001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.commons.jcs3.jcache.extras.loader;
020
021import javax.cache.configuration.Factory;
022import javax.cache.integration.CacheLoader;
023import javax.cache.integration.CacheLoaderException;
024
025import org.apache.commons.jcs3.jcache.extras.closeable.Closeables;
026
027import java.io.Closeable;
028import java.io.IOException;
029import java.util.ArrayList;
030import java.util.Collection;
031import java.util.HashMap;
032import java.util.Map;
033
034public class CompositeCacheLoader<K, V> implements CacheLoader<K, V>, Closeable, Factory<CacheLoader<K, V>>
035{
036    private final CacheLoader<K, V>[] delegates;
037
038    public CompositeCacheLoader(final CacheLoader<K, V>... delegates)
039    {
040        this.delegates = delegates;
041    }
042
043    @Override
044    public V load(final K key) throws CacheLoaderException
045    {
046        for (final CacheLoader<K, V> delegate : delegates)
047        {
048            final V v = delegate.load(key);
049            if (v != null)
050            {
051                return v;
052            }
053        }
054        return null;
055    }
056
057    @Override
058    public Map<K, V> loadAll(final Iterable<? extends K> keys) throws CacheLoaderException
059    {
060        final Collection<K> list = new ArrayList<>();
061        for (final K k : keys)
062        {
063            list.add(k);
064        }
065
066        final Map<K, V> result = new HashMap<>();
067        for (final CacheLoader<K, V> delegate : delegates)
068        {
069            final Map<K, V> v = delegate.loadAll(list);
070            if (v != null)
071            {
072                result.putAll(v);
073                list.removeAll(v.keySet());
074                if (list.isEmpty())
075                {
076                    return v;
077                }
078            }
079        }
080
081        return result;
082    }
083
084    @Override
085    public void close() throws IOException
086    {
087        Closeables.close(delegates);
088    }
089
090    @Override
091    public CacheLoader<K, V> create()
092    {
093        return this;
094    }
095}