1 /*
2 * Copyright (c) 2002, 2006, 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
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23 * questions.
24 */
25 package jdk.internal.perf;
26
27 import java.nio.ByteBuffer;
28 import java.security.Permission;
29 import java.security.PrivilegedAction;
30 import java.io.IOException;
31 import java.io.UnsupportedEncodingException;
32 import jdk.internal.ref.CleanerFactory;
33
34 /**
35 * The Perf class provides the ability to attach to an instrumentation
36 * buffer maintained by a Java virtual machine. The instrumentation
37 * buffer may be for the Java virtual machine running the methods of
38 * this class or it may be for another Java virtual machine on the
39 * same system.
40 * <p>
41 * In addition, this class provides methods to create instrumentation
42 * objects in the instrumentation buffer for the Java virtual machine
43 * that is running these methods. It also contains methods for acquiring
44 * the value of a platform specific high resolution clock for time
45 * stamp and interval measurement purposes.
46 *
47 * @author Brian Doherty
48 * @since 1.4.2
49 * @see #getPerf
50 * @see jdk.internal.perf.Perf.GetPerfAction
51 * @see java.nio.ByteBuffer
52 */
53 public final class Perf {
54
55 private static Perf instance;
56
57 private static final int PERF_MODE_RO = 0;
58 private static final int PERF_MODE_RW = 1;
59
60 private Perf() { } // prevent instantiation
61
62 /**
63 * The GetPerfAction class is a convenience class for acquiring access
64 * to the singleton Perf instance using the
65 * <code>AccessController.doPrivileged()</code> method.
66 * <p>
67 * An instance of this class can be used as the argument to
68 * <code>AccessController.doPrivileged(PrivilegedAction)</code>.
69 * <p> Here is a suggested idiom for use of this class:
70 *
71 * <blockquote><pre>{@code
72 * class MyTrustedClass {
73 * private static final Perf perf =
74 * AccessController.doPrivileged(new Perf.GetPerfAction<Perf>());
75 * ...
76 * }
77 * }</pre></blockquote>
78 * <p>
79 * In the presence of a security manager, the <code>MyTrustedClass</code>
80 * class in the above example will need to be granted the
81 * <em>"sun.misc.Perf.getPerf"</em> <code>RuntimePermission</code>
82 * permission in order to successfully acquire the singleton Perf instance.
83 * <p>
84 * Please note that the <em>"sun.misc.Perf.getPerf"</em> permission
85 * is not a JDK specified permission.
86 *
87 * @see java.security.AccessController#doPrivileged(PrivilegedAction)
88 * @see java.lang.RuntimePermission
89 */
90 public static class GetPerfAction implements PrivilegedAction<Perf>
91 {
92 /**
93 * Run the <code>Perf.getPerf()</code> method in a privileged context.
94 *
95 * @see #getPerf
96 */
97 public Perf run() {
98 return getPerf();
99 }
100 }
101
102 /**
103 * Return a reference to the singleton Perf instance.
104 * <p>
105 * The getPerf() method returns the singleton instance of the Perf
106 * class. The returned object provides the caller with the capability
107 * for accessing the instrumentation buffer for this or another local
108 * Java virtual machine.
109 * <p>
110 * If a security manager is installed, its <code>checkPermission</code>
111 * method is called with a <code>RuntimePermission</code> with a target
112 * of <em>"sun.misc.Perf.getPerf"</em>. A security exception will result
113 * if the caller has not been granted this permission.
114 * <p>
115 * Access to the returned <code>Perf</code> object should be protected
116 * by its caller and not passed on to untrusted code. This object can
117 * be used to attach to the instrumentation buffer provided by this Java
118 * virtual machine or for those of other Java virtual machines running
119 * on the same system. The instrumentation buffer may contain senstitive
120 * information. API's built on top of this interface may want to provide
121 * finer grained access control to the contents of individual
122 * instrumentation objects contained within the buffer.
123 * <p>
124 * Please note that the <em>"sun.misc.Perf.getPerf"</em> permission
125 * is not a JDK specified permission.
