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1 /*
2
3  ============================================================================
4                    The Apache Software License, Version 1.1
5  ============================================================================
6  
7  Copyright (C) 1999-2003 The Apache Software Foundation. All rights reserved.
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9  Redistribution and use in source and binary forms, with or without modifica-
10  tion, are permitted provided that the following conditions are met:
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13     this list of conditions and the following disclaimer.
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22     Alternately, this acknowledgment may appear in the software itself, if
23     and wherever such third-party acknowledgments normally appear.
24  
25  4. The names "Jakarta", "Avalon", "Excalibur" and "Apache Software Foundation"
26     must not be used to endorse or promote products derived from this software
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30  5. Products derived from this software may not be called "Apache", nor may
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45  This software consists of voluntary contributions made by many individuals
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49 */
50 package org.apache.excalibur.instrument.manager;
51
52 import org.apache.avalon.framework.configuration.Configuration;
53 import org.apache.avalon.framework.configuration.ConfigurationException;
54 import org.apache.avalon.framework.configuration.DefaultConfiguration;
55 import org.apache.excalibur.instrument.manager.interfaces.InstrumentManagerClient;
56
57 /**
58  * A InstrumentSample which stores the minimum value set during the sample
59  * period.
60  *
61  * @author <a HREF="mailto:leif@tanukisoftware.com">Leif Mortenson</a>
62  * @version CVS $Revision: 1.3 $ $Date: 2003/02/25 16:28:16 $
63  * @since 4.1
64  */
65 class MinimumValueInstrumentSample
66     extends AbstractValueInstrumentSample
67 {
68     /** Last value set to the sample for use for sample periods where no value is set. */
69     private int m_lastValue;
70     
71     /*---------------------------------------------------------------
72      * Constructors
73      *-------------------------------------------------------------*/
74     /**
75      * Creates a new MinimumValueInstrumentSample
76      *
77      * @param instrumentProxy The InstrumentProxy which owns the
78      * InstrumentSample.
79      * @param name The name of the new InstrumentSample.
80      * @param interval The sample interval of the new InstrumentSample.
81      * @param size The number of samples to store as history. Assumes that size is at least 1.
82      * @param description The description of the new InstrumentSample.
83      * @param lease The length of the lease in milliseconds.
84      */
85     MinimumValueInstrumentSample( InstrumentProxy instrumentProxy,
86                                   String JavaDoc name,
87                                   long interval,
88                                   int size,
89                                   String JavaDoc description,
90                                   long lease )
91     {
92         super( instrumentProxy, name, interval, size, description, lease );
93     }
94     
95     /*---------------------------------------------------------------
96      * InstrumentSample Methods
97      *-------------------------------------------------------------*/
98     /**
99      * Returns the type of the Instrument Sample.
100      *
101      * @return The type of the Instrument Sample.
102      */
103     public int getType()
104     {
105         return InstrumentManagerClient.INSTRUMENT_SAMPLE_TYPE_MINIMUM;
106     }
107     
108     /*---------------------------------------------------------------
109      * AbstractInstrumentSample Methods
110      *-------------------------------------------------------------*/
111     /**
112      * The current sample has already been stored. Reset the current sample
113      * and move on to the next.
114      * <p>
115      * Should only be called when synchronized.
116      */
117     protected void advanceToNextSample()
118     {
119         // Reset the value count and set the value to the last known value.
120 m_value = m_lastValue;
121         m_valueCount = 0;
122     }
123     
124     /**
125      * Allow subclasses to add information into the saved state.
126      *
127      * @param state State configuration.
128      */
129     protected void saveState( DefaultConfiguration state )
130     {
131         super.saveState( state );
132         
133         state.setAttribute( "last-value", Integer.toString( m_lastValue ) );
134     }
135     
136     /**
137      * Used to load the state, called from AbstractInstrumentSample.loadState();
138      * <p>
139      * Should only be called when synchronized.
140      *
141      * @param value Current value loaded from the state.
142      * @param state Configuration object to load state from.
143      *
144      * @throws ConfigurationException If there were any problems loading the
145      * state.
146      */
147     protected void loadState( int value, Configuration state )
148         throws ConfigurationException
149     {
150         super.loadState( value, state );
151         
152         m_lastValue = state.getAttributeAsInteger( "last-value" );
153     }
154     
155     /**
156      * Called after a state is loaded if the sample period is not the same
157      * as the last period saved.
158      */
159     protected void postSaveNeedsReset()
160     {
161         super.postSaveNeedsReset();
162         
163         m_lastValue = 0;
164     }
165     
166     /*---------------------------------------------------------------
167      * AbstractValueInstrumentSample Methods
168      *-------------------------------------------------------------*/
169     /**
170      * Sets the current value of the sample. The value will be set as the
171      * sample value if it is the smallest value seen during the sample period.
172      *
173      * @param value New sample value.
174      * @param time Time that the new sample arrives.
175      */
176     protected void setValueInner( int value, long time )
177     {
178         boolean update;
179         int sampleValue;
180         long sampleTime;
181         
182         synchronized(this)
183         {
184             update( time );
185             
186             // Always store the last value to use for samples where a value is not set.
187 m_lastValue = value;
188             
189             if ( m_valueCount > 0 )
190             {
191                 // Additional sample
192 m_valueCount++;
193                 if ( value < m_value )
194                 {
195                     m_value = value;
196                     update = true;
197                 }
198             }
199             else
200             {
201                 // First value of this sample.
202 m_valueCount = 1;
203                 m_value = value;
204             }
205             
206             sampleValue = m_value;
207             sampleTime = m_time;
208                 update = true;
209         }
210         
211         if ( update )
212         {
213             updateListeners( sampleValue, sampleTime );
214         }
215     }
216 }
217
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