CapacityLruLinkedHashMap.java

/*******************************************************************************
 * Copyright French Prime minister Office/SGMAP/DINSIC/Vitam Program (2015-2019)
 *
 * contact.vitam@culture.gouv.fr
 *
 * This software is a computer program whose purpose is to implement a digital archiving back-office system managing
 * high volumetry securely and efficiently.
 *
 * This software is governed by the CeCILL 2.1 license under French law and abiding by the rules of distribution of free
 * software. You can use, modify and/ or redistribute the software under the terms of the CeCILL 2.1 license as
 * circulated by CEA, CNRS and INRIA at the following URL "http://www.cecill.info".
 *
 * As a counterpart to the access to the source code and rights to copy, modify and redistribute granted by the license,
 * users are provided only with a limited warranty and the software's author, the holder of the economic rights, and the
 * successive licensors have only limited liability.
 *
 * In this respect, the user's attention is drawn to the risks associated with loading, using, modifying and/or
 * developing or reproducing the software by the user in light of its specific status of free software, that may mean
 * that it is complicated to manipulate, and that also therefore means that it is reserved for developers and
 * experienced professionals having in-depth computer knowledge. Users are therefore encouraged to load and test the
 * software's suitability as regards their requirements in conditions enabling the security of their systems and/or data
 * to be ensured and, more generally, to use and operate it in the same conditions as regards security.
 *
 * The fact that you are presently reading this means that you have had knowledge of the CeCILL 2.1 license and that you
 * accept its terms.
 *******************************************************************************/
package fr.gouv.vitam.common.lru;

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

/**
 * Capacity based LRU version of LinkedHashMap
 *
 *
 * author Damian Momot
 *
 */
class CapacityLruLinkedHashMap<K, V> extends LinkedHashMap<K, V> {
    /**
     *
     */
    private static final long serialVersionUID = -5064888079959689619L;

    private final int capacity;

    /**
     * Creates LRU LinkedHashMap
     *
     * @param capacity
     * @param initialCapacity
     * @param loadFactor
     * @throws IllegalArgumentException if capacity is not positive
     */
    protected CapacityLruLinkedHashMap(int capacity, int initialCapacity,
        float loadFactor) {
        super(initialCapacity, loadFactor, true);

        if (capacity <= 0) {
            throw new IllegalArgumentException("capacity must be positive");
        }

        this.capacity = capacity;
    }

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

    /**
     * Returns capacity of map
     *
     * @return the capacity
     */
    public int getCapacity() {
        return this.capacity;
    }

}