126 *
127 * @return A reference to the singleton Perf instance.
128 * @throws SecurityException if a security manager exists and its
129 * <code>checkPermission</code> method doesn't allow access
130 * to the <em>"jdk.internal.perf.Perf.getPerf""</em> target.
131 * @see java.lang.RuntimePermission
132 * @see #attach
133 */
134 public static Perf getPerf()
135 {
136 SecurityManager security = System.getSecurityManager();
137 if (security != null) {
138 Permission perm = new RuntimePermission("jdk.internal.perf.Perf.getPerf");
139 security.checkPermission(perm);
140 }
141
142 return instance;
143 }
144
145 /**
146 * Attach to the instrumentation buffer for the specified Java virtual
147 * machine.
148 * <p>
149 * This method will attach to the instrumentation buffer for the
150 * specified virtual machine. It returns a <code>ByteBuffer</code> object
151 * that is initialized to access the instrumentation buffer for the
152 * indicated Java virtual machine. The <code>lvmid</code> parameter is
153 * a integer value that uniquely identifies the target local Java virtual
154 * machine. It is typically, but not necessarily, the process id of
155 * the target Java virtual machine.
156 * <p>
157 * If the <code>lvmid</code> identifies a Java virtual machine different
158 * from the one running this method, then the coherency characteristics
159 * of the buffer are implementation dependent. Implementations that do
160 * not support named, coherent, shared memory may return a
161 * <code>ByteBuffer</code> object that contains only a snap shot of the
162 * data in the instrumentation buffer. Implementations that support named,
163 * coherent, shared memory, may return a <code>ByteBuffer</code> object
164 * that will be changing dynamically over time as the target Java virtual
165 * machine updates its mapping of this buffer.
166 * <p>
167 * If the <code>lvmid</code> is 0 or equal to the actual <code>lvmid</code>
168 * for the Java virtual machine running this method, then the returned
169 * <code>ByteBuffer</code> object will always be coherent and dynamically
170 * changing.
171 * <p>
172 * The attach mode specifies the access permissions requested for the
173 * instrumentation buffer of the target virtual machine. The permitted
174 * access permissions are:
175 * <ul>
176 * <li>"r" - Read only access. This Java virtual machine has only
177 * read access to the instrumentation buffer for the target Java
178 * virtual machine.
179 * <li>"rw" - Read/Write access. This Java virtual machine has read and
180 * write access to the instrumentation buffer for the target Java virtual
181 * machine. This mode is currently not supported and is reserved for
182 * future enhancements.
183 * </ul>
184 *
185 * @param lvmid an integer that uniquely identifies the
186 * target local Java virtual machine.
187 * @param mode a string indicating the attach mode.
188 * @return ByteBuffer a direct allocated byte buffer
189 * @throws IllegalArgumentException The lvmid or mode was invalid.
190 * @throws IOException An I/O error occurred while trying to acquire
191 * the instrumentation buffer.
192 * @throws OutOfMemoryError The instrumentation buffer could not be mapped
193 * into the virtual machine's address space.
194 * @see java.nio.ByteBuffer
195 */
196 public ByteBuffer attach(int lvmid, String mode)
197 throws IllegalArgumentException, IOException
198 {
199 if (mode.compareTo("r") == 0) {
200 return attachImpl(null, lvmid, PERF_MODE_RO);
201 }
202 else if (mode.compareTo("rw") == 0) {
203 return attachImpl(null, lvmid, PERF_MODE_RW);
204 }
205 else {
206 throw new IllegalArgumentException("unknown mode");
207 }
208 }
209
210 /**
211 * Attach to the instrumentation buffer for the specified Java virtual
212 * machine owned by the given user.
213 * <p>
214 * This method behaves just as the <code>attach(int lvmid, String mode)
215 * </code> method, except that it only searches for Java virtual machines
216 * owned by the specified user.
217 *
218 * @param user A <code>String</code> object containing the
219 * name of the user that owns the target Java
220 * virtual machine.
