001 /*
002 // $Id: //open/mondrian/src/main/mondrian/util/MemoryMonitorFactory.java#8 $
003 // This software is subject to the terms of the Common Public License
004 // Agreement, available at the following URL:
005 // http://www.opensource.org/licenses/cpl.html.
006 // Copyright (C) 2002-2002 Kana Software, Inc.
007 // Copyright (C) 2002-2008 Julian Hyde and others
008 // All Rights Reserved.
009 // You must accept the terms of that agreement to use this software.
010 //
011 // jhyde, Dec 23, 2002
012 */
013 package mondrian.util;
014
015 import org.eigenbase.util.property.StringProperty;
016 import mondrian.olap.MondrianProperties;
017 import mondrian.olap.Util;
018
019 /**
020 * The <code>MemoryMonitorFactory</code> is used to get the application's
021 * <code>MemoryMonitor</code>. The <code>MemoryMonitorFactory</code> is
022 * based upon the <code>ObjectFactory.Singleton</code> generic. The
023 * <code>MemoryMonitorFactory</code> implementation has a single, default
024 * <code>MemoryMonitor</code> per JVM instance which can be overridden
025 * using the provided <code>ThreadLocal</code> variable. Normally, this
026 * <code>ThreadLocal</code> override should only be used during JUnit testing.
027 * The JUnit test, set the <code>ThreadLocal</code> variable to the name of its
028 * own implementation of the <code>MemoryMonitor</code> interface and
029 * then calls the <code>ObjectFactory</code> <code>getObject</code> method.
030 * After doing the test, the <code>ThreadLocal</code> variable should
031 * be cleared.
032 * <p>
033 * The <code>ObjectFactory.Singleton</code> permits the use
034 * of <code>System</code> properties to provide a class name to the
035 * factory. This can be used to create a <code>MemoryMonitor</code>
036 * that is not the default one. The property name is the
037 * <code>MemoryMonitor</code> class name, "mondrian.util.MemoryMonitor".
038 *
039 * @author <a>Richard M. Emberson</a>
040 * @since Feb 03 2007
041 * @version $Id: //open/mondrian/src/main/mondrian/util/MemoryMonitorFactory.java#8 $
042 */
043 public final class MemoryMonitorFactory
044 extends ObjectFactory.Singleton<MemoryMonitor> {
045
046 /**
047 * Single instance of the <code>MemoryMonitorFactory</code>.
048 */
049 private static final MemoryMonitorFactory factory;
050 static {
051 factory = new MemoryMonitorFactory();
052 }
053
054 /**
055 * Access the <code>MemoryMonitorFactory</code> instance.
056 *
057 * @return the <code>MemoryMonitor</code>.
058 */
059 public static MemoryMonitor getMemoryMonitor() {
060 return factory.getObject();
061 }
062
063 /**
064 * ThreadLocal used to hold the class name of an <code>MemoryMonitor</code>
065 * implementation. Generally, this should only be used for testing.
066 */
067 private static final ThreadLocal<String> ClassName =
068 new ThreadLocal<String>();
069
070 /**
071 * Get the class name of a <code>MemoryMonitor</code> implementation
072 * or null.
073 *
074 * @return the class name or null.
075 */
076 private static String getThreadLocalClassName() {
077 return ClassName.get();
078 }
079
080 /**
081 * Sets the class name of a <code>MemoryMonitor</code> implementation.
082 * This should be called (obviously) before calling the
083 * <code>MemoryMonitorFactory</code> <code>getMemoryMonitor</code>
084 * method to get the <code>MemoryMonitor</code> implementation.
085 * Generally, this is only used for testing.
086 *
087 * @param className Class name
088 */
089 public static void setThreadLocalClassName(String className) {
090 ClassName.set(className);
091 }
092
093 /**
094 * Clears the class name (regardless of whether a class name was set).
095 * When a class name is set using <code>setThreadLocalClassName</code>,
096 * the setting whould be done in a try-block and a call to this
097 * clear method should be in the finally-clause of that try-block.
098 */
099 public static void clearThreadLocalClassName() {
100 ClassName.set(null);
101 if (factory.testSingleInstance != null) {
102 factory.testSingleInstance.removeAllListener();
103 factory.testSingleInstance = null;
104 }
105 if (factory.singleInstance instanceof MemoryMonitor.Test) {
106 ((MemoryMonitor.Test) factory.singleInstance).resetFromTest();
107 }
108 }
109
110 /**
111 * The constructor for the <code>MemoryMonitorFactory</code>. This passes
112 * the <code>MemoryMonitor</code> class to the <code>ObjectFactory</code>
113 * base class.
114 */
115 private MemoryMonitorFactory() {
116 super(MemoryMonitor.class);
117 }
118
119 /**
120 * Returns whether the use of a <code>MemoryMonitor</code> is enabled.
121 *
122 * @return <code>true</code> if enabled and <code>false</code> otherwise.
123 */
124 protected boolean enabled() {
125 return MondrianProperties.instance().MemoryMonitor.get();
126 }
127
128 /**
129 * Get the class name set in the <code>ThreadLocal</code> or null.
130 *
131 * @return class name or null.
132 */
133 protected String getClassName() {
134 return getThreadLocalClassName();
135 }
136
137 /**
138 * Return the <code>MemoryMonitorFactory</code property name.
139 *
140 * @return <code>MemoryMonitorFactory</code> property name
141 */
142 protected StringProperty getStringProperty() {
143 return MondrianProperties.instance().MemoryMonitorClass;
144 }
145
146 /**
147 * The <code>MemoryMonitorFactory</code>'s implementation of the
148 * <code>ObjectFactory</code>'s abstract method which returns
149 * the default <code>MemoryMonitor</code> instance.
150 * For Java4 or if the <code>MemoryMonitorFactory</code> is not enabled
151 * then this method returns the "faux" <code>MemoryMonitor</code>
152 * implementation, it does nothing. When enabled and for
153 * Java5 and above JVMs, and instance of the
154 * <code>NotificationMemoryMonitor</code> is returned.
155 *
156 * @param parameterTypes not used
157 * @param parameterValues not used
158 * @return <code>MemoryMonitor</code> instance
159 * @throws CreationException if the <code>MemoryMonitor</code> can not be
160 * created.
161 */
162 protected MemoryMonitor getDefault(Class[] parameterTypes,
163 Object[] parameterValues)
164 throws CreationException {
165 return (! enabled() || Util.PreJdk15)
166 // not enabled or Java4 or below
167 ? new FauxMemoryMonitor()
168 // enabled and Java5 or above
169 : new NotificationMemoryMonitor();
170 }
171
172 }
173
174 // End MemoryMonitorFactory.java