1 /*
   2  * Copyright (c) 2000, 2022, 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.value.PrimitiveClass;
  29 import jdk.internal.vm.annotation.ForceInline;
  30 import jdk.internal.misc.VM;
  31 import jdk.internal.reflect.CallerSensitive;
  32 import jdk.internal.reflect.Reflection;
  33 
  34 import java.lang.reflect.Field;
  35 import java.util.Set;
  36 
  37 
  38 /**
  39  * A collection of methods for performing low-level, unsafe operations.
  40  * Although the class and all methods are public, use of this class is
  41  * limited because only trusted code can obtain instances of it.
  42  *
  43  * <em>Note:</em> It is the responsibility of the caller to make sure
  44  * arguments are checked before methods of this class are
  45  * called. While some rudimentary checks are performed on the input,
  46  * the checks are best effort and when performance is an overriding
  47  * priority, as when methods of this class are optimized by the
  48  * runtime compiler, some or all checks (if any) may be elided. Hence,
  49  * the caller must not rely on the checks and corresponding
  50  * exceptions!
  51  *
  52  * @author John R. Rose
  53  * @see #getUnsafe
  54  */
  55 
  56 public final class Unsafe {
  57 
  58     static {
  59         Reflection.registerMethodsToFilter(Unsafe.class, Set.of("getUnsafe"));
  60     }
  61 
  62     private Unsafe() {}
  63 
  64     private static final Unsafe theUnsafe = new Unsafe();
  65     private static final jdk.internal.misc.Unsafe theInternalUnsafe = jdk.internal.misc.Unsafe.getUnsafe();
  66 
  67     /**
  68      * Provides the caller with the capability of performing unsafe
  69      * operations.
  70      *
  71      * <p>The returned {@code Unsafe} object should be carefully guarded
  72      * by the caller, since it can be used to read and write data at arbitrary
  73      * memory addresses.  It must never be passed to untrusted code.
  74      *
  75      * <p>Most methods in this class are very low-level, and correspond to a
  76      * small number of hardware instructions (on typical machines).  Compilers
  77      * are encouraged to optimize these methods accordingly.
  78      *
  79      * <p>Here is a suggested idiom for using unsafe operations:
  80      *
  81      * <pre> {@code
  82      * class MyTrustedClass {
  83      *   private static final Unsafe unsafe = Unsafe.getUnsafe();
  84      *   ...
  85      *   private long myCountAddress = ...;
  86      *   public int getCount() { return unsafe.getByte(myCountAddress); }
  87      * }}</pre>
  88      *
  89      * (It may assist compilers to make the local variable {@code final}.)
  90      *
  91      * @throws  SecurityException if the class loader of the caller
  92      *          class is not in the system domain in which all permissions
  93      *          are granted.
  94      */
  95     @CallerSensitive
  96     public static Unsafe getUnsafe() {
  97         Class<?> caller = Reflection.getCallerClass();
  98         if (!VM.isSystemDomainLoader(caller.getClassLoader()))
  99             throw new SecurityException("Unsafe");
 100         return theUnsafe;
 101     }
 102 
 103     /// peek and poke operations
 104     /// (compilers should optimize these to memory ops)
 105 
 106     // These work on object fields in the Java heap.
 107     // They will not work on elements of packed arrays.
 108 
 109     /**
 110      * Fetches a value from a given Java variable.
 111      * More specifically, fetches a field or array element within the given
 112      * object {@code o} at the given offset, or (if {@code o} is null)
 113      * from the memory address whose numerical value is the given offset.
 114      * <p>
 115      * The results are undefined unless one of the following cases is true:
 116      * <ul>
 117      * <li>The offset was obtained from {@link #objectFieldOffset} on
 118      * the {@link java.lang.reflect.Field} of some Java field and the object
 119      * referred to by {@code o} is of a class compatible with that
 120      * field's class.
 121      *
 122      * <li>The offset and object reference {@code o} (either null or
 123      * non-null) were both obtained via {@link #staticFieldOffset}
 124      * and {@link #staticFieldBase} (respectively) from the
 125      * reflective {@link Field} representation of some Java field.
