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1 /*
2
3  ============================================================================
4                    The Apache Software License, Version 1.1
5  ============================================================================
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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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23     and wherever such third-party acknowledgments normally appear.
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25  4. The names "Jakarta", "Avalon", "Excalibur" and "Apache Software Foundation"
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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.logger.LogEnabled;
55 import org.apache.excalibur.instrument.manager.interfaces.InstrumentSampleSnapshot;
56
57 /**
58  * InstrumentSamples are used to provide an Instrument with state. Samples
59  * have a sample interval, which is the period over which data is grouped.
60  * <p>
61  * InstrmentSamples can be created when the InstrumentManager is created as
62  * part of the configuration process, or as a result of a request from an
63  * InstrumentClient.
64  *
65  * @author <a HREF="mailto:leif@tanukisoftware.com">Leif Mortenson</a>
66  * @version CVS $Revision: 1.4 $ $Date: 2003/02/25 16:28:16 $
67  * @since 4.1
68  */
69 interface InstrumentSample
70     extends LogEnabled
71 {
72     /**
73      * Returns the InstrumentProxy which owns the InstrumentSample.
74      *
75      * @return The InstrumentProxy which owns the InstrumentSample.
76      */
77     InstrumentProxy getInstrumentProxy();
78     
79     /**
80      * Returns true if the InstrumentSample was configured in the instrumentables
81      * section of the configuration.
82      *
83      * @return True if configured.
84      */
85     boolean isConfigured();
86     
87     /**
88      * Returns the name of the sample.
89      *
90      * @return The name of the sample.
91      */
92     String JavaDoc getName();
93     
94     /**
95      * Returns the sample interval. The period of each sample in millisends.
96      *
97      * @return The sample interval.
98      */
99     long getInterval();
100     
101     /**
102      * Returns the number of samples in the sample history.
103      *
104      * @return The size of the sample history.
105      */
106     int getSize();
107     
108     /**
109      * Returns the description of the sample.
110      *
111      * @return The description of the sample.
112      */
113     String JavaDoc getDescription();
114     
115     /**
116      * Returns the type of the Instrument Sample. Possible values include
117      * InstrumentManagerClient.INSTRUMENT_SAMPLE_TYPE_COUNTER,
118      * InstrumentManagerClient.INSTRUMENT_SAMPLE_TYPE_MAXIMUM,
119      * InstrumentManagerClient.INSTRUMENT_SAMPLE_TYPE_MEAN, or
120      * InstrumentManagerClient.INSTRUMENT_SAMPLE_TYPE_MINIMUM.
121      *
122      * @return The type of the Instrument Sample.
123      */
124     int getType();
125     
126     /**
127      * Returns a Descriptor for the InstrumentSample.
128      *
129      * @return A Descriptor for the InstrumentSample.
130      */
131     InstrumentSampleDescriptorLocal getDescriptor();
132     
133     /**
134      * Obtain the value of the sample. All samples are integers, so the profiled
135      * objects must measure quantity (numbers of items), rate (items/period), time in
136      * milliseconds, etc.
137      *
138      * @return The sample value.
139      */
140     int getValue();
141     
142     /**
143      * Obtain the UNIX time of the beginning of the sample.
144      *
145      * @return The UNIX time of the beginning of the sample.
146      */
147     long getTime();
148     
149     /**
150      * Returns the Type of the Instrument which can use the sample. This
151      * should be the same for all instances of a class.
152      * <p>
153      * Should be one of the following: InstrumentManager.PROFILE_POINT_TYPE_COUNTER
154      * or InstrumentManager.PROFILE_POINT_TYPE_VALUE
155      *
156      * @return The Type of the Instrument which can use the sample.
157      */
158     int getInstrumentType();
159     
160     /**
161      * Returns the time that the current lease expires. Permanent samples will
162      * return a value of 0.
163      *
164      * @return The time that the current lease expires.
165      */
166     long getLeaseExpirationTime();
167     
168     /**
169      * Extends the lease to be lease milliseconds from the current time.
170      *
171      * @param lease The length of the lease in milliseconds.
172      *
173      * @return The new lease expiration time. Returns 0 if the sample is
174      * permanent.
175      */
176     long extendLease( long lease );
177     
178     /**
179      * Tells the sample that its lease has expired. No new references to
180      * the sample will be made available, but clients which already have
181      * access to the sample may continue to use it.
182      */
183     void expire();
184     
185     /**
186      * Obtains a static snapshot of the InstrumentSample.
187      *
188      * @return A static snapshot of the InstrumentSample.
189      */
190     InstrumentSampleSnapshot getSnapshot();
191     
192     /**
193      * Returns the stateVersion of the sample. The state version will be
194      * incremented each time any of the configuration of the sample is
195      * modified.
196      * Clients can use this value to tell whether or not anything has
197      * changed without having to do an exhaustive comparison.
198      *
199      * @return The state version of the sample.
200      */
201     int getStateVersion();
202     
203     /**
204      * Registers a InstrumentSampleListener with a InstrumentSample given a name.
205      *
206      * @param listener The listener which should start receiving updates from the
207      * InstrumentSample.
208      */
209     void addInstrumentSampleListener( InstrumentSampleListener listener );
210     
211     /**
212      * Unregisters a InstrumentSampleListener from a InstrumentSample given a name.
213      *
214      * @param listener The listener which should stop receiving updates from the
215      * InstrumentSample.
216      */
217     void removeInstrumentSampleListener( InstrumentSampleListener listener );
218     
219     /**
220      * Saves the current state into a Configuration.
221      *
222      * @return The state as a Configuration. Returns null if the configuration
223      * would not contain any information.
224      */
225     Configuration saveState();
226     
227     /**
228      * Loads the state into the InstrumentSample.
229      *
230      * @param state Configuration object to load state from.
231      *
232      * @throws ConfigurationException If there were any problems loading the
233      * state.
234      */
235     void loadState( Configuration state ) throws ConfigurationException;
236 }
237
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