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.vm.annotation.ForceInline;
29 import jdk.internal.misc.VM;
30 import jdk.internal.reflect.CallerSensitive;
31 import jdk.internal.reflect.Reflection;
32
33 import java.lang.reflect.Field;
34 import java.util.Set;
35
36
37 /**
38 * A collection of methods for performing low-level, unsafe operations.
39 * Although the class and all methods are public, use of this class is
40 * limited because only trusted code can obtain instances of it.
41 *
42 * <em>Note:</em> It is the responsibility of the caller to make sure
43 * arguments are checked before methods of this class are
44 * called. While some rudimentary checks are performed on the input,
45 * the checks are best effort and when performance is an overriding
46 * priority, as when methods of this class are optimized by the
47 * runtime compiler, some or all checks (if any) may be elided. Hence,
48 * the caller must not rely on the checks and corresponding
49 * exceptions!
50 *
51 * @author John R. Rose
52 * @see #getUnsafe
53 */
54
55 public final class Unsafe {
56
57 static {
58 Reflection.registerMethodsToFilter(Unsafe.class, Set.of("getUnsafe"));
59 }
60
61 private Unsafe() {}
62
63 private static final Unsafe theUnsafe = new Unsafe();
64 private static final jdk.internal.misc.Unsafe theInternalUnsafe = jdk.internal.misc.Unsafe.getUnsafe();
65
66 /**
67 * Provides the caller with the capability of performing unsafe
68 * operations.
69 *
70 * <p>The returned {@code Unsafe} object should be carefully guarded
71 * by the caller, since it can be used to read and write data at arbitrary
72 * memory addresses. It must never be passed to untrusted code.
73 *
74 * <p>Most methods in this class are very low-level, and correspond to a
75 * small number of hardware instructions (on typical machines). Compilers
76 * are encouraged to optimize these methods accordingly.
77 *
78 * <p>Here is a suggested idiom for using unsafe operations:
79 *
80 * <pre> {@code
81 * class MyTrustedClass {
82 * private static final Unsafe unsafe = Unsafe.getUnsafe();
83 * ...
84 * private long myCountAddress = ...;
85 * public int getCount() { return unsafe.getByte(myCountAddress); }
86 * }}</pre>
87 *
88 * (It may assist compilers to make the local variable {@code final}.)
89 *
90 * @throws SecurityException if the class loader of the caller
91 * class is not in the system domain in which all permissions
92 * are granted.
93 */
94 @CallerSensitive
95 public static Unsafe getUnsafe() {
96 Class<?> caller = Reflection.getCallerClass();
97 if (!VM.isSystemDomainLoader(caller.getClassLoader()))
98 throw new SecurityException("Unsafe");
99 return theUnsafe;
100 }
101
102 /// peek and poke operations
103 /// (compilers should optimize these to memory ops)
104
105 // These work on object fields in the Java heap.
106 // They will not work on elements of packed arrays.
107
108 /**
109 * Fetches a value from a given Java variable.
110 * More specifically, fetches a field or array element within the given
111 * object {@code o} at the given offset, or (if {@code o} is null)
112 * from the memory address whose numerical value is the given offset.
113 * <p>
114 * The results are undefined unless one of the following cases is true:
115 * <ul>
116 * <li>The offset was obtained from {@link #objectFieldOffset} on
117 * the {@link java.lang.reflect.Field} of some Java field and the object
118 * referred to by {@code o} is of a class compatible with that
119 * field's class.
120 *
121 * <li>The offset and object reference {@code o} (either null or
122 * non-null) were both obtained via {@link #staticFieldOffset}
123 * and {@link #staticFieldBase} (respectively) from the
124 * reflective {@link Field} representation of some Java field.
125 *
126 * <li>The object referred to by {@code o} is an array, and the offset
127 * is an integer of the form {@code B+N*S}, where {@code N} is
128 * a valid index into the array, and {@code B} and {@code S} are
129 * the values obtained by {@link #arrayBaseOffset} and {@link
130 * #arrayIndexScale} (respectively) from the array's class. The value
131 * referred to is the {@code N}<em>th</em> element of the array.
132 *
133 * </ul>
134 * <p>
135 * If one of the above cases is true, the call references a specific Java
136 * variable (field or array element). However, the results are undefined
137 * if that variable is not in fact of the type returned by this method.
138 * <p>
139 * This method refers to a variable by means of two parameters, and so
140 * it provides (in effect) a <em>double-register</em> addressing mode
141 * for Java variables. When the object reference is null, this method
142 * uses its offset as an absolute address. This is similar in operation
143 * to methods such as {@link #getInt(long)}, which provide (in effect) a
144 * <em>single-register</em> addressing mode for non-Java variables.
145 * However, because Java variables may have a different layout in memory
146 * from non-Java variables, programmers should not assume that these
147 * two addressing modes are ever equivalent. Also, programmers should
148 * remember that offsets from the double-register addressing mode cannot
149 * be portably confused with longs used in the single-register addressing
150 * mode.
151 *
152 * @param o Java heap object in which the variable resides, if any, else
153 * null
154 * @param offset indication of where the variable resides in a Java heap
155 * object, if any, else a memory address locating the variable
156 * statically
157 * @return the value fetched from the indicated Java variable
158 * @throws RuntimeException No defined exceptions are thrown, not even
159 * {@link NullPointerException}
160 */
161 @ForceInline
162 public int getInt(Object o, long offset) {
163 return theInternalUnsafe.getInt(o, offset);
164 }
165
166 /**
167 * Stores a value into a given Java variable.
168 * <p>
169 * The first two parameters are interpreted exactly as with
170 * {@link #getInt(Object, long)} to refer to a specific
171 * Java variable (field or array element). The given value
172 * is stored into that variable.