 126      *
 127      * <li>The object referred to by {@code o} is an array, and the offset
 128      * is an integer of the form {@code B+N*S}, where {@code N} is
 129      * a valid index into the array, and {@code B} and {@code S} are
 130      * the values obtained by {@link #arrayBaseOffset} and {@link
 131      * #arrayIndexScale} (respectively) from the array's class.  The value
 132      * referred to is the {@code N}<em>th</em> element of the array.
 133      *
 134      * </ul>
 135      * <p>
 136      * If one of the above cases is true, the call references a specific Java
 137      * variable (field or array element).  However, the results are undefined
 138      * if that variable is not in fact of the type returned by this method.
 139      * <p>
 140      * This method refers to a variable by means of two parameters, and so
 141      * it provides (in effect) a <em>double-register</em> addressing mode
 142      * for Java variables.  When the object reference is null, this method
 143      * uses its offset as an absolute address.  This is similar in operation
 144      * to methods such as {@link #getInt(long)}, which provide (in effect) a
 145      * <em>single-register</em> addressing mode for non-Java variables.
 146      * However, because Java variables may have a different layout in memory
 147      * from non-Java variables, programmers should not assume that these
 148      * two addressing modes are ever equivalent.  Also, programmers should
 149      * remember that offsets from the double-register addressing mode cannot
 150      * be portably confused with longs used in the single-register addressing
 151      * mode.
 152      *
 153      * @param o Java heap object in which the variable resides, if any, else
 154      *        null
 155      * @param offset indication of where the variable resides in a Java heap
 156      *        object, if any, else a memory address locating the variable
 157      *        statically
 158      * @return the value fetched from the indicated Java variable
 159      * @throws RuntimeException No defined exceptions are thrown, not even
 160      *         {@link NullPointerException}
 161      */
 162     @ForceInline
 163     public int getInt(Object o, long offset) {
 164         return theInternalUnsafe.getInt(o, offset);
 165     }
 166 
 167     /**
 168      * Stores a value into a given Java variable.
 169      * <p>
 170      * The first two parameters are interpreted exactly as with
 171      * {@link #getInt(Object, long)} to refer to a specific
 172      * Java variable (field or array element).  The given value
 173      * is stored into that variable.
 174      * <p>
 175      * The variable must be of the same type as the method
 176      * parameter {@code x}.
 177      *
 178      * @param o Java heap object in which the variable resides, if any, else
 179      *        null
 180      * @param offset indication of where the variable resides in a Java heap
 181      *        object, if any, else a memory address locating the variable
 182      *        statically
 183      * @param x the value to store into the indicated Java variable
 184      * @throws RuntimeException No defined exceptions are thrown, not even
 185      *         {@link NullPointerException}
 186      */
 187     @ForceInline
 188     public void putInt(Object o, long offset, int x) {
 189         theInternalUnsafe.putInt(o, offset, x);
 190     }
 191 
 192     /**
 193      * Fetches a reference value from a given Java variable.
 194      * @see #getInt(Object, long)
 195      */
 196     @ForceInline
 197     public Object getObject(Object o, long offset) {
 198         return theInternalUnsafe.getReference(o, offset);
 199     }
 200 
 201     /**
 202      * Stores a reference value into a given Java variable.
 203      * <p>
 204      * Unless the reference {@code x} being stored is either null
 205      * or matches the field type, the results are undefined.
 206      * If the reference {@code o} is non-null, card marks or
 207      * other store barriers for that object (if the VM requires them)
 208      * are updated.
