1 /*
2 * Copyright (c) 2000, 2024, 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
26 package sun.misc;
27
28 import jdk.internal.vm.annotation.ForceInline;
29 import jdk.internal.misc.VM;
30 import jdk.internal.reflect.CallerSensitive;
31 import jdk.internal.reflect.Reflection;
32
33 import java.lang.reflect.Field;
34 import java.util.Set;
35
36
37 /**
38 * A collection of methods for performing low-level, unsafe operations.
39 * Although the class and all methods are public, use of this class is
40 * limited because only trusted code can obtain instances of it.
41 *
42 * <em>Note:</em> It is the responsibility of the caller to make sure
43 * arguments are checked before methods of this class are
44 * called. While some rudimentary checks are performed on the input,
45 * the checks are best effort and when performance is an overriding
46 * priority, as when methods of this class are optimized by the
47 * runtime compiler, some or all checks (if any) may be elided. Hence,
48 * the caller must not rely on the checks and corresponding
49 * exceptions!
50 *
51 * @author John R. Rose
52 * @see #getUnsafe
53 */
54
55 public final class Unsafe {
56
57 static {
58 Reflection.registerMethodsToFilter(Unsafe.class, Set.of("getUnsafe"));
59 }
60
61 private Unsafe() {}
62
63 private static final Unsafe theUnsafe = new Unsafe();
64 private static final jdk.internal.misc.Unsafe theInternalUnsafe = jdk.internal.misc.Unsafe.getUnsafe();
65
66 /**
67 * Provides the caller with the capability of performing unsafe
68 * operations.
69 *
70 * <p>The returned {@code Unsafe} object should be carefully guarded
71 * by the caller, since it can be used to read and write data at arbitrary
72 * memory addresses. It must never be passed to untrusted code.
73 *
74 * <p>Most methods in this class are very low-level, and correspond to a
75 * small number of hardware instructions (on typical machines). Compilers
76 * are encouraged to optimize these methods accordingly.
77 *
78 * <p>Here is a suggested idiom for using unsafe operations:
79 *
80 * <pre> {@code
81 * class MyTrustedClass {
82 * private static final Unsafe unsafe = Unsafe.getUnsafe();
83 * ...
84 * private long myCountAddress = ...;
85 * public int getCount() { return unsafe.getByte(myCountAddress); }
86 * }}</pre>
87 *
88 * (It may assist compilers to make the local variable {@code final}.)
89 *
90 * @throws SecurityException if the class loader of the caller
91 * class is not in the system domain in which all permissions
92 * are granted.
93 */
94 @CallerSensitive
95 public static Unsafe getUnsafe() {
96 Class<?> caller = Reflection.getCallerClass();
97 if (!VM.isSystemDomainLoader(caller.getClassLoader()))
98 throw new SecurityException("Unsafe");
99 return theUnsafe;
100 }
101
102 /// peek and poke operations
103 /// (compilers should optimize these to memory ops)
104
105 // These work on object fields in the Java heap.
106 // They will not work on elements of packed arrays.
107
108 /**
109 * Fetches a value from a given Java variable.
110 * More specifically, fetches a field or array element within the given
111 * object {@code o} at the given offset, or (if {@code o} is null)
112 * from the memory address whose numerical value is the given offset.
113 * <p>
114 * The results are undefined unless one of the following cases is true:
115 * <ul>
116 * <li>The offset was obtained from {@link #objectFieldOffset} on
117 * the {@link java.lang.reflect.Field} of some Java field and the object
118 * referred to by {@code o} is of a class compatible with that
119 * field's class.
120 *
121 * <li>The offset and object reference {@code o} (either null or
122 * non-null) were both obtained via {@link #staticFieldOffset}
123 * and {@link #staticFieldBase} (respectively) from the
124 * reflective {@link Field} representation of some Java field.
125 *
126 * <li>The object referred to by {@code o} is an array, and the offset
127 * is an integer of the form {@code B+N*S}, where {@code N} is
128 * a valid index into the array, and {@code B} and {@code S} are
129 * the values obtained by {@link #arrayBaseOffset} and {@link
130 * #arrayIndexScale} (respectively) from the array's class. The value
131 * referred to is the {@code N}<em>th</em> element of the array.
132 *
133 * </ul>
134 * <p>
135 * If one of the above cases is true, the call references a specific Java
136 * variable (field or array element). However, the results are undefined
137 * if that variable is not in fact of the type returned by this method.
138 * <p>
139 * This method refers to a variable by means of two parameters, and so
140 * it provides (in effect) a <em>double-register</em> addressing mode
141 * for Java variables. When the object reference is null, this method
142 * uses its offset as an absolute address. This is similar in operation
143 * to methods such as {@link #getInt(long)}, which provide (in effect) a
144 * <em>single-register</em> addressing mode for non-Java variables.
145 * However, because Java variables may have a different layout in memory
146 * from non-Java variables, programmers should not assume that these
147 * two addressing modes are ever equivalent. Also, programmers should
148 * remember that offsets from the double-register addressing mode cannot
149 * be portably confused with longs used in the single-register addressing
150 * mode.
151 *
152 * @param o Java heap object in which the variable resides, if any, else
153 * null
154 * @param offset indication of where the variable resides in a Java heap
155 * object, if any, else a memory address locating the variable
156 * statically
157 * @return the value fetched from the indicated Java variable
158 * @throws RuntimeException No defined exceptions are thrown, not even
159 * {@link NullPointerException}
160 */
161 @ForceInline
162 public int getInt(Object o, long offset) {
163 return theInternalUnsafe.getInt(o, offset);
164 }
165
166 /**
167 * Stores a value into a given Java variable.
168 * <p>
169 * The first two parameters are interpreted exactly as with
170 * {@link #getInt(Object, long)} to refer to a specific
171 * Java variable (field or array element). The given value
172 * is stored into that variable.
173 * <p>
174 * The variable must be of the same type as the method
175 * parameter {@code x}.
