    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 *      https://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 behavior
    026 * for a multithreaded environment.
    027 * <p>
    028 * Methods are synchronized, then forwarded to the decorated multiset.
    029 * Iterators must be separately synchronized around the loop.
    030 * </p>
    031 *
    032 * @param <E> The type held in the multiset.
    033 * @since 4.1
    034 */
    035public class SynchronizedMultiSet<E> extends SynchronizedCollection<E> implements MultiSet<E> {
    036
    037    /**
    038     * Synchronized Set for the MultiSet class.
    039     *
    040     * @param <T> The type held in this Set.
    041     */
    042    static class SynchronizedSet<T> extends SynchronizedCollection<T> implements Set<T> {
    043
    044        /** Serialization version */
    045        private static final long serialVersionUID = 20150629L;
    046
    047        /**
    048         * Constructs a new instance.
    049         *
    050         * @param set  The set to decorate
    051         * @param lock  The lock to use, shared with the multiset
    052         */
    053        SynchronizedSet(final Set<T> set, final Object lock) {
    054            super(set, lock);
    055        }
    056    }
    057
    058    /** Serialization version */
    059    private static final long serialVersionUID = 20150629L;
    060
    061    /**
    062     * Factory method to create a synchronized multiset.
    063     *
    064     * @param <E> The type of the elements in the multiset
    065     * @param multiset  The multiset to decorate, must not be null
    066     * @return A new synchronized MultiSet
    067     * @throws NullPointerException if multiset is null
    068     */
    069    public static <E> SynchronizedMultiSet<E> synchronizedMultiSet(final MultiSet<E> multiset) {
    070        return new SynchronizedMultiSet<>(multiset);
    071    }
    072
    073    /**
    074     * Constructor that wraps (not copies).
    075     *
    076     * @param multiset  The multiset to decorate, must not be null
    077     * @throws NullPointerException if multiset is null
    078     */
    079    protected SynchronizedMultiSet(final MultiSet<E> multiset) {
    080        super(multiset);
    081    }
    082
    083    /**
    084     * Constructor that wraps (not copies).
    085     *
    086     * @param multiset  The multiset to decorate, must not be null
    087     * @param lock  The lock to use, must not be null
    088     * @throws NullPointerException if multiset or lock is null
    089     */
    090    protected SynchronizedMultiSet(final MultiSet<E> multiset, final Object lock) {
    091        super(multiset, lock);
    092    }
    093
    094    @Override
    095    public int add(final E object, final int count) {
    096        synchronized (lock) {
    097            return decorated().add(object, count);
    098        }
    099    }
    100
    101    /**
    102     * Gets the multiset being decorated.
    103     *
    104     * @return The decorated multiset
    105     */
    106    @Override
    107    protected MultiSet<E> decorated() {
    108        return (MultiSet<E>) super.decorated();
    109    }
    110
    111    @Override
    112    public Set<Entry<E>> entrySet() {
    113        synchronized (lock) {
    114            final Set<MultiSet.Entry<E>> set = decorated().entrySet();
    115            return new SynchronizedSet<>(set, lock);
    116        }
    117    }
    118
    119    @Override
    120    public boolean equals(final Object object) {
    121        if (object == this) {
    122            return true;
    123        }
    124        synchronized (lock) {
    125            return decorated().equals(object);
    126        }
    127    }
    128
    129    @Override
    130    public int getCount(final Object object) {
    131        synchronized (lock) {
    132            return decorated().getCount(object);
    133        }
    134    }
    135
    136    @Override
    137    public int hashCode() {
    138        synchronized (lock) {
    139            return decorated().hashCode();
    140        }
    141    }
    142
    143    @Override
    144    public int remove(final Object object, final int count) {
    145        synchronized (lock) {
    146            return decorated().remove(object, count);
    147        }
    148    }
    149
    150    @Override
    151    public int setCount(final E object, final int count) {
    152        synchronized (lock) {
    153            return decorated().setCount(object, count);
    154        }
    155    }
    156
    157    @Override
    158    public Set<E> uniqueSet() {
    159        synchronized (lock) {
    160            final Set<E> set = decorated().uniqueSet();
    161            return new SynchronizedSet<>(set, lock);
    162        }
    163    }
    164
    165}