 209      * @see #putInt(Object, long, int)
 210      */
 211     @ForceInline
 212     public void putObject(Object o, long offset, Object x) {
 213         theInternalUnsafe.putReference(o, offset, x);
 214     }
 215 
 216     /** @see #getInt(Object, long) */
 217     @ForceInline
 218     public boolean getBoolean(Object o, long offset) {
 219         return theInternalUnsafe.getBoolean(o, offset);
 220     }
 221 
 222     /** @see #putInt(Object, long, int) */
 223     @ForceInline
 224     public void putBoolean(Object o, long offset, boolean x) {
 225         theInternalUnsafe.putBoolean(o, offset, x);
 226     }
 227 
 228     /** @see #getInt(Object, long) */
 229     @ForceInline
 230     public byte getByte(Object o, long offset) {
 231         return theInternalUnsafe.getByte(o, offset);
 232     }
 233 
 234     /** @see #putInt(Object, long, int) */
 235     @ForceInline
 236     public void putByte(Object o, long offset, byte x) {
 237         theInternalUnsafe.putByte(o, offset, x);
 238     }
 239 
 240     /** @see #getInt(Object, long) */
 241     @ForceInline
 242     public short getShort(Object o, long offset) {
 243         return theInternalUnsafe.getShort(o, offset);
 244     }
 245 
 246     /** @see #putInt(Object, long, int) */
 247     @ForceInline
 248     public void putShort(Object o, long offset, short x) {
 249         theInternalUnsafe.putShort(o, offset, x);
 250     }
 251 
 252     /** @see #getInt(Object, long) */
 253     @ForceInline
 254     public char getChar(Object o, long offset) {
 255         return theInternalUnsafe.getChar(o, offset);
 256     }
 257 
 258     /** @see #putInt(Object, long, int) */
 259     @ForceInline
 260     public void putChar(Object o, long offset, char x) {
 261         theInternalUnsafe.putChar(o, offset, x);
 262     }
 263 
 264     /** @see #getInt(Object, long) */
 265     @ForceInline
 266     public long getLong(Object o, long offset) {
 267         return theInternalUnsafe.getLong(o, offset);
 268     }
 269 
 270     /** @see #putInt(Object, long, int) */
 271     @ForceInline
 272     public void putLong(Object o, long offset, long x) {
 273         theInternalUnsafe.putLong(o, offset, x);
 274     }
 275 
 276     /** @see #getInt(Object, long) */
 277     @ForceInline
 278     public float getFloat(Object o, long offset) {
 279         return theInternalUnsafe.getFloat(o, offset);
 280     }
 281 
 282     /** @see #putInt(Object, long, int) */
 283     @ForceInline
 284     public void putFloat(Object o, long offset, float x) {
 285         theInternalUnsafe.putFloat(o, offset, x);
 286     }
 287 
 288     /** @see #getInt(Object, long) */
 289     @ForceInline
 290     public double getDouble(Object o, long offset) {
 291         return theInternalUnsafe.getDouble(o, offset);
 292     }
 293 
 294     /** @see #putInt(Object, long, int) */
 295     @ForceInline
 296     public void putDouble(Object o, long offset, double x) {
 297         theInternalUnsafe.putDouble(o, offset, x);
 298     }
 299 
 300     // These work on values in the C heap.
 301 
 302     /**
 303      * Fetches a value from a given memory address.  If the address is zero, or
 304      * does not point into a block obtained from {@link #allocateMemory}, the
 305      * results are undefined.
 306      *
 307      * @see #allocateMemory
 308      */
 309     @ForceInline
 310     public byte getByte(long address) {
 311         return theInternalUnsafe.getByte(address);
 312     }
 313 
 314     /**
 315      * Stores a value into a given memory address.  If the address is zero, or
 316      * does not point into a block obtained from {@link #allocateMemory}, the
 317      * results are undefined.
