1 /*
2 * Copyright (c) 2016, 2024, 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 static jdk.jfr.internal.util.Bytecode.invokespecial;
29
30 import java.lang.constant.ClassDesc;
31 import java.lang.constant.ConstantDescs;
32 import java.lang.reflect.AccessFlag;
33 import java.util.ArrayList;
34 import java.util.List;
35 import java.util.concurrent.atomic.AtomicLong;
36
37 import java.lang.classfile.AnnotationValue;
38 import java.lang.classfile.ClassBuilder;
39 import java.lang.classfile.ClassFile;
40 import java.lang.classfile.Label;
41 import java.lang.classfile.attribute.RuntimeVisibleAnnotationsAttribute;
42
43 import jdk.internal.misc.PreviewFeatures;
44
45 import jdk.jfr.AnnotationElement;
46 import jdk.jfr.Event;
47 import jdk.jfr.ValueDescriptor;
48 import jdk.jfr.internal.util.Bytecode;
49 import jdk.jfr.internal.util.Bytecode.MethodDesc;
50
51 // Helper class for building dynamic events
52 public final class EventClassBuilder {
53 private static final ClassDesc TYPE_EVENT = Bytecode.classDesc(Event.class);
54 private static final ClassDesc TYPE_IOBE = Bytecode.classDesc(IndexOutOfBoundsException.class);
55 private static final MethodDesc DEFAULT_CONSTRUCTOR = MethodDesc.of("<init>", "()V");
56 private static final MethodDesc SET_METHOD = MethodDesc.of("set", "(ILjava/lang/Object;)V");
57 private static final AtomicLong idCounter = new AtomicLong();
58
59 private final String fullClassName;
60 private final ClassDesc type;
61 private final List<ValueDescriptor> fields;
62 private final List<AnnotationElement> annotationElements;
63
64 public EventClassBuilder(List<AnnotationElement> annotationElements, List<ValueDescriptor> fields) {
65 this.fullClassName = "jdk.jfr.DynamicEvent" + idCounter.incrementAndGet();
66 this.type = ClassDesc.of(fullClassName);
67 this.fields = fields;
68 this.annotationElements = annotationElements;
69 }
70
71 public Class<? extends Event> build() {
72 byte[] bytes = ClassFile.of().build(ClassDesc.of(fullClassName), cb -> build(cb));
73 Bytecode.log(fullClassName, bytes);
74 return SecuritySupport.defineClass(Event.class, bytes).asSubclass(Event.class);
75 }
76
77 void build(ClassBuilder builder) {
78 buildClassInfo(builder);
79 buildConstructor(builder);
80 buildFields(builder);
81 buildSetMethod(builder);
82 }
83
84 private void buildSetMethod(ClassBuilder builder) {
85 // void Event::set(int index, Object value);
86 builder.withMethod(SET_METHOD.name(), SET_METHOD.descriptor(), ClassFile.ACC_PUBLIC, methodBuilder -> methodBuilder.withCode(codeBuilder -> {
87 int index = 0;
88 for (ValueDescriptor v : fields) {
89 codeBuilder.iload(1);
90 codeBuilder.ldc(index);
91 Label notEqual = codeBuilder.newLabel();
92 codeBuilder.if_icmpne(notEqual);
93 codeBuilder.aload(0); // this
94 codeBuilder.aload(2); // value
95 ClassDesc cd = Bytecode.classDesc(v);
96 Bytecode.unbox(codeBuilder, cd);
97 codeBuilder.putfield(type, v.getName(), cd);
98 codeBuilder.return_();
99 codeBuilder.labelBinding(notEqual);
100 index++;
101 }
102 Bytecode.throwException(codeBuilder, TYPE_IOBE, "Index must between 0 and " + fields.size());
103 }));
104 }
105
106 private void buildConstructor(ClassBuilder builder) {
107 builder.withMethod(ConstantDescs.INIT_NAME, ConstantDescs.MTD_void, ClassFile.ACC_PUBLIC, methodBuilder -> methodBuilder.withCode(codeBuilder -> {
108 codeBuilder.aload(0);
109 invokespecial(codeBuilder, TYPE_EVENT, DEFAULT_CONSTRUCTOR);
110 codeBuilder.return_();
111 }));
112 }
113
114 private void buildClassInfo(ClassBuilder builder) {
115 builder.withSuperclass(Bytecode.classDesc(Event.class));
116 builder.withFlags(AccessFlag.FINAL, AccessFlag.PUBLIC, (PreviewFeatures.isEnabled() ? AccessFlag.IDENTITY : AccessFlag.SUPER));
117 List<java.lang.classfile.Annotation> annotations = new ArrayList<>();
118 for (jdk.jfr.AnnotationElement a : annotationElements) {
119 List<java.lang.classfile.AnnotationElement> list = new ArrayList<>();
120 for (ValueDescriptor v : a.getValueDescriptors()) {
121 // ValueDescriptor can only hold primitive
122 // No need to care about classes/enums
123 var value = a.getValue(v.getName());
124 var av = AnnotationValue.of(value);
125 var ae = java.lang.classfile.AnnotationElement.of(v.getName(), av);
126 list.add(ae);
127 }
128 ClassDesc cd = ClassDesc.of(a.getTypeName());
129 annotations.add(java.lang.classfile.Annotation.of(cd, list));
130 }
131 builder.with(RuntimeVisibleAnnotationsAttribute.of(annotations));
132 }
133
134 private void buildFields(ClassBuilder builder) {
135 for (ValueDescriptor v : fields) {
136 builder.withField(v.getName(), Bytecode.classDesc(v), ClassFile.ACC_PRIVATE);
137 // No need to store annotations on field since they will be replaced anyway.
138 }
139 }
140 }