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}