1 /*
   2  * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  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 
  46         AnnotationInvokationHandler(AnnotationElement a) {
  47             this.annotationElement = a;
  48         }
  49 
  50         @Override
  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;
  63     public AnnotationConstruct(List<AnnotationElement> ann) {
  64         this.annotationElements = ann;
  65     }
  66 
  67     public AnnotationConstruct() {
  68     }
  69 
  70     public void setAnnotationElements(List<AnnotationElement> elements) {
  71         annotationElements = Utils.smallUnmodifiable(elements);
  72     }
  73 
  74     public String getLabel() {
  75         Label label = getAnnotation(Label.class);
  76         if (label == null) {
  77             return null;
  78         }
  79         return label.value();
  80     }
  81 
  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")
  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 
  99     public List<AnnotationElement> getUnmodifiableAnnotationElements() {
 100         return annotationElements;
 101     }
 102 
 103     // package private
 104     boolean remove(AnnotationElement annotation) {
 105         return annotationElements.remove(annotation);
 106     }
 107 
 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 
 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 }