1/* 2 * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26package sun.jvmstat.perfdata.monitor.v1_0; 27 28import sun.jvmstat.monitor.*; 29import sun.jvmstat.perfdata.monitor.*; 30import java.nio.*; 31 32/** 33 * Class representing the 1.0 version of the HotSpot PerfData instrumentation 34 * buffer header. 35 * <p> 36 * The PerfDataBufferPrologue2_0 class supports parsing of the version 37 * specific portions of the PerfDataPrologue C structure: 38 * <pre> 39 * typedef struct { 40 * ... // handled by superclass 41 * jint used; // number of PerfData memory bytes used 42 * jint overflow; // number of bytes of overflow 43 * jlong mod_time_stamp; // time stamp of the last structural modification 44 * } PerfDataPrologue 45 * </pre> 46 * 47 * @author Brian Doherty 48 * @since 1.5 49 */ 50public class PerfDataBufferPrologue extends AbstractPerfDataBufferPrologue { 51 52 private static final int SUPPORTED_MAJOR_VERSION = 1; 53 private static final int SUPPORTED_MINOR_VERSION = 0; 54 55 /* 56 * the following constants must match the field offsets and sizes 57 * in the PerfDataPrologue structure in perfMemory.hpp 58 */ 59 final static int PERFDATA_PROLOG_USED_OFFSET=8; 60 final static int PERFDATA_PROLOG_USED_SIZE=4; // sizeof(int) 61 final static int PERFDATA_PROLOG_OVERFLOW_OFFSET=12; 62 final static int PERFDATA_PROLOG_OVERFLOW_SIZE=4; // sizeof(int) 63 final static int PERFDATA_PROLOG_MODTIMESTAMP_OFFSET=16; 64 final static int PERFDATA_PROLOG_MODTIMESTAMP_SIZE=8; // sizeof(long) 65 final static int PERFDATA_PROLOG_SIZE=24; // sizeof(struct PerfDataProlog) 66 67 // counter names for prologue psuedo counters 68 final static String PERFDATA_BUFFER_SIZE_NAME = "sun.perfdata.size"; 69 final static String PERFDATA_BUFFER_USED_NAME = "sun.perfdata.used"; 70 final static String PERFDATA_OVERFLOW_NAME = "sun.perfdata.overflow"; 71 final static String PERFDATA_MODTIMESTAMP_NAME = "sun.perfdata.timestamp"; 72 73 /** 74 * Create an instance of PerfDataBufferPrologue from the given 75 * ByteBuffer object. 76 * 77 * @param byteBuffer the buffer containing the binary header data 78 */ 79 public PerfDataBufferPrologue(ByteBuffer byteBuffer) 80 throws MonitorException { 81 super(byteBuffer); 82 assert ((getMajorVersion() == 1) && (getMinorVersion() == 0)); 83 } 84 85 /** 86 * {@inheritDoc} 87 */ 88 public boolean supportsAccessible() { 89 return false; 90 } 91 92 /** 93 * {@inheritDoc} 94 */ 95 public boolean isAccessible() { 96 return true; 97 } 98 99 /** 100 * Get the utilization of the instrumentation memory buffer. 101 * 102 * @return int - the utilization of the buffer 103 */ 104 public int getUsed() { 105 byteBuffer.position(PERFDATA_PROLOG_USED_OFFSET); 106 return byteBuffer.getInt(); 107 } 108 109 /** 110 * Get the size of the instrumentation memory buffer. 111 * 112 * @return int - the size of the buffer 113 */ 114 public int getBufferSize() { 115 return byteBuffer.capacity(); 116 } 117 118 /** 119 * Get the buffer overflow amount. This value is non-zero if the 120 * HotSpot JVM has overflowed the instrumentation memory buffer. 121 * The target JVM can be restarted with -XX:PerfDataMemSize=X to 122 * create a larger memory buffer. 123 * 124 * @return int - the size of the buffer 125 */ 126 public int getOverflow() { 127 byteBuffer.position(PERFDATA_PROLOG_OVERFLOW_OFFSET); 128 return byteBuffer.getInt(); 129 } 130 131 /** 132 * Get the time of last modification for the instrumentation 133 * memory buffer. This method returns the time, as ticks since the 134 * start of the target JVM, of the last structural modification to 135 * the instrumentation buffer. Structural modifications correspond to 136 * the addition or deletion of instrumentation objects. Updates to 137 * counter values are not structural modifications. 138 */ 139 public long getModificationTimeStamp() { 140 byteBuffer.position(PERFDATA_PROLOG_MODTIMESTAMP_OFFSET); 141 return byteBuffer.getLong(); 142 } 143 144 /** 145 * {@inheritDoc} 146 */ 147 public int getSize() { 148 return PERFDATA_PROLOG_SIZE; // sizeof(struct PerfDataProlog) 149 } 150 151 /** 152 * Return an IntBuffer that accesses the used value. This is used 153 * to create a Monitor object for this value. 154 * 155 * @return IntBuffer - a ByteBuffer that accesses the used value 156 * in the instrumentation buffer header. 157 * @see #getUsed() 158 */ 159 public IntBuffer usedBuffer() { 160 byteBuffer.position(PERFDATA_PROLOG_USED_OFFSET); 161 IntBuffer ib = byteBuffer.asIntBuffer(); 162 ib.limit(1); 163 return ib; 164 } 165 166 /** 167 * Return an IntBuffer that accesses the size value. This is used 168 * to create a Monitor object for this value. 169 * 170 * @return IntBuffer - a ByteBuffer that accesses the size value 171 * in the instrumentation buffer header. 172 * @see #getBufferSize() 173 */ 174 public IntBuffer sizeBuffer() { 175 IntBuffer ib = IntBuffer.allocate(1); 176 ib.put(byteBuffer.capacity()); 177 return ib; 178 } 179 180 /** 181 * Return an IntBuffer that accesses the overflow value. This is used 182 * to create a Monitor object for this value. 183 * 184 * @return IntBuffer - a ByteBuffer that accesses the overflow value 185 * in the instrumentation buffer header. 186 * @see #getOverflow() 187 */ 188 public IntBuffer overflowBuffer() { 189 byteBuffer.position(PERFDATA_PROLOG_OVERFLOW_OFFSET); 190 IntBuffer ib = byteBuffer.asIntBuffer(); 191 ib.limit(1); 192 return ib; 193 } 194 195 /** 196 * Return an LongBuffer that accesses the modification timestamp value. 197 * This is used* to create a Monitor object for this value. 198 * 199 * @return LongBuffer - a ByteBuffer that accesses the modification time 200 * stamp value in the instrumentation buffer header. 201 * @see #getModificationTimeStamp() 202 */ 203 public LongBuffer modificationTimeStampBuffer() { 204 byteBuffer.position(PERFDATA_PROLOG_MODTIMESTAMP_OFFSET); 205 LongBuffer lb = byteBuffer.asLongBuffer(); 206 lb.limit(1); 207 return lb; 208 } 209} 210