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Java > Open Source Codes > org > apache > excalibur > instrument > AbstractInstrument


1 /*
2
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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;
51
52 /**
53  * The AbstractInstrument class can be used by an class wishing to implement
54  * the Instruement interface.
55  *
56  * @author <a HREF="mailto:leif@tanukisoftware.com">Leif Mortenson</a>
57  * @version CVS $Revision: 1.2 $ $Date: 2003/02/20 17:07:55 $
58  * @since 4.1
59  */
60 public abstract class AbstractInstrument
61     implements Instrument
62 {
63     /** The name of the Instrument. */
64     private String JavaDoc m_name;
65
66     /** Proxy object used to communicate with the InstrumentManager. */
67     private InstrumentProxy m_proxy;
68
69     /*---------------------------------------------------------------
70      * Constructors
71      *-------------------------------------------------------------*/
72     /**
73      * Creates a new AbstractInstrument.
74      *
75      * @param name The name of the Instrument. The value should be a string
76      * which does not contain spaces or periods.
77      */
78     protected AbstractInstrument( String JavaDoc name )
79     {
80         m_name = name;
81     }
82
83     /*---------------------------------------------------------------
84      * Instrument Methods
85      *-------------------------------------------------------------*/
86     /**
87      * Gets the name for the Instrument. When an Instrumentable publishes more
88      * than one Instrument, this name makes it possible to identify each
89      * Instrument. The value should be a string which does not contain
90      * spaces or periods.
91      *
92      * @return The name of the Instrument.
93      */
94     public String JavaDoc getInstrumentName()
95     {
96         return m_name;
97     }
98
99     /*---------------------------------------------------------------
100      * Methods
101      *-------------------------------------------------------------*/
102     /**
103      * When the InstrumentManager is present, an InstrumentProxy will be set
104      * to enable the Instrument to communicate with the InstrumentManager.
105      * Once the InstrumentProxy is set, it should never be changed or set
106      * back to null. This restriction removes the need for synchronization
107      * within the Instrument classes. Which in turn makes them more
108      * efficient.
109      *
110      * @param proxy Proxy object used to communicate with the
111      * InstrumentManager.
112      */
113     public void setInstrumentProxy( InstrumentProxy proxy )
114     {
115         if( m_proxy != null )
116         {
117             throw new IllegalStateException JavaDoc(
118                 "Once an InstrumentProxy has been set, it can not be changed." );
119         }
120         m_proxy = proxy;
121     }
122
123     /**
124      * Used by classes being profiled so that they can avoid unnecessary
125      * code when the data from an Instrument is not being used.
126      *
127      * @return True if an InstrumentProxy has been set and is active.
128      */
129     public boolean isActive()
130     {
131         return ( m_proxy != null ) && ( m_proxy.isActive() );
132     }
133
134     /**
135      * Returns the InstrumentProxy object assigned to the instrument by the
136      * InstrumentManager.
137      *
138      * @return Proxy object used to communicate with the InstrumentManager.
139      */
140     protected InstrumentProxy getInstrumentProxy()
141     {
142         return m_proxy;
143     }
144 }
145
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