1 /*
2 * Copyright (c) 2000, 2023, 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 never be zero, and will be
440 * aligned for all value types. Dispose of this memory by calling {@link
441 * #freeMemory}, 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 public long objectFieldOffset(Field f) {
647 if (f == null) {
648 throw new NullPointerException();
649 }
650 Class<?> declaringClass = f.getDeclaringClass();
651 if (declaringClass.isHidden()) {
652 throw new UnsupportedOperationException("can't get field offset on a hidden class: " + f);
653 }
654 if (declaringClass.isRecord()) {
655 throw new UnsupportedOperationException("can't get field offset on a record class: " + f);
656 }
657 return theInternalUnsafe.objectFieldOffset(f);
658 }
659
660 /**
661 * Reports the location of a given static field, in conjunction with {@link
662 * #staticFieldBase}.
663 * <p>Do not expect to perform any sort of arithmetic on this offset;
664 * it is just a cookie which is passed to the unsafe heap memory accessors.
665 *
666 * <p>Any given field will always have the same offset, and no two distinct
667 * fields of the same class will ever have the same offset.
668 *
669 * <p>As of 1.4.1, offsets for fields are represented as long values,
670 * although the Sun JVM does not use the most significant 32 bits.
671 * It is hard to imagine a JVM technology which needs more than
672 * a few bits to encode an offset within a non-array object,
673 * However, for consistency with other methods in this class,
674 * this method reports its result as a long value.
675 *
676 * @deprecated The guarantee that a field will always have the same offset
677 * and base may not be true in a future release. The ability to provide an
678 * offset and object reference to a heap memory accessor will be removed
679 * in a future release. Use {@link java.lang.invoke.VarHandle} instead.
680 *
681 * @see #getInt(Object, long)
682 */
683 @Deprecated(since="18")
684 @ForceInline
685 public long staticFieldOffset(Field f) {
686 if (f == null) {
687 throw new NullPointerException();
688 }
689 Class<?> declaringClass = f.getDeclaringClass();
690 if (declaringClass.isHidden()) {
691 throw new UnsupportedOperationException("can't get field offset on a hidden class: " + f);
692 }
693 if (declaringClass.isRecord()) {
694 throw new UnsupportedOperationException("can't get field offset on a record class: " + f);
695 }
696 return theInternalUnsafe.staticFieldOffset(f);
697 }
698
699 /**
700 * Reports the location of a given static field, in conjunction with {@link
701 * #staticFieldOffset}.
702 * <p>Fetch the base "Object", if any, with which static fields of the
703 * given class can be accessed via methods like {@link #getInt(Object,
704 * long)}. This value may be null. This value may refer to an object
705 * which is a "cookie", not guaranteed to be a real Object, and it should
706 * not be used in any way except as argument to the get and put routines in
707 * this class.
708 *
709 * @deprecated The guarantee that a field will always have the same offset
710 * and base may not be true in a future release. The ability to provide an
711 * offset and object reference to a heap memory accessor will be removed
712 * in a future release. Use {@link java.lang.invoke.VarHandle} instead.
713 */
714 @Deprecated(since="18")
715 @ForceInline
716 public Object staticFieldBase(Field f) {
717 if (f == null) {
718 throw new NullPointerException();
719 }
720 Class<?> declaringClass = f.getDeclaringClass();
721 if (declaringClass.isHidden()) {
722 throw new UnsupportedOperationException("can't get base address on a hidden class: " + f);
723 }
724 if (declaringClass.isRecord()) {
725 throw new UnsupportedOperationException("can't get base address on a record class: " + f);
726 }
727 return theInternalUnsafe.staticFieldBase(f);
728 }
729
730 /**
731 * Reports the offset of the first element in the storage allocation of a
732 * given array class. If {@link #arrayIndexScale} returns a non-zero value
733 * for the same class, you may use that scale factor, together with this
734 * base offset, to form new offsets to access elements of arrays of the
735 * given class.
