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BAEL-1728: add java instrumentation
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9 files changed

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‎core-java/pom.xml‎

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@@ -173,6 +173,19 @@
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<artifactId>c3p0</artifactId>
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<version>${c3p0.version}</version>
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</dependency>
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<!-- instrumentation -->
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<dependency>
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<groupId>org.javassist</groupId>
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<artifactId>javassist</artifactId>
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<version>${javaassist.version}</version>
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</dependency>
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<dependency>
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<groupId>com.sun</groupId>
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<artifactId>tools</artifactId>
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<version>1.8.0</version>
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<scope>system</scope>
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<systemPath>${java.home}/../lib/tools.jar</systemPath>
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</dependency>
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</dependencies>
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<build>
@@ -400,6 +413,111 @@
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</plugins>
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</build>
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</profile>
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<!-- java instrumentation profiles to build jars -->
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<profile>
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<id>buildAgentLoader</id>
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<build>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-jar-plugin</artifactId>
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<executions>
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<execution>
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<phase>package</phase>
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<goals>
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<goal>jar</goal>
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</goals>
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<configuration>
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<classifier>agentLoader</classifier>
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<classesDirectory>target/classes</classesDirectory>
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<archive>
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<manifest>
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<addClasspath>true</addClasspath>
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</manifest>
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<manifestFile>${project.build.outputDirectory}/META-INF/MANIFEST.MF</manifestFile>
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</archive>
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<includes>
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<include>com/baeldung/instrumentation/application/AgentLoader.class</include>
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<include>com/baeldung/instrumentation/application/Launcher.class</include>
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</includes>
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</configuration>
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</execution>
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</executions>
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</plugin>
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</plugins>
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</build>
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</profile>
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<profile>
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<id>buildApplication</id>
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<build>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-jar-plugin</artifactId>
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<executions>
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<execution>
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<phase>package</phase>
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<goals>
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<goal>jar</goal>
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</goals>
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<configuration>
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<classifier>application</classifier>
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<classesDirectory>target/classes</classesDirectory>
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<archive>
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<manifest>
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<addClasspath>true</addClasspath>
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</manifest>
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<manifestFile>${project.build.outputDirectory}/META-INF/MANIFEST.MF</manifestFile>
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</archive>
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<includes>
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<include>com/baeldung/instrumentation/application/MyAtm.class</include>
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<include>com/baeldung/instrumentation/application/MyAtmApplication.class</include>
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<include>com/baeldung/instrumentation/application/Launcher.class</include>
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</includes>
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</configuration>
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</execution>
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</executions>
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</plugin>
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</plugins>
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</build>
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</profile>
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<profile>
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<id>buildAgent</id>
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<build>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-jar-plugin</artifactId>
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<executions>
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<execution>
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<phase>package</phase>
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<goals>
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<goal>jar</goal>
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</goals>
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<configuration>
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<classifier>agent</classifier>
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<classesDirectory>target/classes</classesDirectory>
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<archive>
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<manifest>
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<addClasspath>true</addClasspath>
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</manifest>
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<manifestFile>${project.build.outputDirectory}/META-INF/MANIFEST.MF</manifestFile>
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</archive>
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<includes>
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<include>com/baeldung/instrumentation/agent/AtmTransformer.class</include>
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<include>com/baeldung/instrumentation/agent/MyInstrumentationAgent.class</include>
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</includes>
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</configuration>
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</execution>
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</executions>
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</plugin>
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</plugins>
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</build>
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</profile>
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</profiles>
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<properties>
@@ -453,6 +571,8 @@
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<!-- Mime Type Libraries -->
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<tika.version>1.18</tika.version>
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<jmime-magic.version>0.1.5</jmime-magic.version>
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<!-- instrumentation -->
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<javaassist.version>3.21.0-GA</javaassist.version>
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</properties>
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</project>

