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/*
* Copyright 2021 Carl Mastrangelo
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.perfmark.agent;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.ModuleVisitor;
import org.objectweb.asm.Opcodes;
final class PerfMarkClassVisitor extends ClassVisitor {
static final String[] ALL_METHODS = new String[0];
private final Runnable changeDetector = new ChangeDetector();
private final String classLoaderName;
private final String className;
private final String[] methodsToRewrite;
private final String[] methodsToWrap;
private String fileName;
private String moduleName;
private String moduleVersion;
private boolean isInterface;
@SuppressWarnings("unused")
private boolean madeChanges;
PerfMarkClassVisitor(
String classLoaderName, String className, String[] methodsToRewrite, String[] methodsToWrap,
ClassVisitor classVisitor) {
super(Opcodes.ASM9, classVisitor);
this.classLoaderName = classLoaderName;
this.className = className;
this.methodsToRewrite = methodsToRewrite == ALL_METHODS ? ALL_METHODS : methodsToRewrite.clone();
this.methodsToWrap = methodsToWrap == ALL_METHODS ? ALL_METHODS : methodsToWrap.clone();
}
@Override
public ModuleVisitor visitModule(String name, int access, String version) {
this.moduleName = name;
this.moduleVersion = version;
return super.visitModule(name, access, version);
}
@Override
public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
this.isInterface = (access & Opcodes.ACC_INTERFACE) != 0;
super.visit(version, access, name, signature, superName, interfaces);
}
@Override
public void visitSource(String source, String debug) {
this.fileName = source;
super.visitSource(source, debug);
}
@Override
public MethodVisitor visitMethod(
int access, String methodName, String descriptor, String signature, String[] exceptions) {
final MethodVisitor superDelegate;
final MethodWrappingWriter methodWrapper;
if (shouldWrap(methodName, access)) {
if (className.startsWith("io/perfmark/") || className.startsWith("jdk/")) {
// Avoid recursion for now.
return super.visitMethod(access, methodName, descriptor, signature, exceptions);
}
String bodyMethodName = methodName + "$perfmark";
int newAccess;
if (!isInterface) {
newAccess = (access | Opcodes.ACC_PRIVATE) & ~(Opcodes.ACC_PROTECTED | Opcodes.ACC_PUBLIC);
} else {
newAccess = access;
}
MethodVisitor visitor = super.visitMethod(newAccess, bodyMethodName, descriptor, signature, exceptions);
MethodVisitorRecorder recorder = new MethodVisitorRecorder(visitor);
superDelegate = recorder;
methodWrapper =
new MethodWrappingWriter(
recorder, access, methodName, descriptor, signature, exceptions, isInterface, className, bodyMethodName,
cv);
} else {
superDelegate = super.visitMethod(access, methodName, descriptor, signature, exceptions);
methodWrapper = null;
}
final MethodVisitor visitor;
if (shouldRewrite(methodName)) {
visitor = new PerfMarkMethodRewriter(
classLoaderName, moduleName, moduleVersion, className, methodName, fileName, changeDetector, superDelegate);
} else {
visitor = superDelegate;
}
return new MethodVisitorWrapper(methodWrapper, visitor);
}
boolean shouldWrap(String methodName, int access) {
if ((access & (Opcodes.ACC_ABSTRACT | Opcodes.ACC_NATIVE)) != 0) {
return false;
}
if (methodsToWrap == ALL_METHODS) {
// not yet supported
if (methodName.equals("<init>") || methodName.equals("<clinit>")) {
return false;
}
return true;
}
for (String method : methodsToWrap) {
if (method.equals(methodName)) {
return true;
}
}
return false;
}
boolean shouldRewrite(String methodName) {
if (methodsToRewrite == ALL_METHODS) {
return true;
}
for (String method : methodsToRewrite) {
if (method.equals(methodName)) {
return true;
}
}
return false;
}
private final class MethodVisitorWrapper extends MethodVisitor {
private final MethodWrappingWriter methodWrapper;
/**
*
* @param methodWrapper the writer of the "wrapper" method. May be {@code null}.
* @param delegate method visitor to inject in the additional method. May be {@code null}.
*/
MethodVisitorWrapper(MethodWrappingWriter methodWrapper, MethodVisitor delegate) {
super(PerfMarkClassVisitor.this.api, delegate);
this.methodWrapper = methodWrapper;
}
@Override
public void visitEnd() {
super.visitEnd();
if (methodWrapper != null) {
madeChanges = true;
methodWrapper.visit();
}
}
}
private final class ChangeDetector implements Runnable {
@Override
public void run() {
madeChanges = true;
}
}
}
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