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