173 * <p>
174 * The variable must be of the same type as the method
175 * parameter {@code x}.
176 *
177 * @param o Java heap object in which the variable resides, if any, else
178 * null
179 * @param offset indication of where the variable resides in a Java heap
180 * object, if any, else a memory address locating the variable
181 * statically
182 * @param x the value to store into the indicated Java variable
183 * @throws RuntimeException No defined exceptions are thrown, not even
184 * {@link NullPointerException}
185 */
186 @ForceInline
187 public void putInt(Object o, long offset, int x) {
188 theInternalUnsafe.putInt(o, offset, x);
189 }
190
191 /**
192 * Fetches a reference value from a given Java variable.
193 * @see #getInt(Object, long)
194 */
195 @ForceInline
196 public Object getObject(Object o, long offset) {
197 return theInternalUnsafe.getReference(o, offset);
198 }
199
200 /**
201 * Stores a reference value into a given Java variable.
202 * <p>
203 * Unless the reference {@code x} being stored is either null
204 * or matches the field type, the results are undefined.
205 * If the reference {@code o} is non-null, card marks or
206 * other store barriers for that object (if the VM requires them)
207 * are updated.
208 * @see #putInt(Object, long, int)
209 */
210 @ForceInline
211 public void putObject(Object o, long offset, Object x) {
212 theInternalUnsafe.putReference(o, offset, x);
213 }
214
215 /** @see #getInt(Object, long) */
216 @ForceInline
217 public boolean getBoolean(Object o, long offset) {
218 return theInternalUnsafe.getBoolean(o, offset);
219 }
220
221 /** @see #putInt(Object, long, int) */
222 @ForceInline
223 public void putBoolean(Object o, long offset, boolean x) {
224 theInternalUnsafe.putBoolean(o, offset, x);
225 }
226
227 /** @see #getInt(Object, long) */
228 @ForceInline
229 public byte getByte(Object o, long offset) {
230 return theInternalUnsafe.getByte(o, offset);
231 }
232
233 /** @see #putInt(Object, long, int) */
234 @ForceInline
235 public void putByte(Object o, long offset, byte x) {
236 theInternalUnsafe.putByte(o, offset, x);
237 }
238
239 /** @see #getInt(Object, long) */
240 @ForceInline
241 public short getShort(Object o, long offset) {
242 return theInternalUnsafe.getShort(o, offset);
243 }
244
245 /** @see #putInt(Object, long, int) */
246 @ForceInline
247 public void putShort(Object o, long offset, short x) {
248 theInternalUnsafe.putShort(o, offset, x);
249 }
250
251 /** @see #getInt(Object, long) */
252 @ForceInline
253 public char getChar(Object o, long offset) {
254 return theInternalUnsafe.getChar(o, offset);
255 }
256
257 /** @see #putInt(Object, long, int) */
258 @ForceInline
259 public void putChar(Object o, long offset, char x) {
260 theInternalUnsafe.putChar(o, offset, x);
261 }
262
263 /** @see #getInt(Object, long) */
264 @ForceInline
265 public long getLong(Object o, long offset) {
266 return theInternalUnsafe.getLong(o, offset);
267 }
268
269 /** @see #putInt(Object, long, int) */
270 @ForceInline
271 public void putLong(Object o, long offset, long x) {
272 theInternalUnsafe.putLong(o, offset, x);
273 }
274
275 /** @see #getInt(Object, long) */
276 @ForceInline
277 public float getFloat(Object o, long offset) {
278 return theInternalUnsafe.getFloat(o, offset);
279 }
280
281 /** @see #putInt(Object, long, int) */
282 @ForceInline
283 public void putFloat(Object o, long offset, float x) {
284 theInternalUnsafe.putFloat(o, offset, x);
285 }
286
287 /** @see #getInt(Object, long) */
288 @ForceInline
289 public double getDouble(Object o, long offset) {
290 return theInternalUnsafe.getDouble(o, offset);
291 }
292
293 /** @see #putInt(Object, long, int) */
294 @ForceInline
295 public void putDouble(Object o, long offset, double x) {
296 theInternalUnsafe.putDouble(o, offset, x);
297 }
298
299 // These work on values in the C heap.
300
301 /**
302 * Fetches a value from a given memory address. If the address is zero, or
303 * does not point into a block obtained from {@link #allocateMemory}, the
304 * results are undefined.
305 *
306 * @see #allocateMemory
307 */
308 @ForceInline
309 public byte getByte(long address) {
310 return theInternalUnsafe.getByte(address);
311 }
312
313 /**
314 * Stores a value into a given memory address. If the address is zero, or
315 * does not point into a block obtained from {@link #allocateMemory}, the
316 * results are undefined.
