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.bag;
018
019import java.util.Set;
020
021import org.apache.commons.collections4.Bag;
022import org.apache.commons.collections4.collection.SynchronizedCollection;
023
024/**
025 * Decorates another {@link Bag} to synchronize its behaviour
026 * for a multi-threaded environment.
027 * <p>
028 * Methods are synchronized, then forwarded to the decorated bag.
029 * Iterators must be separately synchronized around the loop.
030 * <p>
031 * This class is Serializable from Commons Collections 3.1.
032 *
033 * @since 3.0
034 * @version $Id: SynchronizedBag.html 972421 2015-11-14 20:00:04Z tn $
035 */
036public class SynchronizedBag<E> extends SynchronizedCollection<E> implements Bag<E> {
037
038    /** Serialization version */
039    private static final long serialVersionUID = 8084674570753837109L;
040
041    /**
042     * Factory method to create a synchronized bag.
043     *
044     * @param <E> the type of the elements in the bag
045     * @param bag  the bag to decorate, must not be null
046     * @return a new synchronized Bag
047     * @throws IllegalArgumentException if bag is null
048     * @since 4.0
049     */
050    public static <E> SynchronizedBag<E> synchronizedBag(final Bag<E> bag) {
051        return new SynchronizedBag<E>(bag);
052    }
053
054    //-----------------------------------------------------------------------
055    /**
056     * Constructor that wraps (not copies).
057     *
058     * @param bag  the bag to decorate, must not be null
059     * @throws IllegalArgumentException if bag is null
060     */
061    protected SynchronizedBag(final Bag<E> bag) {
062        super(bag);
063    }
064
065    /**
066     * Constructor that wraps (not copies).
067     *
068     * @param bag  the bag to decorate, must not be null
069     * @param lock  the lock to use, must not be null
070     * @throws IllegalArgumentException if bag is null
071     */
072    protected SynchronizedBag(final Bag<E> bag, final Object lock) {
073        super(bag, lock);
074    }
075
076    /**
077     * Gets the bag being decorated.
078     *
079     * @return the decorated bag
080     */
081    protected Bag<E> getBag() {
082        return (Bag<E>) decorated();
083    }
084
085    //-----------------------------------------------------------------------
086
087    public boolean add(final E object, final int count) {
088        synchronized (lock) {
089            return getBag().add(object, count);
090        }
091    }
092
093    public boolean remove(final Object object, final int count) {
094        synchronized (lock) {
095            return getBag().remove(object, count);
096        }
097    }
098
099    public Set<E> uniqueSet() {
100        synchronized (lock) {
101            final Set<E> set = getBag().uniqueSet();
102            return new SynchronizedBagSet(set, lock);
103        }
104    }
105
106    public int getCount(final Object object) {
107        synchronized (lock) {
108            return getBag().getCount(object);
109        }
110    }
111
112    //-----------------------------------------------------------------------
113    /**
114     * Synchronized Set for the Bag class.
115     */
116    class SynchronizedBagSet extends SynchronizedCollection<E> implements Set<E> {
117        /** Serialization version */
118        private static final long serialVersionUID = 2990565892366827855L;
119
120        /**
121         * Constructor.
122         * @param set  the set to decorate
123         * @param lock  the lock to use, shared with the bag
124         */
125        SynchronizedBagSet(final Set<E> set, final Object lock) {
126            super(set, lock);
127        }
128    }
129
130}