ValueExtractor


1   /* ============================================================
2    * JRobin : Pure java implementation of RRDTool's functionality
3    * ============================================================
4    *
5    * Project Info:  http://www.jrobin.org
6    * Project Lead:  Sasa Markovic (saxon@jrobin.org)
7    * 
8    * Developers:    Sasa Markovic (saxon@jrobin.org)
9    *                Arne Vandamme (cobralord@jrobin.org)
10   *
11   * (C) Copyright 2003, by Sasa Markovic.
12   *
13   * This library is free software; you can redistribute it and/or modify it under the terms
14   * of the GNU Lesser General Public License as published by the Free Software Foundation;
15   * either version 2.1 of the License, or (at your option) any later version.
16   *
17   * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
18   * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
19   * See the GNU Lesser General Public License for more details.
20   *
21   * You should have received a copy of the GNU Lesser General Public License along with this
22   * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
23   * Boston, MA 02111-1307, USA.
24   */
25  package org.jrobin.graph;
26  
27  import org.jrobin.core.FetchData;
28  import org.jrobin.core.RrdException;
29  import org.jrobin.core.Util;
30  
31  /**
32   * <p>Class used to extract specific time-based values out of a number of fetched datasources.</p>
33   * 
34   * @author Arne Vandamme (cobralord@jrobin.org)
35   */
36  class ValueExtractor 
37  {
38      // ================================================================
39      // -- Members
40      // ================================================================ 
41      private String  [] varNames;          // Name of the variable, NOT it's dsName in the file
42  
43      private int reduceFactor = 1;
44  
45      private int[] tPos;
46      private long[] steps;
47      private long[][] timestamps;
48  
49      private double[][][] dsValues;
50  
51  
52      // ================================================================
53      // -- Constructors
54      // ================================================================ 
55      /**
56       * Constructs a ValueExtractor object used to extract fetched datapoints for specific points in time.
57       * @param names Array containing the datasource names in the graph definition.
58       * @param values Array of FetchData objects holding all fetched datasources for a specific RRD file.
59       */
60      ValueExtractor( String  [] names, FetchData[] values, int reduceFactor )
61      {
62          this.varNames       = names;
63          this.reduceFactor   = reduceFactor;
64  
65          // Set timestamps
66          tPos                = new int[values.length];
67          steps               = new long[values.length];
68          timestamps          = new long[values.length][];
69  
70          dsValues            = new double[values.length][][];
71  
72          for (int i = 0; i < timestamps.length; i++)
73          {
74              if ( values[i] != null )
75              {
76                  timestamps[i]   = values[i].getTimestamps();
77                  dsValues[i]     = values[i].getValues();
78  
79                  if ( timestamps[i].length >= 2 )
80                      steps[i] = (timestamps[i][1] - timestamps[i][0]);
81              }
82          }
83      }
84  
85  
86      // ================================================================
87      // -- Protected methods
88      // ================================================================
89      int prepareSources( Source[] sources, int offset )
90      {
91          int tblPos  = offset;
92  
93          for ( int i = 0; i < dsValues.length; i++ )
94          {
95              if ( dsValues[i] != null )
96              {
97                  for (int x = 0; x < dsValues[i].length; x++)
98                  {
99                      sources[tblPos++].setFetchedStep( steps[i] );
100                 }
101             }
102         }
103 
104         return tblPos;
105     }
106 
107     /**
108      * Extracts a number of values out of the fetched values, and approximates them
109      * to a specific timestamp, to store them in the complete Source array for the graph definition.
110      * @param timestamp Timestamp to which a fetched value should be approximated.
111      * @param sources Array containing all datasources.
112      * @param row Row index in the Source table where the values should stored.
113      * @param offset Offset in the Source table of where to start storing the values.
114      * @return Table position offset for the next datasource.
115      * @throws RrdException Thrown in case of a JRobin specific error.
116      */
117     int extract( long timestamp, Source[] sources, int row, int offset ) throws RrdException
118     {
119         int tblPos  = offset;
120 
121         for ( int i = 0; i < dsValues.length; i++ )
122         {
123             if ( dsValues[i] == null )
124                 continue;
125 
126             int tIndex      = tPos[i];
127 
128             double[] nValue = new double[ dsValues[i].length ];
129             int[] vValue    = new int[ nValue.length ];             // Counts the actual valid values
130 
131             for ( int j = 0; j < nValue.length; j++ )
132                 nValue[j] = Double.NaN;
133 
134             // Combine the rows
135             int j;
136 
137             for ( j = 0; j < reduceFactor && timestamps[i][tIndex] <= timestamp; j++ )
138             {
139                 for (int x = 0; x < dsValues[i].length; x++)
140                 {
141                     if ( Double.isNaN(dsValues[i][x][tIndex]) )
142                         continue;
143 
144                     vValue[x]++;
145 
146                     if ( Double.isNaN(nValue[x]) )
147                         nValue[x] = dsValues[i][x][tIndex];
148                     else
149                     {
150                         switch ( i )
151                         {
152                             case FetchSource.AVG:
153                                 nValue[x] += dsValues[i][x][tIndex];
154                                 break;
155                             case FetchSource.MAX:
156                                 nValue[x] = Util.max( nValue[x], dsValues[i][x][tIndex] );
157                                 break;
158                             case FetchSource.MIN:
159                                 nValue[x] = Util.min( nValue[x], dsValues[i][x][tIndex] );
160                                 break;
161                             case FetchSource.LAST:
162                                 nValue[x] = dsValues[i][x][tIndex];
163                                 break;
164                         }
165                     }
166                 }
167 
168                 tIndex++;
169             }
170 
171             // See if we are using a stretched timespan
172             if ( j == 0 && row > 0 )
173             {
174                 sources[tblPos++].set( row, timestamp, Double.POSITIVE_INFINITY );
175             }
176             else
177             {
178                 // Finalize
179                 for (int x = 0; x < dsValues[i].length; x++)
180                 {
181                     if ( i == FetchSource.AVG )
182                         nValue[x] /= vValue[x];
183 
184                     sources[tblPos++].set( row, timestamp, nValue[x] );
185                 }
186             }
187 
188             tPos[i] = tIndex;
189         }
190 
191         return tblPos;
192     }
193 
194     String  [] getNames() {
195         return varNames;
196     }
197 }
198
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