 318      *
 319      * @see #getByte(long)
 320      */
 321     @ForceInline
 322     public void putByte(long address, byte x) {
 323         theInternalUnsafe.putByte(address, x);
 324     }
 325 
 326     /** @see #getByte(long) */
 327     @ForceInline
 328     public short getShort(long address) {
 329         return theInternalUnsafe.getShort(address);
 330     }
 331 
 332     /** @see #putByte(long, byte) */
 333     @ForceInline
 334     public void putShort(long address, short x) {
 335         theInternalUnsafe.putShort(address, x);
 336     }
 337 
 338     /** @see #getByte(long) */
 339     @ForceInline
 340     public char getChar(long address) {
 341         return theInternalUnsafe.getChar(address);
 342     }
 343 
 344     /** @see #putByte(long, byte) */
 345     @ForceInline
 346     public void putChar(long address, char x) {
 347         theInternalUnsafe.putChar(address, x);
 348     }
 349 
 350     /** @see #getByte(long) */
 351     @ForceInline
 352     public int getInt(long address) {
 353         return theInternalUnsafe.getInt(address);
 354     }
 355 
 356     /** @see #putByte(long, byte) */
 357     @ForceInline
 358     public void putInt(long address, int x) {
 359         theInternalUnsafe.putInt(address, x);
 360     }
 361 
 362     /** @see #getByte(long) */
 363     @ForceInline
 364     public long getLong(long address) {
 365         return theInternalUnsafe.getLong(address);
 366     }
 367 
 368     /** @see #putByte(long, byte) */
 369     @ForceInline
 370     public void putLong(long address, long x) {
 371         theInternalUnsafe.putLong(address, x);
 372     }
 373 
 374     /** @see #getByte(long) */
 375     @ForceInline
 376     public float getFloat(long address) {
 377         return theInternalUnsafe.getFloat(address);
 378     }
 379 
 380     /** @see #putByte(long, byte) */
 381     @ForceInline
 382     public void putFloat(long address, float x) {
 383         theInternalUnsafe.putFloat(address, x);
 384     }
 385 
 386     /** @see #getByte(long) */
 387     @ForceInline
 388     public double getDouble(long address) {
 389         return theInternalUnsafe.getDouble(address);
 390     }
 391 
 392     /** @see #putByte(long, byte) */
 393     @ForceInline
 394     public void putDouble(long address, double x) {
 395         theInternalUnsafe.putDouble(address, x);
 396     }
 397 
 398 
 399     /**
 400      * Fetches a native pointer from a given memory address.  If the address is
 401      * zero, or does not point into a block obtained from {@link
 402      * #allocateMemory}, the results are undefined.
 403      *
 404      * <p>If the native pointer is less than 64 bits wide, it is extended as
 405      * an unsigned number to a Java long.  The pointer may be indexed by any
 406      * given byte offset, simply by adding that offset (as a simple integer) to
 407      * the long representing the pointer.  The number of bytes actually read
 408      * from the target address may be determined by consulting {@link
 409      * #addressSize}.
 410      *
 411      * @see #allocateMemory
 412      */
 413     @ForceInline
 414     public long getAddress(long address) {
 415         return theInternalUnsafe.getAddress(address);
 416     }
 417 
 418     /**
 419      * Stores a native pointer into a given memory address.  If the address is
 420      * zero, or does not point into a block obtained from {@link
 421      * #allocateMemory}, the results are undefined.
 422      *
 423      * <p>The number of bytes actually written at the target address may be
 424      * determined by consulting {@link #addressSize}.
 425      *
 426      * @see #getAddress(long)
 427      */
 428     @ForceInline
 429     public void putAddress(long address, long x) {
 430         theInternalUnsafe.putAddress(address, x);
 431     }
 432 
 433 
 434     /// wrappers for malloc, realloc, free:
 435 
 436     /**
 437      * Allocates a new block of native memory, of the given size in bytes.  The
 438      * contents of the memory are uninitialized; they will generally be
 439      * garbage.  The resulting native pointer will never be zero, and will be
 440      * aligned for all value types.  Dispose of this memory by calling {@link
 441      * #freeMemory}, or resize it with {@link #reallocateMemory}.
 442      *
 443      * <em>Note:</em> It is the responsibility of the caller to make
 444      * sure arguments are checked before the methods are called. While
 445      * some rudimentary checks are performed on the input, the checks
 446      * are best effort and when performance is an overriding priority,
 447      * as when methods of this class are optimized by the runtime
 448      * compiler, some or all checks (if any) may be elided. Hence, the
 449      * caller must not rely on the checks and corresponding
 450      * exceptions!
