1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.collections4.multiset;
18
19 import java.util.Set;
20
21 import org.apache.commons.collections4.MultiSet;
22 import org.apache.commons.collections4.collection.SynchronizedCollection;
23
24 /**
25 * Decorates another {@link MultiSet} to synchronize its behavior
26 * for a multithreaded environment.
27 * <p>
28 * Methods are synchronized, then forwarded to the decorated multiset.
29 * Iterators must be separately synchronized around the loop.
30 * </p>
31 *
32 * @param <E> The type held in the multiset.
33 * @since 4.1
34 */
35 public class SynchronizedMultiSet<E> extends SynchronizedCollection<E> implements MultiSet<E> {
36
37 /**
38 * Synchronized Set for the MultiSet class.
39 *
40 * @param <T> The type held in this Set.
41 */
42 static class SynchronizedSet<T> extends SynchronizedCollection<T> implements Set<T> {
43
44 /** Serialization version */
45 private static final long serialVersionUID = 20150629L;
46
47 /**
48 * Constructs a new instance.
49 *
50 * @param set The set to decorate
51 * @param lock The lock to use, shared with the multiset
52 */
53 SynchronizedSet(final Set<T> set, final Object lock) {
54 super(set, lock);
55 }
56 }
57
58 /** Serialization version */
59 private static final long serialVersionUID = 20150629L;
60
61 /**
62 * Factory method to create a synchronized multiset.
63 *
64 * @param <E> The type of the elements in the multiset
65 * @param multiset The multiset to decorate, must not be null
66 * @return A new synchronized MultiSet
67 * @throws NullPointerException if multiset is null
68 */
69 public static <E> SynchronizedMultiSet<E> synchronizedMultiSet(final MultiSet<E> multiset) {
70 return new SynchronizedMultiSet<>(multiset);
71 }
72
73 /**
74 * Constructor that wraps (not copies).
75 *
76 * @param multiset The multiset to decorate, must not be null
77 * @throws NullPointerException if multiset is null
78 */
79 protected SynchronizedMultiSet(final MultiSet<E> multiset) {
80 super(multiset);
81 }
82
83 /**
84 * Constructor that wraps (not copies).
85 *
86 * @param multiset The multiset to decorate, must not be null
87 * @param lock The lock to use, must not be null
88 * @throws NullPointerException if multiset or lock is null
89 */
90 protected SynchronizedMultiSet(final MultiSet<E> multiset, final Object lock) {
91 super(multiset, lock);
92 }
93
94 @Override
95 public int add(final E object, final int count) {
96 synchronized (lock) {
97 return decorated().add(object, count);
98 }
99 }
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 }