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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    *      http://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.math.stat.descriptive;
18  
19  /**
20   * Implementation of
21   * {@link org.apache.commons.math.stat.descriptive.DescriptiveStatistics} that
22   * is safe to use in a multithreaded environment.  Multiple threads can safely
23   * operate on a single instance without causing runtime exceptions due to race
24   * conditions.  In effect, this implementation makes modification and access
25   * methods atomic operations for a single instance.  That is to say, as one
26   * thread is computing a statistic from the instance, no other thread can modify
27   * the instance nor compute another statistic. 
28   *
29   * @since 1.2
30   * @version $Revision: 608819 $ $Date: 2008-01-04 05:46:21 -0700 (Fri, 04 Jan 2008) $
31   */
32  public class SynchronizedDescriptiveStatistics extends DescriptiveStatistics {
33  
34      /** Serialization UID */
35      private static final long serialVersionUID = 1L;
36  
37      /**
38       * Construct an instance with infinite window
39       */
40      public SynchronizedDescriptiveStatistics() {
41          this(INFINITE_WINDOW);
42      }
43  
44      /**
45       * Construct an instance with finite window
46       * @param window the finite window size.
47       */
48      public SynchronizedDescriptiveStatistics(int window) {
49          super(window);
50      }
51  
52      /**
53       * @see org.apache.commons.math.stat.descriptive.DescriptiveStatistics#addValue(double)
54       */
55      public synchronized void addValue(double v) {
56          super.addValue(v);
57      }
58  
59      /**
60       * Apply the given statistic to this univariate collection.
61       * @param stat the statistic to apply
62       * @return the computed value of the statistic.
63       */
64      public synchronized double apply(UnivariateStatistic stat) {
65          return super.apply(stat);
66      }
67  
68      /**
69       * @see org.apache.commons.math.stat.descriptive.DescriptiveStatistics#clear()
70       */
71      public synchronized void clear() {
72          super.clear();
73      }
74  
75      /**
76       * @see org.apache.commons.math.stat.descriptive.DescriptiveStatistics#getElement(int)
77       */
78      public synchronized double getElement(int index) {
79          return super.getElement(index);
80      }
81  
82      /**
83       * @see org.apache.commons.math.stat.descriptive.DescriptiveStatistics#getN()
84       */
85      public synchronized long getN() {
86          return super.getN();
87      }
88  
89      /** 
90       * Returns the standard deviation of the available values.
91       * @return The standard deviation, Double.NaN if no values have been added 
92       * or 0.0 for a single value set. 
93       */
94      public synchronized double getStandardDeviation() {
95          return super.getStandardDeviation();
96      }
97  
98      /**
99       * @see org.apache.commons.math.stat.descriptive.DescriptiveStatistics#getValues()
100      */
101     public synchronized double[] getValues() {
102         return super.getValues();
103     }
104 
105     /**
106      * Access the window size.
107      * @return the current window size.
108      */
109     public synchronized int getWindowSize() {
110         return super.getWindowSize();
111     }
112 
113     /**
114      * @see org.apache.commons.math.stat.descriptive.DescriptiveStatistics#setWindowSize(int)
115      */
116     public synchronized void setWindowSize(int windowSize) {
117         super.setWindowSize(windowSize);
118     }
119 
120     /**
121      * Generates a text report displaying univariate statistics from values
122      * that have been added.  Each statistic is displayed on a separate
123      * line.
124      * 
125      * @return String with line feeds displaying statistics
126      */
127     public synchronized String toString() {
128         return super.toString();
129     }
130 }