736 *
737 * @see #getInt(Object, long)
738 * @see #putInt(Object, long, int)
739 */
740 @ForceInline
741 public int arrayBaseOffset(Class<?> arrayClass) {
742 return theInternalUnsafe.arrayBaseOffset(arrayClass);
743 }
744
745 /** The value of {@code arrayBaseOffset(boolean[].class)} */
746 public static final int ARRAY_BOOLEAN_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_BOOLEAN_BASE_OFFSET;
747
748 /** The value of {@code arrayBaseOffset(byte[].class)} */
749 public static final int ARRAY_BYTE_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_BYTE_BASE_OFFSET;
750
751 /** The value of {@code arrayBaseOffset(short[].class)} */
752 public static final int ARRAY_SHORT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_SHORT_BASE_OFFSET;
753
754 /** The value of {@code arrayBaseOffset(char[].class)} */
755 public static final int ARRAY_CHAR_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_CHAR_BASE_OFFSET;
756
757 /** The value of {@code arrayBaseOffset(int[].class)} */
758 public static final int ARRAY_INT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_INT_BASE_OFFSET;
759
760 /** The value of {@code arrayBaseOffset(long[].class)} */
761 public static final int ARRAY_LONG_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_LONG_BASE_OFFSET;
762
763 /** The value of {@code arrayBaseOffset(float[].class)} */
764 public static final int ARRAY_FLOAT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_FLOAT_BASE_OFFSET;
765
766 /** The value of {@code arrayBaseOffset(double[].class)} */
767 public static final int ARRAY_DOUBLE_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_DOUBLE_BASE_OFFSET;
768
769 /** The value of {@code arrayBaseOffset(Object[].class)} */
770 public static final int ARRAY_OBJECT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_OBJECT_BASE_OFFSET;
771
772 /**
773 * Reports the scale factor for addressing elements in the storage
774 * allocation of a given array class. However, arrays of "narrow" types
775 * will generally not work properly with accessors like {@link
776 * #getByte(Object, long)}, so the scale factor for such classes is reported
777 * as zero.
778 *
779 * @see #arrayBaseOffset
780 * @see #getInt(Object, long)
781 * @see #putInt(Object, long, int)
782 */
783 @ForceInline
784 public int arrayIndexScale(Class<?> arrayClass) {
785 return theInternalUnsafe.arrayIndexScale(arrayClass);
786 }
787
788 /** The value of {@code arrayIndexScale(boolean[].class)} */
789 public static final int ARRAY_BOOLEAN_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_BOOLEAN_INDEX_SCALE;
790
791 /** The value of {@code arrayIndexScale(byte[].class)} */
792 public static final int ARRAY_BYTE_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_BYTE_INDEX_SCALE;
793
794 /** The value of {@code arrayIndexScale(short[].class)} */
795 public static final int ARRAY_SHORT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_SHORT_INDEX_SCALE;
796
797 /** The value of {@code arrayIndexScale(char[].class)} */
798 public static final int ARRAY_CHAR_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_CHAR_INDEX_SCALE;
799
800 /** The value of {@code arrayIndexScale(int[].class)} */
801 public static final int ARRAY_INT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_INT_INDEX_SCALE;
802
803 /** The value of {@code arrayIndexScale(long[].class)} */
804 public static final int ARRAY_LONG_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_LONG_INDEX_SCALE;
805
806 /** The value of {@code arrayIndexScale(float[].class)} */
807 public static final int ARRAY_FLOAT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_FLOAT_INDEX_SCALE;
808
809 /** The value of {@code arrayIndexScale(double[].class)} */
810 public static final int ARRAY_DOUBLE_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_DOUBLE_INDEX_SCALE;
811
812 /** The value of {@code arrayIndexScale(Object[].class)} */
813 public static final int ARRAY_OBJECT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_OBJECT_INDEX_SCALE;
814
815 /**
816 * Reports the size in bytes of a native pointer, as stored via {@link
817 * #putAddress}. This value will be either 4 or 8. Note that the sizes of
818 * other primitive types (as stored in native memory blocks) is determined
819 * fully by their information content.
820 */
821 @ForceInline
822 public int addressSize() {
823 return theInternalUnsafe.addressSize();
824 }
825
826 /** The value of {@code addressSize()} */
827 public static final int ADDRESS_SIZE = theInternalUnsafe.addressSize();
828
829 /**
830 * Reports the size in bytes of a native memory page (whatever that is).
831 * This value will always be a power of two.
