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