176 *
177 * @param o Java heap object in which the variable resides, if any, else
178 * null
179 * @param offset indication of where the variable resides in a Java heap
180 * object, if any, else a memory address locating the variable
181 * statically
182 * @param x the value to store into the indicated Java variable
183 * @throws RuntimeException No defined exceptions are thrown, not even
184 * {@link NullPointerException}
185 */
186 @ForceInline
187 public void putInt(Object o, long offset, int x) {
188 theInternalUnsafe.putInt(o, offset, x);
189 }
190
191 /**
192 * Fetches a reference value from a given Java variable.
193 * @see #getInt(Object, long)
194 */
195 @ForceInline
196 public Object getObject(Object o, long offset) {
197 return theInternalUnsafe.getReference(o, offset);
198 }
199
200 /**
201 * Stores a reference value into a given Java variable.
202 * <p>
203 * Unless the reference {@code x} being stored is either null
204 * or matches the field type, the results are undefined.
205 * If the reference {@code o} is non-null, card marks or
206 * other store barriers for that object (if the VM requires them)
207 * are updated.
208 * @see #putInt(Object, long, int)
209 */
210 @ForceInline
211 public void putObject(Object o, long offset, Object x) {
212 theInternalUnsafe.putReference(o, offset, x);
213 }
214
215 /** @see #getInt(Object, long) */
216 @ForceInline
217 public boolean getBoolean(Object o, long offset) {
218 return theInternalUnsafe.getBoolean(o, offset);
219 }
220
221 /** @see #putInt(Object, long, int) */
222 @ForceInline
223 public void putBoolean(Object o, long offset, boolean x) {
224 theInternalUnsafe.putBoolean(o, offset, x);
225 }
226
227 /** @see #getInt(Object, long) */
228 @ForceInline
229 public byte getByte(Object o, long offset) {
230 return theInternalUnsafe.getByte(o, offset);
231 }
232
233 /** @see #putInt(Object, long, int) */
234 @ForceInline
235 public void putByte(Object o, long offset, byte x) {
236 theInternalUnsafe.putByte(o, offset, x);
237 }
238
239 /** @see #getInt(Object, long) */
240 @ForceInline
241 public short getShort(Object o, long offset) {
242 return theInternalUnsafe.getShort(o, offset);
243 }
244
245 /** @see #putInt(Object, long, int) */
246 @ForceInline
247 public void putShort(Object o, long offset, short x) {
248 theInternalUnsafe.putShort(o, offset, x);
249 }
250
251 /** @see #getInt(Object, long) */
252 @ForceInline
253 public char getChar(Object o, long offset) {
254 return theInternalUnsafe.getChar(o, offset);
255 }
256
257 /** @see #putInt(Object, long, int) */
258 @ForceInline
259 public void putChar(Object o, long offset, char x) {
260 theInternalUnsafe.putChar(o, offset, x);
261 }
262
263 /** @see #getInt(Object, long) */
264 @ForceInline
265 public long getLong(Object o, long offset) {
266 return theInternalUnsafe.getLong(o, offset);
267 }
268
269 /** @see #putInt(Object, long, int) */
270 @ForceInline
271 public void putLong(Object o, long offset, long x) {
272 theInternalUnsafe.putLong(o, offset, x);
273 }
274
275 /** @see #getInt(Object, long) */
276 @ForceInline
277 public float getFloat(Object o, long offset) {
278 return theInternalUnsafe.getFloat(o, offset);
279 }
280
281 /** @see #putInt(Object, long, int) */
282 @ForceInline
283 public void putFloat(Object o, long offset, float x) {
284 theInternalUnsafe.putFloat(o, offset, x);
285 }
286
287 /** @see #getInt(Object, long) */
288 @ForceInline
289 public double getDouble(Object o, long offset) {
290 return theInternalUnsafe.getDouble(o, offset);
291 }
292
293 /** @see #putInt(Object, long, int) */
294 @ForceInline
295 public void putDouble(Object o, long offset, double x) {
296 theInternalUnsafe.putDouble(o, offset, x);
297 }
298
299 // These work on values in the C heap.
300
301 /**
302 * Fetches a value from a given memory address. If the address is zero, or
303 * does not point into a block obtained from {@link #allocateMemory}, the
304 * results are undefined.
305 *
306 * @see #allocateMemory
307 */
308 @ForceInline
309 public byte getByte(long address) {
310 return theInternalUnsafe.getByte(address);
311 }
312
313 /**
314 * Stores a value into a given memory address. If the address is zero, or
315 * does not point into a block obtained from {@link #allocateMemory}, the
316 * results are undefined.
317 *
318 * @see #getByte(long)
319 */
320 @ForceInline
321 public void putByte(long address, byte x) {
322 theInternalUnsafe.putByte(address, x);
323 }
324
325 /** @see #getByte(long) */
326 @ForceInline
327 public short getShort(long address) {
328 return theInternalUnsafe.getShort(address);
329 }
330
331 /** @see #putByte(long, byte) */
332 @ForceInline
333 public void putShort(long address, short x) {
334 theInternalUnsafe.putShort(address, x);
335 }
336
337 /** @see #getByte(long) */
338 @ForceInline
339 public char getChar(long address) {
340 return theInternalUnsafe.getChar(address);
341 }
342
343 /** @see #putByte(long, byte) */
344 @ForceInline
345 public void putChar(long address, char x) {
346 theInternalUnsafe.putChar(address, x);
347 }
348
349 /** @see #getByte(long) */
350 @ForceInline
351 public int getInt(long address) {
352 return theInternalUnsafe.getInt(address);
353 }
354
355 /** @see #putByte(long, byte) */
356 @ForceInline
357 public void putInt(long address, int x) {
358 theInternalUnsafe.putInt(address, x);
359 }
360
361 /** @see #getByte(long) */
362 @ForceInline
363 public long getLong(long address) {
364 return theInternalUnsafe.getLong(address);
365 }
366
367 /** @see #putByte(long, byte) */
368 @ForceInline
369 public void putLong(long address, long x) {
370 theInternalUnsafe.putLong(address, x);
371 }
372
373 /** @see #getByte(long) */
374 @ForceInline
375 public float getFloat(long address) {
376 return theInternalUnsafe.getFloat(address);
377 }
378
379 /** @see #putByte(long, byte) */
380 @ForceInline
381 public void putFloat(long address, float x) {
382 theInternalUnsafe.putFloat(address, x);
383 }
384
385 /** @see #getByte(long) */
386 @ForceInline
387 public double getDouble(long address) {
388 return theInternalUnsafe.getDouble(address);
389 }
390
391 /** @see #putByte(long, byte) */
392 @ForceInline
393 public void putDouble(long address, double x) {
394 theInternalUnsafe.putDouble(address, x);
395 }
396
397
398 /**
399 * Fetches a native pointer from a given memory address. If the address is
400 * zero, or does not point into a block obtained from {@link
401 * #allocateMemory}, the results are undefined.