‎core-java/src/main/java/com/baeldung/instrumentation/agent/AtmTransformer.java‎

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package com.baeldung.instrumentation.agent;
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import javassist.CannotCompileException;
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import javassist.ClassPool;
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import javassist.CtClass;
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import javassist.CtMethod;
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import javassist.NotFoundException;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import java.io.IOException;
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import java.lang.instrument.ClassFileTransformer;
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import java.lang.instrument.IllegalClassFormatException;
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import java.security.ProtectionDomain;
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public class AtmTransformer implements ClassFileTransformer {
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private static Logger LOGGER = LoggerFactory.getLogger(AtmTransformer.class);
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private static final String WITHDRAW_MONEY_METHOD = "withdrawMoney";
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/** The internal form class name of the class to transform */
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private String targetClassName;
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/** The class loader of the class we want to transform */
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private ClassLoader targetClassLoader;
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public AtmTransformer(String targetClassName, ClassLoader targetClassLoader) {
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this.targetClassName = targetClassName;
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this.targetClassLoader = targetClassLoader;
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}
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@Override
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public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
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ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
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byte[] byteCode = classfileBuffer;
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String finalTargetClassName = this.targetClassName.replaceAll("\\.", "/"); //replace . with /
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if (!className.equals(finalTargetClassName)) {
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return byteCode;
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}
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if (className.equals(finalTargetClassName) && loader.equals(targetClassLoader)) {
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LOGGER.info("[Agent] Transforming class MyAtm");
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try {
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ClassPool cp = ClassPool.getDefault();
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CtClass cc = cp.get(targetClassName);
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CtMethod m = cc.getDeclaredMethod(WITHDRAW_MONEY_METHOD);
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m.addLocalVariable("startTime", CtClass.longType);
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m.insertBefore("startTime = System.currentTimeMillis();");
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StringBuilder endBlock = new StringBuilder();
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m.addLocalVariable("endTime", CtClass.longType);
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m.addLocalVariable("opTime", CtClass.longType);
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endBlock.append("endTime = System.currentTimeMillis();");
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endBlock.append("opTime = (endTime-startTime)/1000;");
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endBlock.append("LOGGER.info(\"[Application] Withdrawal operation completed in:\" + opTime + \" seconds!\");");
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m.insertAfter(endBlock.toString());
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byteCode = cc.toBytecode();
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cc.detach();
64+
} catch (NotFoundException | CannotCompileException | IOException e) {
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LOGGER.error("Exception", e);
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}
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}
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return byteCode;
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}
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}

‎core-java/src/main/java/com/baeldung/instrumentation/agent/MyInstrumentationAgent.java‎

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package com.baeldung.instrumentation.agent;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import java.lang.instrument.Instrumentation;
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public class MyInstrumentationAgent {
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private static Logger LOGGER = LoggerFactory.getLogger(MyInstrumentationAgent.class);
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public static void premain(String agentArgs, Instrumentation inst) {
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LOGGER.info("[Agent] In premain method");
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String className = "com.baeldung.instrumentation.application.MyAtm";
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transformClass(className,inst);
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}
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public static void agentmain(String agentArgs, Instrumentation inst) {
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LOGGER.info("[Agent] In agentmain method");
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String className = "com.baeldung.instrumentation.application.MyAtm";
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transformClass(className,inst);
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}
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private static void transformClass(String className, Instrumentation instrumentation) {
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Class<?> targetCls = null;
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ClassLoader targetClassLoader = null;
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// see if we can get the class using forName
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try {
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targetCls = Class.forName(className);
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targetClassLoader = targetCls.getClassLoader();
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transform(targetCls, targetClassLoader, instrumentation);
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return;
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} catch (Exception ex) {
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LOGGER.error("Class [{}] not found with Class.forName");
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}
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// otherwise iterate all loaded classes and find what we want
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for(Class<?> clazz: instrumentation.getAllLoadedClasses()) {
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if(clazz.getName().equals(className)) {
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targetCls = clazz;
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targetClassLoader = targetCls.getClassLoader();
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transform(targetCls, targetClassLoader, instrumentation);
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return;
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}
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}
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throw new RuntimeException("Failed to find class [" + className + "]");
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}
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private static void transform(Class<?> clazz, ClassLoader classLoader, Instrumentation instrumentation) {
50+
AtmTransformer dt = new AtmTransformer(clazz.getName(), classLoader);
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instrumentation.addTransformer(dt, true);
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try {
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instrumentation.retransformClasses(clazz);
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} catch (Exception ex) {
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throw new RuntimeException("Transform failed for class: [" + clazz.getName() + "]", ex);
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}
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}
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}

