1 /*
2 * Copyright (c) 2000, 2018, 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.unsupported.UnsafeForwarder;
29 import jdk.internal.vm.annotation.ForceInline;
30 import jdk.internal.reflect.CallerSensitive;
31 import jdk.internal.reflect.Reflection;
32
33 import java.lang.reflect.Field;
34 import java.util.Set;
35
36
37 /**
38 * A collection of methods for performing low-level, unsafe operations.
39 * Although the class and all methods are public, use of this class is
40 * limited because only trusted code can obtain instances of it.
41 *
42 * <em>Note:</em> It is the resposibility of the caller to make sure
43 * arguments are checked before methods of this class are
44 * called. While some rudimentary checks are performed on the input,
45 * the checks are best effort and when performance is an overriding
46 * priority, as when methods of this class are optimized by the
47 * runtime compiler, some or all checks (if any) may be elided. Hence,
48 * the caller must not rely on the checks and corresponding
49 * exceptions!
50 *
51 * @author John R. Rose
52 * @see #getUnsafe
53 */
54
55 public final class Unsafe {
56
57 static {
58 Reflection.registerMethodsToFilter(Unsafe.class, Set.of("getUnsafe"));
59 }
60
61 private Unsafe() {}
62
63 private static final Unsafe theUnsafe = new Unsafe();
64 private static final UnsafeForwarder theInternalUnsafe = UnsafeForwarder.getUnsafeHelper();
65
66 /**
67 * Provides the caller with the capability of performing unsafe
68 * operations.
69 *
70 * <p>The returned {@code Unsafe} object should be carefully guarded
71 * by the caller, since it can be used to read and write data at arbitrary
72 * memory addresses. It must never be passed to untrusted code.
73 *
74 * <p>Most methods in this class are very low-level, and correspond to a
75 * small number of hardware instructions (on typical machines). Compilers
76 * are encouraged to optimize these methods accordingly.
77 *
78 * <p>Here is a suggested idiom for using unsafe operations:
79 *
80 * <pre> {@code
81 * class MyTrustedClass {
82 * private static final Unsafe unsafe = Unsafe.getUnsafe();
83 * ...
84 * private long myCountAddress = ...;
85 * public int getCount() { return unsafe.getByte(myCountAddress); }
86 * }}</pre>
87 *
88 * (It may assist compilers to make the local variable {@code final}.)
89 *
90 * @throws SecurityException if the class loader of the caller
91 * class is not in the system domain in which all permissions
92 * are granted.
93 */
94 @CallerSensitive
95 public static Unsafe getUnsafe() {
96 Class<?> caller = Reflection.getCallerClass();
97 ClassLoader loader = caller.getClassLoader();
98 if (loader != null && loader != ClassLoader.getPlatformClassLoader())
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 resposibility 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 resposibility 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 resposibility 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 resposibility 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 resposibility 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.unsupported.UnsafeForwarder.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 * @see #getInt(Object, long)
637 */
638 @ForceInline
639 public long objectFieldOffset(Field f) {
640 return theInternalUnsafe.objectFieldOffset(f);
641 }
642
643 /**
644 * Reports the location of a given static field, in conjunction with {@link
645 * #staticFieldBase}.
646 * <p>Do not expect to perform any sort of arithmetic on this offset;
647 * it is just a cookie which is passed to the unsafe heap memory accessors.
648 *
649 * <p>Any given field will always have the same offset, and no two distinct
650 * fields of the same class will ever have the same offset.
651 *
652 * <p>As of 1.4.1, offsets for fields are represented as long values,
653 * although the Sun JVM does not use the most significant 32 bits.
654 * It is hard to imagine a JVM technology which needs more than
655 * a few bits to encode an offset within a non-array object,
656 * However, for consistency with other methods in this class,
657 * this method reports its result as a long value.
658 * @see #getInt(Object, long)
659 */
660 @ForceInline
661 public long staticFieldOffset(Field f) {
662 return theInternalUnsafe.staticFieldOffset(f);
663 }
664
665 /**
666 * Reports the location of a given static field, in conjunction with {@link
667 * #staticFieldOffset}.