402 *
403 * <p>If the native pointer is less than 64 bits wide, it is extended as
404 * an unsigned number to a Java long. The pointer may be indexed by any
405 * given byte offset, simply by adding that offset (as a simple integer) to
406 * the long representing the pointer. The number of bytes actually read
407 * from the target address may be determined by consulting {@link
408 * #addressSize}.
409 *
410 * @see #allocateMemory
411 */
412 @ForceInline
413 public long getAddress(long address) {
414 return theInternalUnsafe.getAddress(address);
415 }
416
417 /**
418 * Stores a native pointer into a given memory address. If the address is
419 * zero, or does not point into a block obtained from {@link
420 * #allocateMemory}, the results are undefined.
421 *
422 * <p>The number of bytes actually written at the target address may be
423 * determined by consulting {@link #addressSize}.
424 *
425 * @see #getAddress(long)
426 */
427 @ForceInline
428 public void putAddress(long address, long x) {
429 theInternalUnsafe.putAddress(address, x);
430 }
431
432
433 /// wrappers for malloc, realloc, free:
434
435 /**
436 * Allocates a new block of native memory, of the given size in bytes. The
437 * contents of the memory are uninitialized; they will generally be
438 * garbage. The resulting native pointer will be zero if and only if the
439 * requested size is zero. The resulting native pointer will be aligned for
440 * all value types. Dispose of this memory by calling {@link #freeMemory}
441 * or resize it with {@link #reallocateMemory}.
442 *
443 * <em>Note:</em> It is the responsibility of the caller to make
444 * sure arguments are checked before the methods are called. While
445 * some rudimentary checks are performed on the input, the checks
446 * are best effort and when performance is an overriding priority,
447 * as when methods of this class are optimized by the runtime
448 * compiler, some or all checks (if any) may be elided. Hence, the
449 * caller must not rely on the checks and corresponding
450 * exceptions!
451 *
452 * @throws RuntimeException if the size is negative or too large
453 * for the native size_t type
454 *
455 * @throws OutOfMemoryError if the allocation is refused by the system
456 *
457 * @see #getByte(long)
458 * @see #putByte(long, byte)
459 */
460 @ForceInline
461 public long allocateMemory(long bytes) {
462 return theInternalUnsafe.allocateMemory(bytes);
463 }
464
465 /**
466 * Resizes a new block of native memory, to the given size in bytes. The
467 * contents of the new block past the size of the old block are
468 * uninitialized; they will generally be garbage. The resulting native
469 * pointer will be zero if and only if the requested size is zero. The
470 * resulting native pointer will be aligned for all value types. Dispose
471 * of this memory by calling {@link #freeMemory}, or resize it with {@link
472 * #reallocateMemory}. The address passed to this method may be null, in
473 * which case an allocation will be performed.
474 *
475 * <em>Note:</em> It is the responsibility of the caller to make
476 * sure arguments are checked before the methods are called. While
477 * some rudimentary checks are performed on the input, the checks
478 * are best effort and when performance is an overriding priority,
479 * as when methods of this class are optimized by the runtime
480 * compiler, some or all checks (if any) may be elided. Hence, the
481 * caller must not rely on the checks and corresponding
482 * exceptions!
483 *
484 * @throws RuntimeException if the size is negative or too large
485 * for the native size_t type
486 *
487 * @throws OutOfMemoryError if the allocation is refused by the system
488 *
489 * @see #allocateMemory
490 */
491 @ForceInline
492 public long reallocateMemory(long address, long bytes) {
493 return theInternalUnsafe.reallocateMemory(address, bytes);
494 }
495
496 /**
497 * Sets all bytes in a given block of memory to a fixed value
498 * (usually zero).
499 *
500 * <p>This method determines a block's base address by means of two parameters,
501 * and so it provides (in effect) a <em>double-register</em> addressing mode,
502 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
503 * the offset supplies an absolute base address.
504 *
505 * <p>The stores are in coherent (atomic) units of a size determined
506 * by the address and length parameters. If the effective address and
507 * length are all even modulo 8, the stores take place in 'long' units.
508 * If the effective address and length are (resp.) even modulo 4 or 2,
509 * the stores take place in units of 'int' or 'short'.
510 *
511 * <em>Note:</em> It is the responsibility of the caller to make
512 * sure arguments are checked before the methods are called. While
513 * some rudimentary checks are performed on the input, the checks
514 * are best effort and when performance is an overriding priority,
515 * as when methods of this class are optimized by the runtime
516 * compiler, some or all checks (if any) may be elided. Hence, the
517 * caller must not rely on the checks and corresponding
518 * exceptions!
519 *
520 * @throws RuntimeException if any of the arguments is invalid
521 *
522 * @since 1.7
523 */
524 @ForceInline
525 public void setMemory(Object o, long offset, long bytes, byte value) {
526 theInternalUnsafe.setMemory(o, offset, bytes, value);
527 }
528
529 /**
530 * Sets all bytes in a given block of memory to a fixed value
531 * (usually zero). This provides a <em>single-register</em> addressing mode,
532 * as discussed in {@link #getInt(Object,long)}.
