001/*
002 * Copyright 2002-2016 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.aop.aspectj.annotation;
018
019import java.io.Serializable;
020
021import org.springframework.util.Assert;
022
023/**
024 * Decorator to cause a {@link MetadataAwareAspectInstanceFactory} to instantiate only once.
025 *
026 * @author Rod Johnson
027 * @author Juergen Hoeller
028 * @since 2.0
029 */
030@SuppressWarnings("serial")
031public class LazySingletonAspectInstanceFactoryDecorator implements MetadataAwareAspectInstanceFactory, Serializable {
032
033        private final MetadataAwareAspectInstanceFactory maaif;
034
035        private volatile Object materialized;
036
037
038        /**
039         * Create a new lazily initializing decorator for the given AspectInstanceFactory.
040         * @param maaif the MetadataAwareAspectInstanceFactory to decorate
041         */
042        public LazySingletonAspectInstanceFactoryDecorator(MetadataAwareAspectInstanceFactory maaif) {
043                Assert.notNull(maaif, "AspectInstanceFactory must not be null");
044                this.maaif = maaif;
045        }
046
047
048        @Override
049        public Object getAspectInstance() {
050                if (this.materialized == null) {
051                        Object mutex = this.maaif.getAspectCreationMutex();
052                        if (mutex == null) {
053                                this.materialized = this.maaif.getAspectInstance();
054                        }
055                        else {
056                                synchronized (mutex) {
057                                        if (this.materialized == null) {
058                                                this.materialized = this.maaif.getAspectInstance();
059                                        }
060                                }
061                        }
062                }
063                return this.materialized;
064        }
065
066        public boolean isMaterialized() {
067                return (this.materialized != null);
068        }
069
070        @Override
071        public ClassLoader getAspectClassLoader() {
072                return this.maaif.getAspectClassLoader();
073        }
074
075        @Override
076        public AspectMetadata getAspectMetadata() {
077                return this.maaif.getAspectMetadata();
078        }
079
080        @Override
081        public Object getAspectCreationMutex() {
082                return this.maaif.getAspectCreationMutex();
083        }
084
085        @Override
086        public int getOrder() {
087                return this.maaif.getOrder();
088        }
089
090
091        @Override
092        public String toString() {
093                return "LazySingletonAspectInstanceFactoryDecorator: decorating " + this.maaif;
094        }
095
096}