668 * <p>Fetch the base "Object", if any, with which static fields of the
669 * given class can be accessed via methods like {@link #getInt(Object,
670 * long)}. This value may be null. This value may refer to an object
671 * which is a "cookie", not guaranteed to be a real Object, and it should
672 * not be used in any way except as argument to the get and put routines in
673 * this class.
674 */
675 @ForceInline
676 public Object staticFieldBase(Field f) {
677 return theInternalUnsafe.staticFieldBase(f);
678 }
679
680 /**
681 * Detects if the given class may need to be initialized. This is often
682 * needed in conjunction with obtaining the static field base of a
683 * class.
684 * @return false only if a call to {@code ensureClassInitialized} would have no effect
685 */
686 @ForceInline
687 public boolean shouldBeInitialized(Class<?> c) {
688 return theInternalUnsafe.shouldBeInitialized(c);
689 }
690
691 /**
692 * Ensures the given class has been initialized. This is often
693 * needed in conjunction with obtaining the static field base of a
694 * class.
695 */
696 @ForceInline
697 public void ensureClassInitialized(Class<?> c) {
698 theInternalUnsafe.ensureClassInitialized(c);
699 }
700
701 /**
702 * Reports the offset of the first element in the storage allocation of a
703 * given array class. If {@link #arrayIndexScale} returns a non-zero value
704 * for the same class, you may use that scale factor, together with this
705 * base offset, to form new offsets to access elements of arrays of the
706 * given class.
707 *
708 * @see #getInt(Object, long)
709 * @see #putInt(Object, long, int)
710 */
711 @ForceInline
712 public int arrayBaseOffset(Class<?> arrayClass) {
713 return theInternalUnsafe.arrayBaseOffset(arrayClass);
714 }
715
716 /** The value of {@code arrayBaseOffset(boolean[].class)} */
717 public static final int ARRAY_BOOLEAN_BASE_OFFSET = jdk.internal.unsupported.UnsafeForwarder.ARRAY_BOOLEAN_BASE_OFFSET;
718
719 /** The value of {@code arrayBaseOffset(byte[].class)} */
720 public static final int ARRAY_BYTE_BASE_OFFSET = jdk.internal.unsupported.UnsafeForwarder.ARRAY_BYTE_BASE_OFFSET;
721
722 /** The value of {@code arrayBaseOffset(short[].class)} */
723 public static final int ARRAY_SHORT_BASE_OFFSET = jdk.internal.unsupported.UnsafeForwarder.ARRAY_SHORT_BASE_OFFSET;
724
725 /** The value of {@code arrayBaseOffset(char[].class)} */
726 public static final int ARRAY_CHAR_BASE_OFFSET = jdk.internal.unsupported.UnsafeForwarder.ARRAY_CHAR_BASE_OFFSET;
727
728 /** The value of {@code arrayBaseOffset(int[].class)} */
729 public static final int ARRAY_INT_BASE_OFFSET = jdk.internal.unsupported.UnsafeForwarder.ARRAY_INT_BASE_OFFSET;
730
731 /** The value of {@code arrayBaseOffset(long[].class)} */
732 public static final int ARRAY_LONG_BASE_OFFSET = jdk.internal.unsupported.UnsafeForwarder.ARRAY_LONG_BASE_OFFSET;
733
734 /** The value of {@code arrayBaseOffset(float[].class)} */
735 public static final int ARRAY_FLOAT_BASE_OFFSET = jdk.internal.unsupported.UnsafeForwarder.ARRAY_FLOAT_BASE_OFFSET;
736
737 /** The value of {@code arrayBaseOffset(double[].class)} */
738 public static final int ARRAY_DOUBLE_BASE_OFFSET = jdk.internal.unsupported.UnsafeForwarder.ARRAY_DOUBLE_BASE_OFFSET;
739
740 /** The value of {@code arrayBaseOffset(Object[].class)} */
741 public static final int ARRAY_OBJECT_BASE_OFFSET = jdk.internal.unsupported.UnsafeForwarder.ARRAY_OBJECT_BASE_OFFSET;
742
743 /**
744 * Reports the scale factor for addressing elements in the storage
745 * allocation of a given array class. However, arrays of "narrow" types
746 * will generally not work properly with accessors like {@link
747 * #getByte(Object, long)}, so the scale factor for such classes is reported
748 * as zero.
