1 /* ============================================================
2 * JRobin : Pure java implementation of RRDTool's functionality
3 * ============================================================
4 *
5 * Project Info: http://www.jrobin.org
6 * Project Lead: Sasa Markovic (saxon@jrobin.org);
7 *
8 * (C) Copyright 2003-2005, by Sasa Markovic.
9 *
10 * Developers: Sasa Markovic (saxon@jrobin.org)
11 *
12 *
13 * This library is free software; you can redistribute it and/or modify it under the terms
14 * of the GNU Lesser General Public License as published by the Free Software Foundation;
15 * either version 2.1 of the License, or (at your option) any later version.
16 *
17 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
18 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
19 * See the GNU Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public License along with this
22 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
23 * Boston, MA 02111-1307, USA.
24 */
25
26 package net.bull.javamelody.internal.model;
27
28 import java.io.IOException;
29 import java.lang.reflect.Field;
30 import java.lang.reflect.Method;
31 import java.nio.ByteBuffer;
32 import java.nio.MappedByteBuffer;
33 import java.nio.channels.FileChannel;
34 import java.util.Timer;
35 import java.util.TimerTask;
36
37 import org.jrobin.core.RrdFileBackend;
38
39 import sun.nio.ch.DirectBuffer; // NOPMD
40
41 /**
42 * JRobin backend which is used to store RRD data to ordinary disk files
43 * by using fast java.nio.* package. This is the default backend engine since JRobin 1.4.0.
44 */
45 public class RrdNioBackend extends RrdFileBackend {
46 private static final Object THE_UNSAFE = getTheUnsafe();
47 private static final Method JAVA9_INVOKE_CLEANER = getJava9InvokeCleaner();
48 private static Timer fileSyncTimer;
49
50 private MappedByteBuffer byteBuffer;
51 private final TimerTask syncTask = new TimerTask() {
52 @Override
53 public void run() {
54 sync();
55 }
56 };
57
58 /**
59 * Creates RrdFileBackend object for the given file path, backed by java.nio.* classes.
60 *
61 * @param path Path to a file
62 * @param readOnly True, if file should be open in a read-only mode. False otherwise
63 * @param syncPeriod See {@link RrdNioBackendFactory#setSyncPeriod(int)} for explanation
64 * @throws IOException Thrown in case of I/O error
65 */
66 protected RrdNioBackend(String path, boolean readOnly, int syncPeriod) throws IOException {
67 super(path, readOnly);
68 try {
69 mapFile();
70 if (!readOnly) {
71 fileSyncTimer.schedule(syncTask, syncPeriod * 1000L, syncPeriod * 1000L);
72 }
73 } catch (final IOException ioe) {
74 super.close(); // NOPMD
75 throw ioe;
76 } catch (final IllegalStateException e) {
77 // issue #592 (IllegalStateException: Timer already cancelled)
78 unmapFile();
79 super.close(); // NOPMD
80 throw e;
81 }
82 }
83
84 /**
85 * @return The timer to synchronize files.
86 */
87 public static Timer getFileSyncTimer() {
88 return fileSyncTimer;
89 }
90
91 /**
92 * Sets the timer.
93 * @param timer timer to synchronize files.
94 */
95 public static void setFileSyncTimer(Timer timer) {
96 fileSyncTimer = timer;
97 }
98
99 private void mapFile() throws IOException {
100 final long length = getLength();
101 if (length > 0) {
102 final FileChannel.MapMode mapMode =
103 // (issue 328) readOnly ? FileChannel.MapMode.READ_ONLY :
104 FileChannel.MapMode.READ_WRITE;
105 byteBuffer = file.getChannel().map(mapMode, 0, length);
106 }
107 }
108
109 private void unmapFile() {
110 if (byteBuffer != null) {
111 if (JAVA9_INVOKE_CLEANER == null || THE_UNSAFE == null) {
112 if (byteBuffer instanceof DirectBuffer) {
113 // for Java 8 and before
114 ((DirectBuffer) byteBuffer).cleaner().clean();
115 }
116 } else {
117 // for Java 9 and later:
118 // sun.nio.ch.DirectBuffer methods are not accessible,
119 // so the new sun.misc.Unsafe.theUnsafe.invokeCleaner(ByteBuffer) is used.
120 // See https://bugs.openjdk.java.net/browse/JDK-8171377
121 try {
122 JAVA9_INVOKE_CLEANER.invoke(THE_UNSAFE, byteBuffer);
123 } catch (final Exception e) {
124 throw new IllegalStateException(e);
125 }
126 }
127 byteBuffer = null;
128 }
129 }
130
131 private static Object getTheUnsafe() {
132 try {
133 final Class<?> unsafeClass = Class.forName("sun.misc.Unsafe");
134 final Field theUnsafeField = unsafeClass.getDeclaredField("theUnsafe");
135 theUnsafeField.setAccessible(true);
136 return theUnsafeField.get(null);
137 } catch (final Exception e) {
138 return null;
139 }
140 }
141
142 private static Method getJava9InvokeCleaner() {
143 try {
144 final Class<?> unsafeClass = Class.forName("sun.misc.Unsafe");
145 return unsafeClass.getMethod("invokeCleaner", ByteBuffer.class);
146 } catch (final Exception e) {
147 return null;
148 }
149 }
150
151 /**
152 * Sets length of the underlying RRD file. This method is called only once, immediately
153 * after a new RRD file gets created.
154 *
155 * @param newLength Length of the RRD file
156 * @throws IOException Thrown in case of I/O error.
157 */
158 @Override
159 protected synchronized void setLength(long newLength) throws IOException {
160 unmapFile();
161 super.setLength(newLength);
162 mapFile();
163 }
164
165 /**
166 * Writes bytes to the underlying RRD file on the disk
167 *
168 * @param offset Starting file offset
169 * @param b Bytes to be written.
170 */
171 @Override
172 protected synchronized void write(long offset, byte[] b) throws IOException {
173 if (byteBuffer != null) {
174 byteBuffer.position((int) offset);
175 byteBuffer.put(b);
176 } else {
177 throw new IOException("Write failed, file " + getPath() + " not mapped for I/O");
178 }
179 }
180
181 /**
182 * Reads a number of bytes from the RRD file on the disk
183 *
184 * @param offset Starting file offset
185 * @param b Buffer which receives bytes read from the file.
186 */
187 @Override
188 protected synchronized void read(long offset, byte[] b) throws IOException {
189 if (byteBuffer != null) {
190 byteBuffer.position((int) offset);
191 byteBuffer.get(b);
192 } else {
193 throw new IOException("Read failed, file " + getPath() + " not mapped for I/O");
194 }
195 }
196
197 /**
198 * Closes the underlying RRD file.
199 *
200 * @throws IOException Thrown in case of I/O error
201 */
202 @Override
203 public synchronized void close() throws IOException {
204 // cancel synchronization
205 try {
206 if (syncTask != null) {
207 syncTask.cancel();
208 }
209 sync();
210 unmapFile();
211 } finally {
212 super.close();
213 }
214 }
215
216 /**
217 * This method forces all data cached in memory but not yet stored in the file,
218 * to be stored in it.
219 */
220 protected synchronized void sync() {
221 if (byteBuffer != null) {
222 byteBuffer.force();
223 }
224 }
225 }
226