 451      *
 452      * @throws RuntimeException if the size is negative or too large
 453      *         for the native size_t type
 454      *
 455      * @throws OutOfMemoryError if the allocation is refused by the system
 456      *
 457      * @see #getByte(long)
 458      * @see #putByte(long, byte)
 459      */
 460     @ForceInline
 461     public long allocateMemory(long bytes) {
 462         return theInternalUnsafe.allocateMemory(bytes);
 463     }
 464 
 465     /**
 466      * Resizes a new block of native memory, to the given size in bytes.  The
 467      * contents of the new block past the size of the old block are
 468      * uninitialized; they will generally be garbage.  The resulting native
 469      * pointer will be zero if and only if the requested size is zero.  The
 470      * resulting native pointer will be aligned for all value types.  Dispose
 471      * of this memory by calling {@link #freeMemory}, or resize it with {@link
 472      * #reallocateMemory}.  The address passed to this method may be null, in
 473      * which case an allocation will be performed.
 474      *
 475      * <em>Note:</em> It is the responsibility of the caller to make
 476      * sure arguments are checked before the methods are called. While
 477      * some rudimentary checks are performed on the input, the checks
 478      * are best effort and when performance is an overriding priority,
 479      * as when methods of this class are optimized by the runtime
 480      * compiler, some or all checks (if any) may be elided. Hence, the
 481      * caller must not rely on the checks and corresponding
 482      * exceptions!
 483      *
 484      * @throws RuntimeException if the size is negative or too large
 485      *         for the native size_t type
 486      *
 487      * @throws OutOfMemoryError if the allocation is refused by the system
 488      *
 489      * @see #allocateMemory
 490      */
 491     @ForceInline
 492     public long reallocateMemory(long address, long bytes) {
 493         return theInternalUnsafe.reallocateMemory(address, bytes);
 494     }
 495 
 496     /**
 497      * Sets all bytes in a given block of memory to a fixed value
 498      * (usually zero).
 499      *
 500      * <p>This method determines a block's base address by means of two parameters,
 501      * and so it provides (in effect) a <em>double-register</em> addressing mode,
 502      * as discussed in {@link #getInt(Object,long)}.  When the object reference is null,
 503      * the offset supplies an absolute base address.
 504      *
 505      * <p>The stores are in coherent (atomic) units of a size determined
 506      * by the address and length parameters.  If the effective address and
 507      * length are all even modulo 8, the stores take place in 'long' units.
 508      * If the effective address and length are (resp.) even modulo 4 or 2,
 509      * the stores take place in units of 'int' or 'short'.
 510      *
 511      * <em>Note:</em> It is the responsibility of the caller to make
 512      * sure arguments are checked before the methods are called. While
 513      * some rudimentary checks are performed on the input, the checks
 514      * are best effort and when performance is an overriding priority,
 515      * as when methods of this class are optimized by the runtime
 516      * compiler, some or all checks (if any) may be elided. Hence, the
 517      * caller must not rely on the checks and corresponding
 518      * exceptions!
 519      *
 520      * @throws RuntimeException if any of the arguments is invalid
 521      *
 522      * @since 1.7
 523      */
 524     @ForceInline
 525     public void setMemory(Object o, long offset, long bytes, byte value) {
 526         theInternalUnsafe.setMemory(o, offset, bytes, value);
 527     }
 528 
 529     /**
 530      * Sets all bytes in a given block of memory to a fixed value
 531      * (usually zero).  This provides a <em>single-register</em> addressing mode,
 532      * as discussed in {@link #getInt(Object,long)}.
 533      *
 534      * <p>Equivalent to {@code setMemory(null, address, bytes, value)}.
 535      */
 536     @ForceInline
 537     public void setMemory(long address, long bytes, byte value) {
 538         theInternalUnsafe.setMemory(address, bytes, value);
 539     }
 540 
 541     /**
 542      * Sets all bytes in a given block of memory to a copy of another
 543      * block.
 544      *
 545      * <p>This method determines each block's base address by means of two parameters,
 546      * and so it provides (in effect) a <em>double-register</em> addressing mode,
 547      * as discussed in {@link #getInt(Object,long)}.  When the object reference is null,
 548      * the offset supplies an absolute base address.
 549      *
 550      * <p>The transfers are in coherent (atomic) units of a size determined
 551      * by the address and length parameters.  If the effective addresses and
 552      * length are all even modulo 8, the transfer takes place in 'long' units.
