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    /*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2012-2015 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */

package org.jvnet.hk2.internal;

import java.io.Serializable;
import java.lang.annotation.Annotation;
import java.util.Comparator;
import java.util.List;
import java.util.TreeSet;

import javax.inject.Singleton;

import org.glassfish.hk2.api.ActiveDescriptor;
import org.glassfish.hk2.api.Context;
import org.glassfish.hk2.api.MultiException;
import org.glassfish.hk2.api.ServiceHandle;
import org.glassfish.hk2.utilities.BuilderHelper;
import org.glassfish.hk2.utilities.ContextualInput;
import org.glassfish.hk2.utilities.cache.Cache;
import org.glassfish.hk2.utilities.cache.Computable;
import org.glassfish.hk2.utilities.reflection.Logger;

/**
 * @author jwells
 *
 */
@Singleton
public class SingletonContext implements Context {
    private int generationNumber = Integer.MIN_VALUE;
    private final ServiceLocatorImpl locator;

    private final Cache, Object> valueCache =
            new Cache, Object>(new Computable, Object>() {

        @Override
        public Object compute(ContextualInput a) {

            final ActiveDescriptor activeDescriptor = a.getDescriptor();

            final Object cachedVal = activeDescriptor.getCache();
            if (cachedVal != null) {
                return cachedVal;
            }

            final Object createdVal = activeDescriptor.create(a.getRoot());
            activeDescriptor.setCache(createdVal);
            if (activeDescriptor instanceof SystemDescriptor) {
                ((SystemDescriptor) activeDescriptor).setSingletonGeneration(generationNumber++);
            }

            return createdVal;
        }
    }, new Cache.CycleHandler>(){

        @Override
        public void handleCycle(ContextualInput key) {
            throw new MultiException(new IllegalStateException(
                            "A circular dependency involving Singleton service " + key.getDescriptor().getImplementation() +
                            " was found.  Full descriptor is " + key.getDescriptor()));
        }
    });

    /* package */ SingletonContext(ServiceLocatorImpl impl) {
        locator = impl;
    }

    /* (non-Javadoc)
     * @see org.glassfish.hk2.api.Context#getScope()
     */
    @Override
    public Class getScope() {
        return Singleton.class;
    }

    /* (non-Javadoc)
     * @see org.glassfish.hk2.api.Context#findOrCreate(org.glassfish.hk2.api.ActiveDescriptor, org.glassfish.hk2.api.ServiceHandle)
     */
    @SuppressWarnings("unchecked")
    @Override
    public  T findOrCreate(ActiveDescriptor activeDescriptor,
            ServiceHandle root) {

        try {
            return (T)valueCache.compute(new ContextualInput((ActiveDescriptor) activeDescriptor, root));
        } catch (Throwable th) {
            if (th instanceof MultiException) {
                throw (MultiException) th;
            }
            throw new MultiException(th);
        }
    }

    /* (non-Javadoc)
     * @see org.glassfish.hk2.api.Context#find(org.glassfish.hk2.api.Descriptor)
     */
    @SuppressWarnings("unchecked")
    @Override
    public boolean containsKey(ActiveDescriptor descriptor) {
        return valueCache.containsKey(new ContextualInput((ActiveDescriptor) descriptor, null));
    }

    /* (non-Javadoc)
     * @see org.glassfish.hk2.api.Context#isActive()
     */
    @Override
    public boolean isActive() {
        return true;
    }

    /* (non-Javadoc)
     * @see org.glassfish.hk2.api.Context#supportsNullCreation()
     */
    @Override
    public boolean supportsNullCreation() {
        return false;
    }

    /* (non-Javadoc)
     * @see org.glassfish.hk2.api.Context#supportsNullCreation()
     */
    @SuppressWarnings("unchecked")
    @Override
    public void shutdown() {
        List> all = locator.getDescriptors(BuilderHelper.allFilter());

        long myLocatorId = locator.getLocatorId();

        TreeSet> singlesOnly = new TreeSet>(
                new GenerationComparator());
        for (ActiveDescriptor one : all) {
            if (one.getScope() == null || !one.getScope().equals(Singleton.class.getName())) continue;

            synchronized (this) {
                if (one.getCache() == null) continue;
            }

            if (one.getLocatorId() == null || one.getLocatorId().longValue() != myLocatorId) continue;

            SystemDescriptor oneAsObject = (SystemDescriptor) one;

            singlesOnly.add(oneAsObject);
        }

        for (SystemDescriptor one : singlesOnly) {
            destroyOne(one);
        }
    }

    /**
     * Release one system descriptor
     *
     * @param one The descriptor to release (may not be null).  Further, the cache MUST be set
     */
    @SuppressWarnings("unchecked")
    @Override
    public void destroyOne(ActiveDescriptor one) {
        Object value;
        valueCache.remove(new ContextualInput((ActiveDescriptor) one, null));
        value = one.getCache();
        one.releaseCache();

        if (value == null) return;

        try {
            ((ActiveDescriptor) one).dispose(value);
        }
        catch (Throwable th) {
            Logger.getLogger().debug("SingletonContext", "releaseOne", th);
        }

    }

    private static class GenerationComparator implements Comparator>, Serializable {

        /**
         * For serialization
         */
        private static final long serialVersionUID = -6931828935035131179L;

        @Override
        public int compare(SystemDescriptor o1,
                SystemDescriptor o2) {
            if (o1.getSingletonGeneration() > o2.getSingletonGeneration()) {
                return -1;
            }
            if (o1.getSingletonGeneration() == o2.getSingletonGeneration()) {
                return 0;
            }

            return 1;
        }

    }
}
    
    
    
    

    




    
    
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