221 * @param lvmid an integer that uniquely identifies the
222 * target local Java virtual machine.
223 * @param mode a string indicating the attach mode.
224 * @return ByteBuffer a direct allocated byte buffer
225 * @throws IllegalArgumentException The lvmid or mode was invalid.
226 * @throws IOException An I/O error occurred while trying to acquire
227 * the instrumentation buffer.
228 * @throws OutOfMemoryError The instrumentation buffer could not be mapped
229 * into the virtual machine's address space.
230 * @see java.nio.ByteBuffer
231 */
232 public ByteBuffer attach(String user, int lvmid, String mode)
233 throws IllegalArgumentException, IOException
234 {
235 if (mode.compareTo("r") == 0) {
236 return attachImpl(user, lvmid, PERF_MODE_RO);
237 }
238 else if (mode.compareTo("rw") == 0) {
239 return attachImpl(user, lvmid, PERF_MODE_RW);
240 }
241 else {
242 throw new IllegalArgumentException("unknown mode");
243 }
244 }
245
246 /**
247 * Call the implementation specific attach method.
248 * <p>
249 * This method calls into the Java virtual machine to perform the platform
250 * specific attach method. Buffers returned from this method are
251 * internally managed as <code>PhantomRefereces</code> to provide for
252 * guaranteed, secure release of the native resources.
253 *
254 * @param user A <code>String</code> object containing the
255 * name of the user that owns the target Java
256 * virtual machine.
257 * @param lvmid an integer that uniquely identifies the
258 * target local Java virtual machine.
259 * @param mode a string indicating the attach mode.
260 * @return ByteBuffer a direct allocated byte buffer
261 * @throws IllegalArgumentException The lvmid or mode was invalid.
262 * @throws IOException An I/O error occurred while trying to acquire
263 * the instrumentation buffer.
264 * @throws OutOfMemoryError The instrumentation buffer could not be mapped
265 * into the virtual machine's address space.
266 */
267 private ByteBuffer attachImpl(String user, int lvmid, int mode)
268 throws IllegalArgumentException, IOException
269 {
270 final ByteBuffer b = attach(user, lvmid, mode);
271
272 if (lvmid == 0) {
273 // The native instrumentation buffer for this Java virtual
274 // machine is never unmapped.
275 return b;
276 }
277 else {
278 // This is an instrumentation buffer for another Java virtual
279 // machine with native resources that need to be managed. We
280 // create a duplicate of the native ByteBuffer and manage it
281 // with a Cleaner. When the duplicate becomes phantom reachable,
282 // the native resources will be released.
283
284 final ByteBuffer dup = b.duplicate();
285
286 CleanerFactory.cleaner()
287 .register(dup, new CleanerAction(instance, b));
288 return dup;
289 }
290 }
291
292 private static class CleanerAction implements Runnable {
293 private final ByteBuffer bb;
294 private final Perf perf;
295 CleanerAction(Perf perf, ByteBuffer bb) {
296 this.perf = perf;
297 this.bb = bb;
298 }
299 public void run() {
300 try {
301 perf.detach(bb);
302 } catch (Throwable th) {
303 // avoid crashing the reference handler thread,
304 // but provide for some diagnosability
305 assert false : th.toString();
306 }
307 }
308 }
309
310 /**
311 * Native method to perform the implementation specific attach mechanism.
312 * <p>
313 * The implementation of this method may return distinct or identical
314 * <code>ByteBuffer</code> objects for two distinct calls requesting
315 * attachment to the same Java virtual machine.
316 * <p>
317 * For the Sun HotSpot JVM, two distinct calls to attach to the same
318 * target Java virtual machine will result in two distinct ByteBuffer
319 * objects returned by this method. This may change in a future release.
320 *
321 * @param user A <code>String</code> object containing the
322 * name of the user that owns the target Java
323 * virtual machine.
324 * @param lvmid an integer that uniquely identifies the
325 * target local Java virtual machine.
326 * @param mode a string indicating the attach mode.
327 * @return ByteBuffer a direct allocated byte buffer
328 * @throws IllegalArgumentException The lvmid or mode was invalid.