317 *
318 * @see #getByte(long)
319 */
320 @ForceInline
321 public void putByte(long address, byte x) {
322 theInternalUnsafe.putByte(address, x);
323 }
324
325 /** @see #getByte(long) */
326 @ForceInline
327 public short getShort(long address) {
328 return theInternalUnsafe.getShort(address);
329 }
330
331 /** @see #putByte(long, byte) */
332 @ForceInline
333 public void putShort(long address, short x) {
334 theInternalUnsafe.putShort(address, x);
335 }
336
337 /** @see #getByte(long) */
338 @ForceInline
339 public char getChar(long address) {
340 return theInternalUnsafe.getChar(address);
341 }
342
343 /** @see #putByte(long, byte) */
344 @ForceInline
345 public void putChar(long address, char x) {
346 theInternalUnsafe.putChar(address, x);
347 }
348
349 /** @see #getByte(long) */
350 @ForceInline
351 public int getInt(long address) {
352 return theInternalUnsafe.getInt(address);
353 }
354
355 /** @see #putByte(long, byte) */
356 @ForceInline
357 public void putInt(long address, int x) {
358 theInternalUnsafe.putInt(address, x);
359 }
360
361 /** @see #getByte(long) */
362 @ForceInline
363 public long getLong(long address) {
364 return theInternalUnsafe.getLong(address);
365 }
366
367 /** @see #putByte(long, byte) */
368 @ForceInline
369 public void putLong(long address, long x) {
370 theInternalUnsafe.putLong(address, x);
371 }
372
373 /** @see #getByte(long) */
374 @ForceInline
375 public float getFloat(long address) {
376 return theInternalUnsafe.getFloat(address);
377 }
378
379 /** @see #putByte(long, byte) */
380 @ForceInline
381 public void putFloat(long address, float x) {
382 theInternalUnsafe.putFloat(address, x);
383 }
384
385 /** @see #getByte(long) */
386 @ForceInline
387 public double getDouble(long address) {
388 return theInternalUnsafe.getDouble(address);
389 }
390
391 /** @see #putByte(long, byte) */
392 @ForceInline
393 public void putDouble(long address, double x) {
394 theInternalUnsafe.putDouble(address, x);
395 }
396
397
398 /**
399 * Fetches a native pointer from a given memory address. If the address is
400 * zero, or does not point into a block obtained from {@link
401 * #allocateMemory}, the results are undefined.
402 *
403 * <p>If the native pointer is less than 64 bits wide, it is extended as
404 * an unsigned number to a Java long. The pointer may be indexed by any
405 * given byte offset, simply by adding that offset (as a simple integer) to
406 * the long representing the pointer. The number of bytes actually read
407 * from the target address may be determined by consulting {@link
408 * #addressSize}.
409 *
410 * @see #allocateMemory
411 */
412 @ForceInline
413 public long getAddress(long address) {
414 return theInternalUnsafe.getAddress(address);
415 }
416
417 /**
418 * Stores a native pointer into a given memory address. If the address is
419 * zero, or does not point into a block obtained from {@link
420 * #allocateMemory}, the results are undefined.
421 *
422 * <p>The number of bytes actually written at the target address may be
423 * determined by consulting {@link #addressSize}.
424 *
425 * @see #getAddress(long)
426 */
427 @ForceInline
428 public void putAddress(long address, long x) {
429 theInternalUnsafe.putAddress(address, x);
430 }
431
432
433 /// wrappers for malloc, realloc, free:
434
435 /**
436 * Allocates a new block of native memory, of the given size in bytes. The
437 * contents of the memory are uninitialized; they will generally be
438 * garbage. The resulting native pointer will never be zero, and will be
439 * aligned for all value types. Dispose of this memory by calling {@link
440 * #freeMemory}, or resize it with {@link #reallocateMemory}.
441 *
442 * <em>Note:</em> It is the responsibility of the caller to make
443 * sure arguments are checked before the methods are called. While
444 * some rudimentary checks are performed on the input, the checks
445 * are best effort and when performance is an overriding priority,
446 * as when methods of this class are optimized by the runtime
447 * compiler, some or all checks (if any) may be elided. Hence, the
448 * caller must not rely on the checks and corresponding
449 * exceptions!
450 *
451 * @throws RuntimeException if the size is negative or too large
452 * for the native size_t type
453 *
454 * @throws OutOfMemoryError if the allocation is refused by the system
455 *
456 * @see #getByte(long)
457 * @see #putByte(long, byte)
458 */
459 @ForceInline
460 public long allocateMemory(long bytes) {
461 return theInternalUnsafe.allocateMemory(bytes);
462 }
463
464 /**
465 * Resizes a new block of native memory, to the given size in bytes. The
466 * contents of the new block past the size of the old block are
467 * uninitialized; they will generally be garbage. The resulting native
468 * pointer will be zero if and only if the requested size is zero. The
469 * resulting native pointer will be aligned for all value types. Dispose
470 * of this memory by calling {@link #freeMemory}, or resize it with {@link
471 * #reallocateMemory}. The address passed to this method may be null, in
472 * which case an allocation will be performed.
473 *
474 * <em>Note:</em> It is the responsibility of the caller to make
475 * sure arguments are checked before the methods are called. While
476 * some rudimentary checks are performed on the input, the checks
477 * are best effort and when performance is an overriding priority,
478 * as when methods of this class are optimized by the runtime
479 * compiler, some or all checks (if any) may be elided. Hence, the
480 * caller must not rely on the checks and corresponding
481 * exceptions!
482 *
483 * @throws RuntimeException if the size is negative or too large
484 * for the native size_t type
485 *
486 * @throws OutOfMemoryError if the allocation is refused by the system
487 *
488 * @see #allocateMemory
489 */
490 @ForceInline
491 public long reallocateMemory(long address, long bytes) {
492 return theInternalUnsafe.reallocateMemory(address, bytes);
493 }
494
495 /**
496 * Sets all bytes in a given block of memory to a fixed value
497 * (usually zero).
498 *
499 * <p>This method determines a block's base address by means of two parameters,
500 * and so it provides (in effect) a <em>double-register</em> addressing mode,
501 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
502 * the offset supplies an absolute base address.
503 *
504 * <p>The stores are in coherent (atomic) units of a size determined
505 * by the address and length parameters. If the effective address and
506 * length are all even modulo 8, the stores take place in 'long' units.
507 * If the effective address and length are (resp.) even modulo 4 or 2,
508 * the stores take place in units of 'int' or 'short'.
509 *
510 * <em>Note:</em> It is the responsibility of the caller to make
511 * sure arguments are checked before the methods are called. While
512 * some rudimentary checks are performed on the input, the checks
513 * are best effort and when performance is an overriding priority,
514 * as when methods of this class are optimized by the runtime
515 * compiler, some or all checks (if any) may be elided. Hence, the
516 * caller must not rely on the checks and corresponding
517 * exceptions!
