Chapter List | Focus on Wechat Public Number, bugstack wormhole stack, reply to <Java Agent-based Full Link Monitoring> Get Source Code

• Java Agent-based full-link monitoring Java Agent
• Java Agent-based Full Link Monitoring II "Increasing Monitoring Execution Time by Bytecode"
• Java Agent-based Full Link Monitoring Three ByteBuddy Operational Monitoring Method Bytecode
• Java Agent-based Full Link Monitoring IV "JVM Memory and GC Information"
• Java Agent-based Full Link Monitoring Five "ThreadLocal Link Tracking"
• Java Agent-based Full Link Monitoring VI "Development and Application Level Monitoring"

Brief description of cases
Through the introduction of the previous chapter, "Hi! java Agent, we already know that by configuring - javaagent: file. jar, the premain method is executed when the java program starts. Next, we use javassist bytecode enhancement to monitor the time-consuming execution of method programs.

Environmental preparation
1,IntelliJ IDEA Community Edition
2. jdk1.8.0_4564 bits

Configuration information (path-related modifications for your own)
1. Configuration location: Run/Debug Configurations - > VM options
2. Configuration: - javaagent: E: itstack GIT itstack. org itstack - Demo - agent itstack - Demo - agent - 02 target itstack - Demo - agent - 02 - 1.0.0 - SNAPSHOT. jar = args

Code examples

itstack-demo-agent-02
├── pom.xml
└── src
    ├── main
    │   ├── java
    │   │   └── org.itstack.demo.agent
    │   │       ├── MyAgent.java
    │   │	    └── MyMonitorTransformer.java
    │	└── resources
    │       └── META-INF
    │           └── MANIFEST.MF 	
    └── test
         └── java
             └── org.itstack.demo.test
                 └── ApiTest.java

 <properties>
        <!-- Build args -->
	<argline>-Xms512m -Xmx512m</argline>
	<skip_maven_deploy>false</skip_maven_deploy>
	<updateReleaseInfo>true</updateReleaseInfo>
	<project.build.sourceEncoding>utf-8</project.build.sourceEncoding>
	<maven.test.skip>true</maven.test.skip>
	<!-- custom MANIFEST.MF -->
	<maven.configuration.manifestFile>src/main/resources/META-INF/MANIFEST.MF</maven.configuration.manifestFile>
</properties>

<dependencies>
	<dependency>
		<groupId>javassist</groupId>
		<artifactId>javassist</artifactId>
		<version>3.12.1.GA</version>
		<type>jar</type>
	</dependency>
</dependencies>

<!-- take javassist Packing to Agent in -->
<plugin>
	<groupId>org.apache.maven.plugins</groupId>
	<artifactId>maven-shade-plugin</artifactId>
	<executions>
		<execution>
			<phase>package</phase>
			<goals>
				<goal>shade</goal>
			</goals>
		</execution>
	</executions>
	<configuration>
		<artifactSet>
			<includes>
				<include>javassist:javassist:jar:</include>
			</includes>
		</artifactSet>
	</configuration>
</plugin>            

MyAgent.java

/**
 * Blog: http://itstack.org
 * Forum: http://bugstack.cn
 * Public number: bugstack wormhole stack
 * create by fuzhengwei on 2019
 */
public class MyAgent {

    //The JVM first attempts to invoke the following method on the proxy class
    public static void premain(String agentArgs, Instrumentation inst) {
        System.out.println("this is my agent: " + agentArgs);
        MyMonitorTransformer monitor = new MyMonitorTransformer();
        inst.addTransformer(monitor);
    }

    //If the proxy class does not implement the above method, the JVM will attempt to invoke the method
    public static void premain(String agentArgs) {
    }

}

MyMonitorTransformer.java

/**
 * Blog: http://itstack.org
 * Forum: http://bugstack.cn
 * Public number: bugstack wormhole stack
 * create by fuzhengwei on 2019
 */
public class MyMonitorTransformer implements ClassFileTransformer {

    private static final Set<String> classNameSet = new HashSet<>();

    static {
        classNameSet.add("org.itstack.demo.test.ApiTest");
    }

    @Override
    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) {
        try {
            String currentClassName = className.replaceAll("/", ".");
            if (!classNameSet.contains(currentClassName)) { // Promote the classes contained in the classNameSet
                return null;
            }
            System.out.println("transform: [" + currentClassName + "]");

            CtClass ctClass = ClassPool.getDefault().get(currentClassName);
            CtBehavior[] methods = ctClass.getDeclaredBehaviors();
            for (CtBehavior method : methods) {
                enhanceMethod(method);
            }
            return ctClass.toBytecode();
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        return null;

    }


    private void enhanceMethod(CtBehavior method) throws Exception {
        if (method.isEmpty()) {
            return;
        }
        String methodName = method.getName();
        if ("main".equalsIgnoreCase(methodName)) {
            return;
        }

        final StringBuilder source = new StringBuilder();
        // Pre-Enhancement: Input Timestamp
        // Keep the original code processing logic
        source.append("{")
                .append("long start = System.nanoTime();\n") //Pre-Enhancement: Input Timestamp
                .append("$_ = $proceed($$);\n")              //Call the original code, similar to method(); ($$) represents all the parameters
                .append("System.out.print(\"method:[")
                .append(methodName).append("]\");").append("\n")
                .append("System.out.println(\" cost:[\" +(System.nanoTime() - start)+ \"ns]\");") // Post-enhancement, computational output method execution time-consuming
                .append("}");

        ExprEditor editor = new ExprEditor() {
            @Override
            public void edit(MethodCall methodCall) throws CannotCompileException {
                methodCall.replace(source.toString());
            }
        };
        method.instrument(editor);
    }

}

MANIFEST.MF

Manifest-Version: 1.0
Premain-Class: org.itstack.demo.agent.MyAgent
Can-Redefine-Classes: true

ApiTest.java

/**
 * Blog: http://itstack.org
 * Forum: http://bugstack.cn
 * Public number: bugstack wormhole stack
 * create by fuzhengwei on 2019
 *
 * VM options: 
 * -javaagent:E:\itstack\GIT\itstack.org\itstack-demo-agent\itstack-demo-agent-02\target\itstack-demo-agent-02-1.0.0-SNAPSHOT.jar=testargs
 *
 */
public class ApiTest {

    public static void main(String[] args) {
        ApiTest apiTest = new ApiTest();
        apiTest.echoHi();
    }

    private void echoHi(){
        System.out.println("hi agent");
    }

}

test result

this is my agent: testargs
transform: [org.itstack.demo.test.ApiTest]
hi agent
method:[echoHi] cost:[294845ns]

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