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https://github.com/brutusin/instrumentation

An extensible java agent framework that instruments (modifies the bytecode at class loading time) programs running on the JVM, with the purpose of capturing method invocation events (start, finish, errors ...) and notifying custom listeners.
https://github.com/brutusin/instrumentation

aop bytecode bytecode-manipulation instrumentation

Last synced: about 15 hours ago
JSON representation

Host: GitHub
URL: https://github.com/brutusin/instrumentation
Owner: brutusin
License: apache-2.0
Created: 2015-01-22T08:43:02.000Z (almost 10 years ago)
Default Branch: master
Last Pushed: 2020-03-12T23:21:29.000Z (over 4 years ago)
Last Synced: 2023-07-26T23:26:37.716Z (over 1 year ago)
Topics: aop, bytecode, bytecode-manipulation, instrumentation
Language: Java
Homepage: http://brutusin.org/instrumentation
Size: 523 KB
Stars: 43
Watchers: 5
Forks: 10
Open Issues: 6
Metadata Files:
- Readme: README.md
- License: LICENSE

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README

        > Check out https://github.com/ShiftLeftSecurity/bctrace instead. A more mature and stable version of this project

# org.brutusin:instrumentation [![Build Status](https://api.travis-ci.org/brutusin/instrumentation.svg?branch=master)](https://travis-ci.org/brutusin/instrumentation) [![Maven Central Latest Version](https://maven-badges.herokuapp.com/maven-central/org.brutusin/instrumentation/badge.svg)](https://maven-badges.herokuapp.com/maven-central/org.brutusin/instrumentation/)

An extensible java agent framework that instruments programs running on the JVM (modifying the bytecode at class loading time), with the purpose of capturing method invocation events (start, finish, errors ...) and notifying custom listeners.

**Table of Contents**

- [org.brutusin:instrumentation](#orgbrutusininstrumentation)

  - [How it works](#how-it-works)

  - [Maven dependency](#maven-dependency)

  - [Example](#example)

    - [Implementation](#implementation)

    - [Packaging](#packaging)

    - [JRE launching](#jre-launching)

    - [Main stack](#main-stack)

    - [Brutusin dependent modules](#brutusin-dependent-modules)

    - [Support, bugs and requests](#support-bugs-and-requests)

    - [Authors](#authors)

    - [License](#license)

	

## How it works

The [java instrumentation package](http://docs.oracle.com/javase/8/docs/api/java/lang/instrument/package-summary.html) introduced in JDK1.5, provides a simple way to transform java-class definition at loading time, consisting basically in a `byte[]` to `byte[]` transformation, by the so called "java agents".

This module provides an agent ([org.brutusin.instrumentation.Agent](src/main/java/org/brutusin/instrumentation/Agent.java)) that creates an execution listener instance (from the name of a concrete class extending [org.brutusin.instrumentation.Interceptor](src/main/java/org/brutusin/instrumentation/Interceptor.java) passed from the JVM agent arguments) and, making use of the [ASM library](http://asm.ow2.org/), introduces a series of instructions in the method definitions of the classes to be loaded (classes and methods can be skipped) to notify these execution events to the listener.

From a simplified point of view, the dynamic transformation turns a method like this: 

```java

public Object foo(Object bar){

    return new Object();

}

```

into that:

```java

public Object foo(Object bar){

    onStart(bar);

    try{

        Object ret = new Object();

        onFinished(ret);

        return ret;

    } catch(Throwable th){

        onThrowable(th);

        throw th; // at bytecode level this is legal

    }

}

```

allowing your custom listener to be notified.

## Maven dependency 

```xml

    org.brutusin

    instrumentation

```

Click [here](http://search.maven.org/#search%7Cga%7C1%7Cg%3A%22org.brutusin%22%20a%3A%22instrumentation%22) to see the latest available version released to the Maven Central Repository.

If you are not using maven and need help you can ask [here](https://github.com/brutusin/instrumentation/issues).

## Example

*See [logging-instrumentation](https://github.com/brutusin/logging-instrumentation) for a complete working example.*

### Implementation

Create the following listener implementation:

```java

package mypackage;

public class MyInterceptor extends Interceptor {

    @Override

    public void init(String arg) {

        System.out.println("Interceptor args: " + arg);

    }

    @Override

    public boolean interceptClass(String className, byte[] byteCode) {

        return true; // all classes can be intrumented

    }

    @Override

    public boolean interceptMethod(ClassNode cn, MethodNode mn) {

        return true; // all methods are instrumented

    }

    @Override

    protected void doOnStart(Method m, Object[] arg, String executionId) {

        System.out.println("doOnStart " + m + " " + executionId);

    }

    @Override

    protected void doOnThrowableThrown(Method m, Throwable throwable, String executionId) {

        System.out.println("doOnThrowableThrown " + m + " " + executionId);

    }

    @Override

    protected void doOnThrowableUncatched(Method m, Throwable throwable, String executionId) {

        System.out.println("doOnThrowableUncatched " + m + " " + executionId);

    }

    @Override

    protected void doOnFinish(Method m, Object result, String executionId) {

        System.out.println("doOnFinish " + m + " " + executionId);

    }

}

```

### Packaging

Create a [fat-jar](http://maven.apache.org/plugins/maven-assembly-plugin/descriptor-refs.html#jar-with-dependencies) with the previous class and its dependencies. Add the following attribute to  the manifest of the agent JAR:

```

Premain-Class: org.brutusin.instrumentation.Agent

```

Suppose this jar to be named `myagent.jar`

### JRE launching

Run (at least JRE 1.5) the desired java application with the following JVM options: (suppossing myagent.jar located in the working directory)

```

-javaagent:myagent.jar=mypackage.MyInterceptor;an_interceptor_optional_parameter

```

## Main stack

This module could not be possible without:

* [org.ow2.asm:asm-all](http://asm.ow2.org/)

## Brutusin dependent modules

* [org.brutusin:logging-instrumentation](https://github.com/brutusin/logging-instrumentation)

## Support, bugs and requests

https://github.com/brutusin/instrumentation/issues

## Authors

- Ignacio del Valle Alles ()

Contributions are always welcome and greatly appreciated!

## License

Apache License, Version 2.0

http://www.apache.org/licenses/LICENSE-2.0