329 * @throws IOException An I/O error occurred while trying to acquire
330 * the instrumentation buffer.
331 * @throws OutOfMemoryError The instrumentation buffer could not be mapped
332 * into the virtual machine's address space.
333 */
334 private native ByteBuffer attach(String user, int lvmid, int mode)
335 throws IllegalArgumentException, IOException;
336
337 /**
338 * Native method to perform the implementation specific detach mechanism.
339 * <p>
340 * If this method is passed a <code>ByteBuffer</code> object that is
341 * not created by the <code>attach</code> method, then the results of
342 * this method are undefined, with unpredictable and potentially damaging
343 * effects to the Java virtual machine. To prevent accidental or malicious
344 * use of this method, all native ByteBuffer created by the <code>
345 * attach</code> method are managed internally as PhantomReferences
346 * and resources are freed by the system.
347 * <p>
348 * If this method is passed a <code>ByteBuffer</code> object created
349 * by the <code>attach</code> method with a lvmid for the Java virtual
350 * machine running this method (lvmid=0, for example), then the detach
351 * request is silently ignored.
352 *
353 * @param bb A direct allocated byte buffer created by the
354 * <code>attach</code> method.
355 * @see java.nio.ByteBuffer
356 * @see #attach
357 */
358 private native void detach(ByteBuffer bb);
359
360 /**
361 * Create a <code>long</code> scalar entry in the instrumentation buffer
362 * with the given variability characteristic, units, and initial value.
363 * <p>
364 * Access to the instrument is provided through the returned <code>
365 * ByteBuffer</code> object. Typically, this object should be wrapped
366 * with <code>LongBuffer</code> view object.
367 *
368 * @param variability the variability characteristic for this entry.
369 * @param units the units for this entry.
370 * @param name the name of this entry.
371 * @param value the initial value for this entry.
372 * @return ByteBuffer a direct allocated ByteBuffer object that
373 * allows write access to a native memory location
374 * containing a <code>long</code> value.
375 *
376 * see sun.misc.perf.Variability
377 * see sun.misc.perf.Units
378 * @see java.nio.ByteBuffer
379 */
380 public native ByteBuffer createLong(String name, int variability,
381 int units, long value);
382
383 /**
384 * Create a <code>String</code> entry in the instrumentation buffer with
385 * the given variability characteristic, units, and initial value.
386 * <p>
387 * The maximum length of the <code>String</code> stored in this string
388 * instrument is given in by <code>maxLength</code> parameter. Updates
389 * to this instrument with <code>String</code> values with lengths greater
390 * than <code>maxLength</code> will be truncated to <code>maxLength</code>.
391 * The truncated value will be terminated by a null character.
392 * <p>
393 * The underlying implementation may further limit the length of the
394 * value, but will continue to preserve the null terminator.
395 * <p>
396 * Access to the instrument is provided through the returned <code>
397 * ByteBuffer</code> object.
398 *
399 * @param variability the variability characteristic for this entry.
400 * @param units the units for this entry.
401 * @param name the name of this entry.
402 * @param value the initial value for this entry.
403 * @param maxLength the maximum string length for this string
404 * instrument.
405 * @return ByteBuffer a direct allocated ByteBuffer that allows
406 * write access to a native memory location
407 * containing a <code>long</code> value.
408 *
409 * see sun.misc.perf.Variability
410 * see sun.misc.perf.Units
411 * @see java.nio.ByteBuffer
412 */
413 public ByteBuffer createString(String name, int variability,
414 int units, String value, int maxLength)
415 {
416 byte[] v = getBytes(value);
417 byte[] v1 = new byte[v.length+1];
418 System.arraycopy(v, 0, v1, 0, v.length);
419 v1[v.length] = '\0';
420 return createByteArray(name, variability, units, v1, Math.max(v1.length, maxLength));
421 }
422
423 /**
424 * Create a <code>String</code> entry in the instrumentation buffer with
425 * the given variability characteristic, units, and initial value.
