Sdef


1   package org.jrobin.graph;
2   
3   import java.util.HashMap  ;
4   
5   import org.jrobin.core.RrdException;
6   import org.jrobin.core.XmlWriter;
7   
8   /**
9    * <p>Represents a 'static' datasource for a graph.  A static datasource is a single value (constant),
10   * but can only be the result of applying a consolidation function (AVG, MIN, MAX, LAST, FIRST or TOTAL)
11   * to one of the other, already defined, datasources.</p>
12   *
13   * @author Arne Vandamme (cobralord@jrobin.org)
14   */
15  class Sdef extends Cdef
16  {
17      // ================================================================
18      // -- Members
19      // ================================================================
20      private int defIndex        = -1;
21  
22      private String   defName      = "";
23      private String   consolFunc   = "AVERAGE";
24      private int aggregate       = Source.AGG_AVERAGE;
25  
26      private boolean calculated  = false;
27      private double[] value      = null;
28  
29  
30      // ================================================================
31      // -- Constructors
32      // ================================================================
33      /**
34       * Constructs a new Sdef object based on an existing datasource (Def, Cdef or Pdef)
35       * and the consolidation function to apply to that datasource.
36       *
37       * @param name Name of the datasource in the graph definition.
38       * @param defName Name of the datasource this Sdef is derived from.
39       * @param consolFunc Consolidation function to apply to the referring datasource (defName).
40       * @throws RrdException Thrown in case of invalid consolidation function specified.
41       */
42      Sdef( String   name, String   defName, String   consolFunc ) throws RrdException
43      {
44          super( name );
45  
46          this.defName    = defName;
47          this.consolFunc = consolFunc;
48  
49          // -- Parse the consolidation function to be used
50          if ( consolFunc.equalsIgnoreCase("AVERAGE") || consolFunc.equalsIgnoreCase("AVG") )
51              aggregate = Source.AGG_AVERAGE;
52          else if ( consolFunc.equalsIgnoreCase("MAX") || consolFunc.equalsIgnoreCase("MAXIMUM") )
53              aggregate = Source.AGG_MAXIMUM;
54          else if ( consolFunc.equalsIgnoreCase("MIN") || consolFunc.equalsIgnoreCase("MINIMUM") )
55              aggregate = Source.AGG_MINIMUM;
56          else if ( consolFunc.equalsIgnoreCase("LAST") )
57              aggregate = Source.AGG_LAST;
58          else if ( consolFunc.equalsIgnoreCase("FIRST") )
59              aggregate = Source.AGG_FIRST;
60          else if ( consolFunc.equalsIgnoreCase("TOTAL") )
61              aggregate = Source.AGG_TOTAL;
62          else
63              throw new RrdException( "Invalid consolidation function specified." );
64      }
65  
66      // ================================================================
67      // -- Protected methods
68      // ================================================================
69      /**
70       * Prepares the Sdef for faster value calculation by setting the internal
71       * array and references.  Override from Cdef parent class.
72       *
73       * @param sourceIndex Lookup table holding the name - index pairs for all datasources.
74       * @param numPoints Number of points used as graph resolution (size of the value table).
75       * @throws RrdException Thrown in case of the requested datasource is not available in the sourceIndex
76       */
77      void prepare( HashMap   sourceIndex, int numPoints, int aggregatePoints ) throws RrdException
78      {
79          if ( sourceIndex.containsKey( defName ) )
80              defIndex = ( (Integer  ) sourceIndex.get( defName ) ).intValue();
81          else
82              throw new RrdException( "Datasource not found: " + defName );
83  
84          values                  = new double[ numPoints ];
85          this.aggregatePoints    = aggregatePoints;
86          calculated              = false;
87      }
88  
89      /**
90       * Returns the level this Sdef would have in the calculation tree.  The level defines when
91       * the Sdef can be calculated.  The level of the Sdef will always be one higher than that of
92       * its referring datasource, since it can only be calculated after that datasource has already
93       * been calculated.
94       *
95       * @param levels Array containing the previously calculated calculation levels.
96       * @return Level of this Sdef in the calculation tree.
97       */
98      int calculateLevel( int[] levels )
99      {
100         // An Sdef is always one lower in the tree than its source
101         return levels[defIndex] + 1;
102     }
103 
104     /**
105      * Gets the value of the datapoint at a particular position in the datapoint array.
106      * In case of an Sdef, the value will be the same for every different position.
107      *
108      * @param pos Inherited from Cdef
109      * @return The consolidated value of the referring datasource as double
110      */
111     double get( int pos )
112     {
113         return values[0];
114     }
115 
116     /**
117      * Calculates the internal value of this Sdef.
118      *
119      * @param sources Array of the calculated datasources.
120      */
121     void set( Source[] sources )
122     {
123         if ( calculated ) return;
124 
125         double value = sources[ defIndex ].getAggregate( aggregate );
126         for ( int i = 0; i < values.length; i++ )
127             values[i] = value;
128 
129         calculated = true;
130     }
131 
132     /**
133      * Override from the corresponding method in the Source parent class,
134      * overridden for faster implementation.
135      *
136      * Five of the possible aggregation methods return the actual value
137      * of the Sdef:
138      * <code>AGG_MINIMUM, AGG_MAXIMUM, AGG_AVERAGE, AGG_FIRST and AGG_LAST</code>
139      *
140      * Only <code>AGG_TOTAL</code> will return value summed over the number of
141      * samples in the graph.
142      *
143      * @param aggType Type of the aggregate requested.
144      * @return The double value of the requested aggregate.
145      */
146     double getAggregate( int aggType )
147     {
148         switch ( aggType )
149         {
150             case AGG_MINIMUM:
151             case AGG_MAXIMUM:
152             case AGG_AVERAGE:
153             case AGG_FIRST:
154             case AGG_LAST:
155                 return values[0];
156 
157             case AGG_TOTAL:
158                 return (values[0] * values.length) ;
159         }
160 
161         return Double.NaN;
162     }
163 
164 
165     void exportXml(XmlWriter xml) {
166         xml.startTag( "def" );
167         xml.writeTag( "name", getName() );
168         xml.writeTag( "datasource", defName );
169         xml.writeTag( "cf", consolFunc );
170         xml.closeTag(); // def
171     }
172 }
173
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