533 *
534 * <p>Equivalent to {@code setMemory(null, address, bytes, value)}.
535 */
536 @ForceInline
537 public void setMemory(long address, long bytes, byte value) {
538 theInternalUnsafe.setMemory(address, bytes, value);
539 }
540
541 /**
542 * Sets all bytes in a given block of memory to a copy of another
543 * block.
544 *
545 * <p>This method determines each block's base address by means of two parameters,
546 * and so it provides (in effect) a <em>double-register</em> addressing mode,
547 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
548 * the offset supplies an absolute base address.
549 *
550 * <p>The transfers are in coherent (atomic) units of a size determined
551 * by the address and length parameters. If the effective addresses and
552 * length are all even modulo 8, the transfer takes place in 'long' units.
553 * If the effective addresses and length are (resp.) even modulo 4 or 2,
554 * the transfer takes place in units of 'int' or 'short'.
555 *
556 * <em>Note:</em> It is the responsibility of the caller to make
557 * sure arguments are checked before the methods are called. While
558 * some rudimentary checks are performed on the input, the checks
559 * are best effort and when performance is an overriding priority,
560 * as when methods of this class are optimized by the runtime
561 * compiler, some or all checks (if any) may be elided. Hence, the
562 * caller must not rely on the checks and corresponding
563 * exceptions!
564 *
565 * @throws RuntimeException if any of the arguments is invalid
566 *
567 * @since 1.7
568 */
569 @ForceInline
570 public void copyMemory(Object srcBase, long srcOffset,
571 Object destBase, long destOffset,
572 long bytes) {
573 theInternalUnsafe.copyMemory(srcBase, srcOffset, destBase, destOffset, bytes);
574 }
575
576 /**
577 * Sets all bytes in a given block of memory to a copy of another
578 * block. This provides a <em>single-register</em> addressing mode,
579 * as discussed in {@link #getInt(Object,long)}.
580 *
581 * Equivalent to {@code copyMemory(null, srcAddress, null, destAddress, bytes)}.
582 */
583 @ForceInline
584 public void copyMemory(long srcAddress, long destAddress, long bytes) {
585 theInternalUnsafe.copyMemory(srcAddress, destAddress, bytes);
586 }
587
588 /**
589 * Disposes of a block of native memory, as obtained from {@link
590 * #allocateMemory} or {@link #reallocateMemory}. The address passed to
591 * this method may be null, in which case no action is taken.
592 *
593 * <em>Note:</em> It is the responsibility of the caller to make
594 * sure arguments are checked before the methods are called. While
595 * some rudimentary checks are performed on the input, the checks
596 * are best effort and when performance is an overriding priority,
597 * as when methods of this class are optimized by the runtime
598 * compiler, some or all checks (if any) may be elided. Hence, the
599 * caller must not rely on the checks and corresponding
600 * exceptions!
601 *
602 * @throws RuntimeException if any of the arguments is invalid
603 *
604 * @see #allocateMemory
605 */
606 @ForceInline
607 public void freeMemory(long address) {
608 theInternalUnsafe.freeMemory(address);
609 }
610
611 /// random queries
612
613 /**
614 * This constant differs from all results that will ever be returned from
615 * {@link #staticFieldOffset}, {@link #objectFieldOffset},
616 * or {@link #arrayBaseOffset}.
617 */
618 public static final int INVALID_FIELD_OFFSET = jdk.internal.misc.Unsafe.INVALID_FIELD_OFFSET;
619
620 /**
621 * Reports the location of a given field in the storage allocation of its
622 * class. Do not expect to perform any sort of arithmetic on this offset;
623 * it is just a cookie which is passed to the unsafe heap memory accessors.
624 *
625 * <p>Any given field will always have the same offset and base, and no
626 * two distinct fields of the same class will ever have the same offset
627 * and base.
628 *
629 * <p>As of 1.4.1, offsets for fields are represented as long values,
630 * although the Sun JVM does not use the most significant 32 bits.
631 * However, JVM implementations which store static fields at absolute
632 * addresses can use long offsets and null base pointers to express
633 * the field locations in a form usable by {@link #getInt(Object,long)}.
634 * Therefore, code which will be ported to such JVMs on 64-bit platforms
635 * must preserve all bits of static field offsets.
636 *
637 * @deprecated The guarantee that a field will always have the same offset
638 * and base may not be true in a future release. The ability to provide an
639 * offset and object reference to a heap memory accessor will be removed
640 * in a future release. Use {@link java.lang.invoke.VarHandle} instead.
641 *
642 * @see #getInt(Object, long)
643 */
644 @Deprecated(since="18")
645 @ForceInline
646 @SuppressWarnings("preview")
647 public long objectFieldOffset(Field f) {
648 if (f == null) {
649 throw new NullPointerException();
650 }
651 Class<?> declaringClass = f.getDeclaringClass();
652 if (declaringClass.isHidden()) {
653 throw new UnsupportedOperationException("can't get field offset on a hidden class: " + f);
654 }
655 if (declaringClass.isRecord()) {
656 throw new UnsupportedOperationException("can't get field offset on a record class: " + f);
657 }
658 if (declaringClass.isValue()) {
659 throw new UnsupportedOperationException("can't get field offset on a value class: " + f);
660 }
661 return theInternalUnsafe.objectFieldOffset(f);
662 }
663
664 /**
665 * Reports the location of a given static field, in conjunction with {@link
666 * #staticFieldBase}.
667 * <p>Do not expect to perform any sort of arithmetic on this offset;
668 * it is just a cookie which is passed to the unsafe heap memory accessors.
669 *
670 * <p>Any given field will always have the same offset, and no two distinct
671 * fields of the same class will ever have the same offset.
672 *
673 * <p>As of 1.4.1, offsets for fields are represented as long values,
674 * although the Sun JVM does not use the most significant 32 bits.
675 * It is hard to imagine a JVM technology which needs more than
676 * a few bits to encode an offset within a non-array object,
677 * However, for consistency with other methods in this class,
678 * this method reports its result as a long value.