832 */
833 @ForceInline
834 public int pageSize() {
835 return theInternalUnsafe.pageSize();
836 }
837
838
839 /// random trusted operations from JNI:
840
841 /**
842 * Allocates an instance but does not run any constructor.
843 * Initializes the class if it has not yet been.
844 */
845 @ForceInline
846 public Object allocateInstance(Class<?> cls)
847 throws InstantiationException {
848 return theInternalUnsafe.allocateInstance(cls);
849 }
850
851 /** Throws the exception without telling the verifier. */
852 @ForceInline
853 public void throwException(Throwable ee) {
854 theInternalUnsafe.throwException(ee);
855 }
856
857 /**
858 * Atomically updates Java variable to {@code x} if it is currently
859 * holding {@code expected}.
860 *
861 * <p>This operation has memory semantics of a {@code volatile} read
862 * and write. Corresponds to C11 atomic_compare_exchange_strong.
863 *
864 * @return {@code true} if successful
865 */
866 @ForceInline
867 public final boolean compareAndSwapObject(Object o, long offset,
868 Object expected,
869 Object x) {
870 return theInternalUnsafe.compareAndSetReference(o, offset, expected, x);
871 }
872
873 /**
874 * Atomically updates Java variable to {@code x} if it is currently
875 * holding {@code expected}.
876 *
877 * <p>This operation has memory semantics of a {@code volatile} read
878 * and write. Corresponds to C11 atomic_compare_exchange_strong.
879 *
880 * @return {@code true} if successful
881 */
882 @ForceInline
883 public final boolean compareAndSwapInt(Object o, long offset,
884 int expected,
885 int x) {
886 return theInternalUnsafe.compareAndSetInt(o, offset, expected, x);
887 }
888
889 /**
890 * Atomically updates Java variable to {@code x} if it is currently
891 * holding {@code expected}.
892 *
893 * <p>This operation has memory semantics of a {@code volatile} read
894 * and write. Corresponds to C11 atomic_compare_exchange_strong.
895 *
896 * @return {@code true} if successful
897 */
898 @ForceInline
899 public final boolean compareAndSwapLong(Object o, long offset,
900 long expected,
901 long x) {
902 return theInternalUnsafe.compareAndSetLong(o, offset, expected, x);
903 }
904
905 /**
906 * Fetches a reference value from a given Java variable, with volatile
907 * load semantics. Otherwise identical to {@link #getObject(Object, long)}
908 */
909 @ForceInline
910 public Object getObjectVolatile(Object o, long offset) {
911 return theInternalUnsafe.getReferenceVolatile(o, offset);
912 }
913
914 /**
915 * Stores a reference value into a given Java variable, with
916 * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)}
917 */
918 @ForceInline
919 public void putObjectVolatile(Object o, long offset, Object x) {
920 theInternalUnsafe.putReferenceVolatile(o, offset, x);
921 }
922
923 /** Volatile version of {@link #getInt(Object, long)} */
924 @ForceInline
925 public int getIntVolatile(Object o, long offset) {
926 return theInternalUnsafe.getIntVolatile(o, offset);
927 }
928
929 /** Volatile version of {@link #putInt(Object, long, int)} */
930 @ForceInline
931 public void putIntVolatile(Object o, long offset, int x) {
932 theInternalUnsafe.putIntVolatile(o, offset, x);
933 }
934
935 /** Volatile version of {@link #getBoolean(Object, long)} */
936 @ForceInline
937 public boolean getBooleanVolatile(Object o, long offset) {
938 return theInternalUnsafe.getBooleanVolatile(o, offset);
939 }
940
941 /** Volatile version of {@link #putBoolean(Object, long, boolean)} */
942 @ForceInline
943 public void putBooleanVolatile(Object o, long offset, boolean x) {
944 theInternalUnsafe.putBooleanVolatile(o, offset, x);
945 }
946
947 /** Volatile version of {@link #getByte(Object, long)} */
948 @ForceInline
949 public byte getByteVolatile(Object o, long offset) {
950 return theInternalUnsafe.getByteVolatile(o, offset);
951 }
952
953 /** Volatile version of {@link #putByte(Object, long, byte)} */
