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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.
8  
9  Redistribution and use in source and binary forms, with or without modifica-
10  tion, are permitted provided that the following conditions are met:
11  
12  1. Redistributions of source code must retain the above copyright notice,
13     this list of conditions and the following disclaimer.
14  
15  2. Redistributions in binary form must reproduce the above copyright notice,
16     this list of conditions and the following disclaimer in the documentation
17     and/or other materials provided with the distribution.
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19  3. The end-user documentation included with the redistribution, if any, must
20     include the following acknowledgment: "This product includes software
21     developed by the Apache Software Foundation (http://www.apache.org/)."
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
27     without prior written permission. For written permission, please contact
28     apache@apache.org.
29  
30  5. Products derived from this software may not be called "Apache", nor may
31     "Apache" appear in their name, without prior written permission of the
32     Apache Software Foundation.
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34  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
35  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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39  DING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
40  OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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45  This software consists of voluntary contributions made by many individuals
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47  Apache Software Foundation, please see <http://www.apache.org/>.
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49 */
50 package org.apache.avalon.excalibur.monitor.impl;
51
52 import java.util.Collection JavaDoc;
53 import java.util.HashMap JavaDoc;
54 import java.util.Map JavaDoc;
55
56 import org.apache.avalon.excalibur.monitor.Monitor;
57 import org.apache.avalon.excalibur.monitor.Resource;
58 import org.apache.avalon.framework.logger.AbstractLogEnabled;
59
60 /**
61  * The AbstractMonitor class is a useful base class which all Monitors
62  * can extend. The particular monitoring policy is defined by the particular
63  * implementation.
64  *
65  * @author <a HREF="mailto:bloritsch@apache.org">Berin Loritsch</a>
66  * @author <a HREF="mailto:peter at apache.org">Peter Donald</a>
67  * @version $Id: AbstractMonitor.java,v 1.11 2003/05/23 17:41:04 bloritsch Exp $
68  */
69 public abstract class AbstractMonitor
70     implements Monitor
71 {
72     /**
73      * The set of resources that the monitor is monitoring.
74      */
75     private Map JavaDoc m_resources = new HashMap JavaDoc();
76
77     /**
78      * Add an array of resources to monitor.
79      *
80      * @param resources the resources to monitor
81      */
82     public final void addResources( final Resource[] resources )
83     {
84         for( int i = 0; i < resources.length; i++ )
85         {
86             addResource( resources[ i ] );
87         }
88     }
89
90     /**
91      * Add a resource to monitor. The resource key referenced in the other
92      * interfaces is derived from the resource object.
93      */
94     public final void addResource( final Resource resource )
95     {
96         synchronized( m_resources )
97         {
98             final String JavaDoc resourceKey = resource.getResourceKey();
99             if( m_resources.containsKey( resourceKey ) )
100             {
101                 final Resource original =
102                     (Resource)m_resources.get( resourceKey );
103                 original.addPropertyChangeListenersFrom( resource );
104             }
105             else
106             {
107                 m_resources.put( resourceKey, resource );
108             }
109         }
110     }
111
112     /**
113      * Find a monitored resource. If no resource is available, return null
114      */
115     public Resource getResource( final String JavaDoc key )
116     {
117         synchronized( m_resources )
118         {
119             return (Resource)m_resources.get( key );
120         }
121     }
122
123     /**
124      * Remove a monitored resource by key.
125      */
126     public final void removeResource( final String JavaDoc key )
127     {
128         synchronized( m_resources )
129         {
130             final Resource resource =
131                 (Resource)m_resources.remove( key );
132             resource.removeAllPropertyChangeListeners();
133         }
134     }
135
136     /**
137      * Remove a monitored resource by reference.
138      */
139     public final void removeResource( final Resource resource )
140     {
141         removeResource( resource.getResourceKey() );
142     }
143
144     /**
145      * Return an array containing all the resources currently monitored.
146      *
147      * @return an array containing all the resources currently monitored.
148      */
149     protected Resource[] getResources()
150     {
151         final Collection JavaDoc collection = m_resources.values();
152         return (Resource[])collection.toArray( new Resource[ collection.size() ] );
153     }
154
155     /**
156      * Scan through all resources to determine if they have changed.
157      */
158     protected void scanAllResources()
159     {
160         final long currentTestTime = System.currentTimeMillis();
161         final Resource[] resources = getResources();
162         for( int i = 0; i < resources.length; i++ )
163         {
164             resources[ i ].testModifiedAfter( currentTestTime );
165         }
166     }
167 }
168
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