749 *
750 * @see #arrayBaseOffset
751 * @see #getInt(Object, long)
752 * @see #putInt(Object, long, int)
753 */
754 @ForceInline
755 public int arrayIndexScale(Class<?> arrayClass) {
756 return theInternalUnsafe.arrayIndexScale(arrayClass);
757 }
758
759 /** The value of {@code arrayIndexScale(boolean[].class)} */
760 public static final int ARRAY_BOOLEAN_INDEX_SCALE = jdk.internal.unsupported.UnsafeForwarder.ARRAY_BOOLEAN_INDEX_SCALE;
761
762 /** The value of {@code arrayIndexScale(byte[].class)} */
763 public static final int ARRAY_BYTE_INDEX_SCALE = jdk.internal.unsupported.UnsafeForwarder.ARRAY_BYTE_INDEX_SCALE;
764
765 /** The value of {@code arrayIndexScale(short[].class)} */
766 public static final int ARRAY_SHORT_INDEX_SCALE = jdk.internal.unsupported.UnsafeForwarder.ARRAY_SHORT_INDEX_SCALE;
767
768 /** The value of {@code arrayIndexScale(char[].class)} */
769 public static final int ARRAY_CHAR_INDEX_SCALE = jdk.internal.unsupported.UnsafeForwarder.ARRAY_CHAR_INDEX_SCALE;
770
771 /** The value of {@code arrayIndexScale(int[].class)} */
772 public static final int ARRAY_INT_INDEX_SCALE = jdk.internal.unsupported.UnsafeForwarder.ARRAY_INT_INDEX_SCALE;
773
774 /** The value of {@code arrayIndexScale(long[].class)} */
775 public static final int ARRAY_LONG_INDEX_SCALE = jdk.internal.unsupported.UnsafeForwarder.ARRAY_LONG_INDEX_SCALE;
776
777 /** The value of {@code arrayIndexScale(float[].class)} */
778 public static final int ARRAY_FLOAT_INDEX_SCALE = jdk.internal.unsupported.UnsafeForwarder.ARRAY_FLOAT_INDEX_SCALE;
779
780 /** The value of {@code arrayIndexScale(double[].class)} */
781 public static final int ARRAY_DOUBLE_INDEX_SCALE = jdk.internal.unsupported.UnsafeForwarder.ARRAY_DOUBLE_INDEX_SCALE;
782
783 /** The value of {@code arrayIndexScale(Object[].class)} */
784 public static final int ARRAY_OBJECT_INDEX_SCALE = jdk.internal.unsupported.UnsafeForwarder.ARRAY_OBJECT_INDEX_SCALE;
785
786 /**
787 * Reports the size in bytes of a native pointer, as stored via {@link
788 * #putAddress}. This value will be either 4 or 8. Note that the sizes of
789 * other primitive types (as stored in native memory blocks) is determined
790 * fully by their information content.
791 */
792 @ForceInline
793 public int addressSize() {
794 return theInternalUnsafe.addressSize();
795 }
796
797 /** The value of {@code addressSize()} */
798 public static final int ADDRESS_SIZE = theInternalUnsafe.addressSize();
799
800 /**
801 * Reports the size in bytes of a native memory page (whatever that is).
802 * This value will always be a power of two.
803 */
804 @ForceInline
805 public int pageSize() {
806 return theInternalUnsafe.pageSize();
807 }
808
809
810 /// random trusted operations from JNI:
811
812 /**
813 * Defines a class but does not make it known to the class loader or system dictionary.
