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25 
26 package jdk.jfr.internal;
27 
28 import java.lang.annotation.Annotation;
29 import java.lang.reflect.InvocationHandler;
30 import java.lang.reflect.Method;
31 import java.lang.reflect.Proxy;
32 import java.util.Collections;
33 import java.util.List;
34 
35 import jdk.jfr.AnnotationElement;
36 import jdk.jfr.Description;
37 import jdk.jfr.Label;
38 import jdk.jfr.Unsigned;
39 
40 public final class AnnotationConstruct {
41 
42     private static final class AnnotationInvokationHandler implements InvocationHandler {
43 
44         private final AnnotationElement annotationElement;
45 
AnnotationInvokationHandler(AnnotationElement a)46         AnnotationInvokationHandler(AnnotationElement a) {
47             this.annotationElement = a;
48         }
49 
50         @Override
invoke(Object proxy, Method method, Object[] args)51         public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
52             String methodName = method.getName();
53             int parameters = method.getTypeParameters().length;
54             if (parameters == 0 && annotationElement.hasValue(methodName)) {
55                 return annotationElement.getValue(methodName);
56             }
57             throw new UnsupportedOperationException("Flight Recorder proxy only supports members declared in annotation interfaces, i.e. not toString, equals etc.");
58         }
59     }
60 
61     private List<AnnotationElement> annotationElements = Collections.emptyList();
62     private byte unsignedFlag = -1;
AnnotationConstruct(List<AnnotationElement> ann)63     public AnnotationConstruct(List<AnnotationElement> ann) {
64         this.annotationElements = ann;
65     }
66 
AnnotationConstruct()67     public AnnotationConstruct() {
68     }
69 
setAnnotationElements(List<AnnotationElement> elements)70     public void setAnnotationElements(List<AnnotationElement> elements) {
71         annotationElements = Utils.smallUnmodifiable(elements);
72     }
73 
getLabel()74     public String getLabel() {
75         Label label = getAnnotation(Label.class);
76         if (label == null) {
77             return null;
78         }
79         return label.value();
80     }
81 
getDescription()82     public String getDescription() {
83         Description description = getAnnotation(Description.class);
84         if (description == null) {
85             return null;
86         }
87         return description.value();
88     }
89 
90     @SuppressWarnings("unchecked")
getAnnotation(Class<? extends Annotation> clazz)91     public final <T> T getAnnotation(Class<? extends Annotation> clazz) {
92         AnnotationElement ae = getAnnotationElement(clazz);
93         if (ae != null) {
94             return (T) Proxy.newProxyInstance(clazz.getClassLoader(), new Class<?>[] { clazz }, new AnnotationInvokationHandler(ae));
95         }
96         return null;
97     }
98 
getUnmodifiableAnnotationElements()99     public List<AnnotationElement> getUnmodifiableAnnotationElements() {
100         return annotationElements;
101     }
102 
103     // package private
remove(AnnotationElement annotation)104     boolean remove(AnnotationElement annotation) {
105         return annotationElements.remove(annotation);
106     }
107 
getAnnotationElement(Class<? extends Annotation> clazz)108     private AnnotationElement getAnnotationElement(Class<? extends Annotation> clazz) {
109         // if multiple annotation elements with the same name exists, prioritize
110         // the one with the same id. Note, id alone is not a guarantee, since it
111         // may differ between JVM instances.
112         long id = Type.getTypeId(clazz);
113         String className = clazz.getName();
114         for (AnnotationElement a : getUnmodifiableAnnotationElements()) {
115             if (a.getTypeId() == id && a.getTypeName().equals(className)) {
116                 return a;
117             }
118         }
119         for (AnnotationElement a : getUnmodifiableAnnotationElements()) {
120             if (a.getTypeName().equals(className)) {
121                 return a;
122             }
123         }
124         return null;
125     }
126 
hasUnsigned()127     public boolean hasUnsigned() {
128         // Must be initialized lazily since some annotation elements
129         // are added after construction
130         if (unsignedFlag < 0) {
131             Unsigned unsigned = getAnnotation(Unsigned.class);
132             unsignedFlag = (byte) (unsigned == null ? 0 :1);
133         }
134         return unsignedFlag == (byte)1 ? true : false;
135     }
136 }
137