679 *
680 * @deprecated The guarantee that a field will always have the same offset
681 * and base may not be true in a future release. The ability to provide an
682 * offset and object reference to a heap memory accessor will be removed
683 * in a future release. Use {@link java.lang.invoke.VarHandle} instead.
684 *
685 * @see #getInt(Object, long)
686 */
687 @Deprecated(since="18")
688 @ForceInline
689 @SuppressWarnings("preview")
690 public long staticFieldOffset(Field f) {
691 if (f == null) {
692 throw new NullPointerException();
693 }
694 Class<?> declaringClass = f.getDeclaringClass();
695 if (declaringClass.isHidden()) {
696 throw new UnsupportedOperationException("can't get field offset on a hidden class: " + f);
697 }
698 if (declaringClass.isRecord()) {
699 throw new UnsupportedOperationException("can't get field offset on a record class: " + f);
700 }
701 if (declaringClass.isValue()) {
702 throw new UnsupportedOperationException("can't get field offset on a value class: " + f);
703 }
704 return theInternalUnsafe.staticFieldOffset(f);
705 }
706
707 /**
708 * Reports the location of a given static field, in conjunction with {@link
709 * #staticFieldOffset}.
710 * <p>Fetch the base "Object", if any, with which static fields of the
711 * given class can be accessed via methods like {@link #getInt(Object,
712 * long)}. This value may be null. This value may refer to an object
713 * which is a "cookie", not guaranteed to be a real Object, and it should
714 * not be used in any way except as argument to the get and put routines in
715 * this class.
716 *
717 * @deprecated The guarantee that a field will always have the same offset
718 * and base may not be true in a future release. The ability to provide an
719 * offset and object reference to a heap memory accessor will be removed
720 * in a future release. Use {@link java.lang.invoke.VarHandle} instead.
721 */
722 @Deprecated(since="18")
723 @ForceInline
724 @SuppressWarnings("preview")
725 public Object staticFieldBase(Field f) {
726 if (f == null) {
727 throw new NullPointerException();
728 }
729 Class<?> declaringClass = f.getDeclaringClass();
730 if (declaringClass.isHidden()) {
731 throw new UnsupportedOperationException("can't get base address on a hidden class: " + f);
732 }
733 if (declaringClass.isRecord()) {
734 throw new UnsupportedOperationException("can't get base address on a record class: " + f);
735 }
736 if (declaringClass.isValue()) {
737 throw new UnsupportedOperationException("can't get field offset on a value class: " + f);
738 }
739 return theInternalUnsafe.staticFieldBase(f);
740 }
741
742 /**
743 * Reports the offset of the first element in the storage allocation of a
744 * given array class. If {@link #arrayIndexScale} returns a non-zero value
745 * for the same class, you may use that scale factor, together with this
746 * base offset, to form new offsets to access elements of arrays of the
747 * given class.
748 *
749 * @see #getInt(Object, long)
750 * @see #putInt(Object, long, int)
751 */
752 @ForceInline
753 public int arrayBaseOffset(Class<?> arrayClass) {
754 return theInternalUnsafe.arrayBaseOffset(arrayClass);
755 }
756
757 /** The value of {@code arrayBaseOffset(boolean[].class)} */
758 public static final int ARRAY_BOOLEAN_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_BOOLEAN_BASE_OFFSET;
759
760 /** The value of {@code arrayBaseOffset(byte[].class)} */
761 public static final int ARRAY_BYTE_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_BYTE_BASE_OFFSET;
762
763 /** The value of {@code arrayBaseOffset(short[].class)} */
764 public static final int ARRAY_SHORT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_SHORT_BASE_OFFSET;
765
766 /** The value of {@code arrayBaseOffset(char[].class)} */
767 public static final int ARRAY_CHAR_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_CHAR_BASE_OFFSET;
768
769 /** The value of {@code arrayBaseOffset(int[].class)} */
770 public static final int ARRAY_INT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_INT_BASE_OFFSET;
771
772 /** The value of {@code arrayBaseOffset(long[].class)} */
773 public static final int ARRAY_LONG_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_LONG_BASE_OFFSET;
774
775 /** The value of {@code arrayBaseOffset(float[].class)} */
776 public static final int ARRAY_FLOAT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_FLOAT_BASE_OFFSET;
777
778 /** The value of {@code arrayBaseOffset(double[].class)} */
779 public static final int ARRAY_DOUBLE_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_DOUBLE_BASE_OFFSET;
780
781 /** The value of {@code arrayBaseOffset(Object[].class)} */
782 public static final int ARRAY_OBJECT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_OBJECT_BASE_OFFSET;
783
784 /**
785 * Reports the scale factor for addressing elements in the storage
786 * allocation of a given array class. However, arrays of "narrow" types
787 * will generally not work properly with accessors like {@link
788 * #getByte(Object, long)}, so the scale factor for such classes is reported
789 * as zero.
790 *
791 * @see #arrayBaseOffset
792 * @see #getInt(Object, long)
793 * @see #putInt(Object, long, int)
794 */
795 @ForceInline
796 public int arrayIndexScale(Class<?> arrayClass) {
797 return theInternalUnsafe.arrayIndexScale(arrayClass);
798 }
799
800 /** The value of {@code arrayIndexScale(boolean[].class)} */
801 public static final int ARRAY_BOOLEAN_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_BOOLEAN_INDEX_SCALE;
802
803 /** The value of {@code arrayIndexScale(byte[].class)} */
804 public static final int ARRAY_BYTE_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_BYTE_INDEX_SCALE;
805
806 /** The value of {@code arrayIndexScale(short[].class)} */
807 public static final int ARRAY_SHORT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_SHORT_INDEX_SCALE;
808
809 /** The value of {@code arrayIndexScale(char[].class)} */
810 public static final int ARRAY_CHAR_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_CHAR_INDEX_SCALE;
811
812 /** The value of {@code arrayIndexScale(int[].class)} */
813 public static final int ARRAY_INT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_INT_INDEX_SCALE;
814
815 /** The value of {@code arrayIndexScale(long[].class)} */
816 public static final int ARRAY_LONG_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_LONG_INDEX_SCALE;
817
818 /** The value of {@code arrayIndexScale(float[].class)} */
819 public static final int ARRAY_FLOAT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_FLOAT_INDEX_SCALE;
820
821 /** The value of {@code arrayIndexScale(double[].class)} */
822 public static final int ARRAY_DOUBLE_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_DOUBLE_INDEX_SCALE;
823
824 /** The value of {@code arrayIndexScale(Object[].class)} */
825 public static final int ARRAY_OBJECT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_OBJECT_INDEX_SCALE;
826
827 /**
828 * Reports the size in bytes of a native pointer, as stored via {@link
829 * #putAddress}. This value will be either 4 or 8. Note that the sizes of
830 * other primitive types (as stored in native memory blocks) is determined
831 * fully by their information content.
