001/* MonitorInfo.java - Information on a monitor lock. 002 Copyright (C) 2006 Free Software Foundation 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038package java.lang.management; 039 040import javax.management.openmbean.CompositeData; 041import javax.management.openmbean.CompositeType; 042import javax.management.openmbean.SimpleType; 043 044/** 045 * Provides information on a monitor lock held by a thread. 046 * A monitor lock is obtained when a thread enters a synchronized 047 * block or method. 048 * 049 * @author Andrew John Hughes (gnu_andrew@member.fsf.org) 050 * @since 1.6 051 */ 052public class MonitorInfo 053 extends LockInfo 054{ 055 056 /** 057 * The stack depth at which the lock was obtained. 058 */ 059 private int stackDepth; 060 061 /** 062 * The stack frame at which the lock was obtained. 063 */ 064 private StackTraceElement stackFrame; 065 066 /** 067 * Constructs a new {@link MonitorInfo} using the specified 068 * lock class name and identity hash code, and the given 069 * stack depth and frame. 070 * 071 * @param className the class name of the lock object. 072 * @param identityHashCode the identity hash code of the lock object. 073 * @param stackDepth the depth of the stack at which the lock 074 * was obtained. 075 * @param stackFrame the frame of the stack at which the lock was 076 * obtained. 077 * @throws IllegalArgumentException if the stack depth and frame are 078 * inconsistent i.e. the frame is 079 * <code>null</code> but the depth is 080 * ≥ 0, or the frame is not 081 * <code>null</code> but the depth is 082 * < 0. 083 */ 084 public MonitorInfo(String className, int identityHashCode, int stackDepth, 085 StackTraceElement stackFrame) 086 { 087 super(className, identityHashCode); 088 if (stackFrame == null && stackDepth >= 0) 089 throw new IllegalArgumentException("The stack frame is null, but the " + 090 "stack depth is greater than or equal " + 091 "to zero."); 092 if (stackFrame != null && stackDepth < 0) 093 throw new IllegalArgumentException("The stack frame is not null, but the " + 094 "stack depth is less than zero."); 095 this.stackDepth = stackDepth; 096 this.stackFrame = stackFrame; 097 } 098 099 /** 100 * <p> 101 * Returns a {@link MonitorInfo} instance using the values 102 * given in the supplied 103 * {@link javax.management.openmbean.CompositeData} object. 104 * The composite data instance should contain the following 105 * attributes with the specified types: 106 * </p> 107 * <table> 108 * <th><td>Name</td><td>Type</td></th> 109 * <tr><td>className</td><td>java.lang.String</td></tr> 110 * <tr><td>identityHashCode</td><td>java.lang.Integer</td></tr> 111 * <tr><td>lockedStackDepth</td><td>java.lang.Integer</td></tr> 112 * <tr><td>lockedStackFrame</td><td>javax.management.openmbean.CompositeData 113 * </td></tr> 114 * </table> 115 * <p> 116 * The stack trace is further described as: 117 * </p> 118 * <table> 119 * <th><td>Name</td><td>Type</td></th> 120 * <tr><td>className</td><td>java.lang.String</td></tr> 121 * <tr><td>methodName</td><td>java.lang.String</td></tr> 122 * <tr><td>fileName</td><td>java.lang.String</td></tr> 123 * <tr><td>lineNumber</td><td>java.lang.Integer</td></tr> 124 * <tr><td>nativeMethod</td><td>java.lang.Boolean</td></tr> 125 * </table> 126 * 127 * @param data the composite data structure to take values from. 128 * @return a new instance containing the values from the 129 * composite data structure, or <code>null</code> 130 * if the data structure was also <code>null</code>. 131 * @throws IllegalArgumentException if the composite data structure 132 * does not match the structure 133 * outlined above. 134 */ 135 public static MonitorInfo from(CompositeData data) 136 { 137 if (data == null) 138 return null; 139 CompositeType type = data.getCompositeType(); 140 ThreadInfo.checkAttribute(type, "ClassName", SimpleType.STRING); 141 ThreadInfo.checkAttribute(type, "IdentityHashCode", SimpleType.INTEGER); 142 ThreadInfo.checkAttribute(type, "LockedStackDepth", SimpleType.INTEGER); 143 ThreadInfo.checkAttribute(type, "LockedStackFrame", 144 ThreadInfo.getStackTraceType()); 145 CompositeData frame = (CompositeData) data.get("LockedStackFrame"); 146 return new MonitorInfo((String) data.get("ClassName"), 147 (Integer) data.get("IdentityHashCode"), 148 (Integer) data.get("LockedStackDepth"), 149 new StackTraceElement((String) frame.get("ClassName"), 150 (String) frame.get("MethodName"), 151 (String) frame.get("FileName"), 152 (Integer) frame.get("LineNumber"))); 153 } 154 155 /** 156 * Returns the depth of the stack at which the lock was obtained. 157 * This works as an index into the array returned by 158 * {@link ThreadInfo#getStackTrace()}. 159 * 160 * @return the depth of the stack at which the lock was obtained, 161 * or a negative number if this information is unavailable. 162 */ 163 public int getLockedStackDepth() 164 { 165 return stackDepth; 166 } 167 168 /** 169 * Returns the stack frame at which the lock was obtained. 170 * 171 * @return the stack frame at which the lock was obtained, 172 * or <code>null</code> if this informati0on is unavailable. 173 */ 174 public StackTraceElement getLockedStackFrame() 175 { 176 return stackFrame; 177 } 178 179}