org.apache.aries.proxy.impl.common
Class AbstractWovenProxyMethodAdapter

java.lang.Object
  org.objectweb.asm.MethodAdapter
      org.objectweb.asm.commons.LocalVariablesSorter
          org.objectweb.asm.commons.GeneratorAdapter
              org.apache.aries.proxy.impl.common.AbstractWovenProxyMethodAdapter

All Implemented Interfaces:

org.objectweb.asm.MethodVisitor

public abstract class AbstractWovenProxyMethodAdapter
extends org.objectweb.asm.commons.GeneratorAdapter

This class weaves dispatch and listener code into a method, there are two known subclasses WovenProxyMethodAdapter is used for weaving instance methods InterfaceUsingWovenProxyMethodAdapter is used to provide a delegating implementation of an interface method. Roughly (but not exactly because it's easier to write working bytecode if you don't have to exactly recreate the Java!) this is trying to do the following: if(dispatcher != null) { int returnValue; Object token = null; boolean inInvoke = false; try { Object toInvoke = dispatcher.call(); if(listener != null) token = listener.preInvoke(toInvoke, method, args); inInvoke = true; returnValue = ((Template) toInvoke).doStuff(args); inInvoke = false; if(listener != null) listener.postInvoke(token, toInvoke, method, args); } catch (Throwable e){ // whether the the exception is an error is an application decision // if we catch an exception we decide carefully which one to // throw onwards Throwable exceptionToRethrow = null; // if the exception came from a precall or postcall // we will rethrow it if (!inInvoke) { exceptionToRethrow = e; } // if the exception didn't come from precall or postcall then it // came from invoke // we will rethrow this exception if it is not a runtime // exception, but we must unwrap InvocationTargetExceptions else { if (!(e instanceof RuntimeException)) { exceptionToRethrow = e; } } try { if(listener != null) listener.postInvokeExceptionalReturn(token, method, null, e); } catch (Throwable f) { // we caught an exception from // postInvokeExceptionalReturn // if we haven't already chosen an exception to rethrow then // we will throw this exception if (exceptionToRethrow == null) { exceptionToRethrow = f; } } // if we made it this far without choosing an exception we // should throw e if (exceptionToRethrow == null) { exceptionToRethrow = e; } throw exceptionToRethrow; } } //...original method body

Field Summary

protected org.objectweb.asm.commons.Method	currentTransformMethod The current method
protected org.objectweb.asm.Type	typeBeingWoven The type of this

Fields inherited from class org.objectweb.asm.commons.GeneratorAdapter

ADD, AND, DIV, EQ, GE, GT, LE, LT, MUL, NE, NEG, OR, REM, SHL, SHR, SUB, USHR, XOR

Fields inherited from class org.objectweb.asm.commons.LocalVariablesSorter

firstLocal, nextLocal

Fields inherited from class org.objectweb.asm.MethodAdapter

mv

Constructor Summary

AbstractWovenProxyMethodAdapter(org.objectweb.asm.MethodVisitor mv, int access, String name, String desc, String methodStaticFieldName, org.objectweb.asm.commons.Method currentTransformMethod, org.objectweb.asm.Type typeBeingWoven)
Construct a new method adapter

Method Summary

protected abstract org.objectweb.asm.Type	getTypeToCastTo() Get the type to which the class should be cast for delegation
protected abstract boolean	isTypeToCastToInterface()
protected void	unwrapEqualsArgument() This method unwraps woven proxy instances for use in the right-hand side of equals methods
abstract void	visitCode()
abstract void	visitMaxs(int stack, int locals)
protected void	writeDispatcher() Write out the bytecode instructions necessary to do the dispatch.

Methods inherited from class org.objectweb.asm.commons.GeneratorAdapter

arrayLength, arrayLoad, arrayStore, box, cast, catchException, checkCast, dup, dup2, dup2X1, dup2X2, dupX1, dupX2, endMethod, getField, getLocalType, getStatic, goTo, ifCmp, ifICmp, ifNonNull, ifNull, ifZCmp, iinc, instanceOf, invokeConstructor, invokeDynamic, invokeInterface, invokeStatic, invokeVirtual, loadArg, loadArgArray, loadArgs, loadArgs, loadLocal, loadLocal, loadThis, mark, mark, math, monitorEnter, monitorExit, newArray, newInstance, newLabel, not, pop, pop2, push, push, push, push, push, push, push, putField, putStatic, ret, returnValue, setLocalType, storeArg, storeLocal, storeLocal, swap, swap, tableSwitch, tableSwitch, throwException, throwException, unbox, valueOf

Methods inherited from class org.objectweb.asm.commons.LocalVariablesSorter

newLocal, newLocalMapping, visitFrame, visitIincInsn, visitLocalVariable, visitVarInsn

Methods inherited from class org.objectweb.asm.MethodAdapter

visitAnnotation, visitAnnotationDefault, visitAttribute, visitEnd, visitFieldInsn, visitInsn, visitIntInsn, visitJumpInsn, visitLabel, visitLdcInsn, visitLineNumber, visitLookupSwitchInsn, visitMethodInsn, visitMultiANewArrayInsn, visitParameterAnnotation, visitTableSwitchInsn, visitTryCatchBlock, visitTypeInsn

Methods inherited from class java.lang.Object

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

Field Detail

currentTransformMethod

protected final org.objectweb.asm.commons.Method currentTransformMethod

The current method

typeBeingWoven

protected final org.objectweb.asm.Type typeBeingWoven

The type of this

Constructor Detail

AbstractWovenProxyMethodAdapter

public AbstractWovenProxyMethodAdapter(org.objectweb.asm.MethodVisitor mv,
                                       int access,
                                       String name,
                                       String desc,
                                       String methodStaticFieldName,
                                       org.objectweb.asm.commons.Method currentTransformMethod,
                                       org.objectweb.asm.Type typeBeingWoven)

Construct a new method adapter

Parameters:

mv - - the method visitor to write to

access - - the access modifiers on this method

name - - the name of this method

desc - - the descriptor of this method

methodStaticFieldName - - the name of the static field that will hold the Method representing this method.

currentTransformMethod - - the ASM representation of this method

proxyType - - the type being woven that contains this method

Method Detail

visitCode

public abstract void visitCode()

Specified by:

visitCode in interface org.objectweb.asm.MethodVisitor

Overrides:

visitCode in class org.objectweb.asm.MethodAdapter

visitMaxs

public abstract void visitMaxs(int stack,
                               int locals)

Specified by:

visitMaxs in interface org.objectweb.asm.MethodVisitor

Overrides:

visitMaxs in class org.objectweb.asm.commons.LocalVariablesSorter

writeDispatcher

protected final void writeDispatcher()

Write out the bytecode instructions necessary to do the dispatch. We know the dispatcher is non-null, and we need a try/catch around the invocation and listener calls.

getTypeToCastTo

protected abstract org.objectweb.asm.Type getTypeToCastTo()

Get the type to which the class should be cast for delegation

Returns:

isTypeToCastToInterface

protected abstract boolean isTypeToCastToInterface()

unwrapEqualsArgument

protected final void unwrapEqualsArgument()

This method unwraps woven proxy instances for use in the right-hand side of equals methods