832 */
833 @ForceInline
834 public int addressSize() {
835 return theInternalUnsafe.addressSize();
836 }
837
838 /** The value of {@code addressSize()} */
839 public static final int ADDRESS_SIZE = theInternalUnsafe.addressSize();
840
841 /**
842 * Reports the size in bytes of a native memory page (whatever that is).
843 * This value will always be a power of two.
844 */
845 @ForceInline
846 public int pageSize() {
847 return theInternalUnsafe.pageSize();
848 }
849
850
851 /// random trusted operations from JNI:
852
853 /**
854 * Allocates an instance but does not run any constructor.
855 * Initializes the class if it has not yet been.
856 */
857 @ForceInline
858 public Object allocateInstance(Class<?> cls)
859 throws InstantiationException {
860 return theInternalUnsafe.allocateInstance(cls);
861 }
862
863 /** Throws the exception without telling the verifier. */
864 @ForceInline
865 public void throwException(Throwable ee) {
866 theInternalUnsafe.throwException(ee);
867 }
868
869 /**
870 * Atomically updates Java variable to {@code x} if it is currently
871 * holding {@code expected}.
872 *
873 * <p>This operation has memory semantics of a {@code volatile} read
874 * and write. Corresponds to C11 atomic_compare_exchange_strong.
875 *
876 * @return {@code true} if successful
877 */
878 @ForceInline
879 public final boolean compareAndSwapObject(Object o, long offset,
880 Object expected,
881 Object x) {
882 return theInternalUnsafe.compareAndSetReference(o, offset, expected, x);
883 }
884
885 /**
886 * Atomically updates Java variable to {@code x} if it is currently
887 * holding {@code expected}.
888 *
889 * <p>This operation has memory semantics of a {@code volatile} read
890 * and write. Corresponds to C11 atomic_compare_exchange_strong.
891 *
892 * @return {@code true} if successful
893 */
894 @ForceInline
895 public final boolean compareAndSwapInt(Object o, long offset,
896 int expected,
897 int x) {
898 return theInternalUnsafe.compareAndSetInt(o, offset, expected, x);
899 }
900
901 /**
902 * Atomically updates Java variable to {@code x} if it is currently
903 * holding {@code expected}.
904 *
905 * <p>This operation has memory semantics of a {@code volatile} read
906 * and write. Corresponds to C11 atomic_compare_exchange_strong.
907 *
908 * @return {@code true} if successful
909 */
910 @ForceInline
911 public final boolean compareAndSwapLong(Object o, long offset,
912 long expected,
913 long x) {
914 return theInternalUnsafe.compareAndSetLong(o, offset, expected, x);
915 }
916
917 /**
918 * Fetches a reference value from a given Java variable, with volatile
919 * load semantics. Otherwise identical to {@link #getObject(Object, long)}
920 */
921 @ForceInline
922 public Object getObjectVolatile(Object o, long offset) {
923 return theInternalUnsafe.getReferenceVolatile(o, offset);
924 }
925
926 /**
927 * Stores a reference value into a given Java variable, with
928 * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)}
929 */
930 @ForceInline
931 public void putObjectVolatile(Object o, long offset, Object x) {
932 theInternalUnsafe.putReferenceVolatile(o, offset, x);
933 }
934
935 /** Volatile version of {@link #getInt(Object, long)} */
936 @ForceInline
937 public int getIntVolatile(Object o, long offset) {
938 return theInternalUnsafe.getIntVolatile(o, offset);
939 }
940
941 /** Volatile version of {@link #putInt(Object, long, int)} */
942 @ForceInline
943 public void putIntVolatile(Object o, long offset, int x) {
944 theInternalUnsafe.putIntVolatile(o, offset, x);
945 }
946
947 /** Volatile version of {@link #getBoolean(Object, long)} */
948 @ForceInline
949 public boolean getBooleanVolatile(Object o, long offset) {
950 return theInternalUnsafe.getBooleanVolatile(o, offset);
951 }
952
953 /** Volatile version of {@link #putBoolean(Object, long, boolean)} */
954 @ForceInline
955 public void putBooleanVolatile(Object o, long offset, boolean x) {
956 theInternalUnsafe.putBooleanVolatile(o, offset, x);
957 }
958
959 /** Volatile version of {@link #getByte(Object, long)} */
960 @ForceInline
961 public byte getByteVolatile(Object o, long offset) {
962 return theInternalUnsafe.getByteVolatile(o, offset);
963 }
964
965 /** Volatile version of {@link #putByte(Object, long, byte)} */
966 @ForceInline
967 public void putByteVolatile(Object o, long offset, byte x) {
968 theInternalUnsafe.putByteVolatile(o, offset, x);
969 }
970
971 /** Volatile version of {@link #getShort(Object, long)} */
972 @ForceInline
973 public short getShortVolatile(Object o, long offset) {
974 return theInternalUnsafe.getShortVolatile(o, offset);
975 }
976
977 /** Volatile version of {@link #putShort(Object, long, short)} */
978 @ForceInline
979 public void putShortVolatile(Object o, long offset, short x) {
980 theInternalUnsafe.putShortVolatile(o, offset, x);
981 }
982
983 /** Volatile version of {@link #getChar(Object, long)} */
984 @ForceInline
985 public char getCharVolatile(Object o, long offset) {
986 return theInternalUnsafe.getCharVolatile(o, offset);
987 }
988
989 /** Volatile version of {@link #putChar(Object, long, char)} */
