Package org.eclipse.steady.java.monitor

Class DynamicTransformer

java.lang.Object

org.eclipse.steady.java.monitor.DynamicTransformer

All Implemented Interfaces:

ClassFileTransformer

public class DynamicTransformer
extends Object
implements ClassFileTransformer

Uses the ClassVisitor to dynamically instrument Java constructors and methods during the class loading process. When executed, the injected code will call the ExecutionMonitor to collect and upload runtime information to the Vulas backend.

The name has been chosen to contrast with static instrumentation, which can be done with help of the Vulas Maven plugin (goal vulas:instr).

Method Summary

Modifier and Type	Method	Description
static DynamicTransformer	getInstance()	Singleton method: Creates (if necessary) and returns the single instance that can be created for this class.
LoaderHierarchy	getLoaderHierarchy()	Getter for the field loaderHierarchy.
static boolean	isInstantiated()	Returns true if the Singleton has been created.
boolean	isTransformationEnabled()	isTransformationEnabled.
static void	premain(String agentArgs, Instrumentation inst)	premain.
void	setTransformationEnabled(boolean transformationEnabled)	Setter for the field transformationEnabled.
String	toString()	toString.
byte[]	transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer)	Adds instrumentation code to all constructors and methods of all classes (thereby considering certain blacklists and whitelists read from the configuration file).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.instrument.ClassFileTransformer

transform

Method Detail

isTransformationEnabled

public boolean isTransformationEnabled()

isTransformationEnabled.

Returns:

a boolean.

setTransformationEnabled

public void setTransformationEnabled(boolean transformationEnabled)

Setter for the field transformationEnabled.

Parameters:

transformationEnabled - a boolean.

getLoaderHierarchy

public LoaderHierarchy getLoaderHierarchy()

Getter for the field loaderHierarchy.

Returns:

a LoaderHierarchy object.

transform

public byte[] transform(ClassLoader loader,
                        String className,
                        Class<?> classBeingRedefined,
                        ProtectionDomain protectionDomain,
                        byte[] classfileBuffer)
                 throws IllegalClassFormatException

Adds instrumentation code to all constructors and methods of all classes (thereby considering certain blacklists and whitelists read from the configuration file).

The method is called by the JRE class loading process and returns the instrumented bytecode for a given class.

Specified by:

transform in interface ClassFileTransformer

Parameters:

loader - a ClassLoader object.

className - a String object.

classBeingRedefined - a Class object.

protectionDomain - a ProtectionDomain object.

classfileBuffer - an array of byte objects.

Returns:

the instrumented bytecode

Throws:

IllegalClassFormatException - if any.

toString

public String toString()

toString.

Overrides:

toString in class Object

Returns:

a String object.

getInstance

public static DynamicTransformer getInstance()

Singleton method: Creates (if necessary) and returns the single instance that can be created for this class.

Returns:

a DynamicTransformer object.

isInstantiated

public static boolean isInstantiated()

Returns true if the Singleton has been created.

Returns:

a boolean.

premain

public static void premain(String agentArgs,
                           Instrumentation inst)

premain.

Parameters:

agentArgs - a String object.

inst - a Instrumentation object.