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package jdk.jfr.internal.instrument;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

import jdk.internal.org.objectweb.asm.ClassReader;
import jdk.internal.org.objectweb.asm.ClassVisitor;
import jdk.internal.org.objectweb.asm.ClassWriter;
import jdk.internal.org.objectweb.asm.Opcodes;
import jdk.internal.org.objectweb.asm.tree.ClassNode;
import jdk.jfr.internal.SecuritySupport;
import jdk.jfr.internal.Utils;

This class will perform byte code instrumentation given an "instrumentor" class.
Author:Staffan Larsen
See Also:
  • JITracer
/** * This class will perform byte code instrumentation given an "instrumentor" class. * * @see JITracer * * @author Staffan Larsen */
@Deprecated final class JIClassInstrumentation { private final Class<?> instrumentor; private final String targetName; private final String instrumentorName; private final byte[] newBytes; private final ClassReader targetClassReader; private final ClassReader instrClassReader;
Creates an instance and performs the instrumentation.
Params:
  • instrumentor – instrumentor class
  • target – target class
  • old_target_bytes – bytes in target
Throws:
/** * Creates an instance and performs the instrumentation. * * @param instrumentor instrumentor class * @param target target class * @param old_target_bytes bytes in target * * @throws ClassNotFoundException * @throws IOException */
JIClassInstrumentation(Class<?> instrumentor, Class<?> target, byte[] old_target_bytes) throws ClassNotFoundException, IOException { instrumentorName = instrumentor.getName(); this.targetName = target.getName(); this.instrumentor = instrumentor; this.targetClassReader = new ClassReader(old_target_bytes); this.instrClassReader = new ClassReader(getOriginalClassBytes(instrumentor)); this.newBytes = makeBytecode(); Utils.writeGeneratedASM(target.getName(), newBytes); } private static byte[] getOriginalClassBytes(Class<?> clazz) throws IOException { ByteArrayOutputStream baos = new ByteArrayOutputStream(); String name = "/" + clazz.getName().replace(".", "/") + ".class"; InputStream is = SecuritySupport.getResourceAsStream(name); int bytesRead; byte[] buffer = new byte[16384]; while ((bytesRead = is.read(buffer, 0, buffer.length)) != -1) { baos.write(buffer, 0, bytesRead); } baos.flush(); is.close(); return baos.toByteArray(); } private byte[] makeBytecode() throws IOException, ClassNotFoundException { // Find the methods to instrument and inline final List<Method> instrumentationMethods = new ArrayList<>(); for (final Method m : instrumentor.getDeclaredMethods()) { JIInstrumentationMethod im = m.getAnnotation(JIInstrumentationMethod.class); if (im != null) { instrumentationMethods.add(m); } } // We begin by inlining the target's methods into the instrumentor ClassNode temporary = new ClassNode(); ClassVisitor inliner = new JIInliner( Opcodes.ASM7, temporary, targetName, instrumentorName, targetClassReader, instrumentationMethods); instrClassReader.accept(inliner, ClassReader.EXPAND_FRAMES); // Now we have the target's methods inlined into the instrumentation code (in 'temporary'). // We now need to replace the target's method with the code in the // instrumentation method. ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES); JIMethodMergeAdapter ma = new JIMethodMergeAdapter( cw, temporary, instrumentationMethods, instrumentor.getAnnotationsByType(JITypeMapping.class)); targetClassReader.accept(ma, ClassReader.EXPAND_FRAMES); return cw.toByteArray(); }
Get the instrumented byte codes that can be used to retransform the class.
Returns:bytes
/** * Get the instrumented byte codes that can be used to retransform the class. * * @return bytes */
public byte[] getNewBytes() { return newBytes.clone(); } }