990 @ForceInline
991 public void putCharVolatile(Object o, long offset, char x) {
992 theInternalUnsafe.putCharVolatile(o, offset, x);
993 }
994
995 /** Volatile version of {@link #getLong(Object, long)} */
996 @ForceInline
997 public long getLongVolatile(Object o, long offset) {
998 return theInternalUnsafe.getLongVolatile(o, offset);
999 }
1000
1001 /** Volatile version of {@link #putLong(Object, long, long)} */
1002 @ForceInline
1003 public void putLongVolatile(Object o, long offset, long x) {
1004 theInternalUnsafe.putLongVolatile(o, offset, x);
1005 }
1006
1007 /** Volatile version of {@link #getFloat(Object, long)} */
1008 @ForceInline
1009 public float getFloatVolatile(Object o, long offset) {
1010 return theInternalUnsafe.getFloatVolatile(o, offset);
1011 }
1012
1013 /** Volatile version of {@link #putFloat(Object, long, float)} */
1014 @ForceInline
1015 public void putFloatVolatile(Object o, long offset, float x) {
1016 theInternalUnsafe.putFloatVolatile(o, offset, x);
1017 }
1018
1019 /** Volatile version of {@link #getDouble(Object, long)} */
1020 @ForceInline
1021 public double getDoubleVolatile(Object o, long offset) {
1022 return theInternalUnsafe.getDoubleVolatile(o, offset);
1023 }
1024
1025 /** Volatile version of {@link #putDouble(Object, long, double)} */
1026 @ForceInline
1027 public void putDoubleVolatile(Object o, long offset, double x) {
1028 theInternalUnsafe.putDoubleVolatile(o, offset, x);
1029 }
1030
1031 /**
1032 * Version of {@link #putObjectVolatile(Object, long, Object)}
1033 * that does not guarantee immediate visibility of the store to
1034 * other threads. This method is generally only useful if the
1035 * underlying field is a Java volatile (or if an array cell, one
1036 * that is otherwise only accessed using volatile accesses).
1037 *
1038 * Corresponds to C11 atomic_store_explicit(..., memory_order_release).
1039 */
1040 @ForceInline
1041 public void putOrderedObject(Object o, long offset, Object x) {
1042 theInternalUnsafe.putReferenceRelease(o, offset, x);
1043 }
1044
1045 /** Ordered/Lazy version of {@link #putIntVolatile(Object, long, int)} */
1046 @ForceInline
1047 public void putOrderedInt(Object o, long offset, int x) {
1048 theInternalUnsafe.putIntRelease(o, offset, x);
1049 }
1050
1051 /** Ordered/Lazy version of {@link #putLongVolatile(Object, long, long)} */
1052 @ForceInline
1053 public void putOrderedLong(Object o, long offset, long x) {
1054 theInternalUnsafe.putLongRelease(o, offset, x);
1055 }
1056
1057 /**
1058 * Unblocks the given thread blocked on {@code park}, or, if it is
1059 * not blocked, causes the subsequent call to {@code park} not to
1060 * block. Note: this operation is "unsafe" solely because the
1061 * caller must somehow ensure that the thread has not been
1062 * destroyed. Nothing special is usually required to ensure this
1063 * when called from Java (in which there will ordinarily be a live
1064 * reference to the thread) but this is not nearly-automatically
1065 * so when calling from native code.
1066 *
1067 * @param thread the thread to unpark.
1068 *
1069 * @deprecated Use {@link java.util.concurrent.locks.LockSupport#unpark(Thread)} instead.
1070 */
1071 @Deprecated(since="22", forRemoval=true)
1072 @ForceInline
1073 public void unpark(Object thread) {
1074 theInternalUnsafe.unpark(thread);
1075 }
1076
1077 /**
1078 * Blocks current thread, returning when a balancing
1079 * {@code unpark} occurs, or a balancing {@code unpark} has
1080 * already occurred, or the thread is interrupted, or, if not
1081 * absolute and time is not zero, the given time nanoseconds have
1082 * elapsed, or if absolute, the given deadline in milliseconds
1083 * since Epoch has passed, or spuriously (i.e., returning for no
1084 * "reason"). Note: This operation is in the Unsafe class only
1085 * because {@code unpark} is, so it would be strange to place it
1086 * elsewhere.
1087 *
1088 * @deprecated Use {@link java.util.concurrent.locks.LockSupport#parkNanos(long)} or
1089 * {@link java.util.concurrent.locks.LockSupport#parkUntil(long)} instead.
1090 */
1091 @Deprecated(since="22", forRemoval=true)
1092 @ForceInline
1093 public void park(boolean isAbsolute, long time) {
1094 theInternalUnsafe.park(isAbsolute, time);
1095 }
1096
1097 /**
1098 * Gets the load average in the system run queue assigned
1099 * to the available processors averaged over various periods of time.
1100 * This method retrieves the given {@code nelem} samples and
1101 * assigns to the elements of the given {@code loadavg} array.
1102 * The system imposes a maximum of 3 samples, representing
1103 * averages over the last 1, 5, and 15 minutes, respectively.
1104 *
1105 * @param loadavg an array of double of size nelems
1106 * @param nelems the number of samples to be retrieved and
1107 * must be 1 to 3.
1108 *
1109 * @return the number of samples actually retrieved; or -1
1110 * if the load average is unobtainable.
1111 *
1112 * @deprecated Use {@link java.lang.management.OperatingSystemMXBean#getSystemLoadAverage()}
1113 * instead.
