    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.collections4.multiset;
    018
    019import java.util.Set;
    020
    021import org.apache.commons.collections4.MultiSet;
    022import org.apache.commons.collections4.collection.SynchronizedCollection;
    023
    024/**
    025 * Decorates another {@link MultiSet} to synchronize its behaviour
    026 * for a multi-threaded environment.
    027 * <p>
    028 * Methods are synchronized, then forwarded to the decorated multiset.
    029 * Iterators must be separately synchronized around the loop.
    030 *
    031 * @param <E> the type held in the multiset
    032 * @since 4.1
    033 */
    034public class SynchronizedMultiSet<E> extends SynchronizedCollection<E> implements MultiSet<E> {
    035
    036    /** Serialization version */
    037    private static final long serialVersionUID = 20150629L;
    038
    039    /**
    040     * Factory method to create a synchronized multiset.
    041     *
    042     * @param <E> the type of the elements in the multiset
    043     * @param multiset  the multiset to decorate, must not be null
    044     * @return a new synchronized MultiSet
    045     * @throws NullPointerException if multiset is null
    046     */
    047    public static <E> SynchronizedMultiSet<E> synchronizedMultiSet(final MultiSet<E> multiset) {
    048        return new SynchronizedMultiSet<>(multiset);
    049    }
    050
    051    //-----------------------------------------------------------------------
    052    /**
    053     * Constructor that wraps (not copies).
    054     *
    055     * @param multiset  the multiset to decorate, must not be null
    056     * @throws NullPointerException if multiset is null
    057     */
    058    protected SynchronizedMultiSet(final MultiSet<E> multiset) {
    059        super(multiset);
    060    }
    061
    062    /**
    063     * Constructor that wraps (not copies).
    064     *
    065     * @param multiset  the multiset to decorate, must not be null
    066     * @param lock  the lock to use, must not be null
    067     * @throws NullPointerException if multiset or lock is null
    068     */
    069    protected SynchronizedMultiSet(final MultiSet<E> multiset, final Object lock) {
    070        super(multiset, lock);
    071    }
    072
    073    /**
    074     * Gets the multiset being decorated.
    075     *
    076     * @return the decorated multiset
    077     */
    078    @Override
    079    protected MultiSet<E> decorated() {
    080        return (MultiSet<E>) super.decorated();
    081    }
    082
    083    @Override
    084    public boolean equals(final Object object) {
    085        if (object == this) {
    086            return true;
    087        }
    088        synchronized (lock) {
    089            return decorated().equals(object);
    090        }
    091    }
    092
    093    @Override
    094    public int hashCode() {
    095        synchronized (lock) {
    096            return decorated().hashCode();
    097        }
    098    }
    099
    100    //-----------------------------------------------------------------------
    101
    102    @Override
    103    public int add(final E object, final int count) {
    104        synchronized (lock) {
    105            return decorated().add(object, count);
    106        }
    107    }
    108
    109    @Override
    110    public int remove(final Object object, final int count) {
    111        synchronized (lock) {
    112            return decorated().remove(object, count);
    113        }
    114    }
    115
    116    @Override
    117    public int getCount(final Object object) {
    118        synchronized (lock) {
    119            return decorated().getCount(object);
    120        }
    121    }
    122
    123    @Override
    124    public int setCount(final E object, final int count) {
    125        synchronized (lock) {
    126            return decorated().setCount(object, count);
    127        }
    128    }
    129
    130    @Override
    131    public Set<E> uniqueSet() {
    132        synchronized (lock) {
    133            final Set<E> set = decorated().uniqueSet();
    134            return new SynchronizedSet<>(set, lock);
    135        }
    136    }
    137
    138    @Override
    139    public Set<Entry<E>> entrySet() {
    140        synchronized (lock) {
    141            final Set<MultiSet.Entry<E>> set = decorated().entrySet();
    142            return new SynchronizedSet<>(set, lock);
    143        }
    144    }
    145
    146    //-----------------------------------------------------------------------
    147    /**
    148     * Synchronized Set for the MultiSet class.
    149     */
    150    static class SynchronizedSet<T> extends SynchronizedCollection<T> implements Set<T> {
    151        /** Serialization version */
    152        private static final long serialVersionUID = 20150629L;
    153
    154        /**
    155         * Constructor.
    156         * @param set  the set to decorate
    157         * @param lock  the lock to use, shared with the multiset
    158         */
    159        SynchronizedSet(final Set<T> set, final Object lock) {
    160            super(set, lock);
    161        }
    162    }
    163
    164}