net.ontopia.persistence.proxy.QueryCache.java Source code

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Here is the source code for net.ontopia.persistence.proxy.QueryCache.java

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/*
 * #!
 * Ontopia Engine
 * #-
 * Copyright (C) 2001 - 2013 The Ontopia Project
 * #-
 * Licensed 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 under the License.
 * !#
 */

package net.ontopia.persistence.proxy;

import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import net.ontopia.persistence.query.sql.DetachedQueryIF;
import net.ontopia.utils.NullObject;
import net.ontopia.utils.ObjectUtils;
import net.ontopia.utils.OntopiaRuntimeException;
import org.apache.commons.collections4.map.LRUMap;

/**
 * INTERNAL: A storage access implementation accessing relational
 * databases using JDBC.
 */

public class QueryCache implements EvictableIF {

    protected DetachedQueryIF query;
    protected CacheIF cache;
    protected Map lru;
    protected int lrusize;

    QueryCache(DetachedQueryIF query, CacheIF cache, int lrusize) {
        this.query = query;
        this.cache = cache;
        this.lru = Collections.synchronizedMap(new LRUMap(lrusize));
        this.lrusize = lrusize;
    }

    public Object executeQuery(StorageAccessIF access, Object cachekey, Object[] query_params) {
        try {
            Object result = cache.get(cachekey);
            if (result == null) {
                // cache miss
                result = query.executeQuery(((RDBMSAccess) access).getConnection(), query_params);
                cache.put(cachekey, (result == null ? NullObject.INSTANCE : result));
                lru.put(cachekey, (result == null ? NullObject.INSTANCE : result));
                return result;
            } else {
                // cache hit
                lru.put(cachekey, result);
                return (ObjectUtils.equals(NullObject.INSTANCE, result) ? null : result);
            }
        } catch (RuntimeException e1) {
            throw e1;
        } catch (Exception e2) {
            throw new OntopiaRuntimeException(e2);
        }
    }

    public Object remove(Object key) {
        return remove(key, true);
    }

    public void removeAll(Collection keys) {
        removeAll(keys, true);
    }

    // -----------------------------------------------------------------------------
    // EvictableIF
    // -----------------------------------------------------------------------------

    // NOTE: following methods used by transactions on commit to evict
    // entries from shared query cache

    public Object remove(Object key, boolean notifyCluster) {
        return cache.remove(key, notifyCluster);
    }

    public void removeAll(Collection keys, boolean notifyCluster) {
        cache.removeAll(keys, notifyCluster);
    }

    public void clear(boolean notifyCluster) {
        lru.clear();
        cache.clear(notifyCluster);
    }

    // -----------------------------------------------------------------------------
    // Report
    // -----------------------------------------------------------------------------

    public void writeReport(java.io.Writer out, boolean dumpCache) throws java.io.IOException {
        cache.writeReport(out, dumpCache);
    }

}