518 *
519 * @throws RuntimeException if any of the arguments is invalid
520 *
521 * @since 1.7
522 */
523 @ForceInline
524 public void setMemory(Object o, long offset, long bytes, byte value) {
525 theInternalUnsafe.setMemory(o, offset, bytes, value);
526 }
527
528 /**
529 * Sets all bytes in a given block of memory to a fixed value
530 * (usually zero). This provides a <em>single-register</em> addressing mode,
531 * as discussed in {@link #getInt(Object,long)}.
532 *
533 * <p>Equivalent to {@code setMemory(null, address, bytes, value)}.
534 */
535 @ForceInline
536 public void setMemory(long address, long bytes, byte value) {
537 theInternalUnsafe.setMemory(address, bytes, value);
538 }
539
540 /**
541 * Sets all bytes in a given block of memory to a copy of another
542 * block.
543 *
544 * <p>This method determines each block's base address by means of two parameters,
545 * and so it provides (in effect) a <em>double-register</em> addressing mode,
546 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
547 * the offset supplies an absolute base address.
548 *
549 * <p>The transfers are in coherent (atomic) units of a size determined
550 * by the address and length parameters. If the effective addresses and
551 * length are all even modulo 8, the transfer takes place in 'long' units.
552 * If the effective addresses and length are (resp.) even modulo 4 or 2,
553 * the transfer takes place in units of 'int' or 'short'.
554 *
555 * <em>Note:</em> It is the responsibility of the caller to make
556 * sure arguments are checked before the methods are called. While
557 * some rudimentary checks are performed on the input, the checks
558 * are best effort and when performance is an overriding priority,
559 * as when methods of this class are optimized by the runtime
560 * compiler, some or all checks (if any) may be elided. Hence, the
561 * caller must not rely on the checks and corresponding
562 * exceptions!
563 *
564 * @throws RuntimeException if any of the arguments is invalid
565 *
566 * @since 1.7
567 */
568 @ForceInline
569 public void copyMemory(Object srcBase, long srcOffset,
570 Object destBase, long destOffset,
571 long bytes) {
572 theInternalUnsafe.copyMemory(srcBase, srcOffset, destBase, destOffset, bytes);
573 }
574
575 /**
576 * Sets all bytes in a given block of memory to a copy of another
577 * block. This provides a <em>single-register</em> addressing mode,
578 * as discussed in {@link #getInt(Object,long)}.
579 *
580 * Equivalent to {@code copyMemory(null, srcAddress, null, destAddress, bytes)}.
581 */
582 @ForceInline
583 public void copyMemory(long srcAddress, long destAddress, long bytes) {
584 theInternalUnsafe.copyMemory(srcAddress, destAddress, bytes);
585 }
586
587 /**
588 * Disposes of a block of native memory, as obtained from {@link
589 * #allocateMemory} or {@link #reallocateMemory}. The address passed to
590 * this method may be null, in which case no action is taken.
591 *
592 * <em>Note:</em> It is the responsibility of the caller to make
593 * sure arguments are checked before the methods are called. While
594 * some rudimentary checks are performed on the input, the checks
595 * are best effort and when performance is an overriding priority,
596 * as when methods of this class are optimized by the runtime
597 * compiler, some or all checks (if any) may be elided. Hence, the
598 * caller must not rely on the checks and corresponding
599 * exceptions!
600 *
601 * @throws RuntimeException if any of the arguments is invalid
602 *
603 * @see #allocateMemory
604 */
605 @ForceInline
606 public void freeMemory(long address) {
607 theInternalUnsafe.freeMemory(address);
608 }
609
610 /// random queries
611
612 /**
613 * This constant differs from all results that will ever be returned from
614 * {@link #staticFieldOffset}, {@link #objectFieldOffset},
615 * or {@link #arrayBaseOffset}.
616 */
617 public static final int INVALID_FIELD_OFFSET = jdk.internal.misc.Unsafe.INVALID_FIELD_OFFSET;
618
619 /**
620 * Reports the location of a given field in the storage allocation of its
621 * class. Do not expect to perform any sort of arithmetic on this offset;
622 * it is just a cookie which is passed to the unsafe heap memory accessors.
623 *
624 * <p>Any given field will always have the same offset and base, and no
625 * two distinct fields of the same class will ever have the same offset
626 * and base.
627 *
628 * <p>As of 1.4.1, offsets for fields are represented as long values,
629 * although the Sun JVM does not use the most significant 32 bits.
630 * However, JVM implementations which store static fields at absolute
631 * addresses can use long offsets and null base pointers to express
632 * the field locations in a form usable by {@link #getInt(Object,long)}.
633 * Therefore, code which will be ported to such JVMs on 64-bit platforms
634 * must preserve all bits of static field offsets.
635 * @see #getInt(Object, long)
636 */
637 @ForceInline
638 public long objectFieldOffset(Field f) {
639 return theInternalUnsafe.objectFieldOffset(f);
640 }
641
642 /**
643 * Reports the location of a given static field, in conjunction with {@link
644 * #staticFieldBase}.
645 * <p>Do not expect to perform any sort of arithmetic on this offset;
646 * it is just a cookie which is passed to the unsafe heap memory accessors.
647 *
648 * <p>Any given field will always have the same offset, and no two distinct
649 * fields of the same class will ever have the same offset.
650 *
651 * <p>As of 1.4.1, offsets for fields are represented as long values,
652 * although the Sun JVM does not use the most significant 32 bits.