‎core-java/src/main/java/com/baeldung/instrumentation/application/AgentLoader.java‎

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package com.baeldung.instrumentation.application;
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import com.sun.tools.attach.VirtualMachine;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import java.io.File;
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import java.util.Optional;
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/**
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* Created by adi on 6/10/18.
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*/
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public class AgentLoader {
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private static Logger LOGGER = LoggerFactory.getLogger(AgentLoader.class);
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public static void run(String[] args) {
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String agentFilePath = "/home/adi/Desktop/agent-1.0.0-jar-with-dependencies.jar";
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String applicationName = "MyAtmApplication";
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//iterate all jvms and get the first one that matches our application name
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Optional<String> jvmProcessOpt = Optional.ofNullable(VirtualMachine.list()
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.stream()
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.filter(jvm -> {
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LOGGER.info("jvm:{}", jvm.displayName());
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return jvm.displayName().contains(applicationName);
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})
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.findFirst().get().id());
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if(!jvmProcessOpt.isPresent()) {
30+
LOGGER.error("Target Application not found");
31+
return;
32+
}
33+
File agentFile = new File(agentFilePath);
34+
try {
35+
String jvmPid = jvmProcessOpt.get();
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LOGGER.info("Attaching to target JVM with PID: " + jvmPid);
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VirtualMachine jvm = VirtualMachine.attach(jvmPid);
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jvm.loadAgent(agentFile.getAbsolutePath());
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jvm.detach();
40+
LOGGER.info("Attached to target JVM and loaded Java agent successfully");
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} catch (Exception e) {
42+
throw new RuntimeException(e);
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}
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}
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}

‎core-java/src/main/java/com/baeldung/instrumentation/application/Launcher.java‎

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package com.baeldung.instrumentation.application;
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/**
4+
* Created by adi on 6/14/18.
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*/
6+
public class Launcher {
7+
public static void main(String[] args) throws Exception {
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if(args[0].equals("StartMyAtmApplication")) {
9+
new MyAtmApplication().run(args);
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} else if(args[0].equals("LoadAgent")) {
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new AgentLoader().run(args);
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}
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}
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}

‎core-java/src/main/java/com/baeldung/instrumentation/application/MyAtm.java‎

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package com.baeldung.instrumentation.application;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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/**
7+
* Created by adi on 6/11/18.
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*/
9+
public class MyAtm {
10+
private static Logger LOGGER = LoggerFactory.getLogger(MyAtm.class);
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private static final int account = 10;
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public static void withdrawMoney(int amount) throws InterruptedException {
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Thread.sleep(2000l); //processing going on here
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LOGGER.info("[Application] Successful Withdrawal of [{}] units!", amount);
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}
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}

‎core-java/src/main/java/com/baeldung/instrumentation/application/MyAtmApplication.java‎

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package com.baeldung.instrumentation.application;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class MyAtmApplication {
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private static Logger LOGGER = LoggerFactory.getLogger(MyAtmApplication.class);
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public static void run(String[] args) throws Exception {
11+
LOGGER.info("[Application] Starting ATM application");
12+
MyAtm.withdrawMoney(Integer.parseInt(args[2]));
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Thread.sleep(Long.valueOf(args[1]));
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MyAtm.withdrawMoney(Integer.parseInt(args[3]));
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}
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}

‎core-java/src/main/resources/META-INF/MANIFEST.MF‎

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Agent-Class: com.baeldung.instrumentation.agent.MyInstrumentationAgent
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Can-Redefine-Classes: true
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Can-Retransform-Classes: true
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Premain-Class: com.baeldung.instrumentation.agent.MyInstrumentationAgent
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Main-Class: com.baeldung.instrumentation.application.Launcher

‎core-java/src/main/resources/log4j2.xml‎

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<?xml version="1.0" encoding="UTF-8"?>
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<Configuration status="WARN">
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<Appenders>
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<Console name="Console" target="SYSTEM_OUT">
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<PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level - %msg%n"/>
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</Console>
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</Appenders>
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<Loggers>
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<Root level="debug">
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<AppenderRef ref="Console"/>
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</Root>
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</Loggers>
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</Configuration>

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