Package com.google.monitoring.runtime.instrumentation

Class ConstructorInstrumenter

  • All Implemented Interfaces:
    java.lang.instrument.ClassFileTransformer
    public class ConstructorInstrumenter
extends java.lang.Object
implements java.lang.instrument.ClassFileTransformer
    Instruments bytecode by inserting a specified call in the constructor of a given class. This class is intended to be loaded by a javaagent; end-users will want to add ConstructorCallbacks by invoking instrumentClass(Class, ConstructorCallback).

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static byte[] instrument​(byte[] originalBytes, java.lang.Class<?> classBeingRedefined)
      Given the bytes representing a class, add invocations of the ConstructorCallback method to the constructor.
      static void instrumentClass​(java.lang.Class<?> c, ConstructorCallback<?> sampler)
      Ensures that the given sampler will be invoked every time a constructor for class c is invoked.
      static void invokeSamplers​(java.lang.Object o)
      Bytecode is rewritten to invoke this method; it calls the sampler for the given class.
      byte[] transform​(java.lang.ClassLoader loader, java.lang.String className, java.lang.Class<?> classBeingRedefined, java.security.ProtectionDomain protectionDomain, byte[] classfileBuffer)

      • Methods inherited from class java.lang.Object

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

      • Methods inherited from interface java.lang.instrument.ClassFileTransformer

        transform

    • Method Detail

      • instrumentClass

        public static void instrumentClass​(java.lang.Class<?> c,
                                   ConstructorCallback<?> sampler)
                            throws java.lang.instrument.UnmodifiableClassException
        Ensures that the given sampler will be invoked every time a constructor for class c is invoked.
        Parameters:
        c - The class to be tracked
        sampler - the code to be invoked when an instance of c is constructed
        Throws:
        java.lang.instrument.UnmodifiableClassException - if c cannot be modified.

      • transform

        public byte[] transform​(java.lang.ClassLoader loader,
                        java.lang.String className,
                        java.lang.Class<?> classBeingRedefined,
                        java.security.ProtectionDomain protectionDomain,
                        byte[] classfileBuffer)
        Specified by:
        transform in interface java.lang.instrument.ClassFileTransformer

      • instrument

        public static byte[] instrument​(byte[] originalBytes,
                                java.lang.Class<?> classBeingRedefined)
        Given the bytes representing a class, add invocations of the ConstructorCallback method to the constructor.
        Parameters:
        originalBytes - the original byte[] code.
        classBeingRedefined - the class being redefined.
        Returns:
        the instrumented byte[] code.

      • invokeSamplers

        public static void invokeSamplers​(java.lang.Object o)
        Bytecode is rewritten to invoke this method; it calls the sampler for the given class. Note that, unless the javaagent command line argument "subclassesAlso" is specified, it won't do anything if o is a subclass of the class that was supposed to be tracked.
        Parameters:
        o - the object passed to the samplers.