1114 */
1115 @Deprecated(since="22", forRemoval=true)
1116 @ForceInline
1117 public int getLoadAverage(double[] loadavg, int nelems) {
1118 return theInternalUnsafe.getLoadAverage(loadavg, nelems);
1119 }
1120
1121 // The following contain CAS-based Java implementations used on
1122 // platforms not supporting native instructions
1123
1124 /**
1125 * Atomically adds the given value to the current value of a field
1126 * or array element within the given object {@code o}
1127 * at the given {@code offset}.
1128 *
1129 * @param o object/array to update the field/element in
1130 * @param offset field/element offset
1131 * @param delta the value to add
1132 * @return the previous value
1133 * @since 1.8
1134 */
1135 @ForceInline
1136 public final int getAndAddInt(Object o, long offset, int delta) {
1137 return theInternalUnsafe.getAndAddInt(o, offset, delta);
1138 }
1139
1140 /**
1141 * Atomically adds the given value to the current value of a field
1142 * or array element within the given object {@code o}
1143 * at the given {@code offset}.
1144 *
1145 * @param o object/array to update the field/element in
1146 * @param offset field/element offset
1147 * @param delta the value to add
1148 * @return the previous value
1149 * @since 1.8
1150 */
1151 @ForceInline
1152 public final long getAndAddLong(Object o, long offset, long delta) {
1153 return theInternalUnsafe.getAndAddLong(o, offset, delta);
1154 }
1155
1156 /**
1157 * Atomically exchanges the given value with the current value of
1158 * a field or array element within the given object {@code o}
1159 * at the given {@code offset}.
1160 *
1161 * @param o object/array to update the field/element in
1162 * @param offset field/element offset
1163 * @param newValue new value
1164 * @return the previous value
1165 * @since 1.8
1166 */
1167 @ForceInline
1168 public final int getAndSetInt(Object o, long offset, int newValue) {
1169 return theInternalUnsafe.getAndSetInt(o, offset, newValue);
1170 }
1171
1172 /**
1173 * Atomically exchanges the given value with the current value of
1174 * a field or array element within the given object {@code o}
1175 * at the given {@code offset}.
1176 *
1177 * @param o object/array to update the field/element in
1178 * @param offset field/element offset
1179 * @param newValue new value
1180 * @return the previous value
1181 * @since 1.8
1182 */
1183 @ForceInline
1184 public final long getAndSetLong(Object o, long offset, long newValue) {
1185 return theInternalUnsafe.getAndSetLong(o, offset, newValue);
1186 }
1187
1188 /**
1189 * Atomically exchanges the given reference value with the current
1190 * reference value of a field or array element within the given
1191 * object {@code o} at the given {@code offset}.
1192 *
1193 * @param o object/array to update the field/element in
1194 * @param offset field/element offset
1195 * @param newValue new value
1196 * @return the previous value
1197 * @since 1.8
1198 */
1199 @ForceInline
1200 public final Object getAndSetObject(Object o, long offset, Object newValue) {
1201 return theInternalUnsafe.getAndSetReference(o, offset, newValue);
1202 }
1203
1204 /**
1205 * Ensures that loads before the fence will not be reordered with loads and
1206 * stores after the fence; a "LoadLoad plus LoadStore barrier".
1207 *
1208 * Corresponds to C11 atomic_thread_fence(memory_order_acquire)
1209 * (an "acquire fence").
1210 *
1211 * A pure LoadLoad fence is not provided, since the addition of LoadStore
1212 * is almost always desired, and most current hardware instructions that
1213 * provide a LoadLoad barrier also provide a LoadStore barrier for free.
1214 *
1215 * @deprecated Use {@link java.lang.invoke.VarHandle#acquireFence()} instead.
1216 * @since 1.8
1217 */
1218 @Deprecated(since="22", forRemoval=true)
1219 @ForceInline
1220 public void loadFence() {
1221 theInternalUnsafe.loadFence();
1222 }
1223
1224 /**
1225 * Ensures that loads and stores before the fence will not be reordered with
1226 * stores after the fence; a "StoreStore plus LoadStore barrier".
1227 *
1228 * Corresponds to C11 atomic_thread_fence(memory_order_release)
1229 * (a "release fence").
1230 *
1231 * A pure StoreStore fence is not provided, since the addition of LoadStore
1232 * is almost always desired, and most current hardware instructions that
1233 * provide a StoreStore barrier also provide a LoadStore barrier for free.
1234 *
1235 * @deprecated Use {@link java.lang.invoke.VarHandle#releaseFence()} instead.
1236 * @since 1.8
1237 */
1238 @Deprecated(since="22", forRemoval=true)
1239 @ForceInline
1240 public void storeFence() {
1241 theInternalUnsafe.storeFence();
1242 }
1243
1244 /**
1245 * Ensures that loads and stores before the fence will not be reordered
1246 * with loads and stores after the fence. Implies the effects of both
1247 * loadFence() and storeFence(), and in addition, the effect of a StoreLoad
1248 * barrier.
1249 *
1250 * Corresponds to C11 atomic_thread_fence(memory_order_seq_cst).
1251 *
1252 * @deprecated Use {@link java.lang.invoke.VarHandle#fullFence()} instead.
1253 * @since 1.8
1254 */
1255 @Deprecated(since="22", forRemoval=true)
1256 @ForceInline
1257 public void fullFence() {
1258 theInternalUnsafe.fullFence();
1259 }
1260
1261 /**
1262 * Invokes the given direct byte buffer's cleaner, if any.
1263 *
1264 * @param directBuffer a direct byte buffer
1265 * @throws NullPointerException if {@code directBuffer} is null
1266 * @throws IllegalArgumentException if {@code directBuffer} is non-direct,
1267 * or is a {@link java.nio.Buffer#slice slice}, or is a
1268 * {@link java.nio.Buffer#duplicate duplicate}
1269 * @since 9
1270 */
1271 public void invokeCleaner(java.nio.ByteBuffer directBuffer) {
1272 if (!directBuffer.isDirect())
1273 throw new IllegalArgumentException("buffer is non-direct");
1274
1275 theInternalUnsafe.invokeCleaner(directBuffer);
1276 }
1277 }