653 * It is hard to imagine a JVM technology which needs more than
654 * a few bits to encode an offset within a non-array object,
655 * However, for consistency with other methods in this class,
656 * this method reports its result as a long value.
657 * @see #getInt(Object, long)
658 */
659 @ForceInline
660 public long staticFieldOffset(Field f) {
661 return theInternalUnsafe.staticFieldOffset(f);
662 }
663
664 /**
665 * Reports the location of a given static field, in conjunction with {@link
666 * #staticFieldOffset}.
667 * <p>Fetch the base "Object", if any, with which static fields of the
668 * given class can be accessed via methods like {@link #getInt(Object,
669 * long)}. This value may be null. This value may refer to an object
670 * which is a "cookie", not guaranteed to be a real Object, and it should
671 * not be used in any way except as argument to the get and put routines in
672 * this class.
673 */
674 @ForceInline
675 public Object staticFieldBase(Field f) {
676 return theInternalUnsafe.staticFieldBase(f);
677 }
678
679 /**
680 * Detects if the given class may need to be initialized. This is often
681 * needed in conjunction with obtaining the static field base of a
682 * class.
683 * @return false only if a call to {@code ensureClassInitialized} would have no effect
684 */
685 @ForceInline
686 public boolean shouldBeInitialized(Class<?> c) {
687 return theInternalUnsafe.shouldBeInitialized(c);
688 }
689
690 /**
691 * Ensures the given class has been initialized. This is often
692 * needed in conjunction with obtaining the static field base of a
693 * class.
694 */
695 @ForceInline
696 public void ensureClassInitialized(Class<?> c) {
697 theInternalUnsafe.ensureClassInitialized(c);
698 }
699
700 /**
701 * Reports the offset of the first element in the storage allocation of a
702 * given array class. If {@link #arrayIndexScale} returns a non-zero value
703 * for the same class, you may use that scale factor, together with this
704 * base offset, to form new offsets to access elements of arrays of the
705 * given class.
706 *
707 * @see #getInt(Object, long)
708 * @see #putInt(Object, long, int)
709 */
710 @ForceInline
711 public int arrayBaseOffset(Class<?> arrayClass) {
712 return theInternalUnsafe.arrayBaseOffset(arrayClass);
713 }
714
715 /** The value of {@code arrayBaseOffset(boolean[].class)} */
716 public static final int ARRAY_BOOLEAN_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_BOOLEAN_BASE_OFFSET;
717
718 /** The value of {@code arrayBaseOffset(byte[].class)} */
719 public static final int ARRAY_BYTE_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_BYTE_BASE_OFFSET;
720
721 /** The value of {@code arrayBaseOffset(short[].class)} */
722 public static final int ARRAY_SHORT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_SHORT_BASE_OFFSET;
723
724 /** The value of {@code arrayBaseOffset(char[].class)} */
725 public static final int ARRAY_CHAR_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_CHAR_BASE_OFFSET;
726
727 /** The value of {@code arrayBaseOffset(int[].class)} */
728 public static final int ARRAY_INT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_INT_BASE_OFFSET;
729
730 /** The value of {@code arrayBaseOffset(long[].class)} */
731 public static final int ARRAY_LONG_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_LONG_BASE_OFFSET;
732
733 /** The value of {@code arrayBaseOffset(float[].class)} */
734 public static final int ARRAY_FLOAT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_FLOAT_BASE_OFFSET;
735
736 /** The value of {@code arrayBaseOffset(double[].class)} */
737 public static final int ARRAY_DOUBLE_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_DOUBLE_BASE_OFFSET;
738
739 /** The value of {@code arrayBaseOffset(Object[].class)} */
740 public static final int ARRAY_OBJECT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_OBJECT_BASE_OFFSET;
741
742 /**
743 * Reports the scale factor for addressing elements in the storage
744 * allocation of a given array class. However, arrays of "narrow" types
745 * will generally not work properly with accessors like {@link
746 * #getByte(Object, long)}, so the scale factor for such classes is reported
747 * as zero.
748 *
749 * @see #arrayBaseOffset
750 * @see #getInt(Object, long)
751 * @see #putInt(Object, long, int)
752 */
753 @ForceInline
754 public int arrayIndexScale(Class<?> arrayClass) {
755 return theInternalUnsafe.arrayIndexScale(arrayClass);
756 }
757
758 /** The value of {@code arrayIndexScale(boolean[].class)} */
759 public static final int ARRAY_BOOLEAN_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_BOOLEAN_INDEX_SCALE;
760
761 /** The value of {@code arrayIndexScale(byte[].class)} */
762 public static final int ARRAY_BYTE_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_BYTE_INDEX_SCALE;
763
764 /** The value of {@code arrayIndexScale(short[].class)} */
765 public static final int ARRAY_SHORT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_SHORT_INDEX_SCALE;
766
767 /** The value of {@code arrayIndexScale(char[].class)} */
768 public static final int ARRAY_CHAR_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_CHAR_INDEX_SCALE;
769
770 /** The value of {@code arrayIndexScale(int[].class)} */
771 public static final int ARRAY_INT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_INT_INDEX_SCALE;
772
773 /** The value of {@code arrayIndexScale(long[].class)} */
774 public static final int ARRAY_LONG_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_LONG_INDEX_SCALE;
775
776 /** The value of {@code arrayIndexScale(float[].class)} */
777 public static final int ARRAY_FLOAT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_FLOAT_INDEX_SCALE;
778
779 /** The value of {@code arrayIndexScale(double[].class)} */
780 public static final int ARRAY_DOUBLE_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_DOUBLE_INDEX_SCALE;
781
782 /** The value of {@code arrayIndexScale(Object[].class)} */
783 public static final int ARRAY_OBJECT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_OBJECT_INDEX_SCALE;
784
785 /**
786 * Reports the size in bytes of a native pointer, as stored via {@link
787 * #putAddress}. This value will be either 4 or 8. Note that the sizes of
788 * other primitive types (as stored in native memory blocks) is determined
789 * fully by their information content.
