresent.length] = directlyPresent;
System.arraycopy(indirectlyPresent, 0, result,
directlyPresentFirst ? 1 : 0,
indirectlyPresent.length);
}
}
return result;
}
Regards, Peter
On 10/25/2013 10:40 AM, Joe Darcy wrote:
Hi Joel and Peter,
On 10/24/2013 07:10 AM, Peter Levart wrote:
Hi Joe,
I see two problems with the implementation in
*AnnotatedElementSupport*. The first is the treatment of
declared-only annotations where the code returns either directly
present or in-directly present repeatable annotations, but not both.
So in the following example:
@Ann(1)
@AnnCont({@Ann(2), @Ann(3)})
it will only return [@Ann(1)], but I think it should return all of
them [@Ann(1), @Ann(2), @Ann(3)] - does the spec. define that?
[snip]
From your feedback (and a closer reading of the specifciation), I've
reworked the specifications and implemenations of the default methods
for get[Declared]AnnotationsByType:
http://cr.openjdk.java.net/~darcy/8005294.2/
Tests still need to be written, but this implementation should be
much closed to what is needed.
Thanks,
-Joe