814 * <p>
815 * For each CP entry, the corresponding CP patch must either be null or have
816 * the a format that matches its tag:
817 * <ul>
818 * <li>Integer, Long, Float, Double: the corresponding wrapper object type from java.lang
819 * <li>Utf8: a string (must have suitable syntax if used as signature or name)
820 * <li>Class: any java.lang.Class object
821 * <li>String: any object (not just a java.lang.String)
822 * <li>InterfaceMethodRef: (NYI) a method handle to invoke on that call site's arguments
823 * </ul>
824 * @param hostClass context for linkage, access control, protection domain, and class loader
825 * @param data bytes of a class file
826 * @param cpPatches where non-null entries exist, they replace corresponding CP entries in data
827 */
828 @ForceInline
829 public Class<?> defineAnonymousClass(Class<?> hostClass, byte[] data, Object[] cpPatches) {
830 return theInternalUnsafe.defineAnonymousClass(hostClass, data, cpPatches);
831 }
832
833 /**
834 * Allocates an instance but does not run any constructor.
835 * Initializes the class if it has not yet been.
836 */
837 @ForceInline
838 public Object allocateInstance(Class<?> cls)
839 throws InstantiationException {
840 return theInternalUnsafe.allocateInstance(cls);
841 }
842
843 /** Throws the exception without telling the verifier. */
844 @ForceInline
845 public void throwException(Throwable ee) {
846 theInternalUnsafe.throwException(ee);
847 }
848
849 /**
850 * Atomically updates Java variable to {@code x} if it is currently
851 * holding {@code expected}.
852 *
853 * <p>This operation has memory semantics of a {@code volatile} read
854 * and write. Corresponds to C11 atomic_compare_exchange_strong.
855 *
856 * @return {@code true} if successful
857 */
858 @ForceInline
859 public final boolean compareAndSwapObject(Object o, long offset,
860 Object expected,
861 Object x) {
862 return theInternalUnsafe.compareAndSetReference(o, offset, expected, x);
863 }
864
865 /**
866 * Atomically updates Java variable to {@code x} if it is currently
867 * holding {@code expected}.
868 *
869 * <p>This operation has memory semantics of a {@code volatile} read
870 * and write. Corresponds to C11 atomic_compare_exchange_strong.
871 *
872 * @return {@code true} if successful
873 */
874 @ForceInline
875 public final boolean compareAndSwapInt(Object o, long offset,
876 int expected,
877 int x) {
878 return theInternalUnsafe.compareAndSetInt(o, offset, expected, x);
879 }
880
881 /**
882 * Atomically updates Java variable to {@code x} if it is currently
883 * holding {@code expected}.
884 *
885 * <p>This operation has memory semantics of a {@code volatile} read
886 * and write. Corresponds to C11 atomic_compare_exchange_strong.
887 *
888 * @return {@code true} if successful
889 */
890 @ForceInline
891 public final boolean compareAndSwapLong(Object o, long offset,
892 long expected,
893 long x) {
894 return theInternalUnsafe.compareAndSetLong(o, offset, expected, x);
895 }
896
897 /**
898 * Fetches a reference value from a given Java variable, with volatile
899 * load semantics. Otherwise identical to {@link #getObject(Object, long)}
900 */
901 @ForceInline
902 public Object getObjectVolatile(Object o, long offset) {
903 return theInternalUnsafe.getReferenceVolatile(o, offset);
904 }
905
906 /**
907 * Stores a reference value into a given Java variable, with
908 * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)}
909 */
910 @ForceInline
911 public void putObjectVolatile(Object o, long offset, Object x) {
912 theInternalUnsafe.putReferenceVolatile(o, offset, x);
913 }
914
915 /** Volatile version of {@link #getInt(Object, long)} */
916 @ForceInline
917 public int getIntVolatile(Object o, long offset) {