426 * <p>
427 * The maximum length of the <code>String</code> stored in this string
428 * instrument is implied by the length of the <code>value</code> parameter.
429 * Subsequent updates to the value of this instrument will be truncated
430 * to this implied maximum length. The truncated value will be terminated
431 * by a null character.
432 * <p>
433 * The underlying implementation may further limit the length of the
434 * initial or subsequent value, but will continue to preserve the null
435 * terminator.
436 * <p>
437 * Access to the instrument is provided through the returned <code>
438 * ByteBuffer</code> object.
439 *
440 * @param variability the variability characteristic for this entry.
441 * @param units the units for this entry.
442 * @param name the name of this entry.
443 * @param value the initial value for this entry.
444 * @return ByteBuffer a direct allocated ByteBuffer that allows
445 * write access to a native memory location
446 * containing a <code>long</code> value.
447 *
448 * see sun.misc.perf.Variability
449 * see sun.misc.perf.Units
450 * @see java.nio.ByteBuffer
451 */
452 public ByteBuffer createString(String name, int variability,
453 int units, String value)
454 {
455 byte[] v = getBytes(value);
456 byte[] v1 = new byte[v.length+1];
457 System.arraycopy(v, 0, v1, 0, v.length);
458 v1[v.length] = '\0';
459 return createByteArray(name, variability, units, v1, v1.length);
460 }
461
462 /**
463 * Create a <code>byte</code> vector entry in the instrumentation buffer
464 * with the given variability characteristic, units, and initial value.
465 * <p>
466 * The <code>maxLength</code> parameter limits the size of the byte
467 * array instrument such that the initial or subsequent updates beyond
468 * this length are silently ignored. No special handling of truncated
469 * updates is provided.
470 * <p>
471 * The underlying implementation may further limit the length of the
472 * length of the initial or subsequent value.
473 * <p>
474 * Access to the instrument is provided through the returned <code>
475 * ByteBuffer</code> object.
476 *
477 * @param variability the variability characteristic for this entry.
478 * @param units the units for this entry.
479 * @param name the name of this entry.
480 * @param value the initial value for this entry.
481 * @param maxLength the maximum length of this byte array.
482 * @return ByteBuffer a direct allocated byte buffer that allows
483 * write access to a native memory location
484 * containing a <code>long</code> value.
485 *
486 * see sun.misc.perf.Variability
487 * see sun.misc.perf.Units
488 * @see java.nio.ByteBuffer
489 */
490 public native ByteBuffer createByteArray(String name, int variability,
491 int units, byte[] value,
492 int maxLength);
493
494
495 /**
496 * convert string to an array of UTF-8 bytes
497 */
498 private static byte[] getBytes(String s)
499 {
500 byte[] bytes = null;
501
502 try {
503 bytes = s.getBytes("UTF-8");
504 }
505 catch (UnsupportedEncodingException e) {
506 // ignore, UTF-8 encoding is always known
507 }
508
509 return bytes;
510 }
511
512 /**
513 * Return the value of the High Resolution Counter.
514 *
515 * The High Resolution Counter returns the number of ticks since
516 * since the start of the Java virtual machine. The resolution of
517 * the counter is machine dependent and can be determined from the
518 * value return by the {@link #highResFrequency} method.
519 *
520 * @return the number of ticks of machine dependent resolution since
521 * the start of the Java virtual machine.
522 *
523 * @see #highResFrequency
524 * @see java.lang.System#currentTimeMillis()
525 */
526 public native long highResCounter();
527
528 /**
529 * Returns the frequency of the High Resolution Counter, in ticks per
530 * second.
531 *
532 * This value can be used to convert the value of the High Resolution
533 * Counter, as returned from a call to the {@link #highResCounter} method,
534 * into the number of seconds since the start of the Java virtual machine.
535 *
536 * @return the frequency of the High Resolution Counter.
537 * @see #highResCounter
538 */
539 public native long highResFrequency();
540
541 private static native void registerNatives();
542
543 static {
544 registerNatives();
545 instance = new Perf();
546 }
547 }