rusch.megan6server.cache.AuxiliaryCache.java Source code

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Here is the source code for rusch.megan6server.cache.AuxiliaryCache.java

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/** 
 * Copyright (C) 2015 Hans-Joachim Ruscheweyh
 *
 * (Some files contain contributions from other authors, who are then mentioned separately.)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package rusch.megan6server.cache;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

import megan.data.IConnector;
import rusch.megan6server.RMAFileHandler;

import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;

/**A caching class so that this simple command does not slow down important I/O
 * 
 * @author Hans-Joachim Ruscheweyh
 * 2:47:26 PM - Dec 23, 2014
 *
 */
public class AuxiliaryCache {

    private final Cache<Integer, Map<String, String>> auxCache;

    public AuxiliaryCache() {
        auxCache = CacheBuilder.newBuilder().maximumSize(10000).build();
    }

    /**Get Auxiliary Block. If possible, use the cache. Otherwise load from file but store it to the cache for later reference.
     * 
     * @param rma3FileHandler
     * @param fileId
     * @return
     * @throws IOException
     */
    public Map<String, String> getAuxBlock(RMAFileHandler rma3FileHandler, String fileId) throws IOException {
        Map<String, String> aux = auxCache.getIfPresent(rma3FileHandler.resolveFileIdentifierToId(fileId));
        if (aux == null) {
            IConnector connector = rma3FileHandler.getIConnector(fileId);
            Map<String, byte[]> map = connector.getAuxiliaryData();
            Map<String, String> map2 = new HashMap<String, String>();
            for (Entry<String, byte[]> entry : map.entrySet()) {
                map2.put(entry.getKey(), new String(entry.getValue()));
            }
            auxCache.put(rma3FileHandler.resolveFileIdentifierToId(fileId), map2);
            return map2;
        } else {
            return aux;
        }
    }

    public synchronized void clear() {
        auxCache.invalidateAll();
    }

}