790 */
791 @ForceInline
792 public int addressSize() {
793 return theInternalUnsafe.addressSize();
794 }
795
796 /** The value of {@code addressSize()} */
797 public static final int ADDRESS_SIZE = theInternalUnsafe.addressSize();
798
799 /**
800 * Reports the size in bytes of a native memory page (whatever that is).
801 * This value will always be a power of two.
802 */
803 @ForceInline
804 public int pageSize() {
805 return theInternalUnsafe.pageSize();
806 }
807
808
809 /// random trusted operations from JNI:
810
811 /**
812 * Defines a class but does not make it known to the class loader or system dictionary.
813 * <p>
814 * For each CP entry, the corresponding CP patch must either be null or have
815 * the a format that matches its tag:
816 * <ul>
817 * <li>Integer, Long, Float, Double: the corresponding wrapper object type from java.lang
818 * <li>Utf8: a string (must have suitable syntax if used as signature or name)
819 * <li>Class: any java.lang.Class object
820 * <li>String: any object (not just a java.lang.String)
821 * <li>InterfaceMethodRef: (NYI) a method handle to invoke on that call site's arguments
822 * </ul>
823 * @param hostClass context for linkage, access control, protection domain, and class loader
824 * @param data bytes of a class file
825 * @param cpPatches where non-null entries exist, they replace corresponding CP entries in data
826 */
827 @ForceInline
828 public Class<?> defineAnonymousClass(Class<?> hostClass, byte[] data, Object[] cpPatches) {
829 return theInternalUnsafe.defineAnonymousClass(hostClass, data, cpPatches);
830 }
831
832 /**
833 * Allocates an instance but does not run any constructor.
834 * Initializes the class if it has not yet been.
835 */
836 @ForceInline
837 public Object allocateInstance(Class<?> cls)
838 throws InstantiationException {
839 return theInternalUnsafe.allocateInstance(cls);
840 }
841
842 /** Throws the exception without telling the verifier. */
843 @ForceInline
844 public void throwException(Throwable ee) {
845 theInternalUnsafe.throwException(ee);
846 }
847
848 /**
849 * Atomically updates Java variable to {@code x} if it is currently
850 * holding {@code expected}.
851 *
852 * <p>This operation has memory semantics of a {@code volatile} read
853 * and write. Corresponds to C11 atomic_compare_exchange_strong.
854 *
855 * @return {@code true} if successful
856 */
857 @ForceInline
858 public final boolean compareAndSwapObject(Object o, long offset,
859 Object expected,
860 Object x) {
861 return theInternalUnsafe.compareAndSetReference(o, offset, expected, x);
862 }
863
864 /**
865 * Atomically updates Java variable to {@code x} if it is currently
866 * holding {@code expected}.
867 *
868 * <p>This operation has memory semantics of a {@code volatile} read
869 * and write. Corresponds to C11 atomic_compare_exchange_strong.
870 *
871 * @return {@code true} if successful
872 */
873 @ForceInline
874 public final boolean compareAndSwapInt(Object o, long offset,
875 int expected,
876 int x) {
877 return theInternalUnsafe.compareAndSetInt(o, offset, expected, x);
878 }
879
880 /**
881 * Atomically updates Java variable to {@code x} if it is currently
882 * holding {@code expected}.
883 *
884 * <p>This operation has memory semantics of a {@code volatile} read
885 * and write. Corresponds to C11 atomic_compare_exchange_strong.
886 *
887 * @return {@code true} if successful
888 */
889 @ForceInline
890 public final boolean compareAndSwapLong(Object o, long offset,
891 long expected,
892 long x) {
893 return theInternalUnsafe.compareAndSetLong(o, offset, expected, x);
894 }
895
896 /**
897 * Fetches a reference value from a given Java variable, with volatile
898 * load semantics. Otherwise identical to {@link #getObject(Object, long)}
899 */
900 @ForceInline
901 public Object getObjectVolatile(Object o, long offset) {
902 return theInternalUnsafe.getReferenceVolatile(o, offset);
903 }
904
905 /**
906 * Stores a reference value into a given Java variable, with
907 * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)}
908 */
909 @ForceInline
910 public void putObjectVolatile(Object o, long offset, Object x) {
911 theInternalUnsafe.putReferenceVolatile(o, offset, x);
912 }
913
914 /** Volatile version of {@link #getInt(Object, long)} */
915 @ForceInline
916 public int getIntVolatile(Object o, long offset) {
917 return theInternalUnsafe.getIntVolatile(o, offset);
918 }
919
920 /** Volatile version of {@link #putInt(Object, long, int)} */
921 @ForceInline
922 public void putIntVolatile(Object o, long offset, int x) {
923 theInternalUnsafe.putIntVolatile(o, offset, x);
924 }
925
926 /** Volatile version of {@link #getBoolean(Object, long)} */
927 @ForceInline
928 public boolean getBooleanVolatile(Object o, long offset) {
929 return theInternalUnsafe.getBooleanVolatile(o, offset);
930 }
931
932 /** Volatile version of {@link #putBoolean(Object, long, boolean)} */
933 @ForceInline
934 public void putBooleanVolatile(Object o, long offset, boolean x) {
935 theInternalUnsafe.putBooleanVolatile(o, offset, x);
936 }
937
938 /** Volatile version of {@link #getByte(Object, long)} */
939 @ForceInline
940 public byte getByteVolatile(Object o, long offset) {
941 return theInternalUnsafe.getByteVolatile(o, offset);
942 }
943
944 /** Volatile version of {@link #putByte(Object, long, byte)} */