954 @ForceInline
955 public void putByteVolatile(Object o, long offset, byte x) {
956 theInternalUnsafe.putByteVolatile(o, offset, x);
957 }
958
959 /** Volatile version of {@link #getShort(Object, long)} */
960 @ForceInline
961 public short getShortVolatile(Object o, long offset) {
962 return theInternalUnsafe.getShortVolatile(o, offset);
963 }
964
965 /** Volatile version of {@link #putShort(Object, long, short)} */
966 @ForceInline
967 public void putShortVolatile(Object o, long offset, short x) {
968 theInternalUnsafe.putShortVolatile(o, offset, x);
969 }
970
971 /** Volatile version of {@link #getChar(Object, long)} */
972 @ForceInline
973 public char getCharVolatile(Object o, long offset) {
974 return theInternalUnsafe.getCharVolatile(o, offset);
975 }
976
977 /** Volatile version of {@link #putChar(Object, long, char)} */
978 @ForceInline
979 public void putCharVolatile(Object o, long offset, char x) {
980 theInternalUnsafe.putCharVolatile(o, offset, x);
981 }
982
983 /** Volatile version of {@link #getLong(Object, long)} */
984 @ForceInline
985 public long getLongVolatile(Object o, long offset) {
986 return theInternalUnsafe.getLongVolatile(o, offset);
987 }
988
989 /** Volatile version of {@link #putLong(Object, long, long)} */
990 @ForceInline
991 public void putLongVolatile(Object o, long offset, long x) {
992 theInternalUnsafe.putLongVolatile(o, offset, x);
993 }
994
995 /** Volatile version of {@link #getFloat(Object, long)} */
996 @ForceInline
997 public float getFloatVolatile(Object o, long offset) {
998 return theInternalUnsafe.getFloatVolatile(o, offset);
999 }
1000
1001 /** Volatile version of {@link #putFloat(Object, long, float)} */
1002 @ForceInline
1003 public void putFloatVolatile(Object o, long offset, float x) {
1004 theInternalUnsafe.putFloatVolatile(o, offset, x);
1005 }
1006
1007 /** Volatile version of {@link #getDouble(Object, long)} */
1008 @ForceInline
1009 public double getDoubleVolatile(Object o, long offset) {
1010 return theInternalUnsafe.getDoubleVolatile(o, offset);
1011 }
1012
1013 /** Volatile version of {@link #putDouble(Object, long, double)} */
1014 @ForceInline
1015 public void putDoubleVolatile(Object o, long offset, double x) {
1016 theInternalUnsafe.putDoubleVolatile(o, offset, x);
1017 }
1018
1019 /**
1020 * Version of {@link #putObjectVolatile(Object, long, Object)}
1021 * that does not guarantee immediate visibility of the store to
1022 * other threads. This method is generally only useful if the
1023 * underlying field is a Java volatile (or if an array cell, one
1024 * that is otherwise only accessed using volatile accesses).
1025 *
1026 * Corresponds to C11 atomic_store_explicit(..., memory_order_release).
1027 */
1028 @ForceInline
1029 public void putOrderedObject(Object o, long offset, Object x) {
1030 theInternalUnsafe.putReferenceRelease(o, offset, x);
1031 }
1032
1033 /** Ordered/Lazy version of {@link #putIntVolatile(Object, long, int)} */
1034 @ForceInline
1035 public void putOrderedInt(Object o, long offset, int x) {
1036 theInternalUnsafe.putIntRelease(o, offset, x);
1037 }
1038
1039 /** Ordered/Lazy version of {@link #putLongVolatile(Object, long, long)} */
1040 @ForceInline
1041 public void putOrderedLong(Object o, long offset, long x) {
1042 theInternalUnsafe.putLongRelease(o, offset, x);
1043 }
1044
1045 /**
1046 * Unblocks the given thread blocked on {@code park}, or, if it is
1047 * not blocked, causes the subsequent call to {@code park} not to
1048 * block. Note: this operation is "unsafe" solely because the
1049 * caller must somehow ensure that the thread has not been
1050 * destroyed. Nothing special is usually required to ensure this
1051 * when called from Java (in which there will ordinarily be a live
1052 * reference to the thread) but this is not nearly-automatically
1053 * so when calling from native code.
