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70 changes: 70 additions & 0 deletions
70
core-java/src/main/java/com/baeldung/instrumentation/agent/AtmTransformer.java
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|---|---|---|
| @@ -0,0 +1,70 @@ | ||
| package com.baeldung.instrumentation.agent; | ||
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| import javassist.CannotCompileException; | ||
| import javassist.ClassPool; | ||
| import javassist.CtClass; | ||
| import javassist.CtMethod; | ||
| import javassist.NotFoundException; | ||
| import org.slf4j.Logger; | ||
| import org.slf4j.LoggerFactory; | ||
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| import java.io.IOException; | ||
| import java.lang.instrument.ClassFileTransformer; | ||
| import java.lang.instrument.IllegalClassFormatException; | ||
| 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 */ | ||
| private String targetClassName; | ||
| /** The class loader of the class we want to transform */ | ||
| private ClassLoader targetClassLoader; | ||
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| public AtmTransformer(String targetClassName, ClassLoader targetClassLoader) { | ||
| this.targetClassName = targetClassName; | ||
| this.targetClassLoader = targetClassLoader; | ||
| } | ||
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| @Override | ||
| public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, | ||
| ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException { | ||
| byte[] byteCode = classfileBuffer; | ||
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| String finalTargetClassName = this.targetClassName.replaceAll("\\.", "/"); //replace . with / | ||
| if (!className.equals(finalTargetClassName)) { | ||
| return byteCode; | ||
| } | ||
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| if (className.equals(finalTargetClassName) && loader.equals(targetClassLoader)) { | ||
| LOGGER.info("[Agent] Transforming class MyAtm"); | ||
| try { | ||
| ClassPool cp = ClassPool.getDefault(); | ||
| CtClass cc = cp.get(targetClassName); | ||
| CtMethod m = cc.getDeclaredMethod(WITHDRAW_MONEY_METHOD); | ||
| m.addLocalVariable("startTime", CtClass.longType); | ||
| m.insertBefore("startTime = System.currentTimeMillis();"); | ||
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| StringBuilder endBlock = new StringBuilder(); | ||
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| m.addLocalVariable("endTime", CtClass.longType); | ||
| m.addLocalVariable("opTime", CtClass.longType); | ||
| endBlock.append("endTime = System.currentTimeMillis();"); | ||
| 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(); | ||
| cc.detach(); | ||
| } catch (NotFoundException | CannotCompileException | IOException e) { | ||
| LOGGER.error("Exception", e); | ||
| } | ||
| } | ||
| return byteCode; | ||
| } | ||
| } |
59 changes: 59 additions & 0 deletions
59
core-java/src/main/java/com/baeldung/instrumentation/agent/MyInstrumentationAgent.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,59 @@ | ||
| package com.baeldung.instrumentation.agent; | ||
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| import org.slf4j.Logger; | ||
| import org.slf4j.LoggerFactory; | ||
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| import java.lang.instrument.Instrumentation; | ||
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| public class MyInstrumentationAgent { | ||
| private static Logger LOGGER = LoggerFactory.getLogger(MyInstrumentationAgent.class); | ||
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| public static void premain(String agentArgs, Instrumentation inst) { | ||
| LOGGER.info("[Agent] In premain method"); | ||
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| String className = "com.baeldung.instrumentation.application.MyAtm"; | ||
| transformClass(className,inst); | ||
| } | ||
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| public static void agentmain(String agentArgs, Instrumentation inst) { | ||
| LOGGER.info("[Agent] In agentmain method"); | ||
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| String className = "com.baeldung.instrumentation.application.MyAtm"; | ||
| transformClass(className,inst); | ||
| } | ||
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| private static void transformClass(String className, Instrumentation instrumentation) { | ||
| Class<?> targetCls = null; | ||
| ClassLoader targetClassLoader = null; | ||
| // see if we can get the class using forName | ||
| try { | ||
| targetCls = Class.forName(className); | ||
| targetClassLoader = targetCls.getClassLoader(); | ||
| transform(targetCls, targetClassLoader, instrumentation); | ||
| return; | ||
| } catch (Exception ex) { | ||
| LOGGER.error("Class [{}] not found with Class.forName"); | ||
| } | ||
| // otherwise iterate all loaded classes and find what we want | ||
| for(Class<?> clazz: instrumentation.getAllLoadedClasses()) { | ||
| if(clazz.getName().equals(className)) { | ||
| targetCls = clazz; | ||
| targetClassLoader = targetCls.getClassLoader(); | ||
| transform(targetCls, targetClassLoader, instrumentation); | ||
| return; | ||
| } | ||
| } | ||
| throw new RuntimeException("Failed to find class [" + className + "]"); | ||
| } | ||
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| private static void transform(Class<?> clazz, ClassLoader classLoader, Instrumentation instrumentation) { | ||
