net.enilink.composition.cache.behaviours.CacheBehaviourMethodProcessor.java Source code

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Here is the source code for net.enilink.composition.cache.behaviours.CacheBehaviourMethodProcessor.java

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/*******************************************************************************
 * Copyright (c) 2010 Fraunhofer IWU and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Fraunhofer IWU - initial API and implementation
 *******************************************************************************/
package net.enilink.composition.cache.behaviours;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

import org.objectweb.asm.Label;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.FieldNode;
import net.enilink.composition.asm.AsmUtils;
import net.enilink.composition.asm.BehaviourClassNode;
import net.enilink.composition.asm.BehaviourMethodProcessor;
import net.enilink.composition.asm.DependsOn;
import net.enilink.composition.asm.ExtendedMethod;
import net.enilink.composition.asm.Types;
import net.enilink.composition.asm.util.BehaviourMethodGenerator;
import net.enilink.composition.cache.IPropertyCache;
import net.enilink.composition.cache.annotations.Cacheable;

import com.google.inject.Inject;

@DependsOn(BehaviourMethodProcessor.class)
public class CacheBehaviourMethodProcessor implements BehaviourMethodProcessor, Opcodes, Types {

    @Override
    public boolean appliesTo(BehaviourClassNode classNode, ExtendedMethod method) {
        return AsmUtils.findAnnotation(Cacheable.class, method.getOverriddenMethod()) != null
                && !method.getOverriddenMethod().getReturnType().equals(Void.TYPE);
    }

    @Override
    public boolean implementsMethod(Class<?> targetClass, Method method) {
        return !Modifier.isAbstract(method.getModifiers())
                && AsmUtils.findAnnotation(Cacheable.class, method) != null
                && !method.getReturnType().equals(Void.TYPE);
    }

    @SuppressWarnings("unchecked")
    @Override
    public void initialize(BehaviourClassNode classNode) throws Exception {
        FieldNode cacheField = new FieldNode(Opcodes.ACC_PRIVATE, "cache", Type.getDescriptor(IPropertyCache.class),
                null, null);
        cacheField.visitAnnotation(Type.getDescriptor(Inject.class), true);
        classNode.fields.add(cacheField);
    }

    @Override
    public void process(BehaviourClassNode classNode, ExtendedMethod method) throws Exception {
        boolean isAbstract = method.instructions.size() == 0;

        Type returnType = Type.getReturnType(method.desc);

        Cacheable cacheable = AsmUtils.findAnnotation(Cacheable.class, method.getOverriddenMethod());
        String cacheKey = cacheable.key().isEmpty() ? method.name : cacheable.key();

        BehaviourMethodGenerator gen = new BehaviourMethodGenerator(method);
        if (!isAbstract) {
            gen.pushInsns();
        }

        gen.loadThis();
        gen.getField("cache", Type.getType(IPropertyCache.class));
        gen.loadBean();
        gen.push(cacheKey);
        gen.loadArgArray();
        gen.invokeInterface(Type.getType(IPropertyCache.class), new org.objectweb.asm.commons.Method("get",
                OBJECT_TYPE, new Type[] { OBJECT_TYPE, OBJECT_TYPE, Type.getType(Object[].class) }));
        gen.dup();

        Label isNull = gen.newLabel();
        gen.ifNull(isNull);

        gen.unbox(returnType);
        gen.returnValue();

        gen.mark(isNull);
        gen.pop();

        if (!isAbstract) {
            gen.peekInsns().insertBefore(gen.peekInsns().getFirst(), gen.instructions);
            gen.instructions.clear();
        }

        int result = gen.newLocal(returnType);

        if (!isAbstract) {
            // add caching instructions
            for (AbstractInsnNode insn : method.instructions.toArray()) {
                if (insn.getOpcode() >= IRETURN & insn.getOpcode() <= ARETURN) {
                    gen.pushInsns();

                    storeValue(result, returnType, cacheKey, gen);

                    gen.peekInsns().insertBefore(insn, gen.instructions);
                    gen.instructions.clear();
                }
            }
        } else {
            // generate super call and store value in cache
            gen.loadThis();
            gen.loadArgs();
            gen.invokeSpecial(classNode.getParentType(),
                    new org.objectweb.asm.commons.Method(method.name, method.desc));
            storeValue(result, returnType, cacheKey, gen);
            gen.returnValue();
        }
    }

    private void storeValue(int resultVar, Type type, String cacheKey, BehaviourMethodGenerator gen) {
        gen.storeLocal(resultVar);

        gen.loadThis();
        gen.getField("cache", Type.getType(IPropertyCache.class));
        gen.loadBean();
        gen.push(cacheKey);
        gen.loadArgArray();
        gen.loadLocal(resultVar);
        gen.box(type);
        gen.invokeInterface(Type.getType(IPropertyCache.class), new org.objectweb.asm.commons.Method("put",
                OBJECT_TYPE, new Type[] { OBJECT_TYPE, OBJECT_TYPE, Type.getType(Object[].class), OBJECT_TYPE }));
        gen.unbox(type);
    }
}