918 return theInternalUnsafe.getIntVolatile(o, offset);
919 }
920
921 /** Volatile version of {@link #putInt(Object, long, int)} */
922 @ForceInline
923 public void putIntVolatile(Object o, long offset, int x) {
924 theInternalUnsafe.putIntVolatile(o, offset, x);
925 }
926
927 /** Volatile version of {@link #getBoolean(Object, long)} */
928 @ForceInline
929 public boolean getBooleanVolatile(Object o, long offset) {
930 return theInternalUnsafe.getBooleanVolatile(o, offset);
931 }
932
933 /** Volatile version of {@link #putBoolean(Object, long, boolean)} */
934 @ForceInline
935 public void putBooleanVolatile(Object o, long offset, boolean x) {
936 theInternalUnsafe.putBooleanVolatile(o, offset, x);
937 }
938
939 /** Volatile version of {@link #getByte(Object, long)} */
940 @ForceInline
941 public byte getByteVolatile(Object o, long offset) {
942 return theInternalUnsafe.getByteVolatile(o, offset);
943 }
944
945 /** Volatile version of {@link #putByte(Object, long, byte)} */
946 @ForceInline
947 public void putByteVolatile(Object o, long offset, byte x) {
948 theInternalUnsafe.putByteVolatile(o, offset, x);
949 }
950
951 /** Volatile version of {@link #getShort(Object, long)} */
952 @ForceInline
953 public short getShortVolatile(Object o, long offset) {
954 return theInternalUnsafe.getShortVolatile(o, offset);
955 }
956
957 /** Volatile version of {@link #putShort(Object, long, short)} */
958 @ForceInline
959 public void putShortVolatile(Object o, long offset, short x) {
960 theInternalUnsafe.putShortVolatile(o, offset, x);
961 }
962
963 /** Volatile version of {@link #getChar(Object, long)} */
964 @ForceInline
965 public char getCharVolatile(Object o, long offset) {
966 return theInternalUnsafe.getCharVolatile(o, offset);
967 }
968
969 /** Volatile version of {@link #putChar(Object, long, char)} */
970 @ForceInline
971 public void putCharVolatile(Object o, long offset, char x) {
972 theInternalUnsafe.putCharVolatile(o, offset, x);
973 }
974
975 /** Volatile version of {@link #getLong(Object, long)} */
976 @ForceInline
977 public long getLongVolatile(Object o, long offset) {
978 return theInternalUnsafe.getLongVolatile(o, offset);
979 }
980
981 /** Volatile version of {@link #putLong(Object, long, long)} */
982 @ForceInline
983 public void putLongVolatile(Object o, long offset, long x) {
984 theInternalUnsafe.putLongVolatile(o, offset, x);
985 }
986
987 /** Volatile version of {@link #getFloat(Object, long)} */
988 @ForceInline
989 public float getFloatVolatile(Object o, long offset) {
990 return theInternalUnsafe.getFloatVolatile(o, offset);
991 }
992
993 /** Volatile version of {@link #putFloat(Object, long, float)} */
994 @ForceInline
995 public void putFloatVolatile(Object o, long offset, float x) {
996 theInternalUnsafe.putFloatVolatile(o, offset, x);
997 }
998
999 /** Volatile version of {@link #getDouble(Object, long)} */
1000 @ForceInline
1001 public double getDoubleVolatile(Object o, long offset) {
1002 return theInternalUnsafe.getDoubleVolatile(o, offset);
1003 }
1004
1005 /** Volatile version of {@link #putDouble(Object, long, double)} */
1006 @ForceInline
1007 public void putDoubleVolatile(Object o, long offset, double x) {
1008 theInternalUnsafe.putDoubleVolatile(o, offset, x);
1009 }
1010
1011 /**
1012 * Version of {@link #putObjectVolatile(Object, long, Object)}
1013 * that does not guarantee immediate visibility of the store to
1014 * other threads. This method is generally only useful if the
1015 * underlying field is a Java volatile (or if an array cell, one
1016 * that is otherwise only accessed using volatile accesses).
1017 *
1018 * Corresponds to C11 atomic_store_explicit(..., memory_order_release).