1054 *
1055 * @param thread the thread to unpark.
1056 *
1057 * @deprecated Use {@link java.util.concurrent.locks.LockSupport#unpark(Thread)} instead.
1058 */
1059 @Deprecated(since="22", forRemoval=true)
1060 @ForceInline
1061 public void unpark(Object thread) {
1062 theInternalUnsafe.unpark(thread);
1063 }
1064
1065 /**
1066 * Blocks current thread, returning when a balancing
1067 * {@code unpark} occurs, or a balancing {@code unpark} has
1068 * already occurred, or the thread is interrupted, or, if not
1069 * absolute and time is not zero, the given time nanoseconds have
1070 * elapsed, or if absolute, the given deadline in milliseconds
1071 * since Epoch has passed, or spuriously (i.e., returning for no
1072 * "reason"). Note: This operation is in the Unsafe class only
1073 * because {@code unpark} is, so it would be strange to place it
1074 * elsewhere.
1075 *
1076 * @deprecated Use {@link java.util.concurrent.locks.LockSupport#parkNanos(long)} or
1077 * {@link java.util.concurrent.locks.LockSupport#parkUntil(long)} instead.
1078 */
1079 @Deprecated(since="22", forRemoval=true)
1080 @ForceInline
1081 public void park(boolean isAbsolute, long time) {
1082 theInternalUnsafe.park(isAbsolute, time);
1083 }
1084
1085 /**
1086 * Gets the load average in the system run queue assigned
1087 * to the available processors averaged over various periods of time.
1088 * This method retrieves the given {@code nelem} samples and
1089 * assigns to the elements of the given {@code loadavg} array.
1090 * The system imposes a maximum of 3 samples, representing
1091 * averages over the last 1, 5, and 15 minutes, respectively.
1092 *
1093 * @param loadavg an array of double of size nelems
1094 * @param nelems the number of samples to be retrieved and
1095 * must be 1 to 3.
1096 *
1097 * @return the number of samples actually retrieved; or -1
1098 * if the load average is unobtainable.
1099 *
1100 * @deprecated Use {@link java.lang.management.OperatingSystemMXBean#getSystemLoadAverage()}
1101 * instead.
1102 */
1103 @Deprecated(since="22", forRemoval=true)
1104 @ForceInline
1105 public int getLoadAverage(double[] loadavg, int nelems) {
1106 return theInternalUnsafe.getLoadAverage(loadavg, nelems);
1107 }
1108
1109 // The following contain CAS-based Java implementations used on
1110 // platforms not supporting native instructions
1111
1112 /**
1113 * Atomically adds the given value to the current value of a field
1114 * or array element within the given object {@code o}
1115 * at the given {@code offset}.
1116 *
1117 * @param o object/array to update the field/element in
1118 * @param offset field/element offset
1119 * @param delta the value to add
1120 * @return the previous value
1121 * @since 1.8
1122 */
1123 @ForceInline
1124 public final int getAndAddInt(Object o, long offset, int delta) {
1125 return theInternalUnsafe.getAndAddInt(o, offset, delta);
1126 }
1127
1128 /**
1129 * Atomically adds the given value to the current value of a field
1130 * or array element within the given object {@code o}
1131 * at the given {@code offset}.
1132 *
1133 * @param o object/array to update the field/element in
1134 * @param offset field/element offset
1135 * @param delta the value to add
1136 * @return the previous value
1137 * @since 1.8
1138 */
1139 @ForceInline
1140 public final long getAndAddLong(Object o, long offset, long delta) {
1141 return theInternalUnsafe.getAndAddLong(o, offset, delta);
1142 }
1143
1144 /**
1145 * Atomically exchanges the given value with the current value of
1146 * a field or array element within the given object {@code o}
1147 * at the given {@code offset}.
1148 *
1149 * @param o object/array to update the field/element in
1150 * @param offset field/element offset
1151 * @param newValue new value
1152 * @return the previous value
1153 * @since 1.8
1154 */
1155 @ForceInline
1156 public final int getAndSetInt(Object o, long offset, int newValue) {
1157 return theInternalUnsafe.getAndSetInt(o, offset, newValue);
1158 }
1159
1160 /**
1161 * Atomically exchanges the given value with the current value of
1162 * a field or array element within the given object {@code o}
1163 * at the given {@code offset}.