| AtmTransformer dt = new AtmTransformer(clazz.getName(), classLoader); | ||
| instrumentation.addTransformer(dt, true); | ||
| try { | ||
| instrumentation.retransformClasses(clazz); | ||
| } catch (Exception ex) { | ||
| throw new RuntimeException("Transform failed for class: [" + clazz.getName() + "]", ex); | ||
| } | ||
| } | ||
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| } |
46 changes: 46 additions & 0 deletions
46
core-java/src/main/java/com/baeldung/instrumentation/application/AgentLoader.java
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|---|---|---|
| @@ -0,0 +1,46 @@ | ||
| package com.baeldung.instrumentation.application; | ||
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| import com.sun.tools.attach.VirtualMachine; | ||
| import org.slf4j.Logger; | ||
| import org.slf4j.LoggerFactory; | ||
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| import java.io.File; | ||
| import java.util.Optional; | ||
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| /** | ||
| * Created by adi on 6/10/18. | ||
| */ | ||
| public class AgentLoader { | ||
| private static Logger LOGGER = LoggerFactory.getLogger(AgentLoader.class); | ||
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| public static void run(String[] args) { | ||
| String agentFilePath = "/home/adi/Desktop/agent-1.0.0-jar-with-dependencies.jar"; | ||
| String applicationName = "MyAtmApplication"; | ||
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| //iterate all jvms and get the first one that matches our application name | ||
| Optional<String> jvmProcessOpt = Optional.ofNullable(VirtualMachine.list() | ||
| .stream() | ||
| .filter(jvm -> { | ||
| LOGGER.info("jvm:{}", jvm.displayName()); | ||
| return jvm.displayName().contains(applicationName); | ||
| }) | ||
| .findFirst().get().id()); | ||
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| if(!jvmProcessOpt.isPresent()) { | ||
| LOGGER.error("Target Application not found"); | ||
| return; | ||
| } | ||
| File agentFile = new File(agentFilePath); | ||
| try { | ||
| String jvmPid = jvmProcessOpt.get(); | ||
| LOGGER.info("Attaching to target JVM with PID: " + jvmPid); | ||
| VirtualMachine jvm = VirtualMachine.attach(jvmPid); | ||
| jvm.loadAgent(agentFile.getAbsolutePath()); | ||
| jvm.detach(); | ||
| LOGGER.info("Attached to target JVM and loaded Java agent successfully"); | ||
| } catch (Exception e) { | ||
| throw new RuntimeException(e); | ||
| } | ||
| } | ||
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| } |
14 changes: 14 additions & 0 deletions
14
core-java/src/main/java/com/baeldung/instrumentation/application/Launcher.java
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| @@ -0,0 +1,14 @@ | ||
| package com.baeldung.instrumentation.application; | ||
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| /** | ||
| * Created by adi on 6/14/18. | ||
| */ | ||
| public class Launcher { | ||
| public static void main(String[] args) throws Exception { | ||
| if(args[0].equals("StartMyAtmApplication")) { | ||
| new MyAtmApplication().run(args); | ||
| } else if(args[0].equals("LoadAgent")) { | ||
| new AgentLoader().run(args); | ||
| } | ||
| } | ||
| } |
19 changes: 19 additions & 0 deletions
19
core-java/src/main/java/com/baeldung/instrumentation/application/MyAtm.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,19 @@ | ||
| package com.baeldung.instrumentation.application; | ||
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| import org.slf4j.Logger; | ||
| import org.slf4j.LoggerFactory; | ||
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| /** | ||
| * Created by adi on 6/11/18. | ||
| */ | ||
| public class MyAtm { | ||
| 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 { | ||
| Thread.sleep(2000l); //processing going on here | ||
| LOGGER.info("[Application] Successful Withdrawal of [{}] units!", amount); | ||
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| } | ||
| } |
19 changes: 19 additions & 0 deletions
19
core-java/src/main/java/com/baeldung/instrumentation/application/MyAtmApplication.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,19 @@ | ||
| package com.baeldung.instrumentation.application; | ||
|
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| import org.slf4j.Logger; | ||
| 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 { | ||
| LOGGER.info("[Application] Starting ATM application"); | ||
| 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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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,5 @@ | ||
| Agent-Class: com.baeldung.instrumentation.agent.MyInstrumentationAgent | ||
| Can-Redefine-Classes: true | ||
| Can-Retransform-Classes: true | ||
| Premain-Class: com.baeldung.instrumentation.agent.MyInstrumentationAgent | ||
| Main-Class: com.baeldung.instrumentation.application.Launcher |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,13 @@ | ||
| <?xml version="1.0" encoding="UTF-8"?> | ||
| <Configuration status="WARN"> | ||
| <Appenders> | ||
| <Console name="Console" target="SYSTEM_OUT"> | ||
| <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level - %msg%n"/> | ||
| </Console> | ||
| </Appenders> | ||
| <Loggers> | ||
| <Root level="debug"> | ||
| <AppenderRef ref="Console"/> | ||
| </Root> | ||
| </Loggers> | ||
| </Configuration> |