1019 */
1020 @ForceInline
1021 public void putOrderedObject(Object o, long offset, Object x) {
1022 theInternalUnsafe.putReferenceRelease(o, offset, x);
1023 }
1024
1025 /** Ordered/Lazy version of {@link #putIntVolatile(Object, long, int)} */
1026 @ForceInline
1027 public void putOrderedInt(Object o, long offset, int x) {
1028 theInternalUnsafe.putIntRelease(o, offset, x);
1029 }
1030
1031 /** Ordered/Lazy version of {@link #putLongVolatile(Object, long, long)} */
1032 @ForceInline
1033 public void putOrderedLong(Object o, long offset, long x) {
1034 theInternalUnsafe.putLongRelease(o, offset, x);
1035 }
1036
1037 /**
1038 * Unblocks the given thread blocked on {@code park}, or, if it is
1039 * not blocked, causes the subsequent call to {@code park} not to
1040 * block. Note: this operation is "unsafe" solely because the
1041 * caller must somehow ensure that the thread has not been
1042 * destroyed. Nothing special is usually required to ensure this
1043 * when called from Java (in which there will ordinarily be a live
1044 * reference to the thread) but this is not nearly-automatically
1045 * so when calling from native code.
1046 *
1047 * @param thread the thread to unpark.
1048 */
1049 @ForceInline
1050 public void unpark(Object thread) {
1051 theInternalUnsafe.unpark(thread);
1052 }
1053
1054 /**
1055 * Blocks current thread, returning when a balancing
1056 * {@code unpark} occurs, or a balancing {@code unpark} has
1057 * already occurred, or the thread is interrupted, or, if not
1058 * absolute and time is not zero, the given time nanoseconds have
1059 * elapsed, or if absolute, the given deadline in milliseconds
1060 * since Epoch has passed, or spuriously (i.e., returning for no
1061 * "reason"). Note: This operation is in the Unsafe class only
1062 * because {@code unpark} is, so it would be strange to place it
1063 * elsewhere.
1064 */
1065 @ForceInline
1066 public void park(boolean isAbsolute, long time) {
1067 theInternalUnsafe.park(isAbsolute, time);
1068 }
1069
1070 /**
1071 * Gets the load average in the system run queue assigned
1072 * to the available processors averaged over various periods of time.
1073 * This method retrieves the given {@code nelem} samples and
1074 * assigns to the elements of the given {@code loadavg} array.
1075 * The system imposes a maximum of 3 samples, representing
1076 * averages over the last 1, 5, and 15 minutes, respectively.
1077 *
1078 * @implNote This method returns -1.
1079 *
1080 * @param loadavg an array of double of size nelems
1081 * @param nelems the number of samples to be retrieved and
1082 * must be 1 to 3.
1083 *
1084 * @return the number of samples actually retrieved; or -1
1085 * if the load average is unobtainable.
1086 *
1087 * @deprecated This method is planned to be removed in a future release.
1088 * To get system load average, use
1089 * {@link java.lang.management.OperatingSystemMXBean#getSystemLoadAverage()}
1090 * instead.
1091 */
1092 @Deprecated(since="12", forRemoval=true)
1093 public int getLoadAverage(double[] loadavg, int nelems) {
1094 return -1;
1095 }
1096
1097 // The following contain CAS-based Java implementations used on
1098 // platforms not supporting native instructions
1099
1100 /**
1101 * Atomically adds the given value to the current value of a field
1102 * or array element within the given object {@code o}
1103 * at the given {@code offset}.
1104 *
1105 * @param o object/array to update the field/element in
1106 * @param offset field/element offset
1107 * @param delta the value to add
1108 * @return the previous value
1109 * @since 1.8
1110 */
1111 @ForceInline
1112 public final int getAndAddInt(Object o, long offset, int delta) {
1113 return theInternalUnsafe.getAndAddInt(o, offset, delta);
1114 }
1115
1116 /**
1117 * Atomically adds the given value to the current value of a field
1118 * or array element within the given object {@code o}
1119 * at the given {@code offset}.
1120 *
1121 * @param o object/array to update the field/element in
1122 * @param offset field/element offset
1123 * @param delta the value to add
1124 * @return the previous value
1125 * @since 1.8
1126 */
1127 @ForceInline
1128 public final long getAndAddLong(Object o, long offset, long delta) {
1129 return theInternalUnsafe.getAndAddLong(o, offset, delta);
1130 }
1131
1132 /**
1133 * Atomically exchanges the given value with the current value of
1134 * a field or array element within the given object {@code o}
1135 * at the given {@code offset}.
