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 }