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