1136 *
1137 * @param o object/array to update the field/element in
1138 * @param offset field/element offset
1139 * @param newValue new value
1140 * @return the previous value
1141 * @since 1.8
1142 */
1143 @ForceInline
1144 public final int getAndSetInt(Object o, long offset, int newValue) {
1145 return theInternalUnsafe.getAndSetInt(o, offset, newValue);
1146 }
1147
1148 /**
1149 * Atomically exchanges the given value with the current value of
1150 * a field or array element within the given object {@code o}
1151 * at the given {@code offset}.
1152 *
1153 * @param o object/array to update the field/element in
1154 * @param offset field/element offset
1155 * @param newValue new value
1156 * @return the previous value
1157 * @since 1.8
1158 */
1159 @ForceInline
1160 public final long getAndSetLong(Object o, long offset, long newValue) {
1161 return theInternalUnsafe.getAndSetLong(o, offset, newValue);
1162 }
1163
1164 /**
1165 * Atomically exchanges the given reference value with the current
1166 * reference value of a field or array element within the given
1167 * object {@code o} at the given {@code offset}.
1168 *
1169 * @param o object/array to update the field/element in
1170 * @param offset field/element offset
1171 * @param newValue new value
1172 * @return the previous value
1173 * @since 1.8
1174 */
1175 @ForceInline
1176 public final Object getAndSetObject(Object o, long offset, Object newValue) {
1177 return theInternalUnsafe.getAndSetReference(o, offset, newValue);
1178 }
1179
1180
1181 /**
1182 * Ensures that loads before the fence will not be reordered with loads and
1183 * stores after the fence; a "LoadLoad plus LoadStore barrier".
1184 *
1185 * Corresponds to C11 atomic_thread_fence(memory_order_acquire)
1186 * (an "acquire fence").
1187 *
1188 * A pure LoadLoad fence is not provided, since the addition of LoadStore
1189 * is almost always desired, and most current hardware instructions that
1190 * provide a LoadLoad barrier also provide a LoadStore barrier for free.
1191 * @since 1.8
1192 */
1193 @ForceInline
1194 public void loadFence() {
1195 theInternalUnsafe.loadFence();
1196 }
1197
1198 /**
1199 * Ensures that loads and stores before the fence will not be reordered with
1200 * stores after the fence; a "StoreStore plus LoadStore barrier".
1201 *
1202 * Corresponds to C11 atomic_thread_fence(memory_order_release)
1203 * (a "release fence").
1204 *
1205 * A pure StoreStore fence is not provided, since the addition of LoadStore
1206 * is almost always desired, and most current hardware instructions that
1207 * provide a StoreStore barrier also provide a LoadStore barrier for free.
1208 * @since 1.8
1209 */
1210 @ForceInline
1211 public void storeFence() {
1212 theInternalUnsafe.storeFence();
1213 }
1214
1215 /**
1216 * Ensures that loads and stores before the fence will not be reordered
1217 * with loads and stores after the fence. Implies the effects of both
1218 * loadFence() and storeFence(), and in addition, the effect of a StoreLoad
1219 * barrier.
1220 *
1221 * Corresponds to C11 atomic_thread_fence(memory_order_seq_cst).
1222 * @since 1.8
1223 */
1224 @ForceInline
1225 public void fullFence() {
1226 theInternalUnsafe.fullFence();
1227 }
1228
1229 /**
1230 * Invokes the given direct byte buffer's cleaner, if any.
1231 *
1232 * @param directBuffer a direct byte buffer
1233 * @throws NullPointerException if {@code directBuffer} is null
1234 * @throws IllegalArgumentException if {@code directBuffer} is non-direct,
1235 * or is a {@link java.nio.Buffer#slice slice}, or is a
1236 * {@link java.nio.Buffer#duplicate duplicate}
1237 * @since 9
1238 */
1239 public void invokeCleaner(java.nio.ByteBuffer directBuffer) {
1240 if (!directBuffer.isDirect())
1241 throw new IllegalArgumentException("buffer is non-direct");
1242
1243 theInternalUnsafe.invokeCleaner(directBuffer);
1244 }
1245 }