1 /*
2 * JBoss, Home of Professional Open Source
3 * Copyright 2005, JBoss Inc., and individual contributors as indicated
4 * by the @authors tag. See the copyright.txt in the distribution for a
5 * full listing of individual contributors.
6 *
7 * This is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU Lesser General Public License as
9 * published by the Free Software Foundation; either version 2.1 of
10 * the License, or (at your option) any later version.
11 *
12 * This software is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with this software; if not, write to the Free
19 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
21 */
22 package org.jboss.mx.interceptor;
23
24 import java.util.Arrays;
25
26 import javax.management.Descriptor;
27 import javax.management.InvalidAttributeValueException;
28 import javax.management.ObjectName;
29
30 import org.jboss.mx.modelmbean.ModelMBeanConstants;
31 import org.jboss.mx.server.Invocation;
32
33
34 /** This interceptor handles the ModelMBean operation caching
35 *
36 * @author <a href="mailto:adrian@jboss.org">Adrian Brock</a>.
37 * @author Scott.Stark@jboss.org
38 * @version $Revision: 37459 $
39 */
40 public class ModelMBeanOperationInterceptor
41 extends AbstractInterceptor
42 implements ModelMBeanConstants
43 {
44 // Constants -----------------------------------------------------
45
46 // Attributes ----------------------------------------------------
47
48 private boolean trace;
49
50 // Constructors --------------------------------------------------
51
52 public ModelMBeanOperationInterceptor()
53 {
54 super("ModelMBean Operation Interceptor");
55 trace = log.isTraceEnabled();
56 }
57
58
59 // Public --------------------------------------------------------
60
61 public Object invoke(Invocation invocation) throws Throwable
62 {
63 // get the operation's descriptor
64 Descriptor d = invocation.getDescriptor();
65 Class clazz = invocation.getReturnTypeClass();
66
67 String name = null;
68 ObjectName objectName = null;
69 if (trace)
70 {
71 if (d != null)
72 name = (String) d.getFieldValue(NAME);
73 objectName = invocation.getInvoker().getObjectName();
74 }
75
76 if (trace)
77 {
78 Object args = invocation.getArgs();
79 if (args != null)
80 args = Arrays.asList((Object[]) args);
81 log.trace("Invoking objectName=" + objectName + " oper=" + name + " args=" + args + " desc=" + d);
82 }
83
84 long limit = CACHE_NEVER_LIMIT;
85
86 if (d != null && clazz != null)
87 {
88 String timeLimit = (String) d.getFieldValue(CURRENCY_TIME_LIMIT);
89 if (timeLimit != null)
90 limit = Long.parseLong(timeLimit);
91
92 // We are never stale
93 if (limit == CACHE_ALWAYS_LIMIT)
94 {
95 String timeStamp = (String)d.getFieldValue(LAST_UPDATED_TIME_STAMP);
96 if (timeStamp != null)
97 {
98 Object value = d.getFieldValue(CACHED_VALUE);
99 if (trace)
100 log.trace("Always cache objectName=" + objectName + " oper=" + name + " value=" + value);
101 checkAssignable("Cached value in descriptor ", clazz, value);
102 return value;
103 }
104 }
105
106 // is caching enabled
107 if (limit != CACHE_NEVER_LIMIT)
108 {
109 String timeStamp = (String) d.getFieldValue(LAST_UPDATED_TIME_STAMP);
110 long lastUpdate = (timeStamp == null) ? 0 : Long.parseLong(timeStamp);
111
112 // if the value hasn't gone stale, return from the descriptor
113 long now = System.currentTimeMillis();
114 long expires = lastUpdate * 1000 + limit * 1000;
115 if (now < expires)
116 {
117 Object value = d.getFieldValue(CACHED_VALUE);
118 if (trace)
119 log.trace("Using cache objectName=" + objectName + " oper=" + name + " value=" + value + " now=" + now + " expires=" + expires);
120 checkAssignable("Cached value in descriptor ", clazz, value);
121 return value;
122 }
123 else
124 {
125 if (trace)
126 log.trace("Cache expired objectName=" + objectName + " oper=" + name + " now=" + now + " expires=" + expires);
127 d.removeField(CACHED_VALUE);
128 }
129 }
130 else
131 {
132 // Unfortunatley we have to cope with stupid users
133 if (trace)
134 log.trace("Removing any cached value objectName=" + objectName + " oper=" + name + " descriptor=" + d);
135 d.removeField(CACHED_VALUE);
136 }
137 }
138
139 // we got here means either stale value in descriptior, or no caching
140 Object value = invocation.invoke();
141 if (trace)
142 log.trace("Got result objectName=" + objectName + " oper=" + name + " value=" + value);
143
144 // update the descriptor (unless not caching)
145 if (d !=null && limit != CACHE_NEVER_LIMIT)
146 {
147 String timestamp = Long.toString(System.currentTimeMillis()/1000);
148 if (trace)
149 log.trace("Cache result objectName=" + objectName + " oper=" + name + " value=" + value + " timestamp=" + timestamp);
150 d.setField(CACHED_VALUE, value);
151 d.setField(LAST_UPDATED_TIME_STAMP, timestamp);
152 }
153 return value;
154 }
155
156 protected void checkAssignable(String context, Class clazz, Object value) throws InvalidAttributeValueException, ClassNotFoundException
157 {
158 if (value != null && clazz.isAssignableFrom(value.getClass()) == false)
159 throw new InvalidAttributeValueException(context + " has class " + value.getClass() + " loaded from " + value.getClass().getClassLoader() +
160 " that is not assignable to attribute class " + clazz + " loaded from " + clazz.getClassLoader());
161 }
162 }
163
164
165
166
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