945 @ForceInline
946 public void putByteVolatile(Object o, long offset, byte x) {
947 theInternalUnsafe.putByteVolatile(o, offset, x);
948 }
949
950 /** Volatile version of {@link #getShort(Object, long)} */
951 @ForceInline
952 public short getShortVolatile(Object o, long offset) {
953 return theInternalUnsafe.getShortVolatile(o, offset);
954 }
955
956 /** Volatile version of {@link #putShort(Object, long, short)} */
957 @ForceInline
958 public void putShortVolatile(Object o, long offset, short x) {
959 theInternalUnsafe.putShortVolatile(o, offset, x);
960 }
961
962 /** Volatile version of {@link #getChar(Object, long)} */
963 @ForceInline
964 public char getCharVolatile(Object o, long offset) {
965 return theInternalUnsafe.getCharVolatile(o, offset);
966 }
967
968 /** Volatile version of {@link #putChar(Object, long, char)} */
969 @ForceInline
970 public void putCharVolatile(Object o, long offset, char x) {
971 theInternalUnsafe.putCharVolatile(o, offset, x);
972 }
973
974 /** Volatile version of {@link #getLong(Object, long)} */
975 @ForceInline
976 public long getLongVolatile(Object o, long offset) {
977 return theInternalUnsafe.getLongVolatile(o, offset);
978 }
979
980 /** Volatile version of {@link #putLong(Object, long, long)} */
981 @ForceInline
982 public void putLongVolatile(Object o, long offset, long x) {
983 theInternalUnsafe.putLongVolatile(o, offset, x);
984 }
985
986 /** Volatile version of {@link #getFloat(Object, long)} */
987 @ForceInline
988 public float getFloatVolatile(Object o, long offset) {
989 return theInternalUnsafe.getFloatVolatile(o, offset);
990 }
991
992 /** Volatile version of {@link #putFloat(Object, long, float)} */
993 @ForceInline
994 public void putFloatVolatile(Object o, long offset, float x) {
995 theInternalUnsafe.putFloatVolatile(o, offset, x);
996 }
997
998 /** Volatile version of {@link #getDouble(Object, long)} */
999 @ForceInline
1000 public double getDoubleVolatile(Object o, long offset) {
1001 return theInternalUnsafe.getDoubleVolatile(o, offset);
1002 }
1003
1004 /** Volatile version of {@link #putDouble(Object, long, double)} */
1005 @ForceInline
1006 public void putDoubleVolatile(Object o, long offset, double x) {
1007 theInternalUnsafe.putDoubleVolatile(o, offset, x);
1008 }
1009
1010 /**
1011 * Version of {@link #putObjectVolatile(Object, long, Object)}
1012 * that does not guarantee immediate visibility of the store to
1013 * other threads. This method is generally only useful if the
1014 * underlying field is a Java volatile (or if an array cell, one
1015 * that is otherwise only accessed using volatile accesses).
1016 *
1017 * Corresponds to C11 atomic_store_explicit(..., memory_order_release).
1018 */
1019 @ForceInline
1020 public void putOrderedObject(Object o, long offset, Object x) {
1021 theInternalUnsafe.putReferenceRelease(o, offset, x);
1022 }
1023
1024 /** Ordered/Lazy version of {@link #putIntVolatile(Object, long, int)} */
1025 @ForceInline
1026 public void putOrderedInt(Object o, long offset, int x) {
1027 theInternalUnsafe.putIntRelease(o, offset, x);
1028 }
1029
1030 /** Ordered/Lazy version of {@link #putLongVolatile(Object, long, long)} */
1031 @ForceInline
1032 public void putOrderedLong(Object o, long offset, long x) {
1033 theInternalUnsafe.putLongRelease(o, offset, x);
1034 }
1035
1036 /**
1037 * Unblocks the given thread blocked on {@code park}, or, if it is
1038 * not blocked, causes the subsequent call to {@code park} not to
1039 * block. Note: this operation is "unsafe" solely because the
1040 * caller must somehow ensure that the thread has not been
1041 * destroyed. Nothing special is usually required to ensure this
1042 * when called from Java (in which there will ordinarily be a live
1043 * reference to the thread) but this is not nearly-automatically
1044 * so when calling from native code.
1045 *
1046 * @param thread the thread to unpark.
1047 */
1048 @ForceInline
1049 public void unpark(Object thread) {
1050 theInternalUnsafe.unpark(thread);
1051 }
1052
1053 /**
1054 * Blocks current thread, returning when a balancing
1055 * {@code unpark} occurs, or a balancing {@code unpark} has
1056 * already occurred, or the thread is interrupted, or, if not
1057 * absolute and time is not zero, the given time nanoseconds have
1058 * elapsed, or if absolute, the given deadline in milliseconds
1059 * since Epoch has passed, or spuriously (i.e., returning for no
1060 * "reason"). Note: This operation is in the Unsafe class only
1061 * because {@code unpark} is, so it would be strange to place it
1062 * elsewhere.
1063 */
1064 @ForceInline
1065 public void park(boolean isAbsolute, long time) {
1066 theInternalUnsafe.park(isAbsolute, time);
1067 }
1068
1069 /**
1070 * Gets the load average in the system run queue assigned
1071 * to the available processors averaged over various periods of time.
1072 * This method retrieves the given {@code nelem} samples and
1073 * assigns to the elements of the given {@code loadavg} array.
1074 * The system imposes a maximum of 3 samples, representing
1075 * averages over the last 1, 5, and 15 minutes, respectively.
1076 *
1077 * @param loadavg an array of double of size nelems
1078 * @param nelems the number of samples to be retrieved and
1079 * must be 1 to 3.
