Package com.google.monitoring.runtime.instrumentation

Class ConstructorInstrumenter

java.lang.Object
com.google.monitoring.runtime.instrumentation.ConstructorInstrumenter
All Implemented Interfaces:
ClassFileTransformer
public class ConstructorInstrumenter extends Object implements 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 Details

    • instrumentClass

      public static void instrumentClass(Class<?> c, ConstructorCallback<?> sampler) throws 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:
      UnmodifiableClassException - if c cannot be modified.

    • transform

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

    • instrument

      public static byte[] instrument(byte[] originalBytes, 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(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.