1164 *
1165 * @param o object/array to update the field/element in
1166 * @param offset field/element offset
1167 * @param newValue new value
1168 * @return the previous value
1169 * @since 1.8
1170 */
1171 @ForceInline
1172 public final long getAndSetLong(Object o, long offset, long newValue) {
1173 return theInternalUnsafe.getAndSetLong(o, offset, newValue);
1174 }
1175
1176 /**
1177 * Atomically exchanges the given reference value with the current
1178 * reference value of a field or array element within the given
1179 * object {@code o} at the given {@code offset}.
1180 *
1181 * @param o object/array to update the field/element in
1182 * @param offset field/element offset
1183 * @param newValue new value
1184 * @return the previous value
1185 * @since 1.8
1186 */
1187 @ForceInline
1188 public final Object getAndSetObject(Object o, long offset, Object newValue) {
1189 return theInternalUnsafe.getAndSetReference(o, offset, newValue);
1190 }
1191
1192 /**
1193 * Ensures that loads before the fence will not be reordered with loads and
1194 * stores after the fence; a "LoadLoad plus LoadStore barrier".
1195 *
1196 * Corresponds to C11 atomic_thread_fence(memory_order_acquire)
1197 * (an "acquire fence").
1198 *
1199 * A pure LoadLoad fence is not provided, since the addition of LoadStore
1200 * is almost always desired, and most current hardware instructions that
1201 * provide a LoadLoad barrier also provide a LoadStore barrier for free.
1202 *
1203 * @deprecated Use {@link java.lang.invoke.VarHandle#acquireFence()} instead.
1204 * @since 1.8
1205 */
1206 @Deprecated(since="22", forRemoval=true)
1207 @ForceInline
1208 public void loadFence() {
1209 theInternalUnsafe.loadFence();
1210 }
1211
1212 /**
1213 * Ensures that loads and stores before the fence will not be reordered with
1214 * stores after the fence; a "StoreStore plus LoadStore barrier".
1215 *
1216 * Corresponds to C11 atomic_thread_fence(memory_order_release)
1217 * (a "release fence").
1218 *
1219 * A pure StoreStore fence is not provided, since the addition of LoadStore
1220 * is almost always desired, and most current hardware instructions that
1221 * provide a StoreStore barrier also provide a LoadStore barrier for free.
1222 *
1223 * @deprecated Use {@link java.lang.invoke.VarHandle#releaseFence()} instead.
1224 * @since 1.8
1225 */
1226 @Deprecated(since="22", forRemoval=true)
1227 @ForceInline
1228 public void storeFence() {
1229 theInternalUnsafe.storeFence();
1230 }
1231
1232 /**
1233 * Ensures that loads and stores before the fence will not be reordered
1234 * with loads and stores after the fence. Implies the effects of both
1235 * loadFence() and storeFence(), and in addition, the effect of a StoreLoad
1236 * barrier.
1237 *
1238 * Corresponds to C11 atomic_thread_fence(memory_order_seq_cst).
1239 *
1240 * @deprecated Use {@link java.lang.invoke.VarHandle#fullFence()} instead.
1241 * @since 1.8
1242 */
1243 @Deprecated(since="22", forRemoval=true)
1244 @ForceInline
1245 public void fullFence() {
1246 theInternalUnsafe.fullFence();
1247 }
1248
1249 /**
1250 * Invokes the given direct byte buffer's cleaner, if any.
1251 *
1252 * @param directBuffer a direct byte buffer
1253 * @throws NullPointerException if {@code directBuffer} is null
1254 * @throws IllegalArgumentException if {@code directBuffer} is non-direct,
1255 * or is a {@link java.nio.Buffer#slice slice}, or is a
1256 * {@link java.nio.Buffer#duplicate duplicate}
1257 * @since 9
1258 */
1259 public void invokeCleaner(java.nio.ByteBuffer directBuffer) {
1260 if (!directBuffer.isDirect())
1261 throw new IllegalArgumentException("buffer is non-direct");
1262
1263 theInternalUnsafe.invokeCleaner(directBuffer);
1264 }
1265 }