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     */
017    package org.apache.commons.math.stat.descriptive;
018    
019    /**
020     * Implementation of
021     * {@link org.apache.commons.math.stat.descriptive.DescriptiveStatistics} that
022     * is safe to use in a multithreaded environment.  Multiple threads can safely
023     * operate on a single instance without causing runtime exceptions due to race
024     * conditions.  In effect, this implementation makes modification and access
025     * methods atomic operations for a single instance.  That is to say, as one
026     * thread is computing a statistic from the instance, no other thread can modify
027     * the instance nor compute another statistic.
028     *
029     * @since 1.2
030     * @version $Revision: 811685 $ $Date: 2009-09-05 19:36:48 +0200 (sam. 05 sept. 2009) $
031     */
032    public class SynchronizedDescriptiveStatistics extends DescriptiveStatistics {
033    
034        /** Serialization UID */
035        private static final long serialVersionUID = 1L;
036    
037        /**
038         * Construct an instance with infinite window
039         */
040        public SynchronizedDescriptiveStatistics() {
041            this(INFINITE_WINDOW);
042        }
043    
044        /**
045         * Construct an instance with finite window
046         * @param window the finite window size.
047         */
048        public SynchronizedDescriptiveStatistics(int window) {
049            super(window);
050        }
051    
052        /**
053         * A copy constructor. Creates a deep-copy of the {@code original}.
054         *
055         * @param original the {@code SynchronizedDescriptiveStatistics} instance to copy
056         */
057        public SynchronizedDescriptiveStatistics(SynchronizedDescriptiveStatistics original) {
058            copy(original, this);
059        }
060    
061        /**
062         * {@inheritDoc}
063         */
064        @Override
065        public synchronized void addValue(double v) {
066            super.addValue(v);
067        }
068    
069        /**
070         * {@inheritDoc}
071         */
072        @Override
073        public synchronized double apply(UnivariateStatistic stat) {
074            return super.apply(stat);
075        }
076    
077        /**
078         * {@inheritDoc}
079         */
080        @Override
081        public synchronized void clear() {
082            super.clear();
083        }
084    
085        /**
086         * {@inheritDoc}
087         */
088        @Override
089        public synchronized double getElement(int index) {
090            return super.getElement(index);
091        }
092    
093        /**
094         * {@inheritDoc}
095         */
096        @Override
097        public synchronized long getN() {
098            return super.getN();
099        }
100    
101        /**
102         * {@inheritDoc}
103         */
104        @Override
105        public synchronized double getStandardDeviation() {
106            return super.getStandardDeviation();
107        }
108    
109        /**
110         * {@inheritDoc}
111         */
112        @Override
113        public synchronized double[] getValues() {
114            return super.getValues();
115        }
116    
117        /**
118         * {@inheritDoc}
119         */
120        @Override
121        public synchronized int getWindowSize() {
122            return super.getWindowSize();
123        }
124    
125        /**
126         * {@inheritDoc}
127         */
128        @Override
129        public synchronized void setWindowSize(int windowSize) {
130            super.setWindowSize(windowSize);
131        }
132    
133        /**
134         * {@inheritDoc}
135         */
136        @Override
137        public synchronized String toString() {
138            return super.toString();
139        }
140    
141        /**
142         * Returns a copy of this SynchronizedDescriptiveStatistics instance with the
143         * same internal state.
144         *
145         * @return a copy of this
146         */
147        @Override
148        public synchronized SynchronizedDescriptiveStatistics copy() {
149            SynchronizedDescriptiveStatistics result =
150                new SynchronizedDescriptiveStatistics();
151            copy(this, result);
152            return result;
153        }
154    
155        /**
156         * Copies source to dest.
157         * <p>Neither source nor dest can be null.</p>
158         * <p>Acquires synchronization lock on source, then dest before copying.</p>
159         *
160         * @param source SynchronizedDescriptiveStatistics to copy
161         * @param dest SynchronizedDescriptiveStatistics to copy to
162         * @throws NullPointerException if either source or dest is null
163         */
164        public static void copy(SynchronizedDescriptiveStatistics source,
165                SynchronizedDescriptiveStatistics dest) {
166            synchronized (source) {
167                synchronized (dest) {
168                    DescriptiveStatistics.copy(source, dest);
169                }
170            }
171        }
172    }