1080 *
1081 * @return the number of samples actually retrieved; or -1
1082 * if the load average is unobtainable.
1083 */
1084 @ForceInline
1085 public int getLoadAverage(double[] loadavg, int nelems) {
1086 return theInternalUnsafe.getLoadAverage(loadavg, nelems);
1087 }
1088
1089 // The following contain CAS-based Java implementations used on
1090 // platforms not supporting native instructions
1091
1092 /**
1093 * Atomically adds the given value to the current value of a field
1094 * or array element within the given object {@code o}
1095 * at the given {@code offset}.
1096 *
1097 * @param o object/array to update the field/element in
1098 * @param offset field/element offset
1099 * @param delta the value to add
1100 * @return the previous value
1101 * @since 1.8
1102 */
1103 @ForceInline
1104 public final int getAndAddInt(Object o, long offset, int delta) {
1105 return theInternalUnsafe.getAndAddInt(o, offset, delta);
1106 }
1107
1108 /**
1109 * Atomically adds the given value to the current value of a field
1110 * or array element within the given object {@code o}
1111 * at the given {@code offset}.
1112 *
1113 * @param o object/array to update the field/element in
1114 * @param offset field/element offset
1115 * @param delta the value to add
1116 * @return the previous value
1117 * @since 1.8
1118 */
1119 @ForceInline
1120 public final long getAndAddLong(Object o, long offset, long delta) {
1121 return theInternalUnsafe.getAndAddLong(o, offset, delta);
1122 }
1123
1124 /**
1125 * Atomically exchanges the given value with the current value of
1126 * a field or array element within the given object {@code o}
1127 * at the given {@code offset}.
1128 *
1129 * @param o object/array to update the field/element in
1130 * @param offset field/element offset
1131 * @param newValue new value
1132 * @return the previous value
1133 * @since 1.8
1134 */
1135 @ForceInline
1136 public final int getAndSetInt(Object o, long offset, int newValue) {
1137 return theInternalUnsafe.getAndSetInt(o, offset, newValue);
1138 }
1139
1140 /**
1141 * Atomically exchanges the given value with the current value of
1142 * a field or array element within the given object {@code o}
1143 * at the given {@code offset}.
1144 *
1145 * @param o object/array to update the field/element in
1146 * @param offset field/element offset
1147 * @param newValue new value
1148 * @return the previous value
1149 * @since 1.8
1150 */
1151 @ForceInline
1152 public final long getAndSetLong(Object o, long offset, long newValue) {
1153 return theInternalUnsafe.getAndSetLong(o, offset, newValue);
1154 }
1155
1156 /**
1157 * Atomically exchanges the given reference value with the current
1158 * reference value of a field or array element within the given
1159 * object {@code o} at the given {@code offset}.
1160 *
1161 * @param o object/array to update the field/element in
1162 * @param offset field/element offset
1163 * @param newValue new value
1164 * @return the previous value
1165 * @since 1.8
1166 */
1167 @ForceInline
1168 public final Object getAndSetObject(Object o, long offset, Object newValue) {
1169 return theInternalUnsafe.getAndSetReference(o, offset, newValue);
1170 }
1171
1172
1173 /**
1174 * Ensures that loads before the fence will not be reordered with loads and
1175 * stores after the fence; a "LoadLoad plus LoadStore barrier".
1176 *
1177 * Corresponds to C11 atomic_thread_fence(memory_order_acquire)
1178 * (an "acquire fence").
1179 *
1180 * A pure LoadLoad fence is not provided, since the addition of LoadStore
1181 * is almost always desired, and most current hardware instructions that
1182 * provide a LoadLoad barrier also provide a LoadStore barrier for free.
1183 * @since 1.8
1184 */
1185 @ForceInline
1186 public void loadFence() {
1187 theInternalUnsafe.loadFence();
1188 }
1189
1190 /**
1191 * Ensures that loads and stores before the fence will not be reordered with
1192 * stores after the fence; a "StoreStore plus LoadStore barrier".
1193 *
1194 * Corresponds to C11 atomic_thread_fence(memory_order_release)
1195 * (a "release fence").
1196 *
1197 * A pure StoreStore fence is not provided, since the addition of LoadStore
1198 * is almost always desired, and most current hardware instructions that
1199 * provide a StoreStore barrier also provide a LoadStore barrier for free.
1200 * @since 1.8
1201 */
1202 @ForceInline
1203 public void storeFence() {
1204 theInternalUnsafe.storeFence();
1205 }
1206
1207 /**
1208 * Ensures that loads and stores before the fence will not be reordered
1209 * with loads and stores after the fence. Implies the effects of both
1210 * loadFence() and storeFence(), and in addition, the effect of a StoreLoad
1211 * barrier.
1212 *
1213 * Corresponds to C11 atomic_thread_fence(memory_order_seq_cst).
1214 * @since 1.8
1215 */
1216 @ForceInline
1217 public void fullFence() {
1218 theInternalUnsafe.fullFence();
1219 }
1220
1221 /**
1222 * Invokes the given direct byte buffer's cleaner, if any.
1223 *
1224 * @param directBuffer a direct byte buffer
1225 * @throws NullPointerException if {@code directBuffer} is null
1226 * @throws IllegalArgumentException if {@code directBuffer} is non-direct,
1227 * or is a {@link java.nio.Buffer#slice slice}, or is a
1228 * {@link java.nio.Buffer#duplicate duplicate}
1229 * @since 9
1230 */
1231 public void invokeCleaner(java.nio.ByteBuffer directBuffer) {
1232 if (!directBuffer.isDirect())
1233 throw new IllegalArgumentException("buffer is non-direct");
1234
1235 theInternalUnsafe.invokeCleaner(directBuffer);
1236 }
1237 }