net.di2e.ecdr.commons.query.cache.QueryRequestCache.java Source code

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Here is the source code for net.di2e.ecdr.commons.query.cache.QueryRequestCache.java

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/**
 * Copyright (c) Cohesive Integrations, LLC
 *
 * This is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation, either version 3 of the License, or 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 Lesser General Public License for more
 * details. A copy of the GNU Lesser General Public License is distributed along with this program and can be found at
 * <http://www.gnu.org/licenses/lgpl.html>.
 * 
 **/
package net.di2e.ecdr.commons.query.cache;

import java.util.LinkedHashMap;
import java.util.Map;

import org.apache.commons.lang.StringUtils;

public class QueryRequestCache {

    private LRUCache<String, Boolean> cache = null;

    public QueryRequestCache(int cacheSize) {
        cache = new LRUCache<String, Boolean>(cacheSize);
    }

    public boolean isQueryIdUnique(String id) {
        boolean unique = true;
        if (StringUtils.isNotBlank(id)) {
            if (cache.containsKey(id)) {
                unique = false;
            } else {
                cache.put(id, Boolean.TRUE);
            }
        }
        return unique;
    }

    public void updateCacheSize(int capacity) {
        cache.updateCacheSize(capacity);
    }

    public void add(String id) {
        cache.put(id, Boolean.TRUE);
    }

    private static final class LRUCache<K, V> extends LinkedHashMap<K, V> {

        private static final long serialVersionUID = 1L;
        private int cacheSize = 0;

        public LRUCache(int capacity) {
            super(capacity + 1, 1.1f, true);
            this.cacheSize = capacity;
        }

        @Override
        protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
            return size() > cacheSize;
        }

        @Override
        public V put(K k, V v) {
            if (cacheSize > 0) {
                return super.put(k, v);
            }
            return null;
        }

        public void updateCacheSize(int size) {
            this.clear();
            cacheSize = size;
        }

    }

}