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Java > Open Source Codes > org > exolab > jms > lease > BaseLease


1 /**
2  * Redistribution and use of this software and associated documentation
3  * ("Software"), with or without modification, are permitted provided
4  * that the following conditions are met:
5  *
6  * 1. Redistributions of source code must retain copyright
7  * statements and notices. Redistributions must also contain a
8  * copy of this document.
9  *
10  * 2. Redistributions in binary form must reproduce the
11  * above copyright notice, this list of conditions and the
12  * following disclaimer in the documentation and/or other
13  * materials provided with the distribution.
14  *
15  * 3. The name "Exolab" must not be used to endorse or promote
16  * products derived from this Software without prior written
17  * permission of Exoffice Technologies. For written permission,
18  * please contact info@exolab.org.
19  *
20  * 4. Products derived from this Software may not be called "Exolab"
21  * nor may "Exolab" appear in their names without prior written
22  * permission of Exoffice Technologies. Exolab is a registered
23  * trademark of Exoffice Technologies.
24  *
25  * 5. Due credit should be given to the Exolab Project
26  * (http://www.exolab.org/).
27  *
28  * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
29  * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
30  * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
31  * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
32  * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
33  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
34  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
35  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
37  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
38  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
39  * OF THE POSSIBILITY OF SUCH DAMAGE.
40  *
41  * Copyright 2000-2005 (C) Exoffice Technologies Inc. All Rights Reserved.
42  *
43  * $Id: BaseLease.java,v 1.2 2005/03/18 03:47:30 tanderson Exp $
44  */
45 package org.exolab.jms.lease;
46
47
48 /**
49  * Generic lease implementation, which may be used to lease any object.
50  *
51  * @author <a HREF="mailto:jima@comware.com.au">Jim Alateras</a>
52  * @author <a HREF="mailto:tma@netspace.net.au">Tim Anderson</a>
53  * @version $Revision: 1.2 $ $Date: 2005/03/18 03:47:30 $
54  */
55 public class BaseLease
56         implements LeaseIfc, Comparable JavaDoc {
57
58     /**
59      * This is the object that is leased.
60      */
61     protected final Object JavaDoc _leasedObject;
62
63     /**
64      * The duration of the lease in milliseconds.
65      */
66     protected long _duration = 0L;
67
68     /**
69      * This is the time that the lease will expire.
70      */
71     protected long _expiryTime = 0L;
72
73     /**
74      * The listener that will be notified when the lease expires.
75      */
76     protected LeaseEventListenerIfc _listener = null;
77
78
79     /**
80      * Construct a new <code>BaseLease</code>.
81      *
82      * @param object the leased object
83      * @param duration the duration of lease, in milliseconds
84      * @param listener the listener to notify of lease events
85      */
86     public BaseLease(Object JavaDoc object, long duration,
87                      LeaseEventListenerIfc listener) {
88         if (object == null) {
89             throw new IllegalArgumentException JavaDoc("Argument 'object' is null");
90         }
91
92         if (listener == null) {
93             throw new IllegalArgumentException JavaDoc("Argument 'listener' is null");
94         }
95
96         _leasedObject = object;
97         _duration = duration;
98         _expiryTime = System.currentTimeMillis() + duration;
99         _listener = listener;
100     }
101
102     /**
103      * Return the absolute expiry time of this lease.
104      *
105      * @return the expiry time of the lease, in milliseconds
106      */
107     public long getExpiryTime() {
108         return _expiryTime;
109     }
110
111     /**
112      * Returns the duration of the lease.
113      *
114      * @return the duration of the lease, in milliseconds
115      */
116     public long getDuration() {
117         return _duration;
118     }
119
120     /**
121      * Change the duration of the lease.
122      *
123      * @param duration the new lease duration, in milliseconds
124      */
125     public void setDuration(long duration) {
126         _duration = duration;
127         _expiryTime = System.currentTimeMillis() + duration;
128     }
129
130     /**
131      * Returns the time remaining on the lease.
132      *
133      * @return the time remaining, in milliseconds
134      */
135     public long getRemainingTime() {
136         return (System.currentTimeMillis() - _expiryTime);
137     }
138
139     /**
140      * Returns the leased object.
141      *
142      * @return the leased object
143      */
144     public Object JavaDoc getLeasedObject() {
145         return _leasedObject;
146     }
147
148     /**
149      * Returns the listener to notify of lease events.
150      *
151      * @return the listener to notify of lease events
152      */
153     public LeaseEventListenerIfc getLeaseEventListener() {
154         return _listener;
155     }
156
157     /**
158      * Compares this object with the specified object. It returns a negative
159      * integer is this object is less than the specified object; zero if this
160      * object is equal to the specified object or a positive integer if this
161      * object is greater than the specified object
162      * <p/>
163      * The comparison is based on the expiration time.
164      */
165     public int compareTo(Object JavaDoc object) {
166         int result = 0;
167
168         if (object instanceof BaseLease) {
169             BaseLease lease = (BaseLease) object;
170             if (lease.getExpiryTime() != this.getExpiryTime()) {
171                 if (lease.getExpiryTime() > this.getExpiryTime()) {
172                     result = -1;
173                 } else {
174                     result = 1;
175                 }
176             }
177         }
178         return result;
179     }
180
181     /**
182      * Returns a string representation of this object.
183      *
184      * @return a string representation of this
185      */
186     public String JavaDoc toString() {
187         StringBuffer JavaDoc buf = new StringBuffer JavaDoc(_leasedObject.toString());
188         buf.append(" duration = ");
189         buf.append(_duration);
190         buf.append(" expiryTime = ");
191         buf.append(_expiryTime);
192
193         return buf.toString();
194     }
195
196     /**
197      * Notify the listeners that this lease has expird. This method has package
198      * level scope.
199      */
200     protected void notifyLeaseExpired() {
201         synchronized (_listener) {
202             _listener.onLeaseExpired(_leasedObject);
203         }
204     }
205
206 }
207
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