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 *   Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
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package org.apache.cayenne.jcache;

import java.util.List;
import javax.cache.processor.EntryProcessor;
import javax.cache.processor.EntryProcessorException;
import javax.cache.processor.MutableEntry;

import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.cache.QueryCacheEntryFactory;

/**
 * @since 4.0
 */
public class JCacheEntryLoader implements EntryProcessor<String, List, List> {

    private QueryCacheEntryFactory entryFactory;

    public JCacheEntryLoader(QueryCacheEntryFactory entryFactory) {
        this.entryFactory = entryFactory;
    }

    @Override
    public List process(MutableEntry<String, List> entry, Object... arguments) throws EntryProcessorException {
        if (!entry.exists()) {
            List result = (List)entryFactory.createObject();
            // sanity checking value
            if (result == null) {
                throw new CayenneRuntimeException("Null object created: %s", entry.getKey());
            }
            entry.setValue(result);
        }

        return entry.getValue();
    }
}