 553      * If the effective addresses and length are (resp.) even modulo 4 or 2,
 554      * the transfer takes place in units of 'int' or 'short'.
 555      *
 556      * <em>Note:</em> It is the responsibility of the caller to make
 557      * sure arguments are checked before the methods are called. While
 558      * some rudimentary checks are performed on the input, the checks
 559      * are best effort and when performance is an overriding priority,
 560      * as when methods of this class are optimized by the runtime
 561      * compiler, some or all checks (if any) may be elided. Hence, the
 562      * caller must not rely on the checks and corresponding
 563      * exceptions!
 564      *
 565      * @throws RuntimeException if any of the arguments is invalid
 566      *
 567      * @since 1.7
 568      */
 569     @ForceInline
 570     public void copyMemory(Object srcBase, long srcOffset,
 571                            Object destBase, long destOffset,
 572                            long bytes) {
 573         theInternalUnsafe.copyMemory(srcBase, srcOffset, destBase, destOffset, bytes);
 574     }
 575 
 576     /**
 577      * Sets all bytes in a given block of memory to a copy of another
 578      * block.  This provides a <em>single-register</em> addressing mode,
 579      * as discussed in {@link #getInt(Object,long)}.
 580      *
 581      * Equivalent to {@code copyMemory(null, srcAddress, null, destAddress, bytes)}.
 582      */
 583     @ForceInline
 584     public void copyMemory(long srcAddress, long destAddress, long bytes) {
 585         theInternalUnsafe.copyMemory(srcAddress, destAddress, bytes);
 586     }
 587 
 588     /**
 589      * Disposes of a block of native memory, as obtained from {@link
 590      * #allocateMemory} or {@link #reallocateMemory}.  The address passed to
 591      * this method may be null, in which case no action is taken.
 592      *
 593      * <em>Note:</em> It is the responsibility of the caller to make
 594      * sure arguments are checked before the methods are called. While
 595      * some rudimentary checks are performed on the input, the checks
 596      * are best effort and when performance is an overriding priority,
 597      * as when methods of this class are optimized by the runtime
 598      * compiler, some or all checks (if any) may be elided. Hence, the
 599      * caller must not rely on the checks and corresponding
 600      * exceptions!
 601      *
 602      * @throws RuntimeException if any of the arguments is invalid
 603      *
 604      * @see #allocateMemory
 605      */
 606     @ForceInline
 607     public void freeMemory(long address) {
 608         theInternalUnsafe.freeMemory(address);
 609     }
 610 
 611     /// random queries
 612 
 613     /**
 614      * This constant differs from all results that will ever be returned from
 615      * {@link #staticFieldOffset}, {@link #objectFieldOffset},
 616      * or {@link #arrayBaseOffset}.
 617      */
 618     public static final int INVALID_FIELD_OFFSET = jdk.internal.misc.Unsafe.INVALID_FIELD_OFFSET;
 619 
 620     /**
 621      * Reports the location of a given field in the storage allocation of its
 622      * class.  Do not expect to perform any sort of arithmetic on this offset;
 623      * it is just a cookie which is passed to the unsafe heap memory accessors.
 624      *
 625      * <p>Any given field will always have the same offset and base, and no
 626      * two distinct fields of the same class will ever have the same offset
 627      * and base.
 628      *
 629      * <p>As of 1.4.1, offsets for fields are represented as long values,
 630      * although the Sun JVM does not use the most significant 32 bits.
 631      * However, JVM implementations which store static fields at absolute
 632      * addresses can use long offsets and null base pointers to express
 633      * the field locations in a form usable by {@link #getInt(Object,long)}.
 634      * Therefore, code which will be ported to such JVMs on 64-bit platforms
 635      * must preserve all bits of static field offsets.
 636      *
 637      * @deprecated The guarantee that a field will always have the same offset
 638      * and base may not be true in a future release. The ability to provide an
 639      * offset and object reference to a heap memory accessor will be removed
 640      * in a future release. Use {@link java.lang.invoke.VarHandle} instead.
 641      *
 642      * @see #getInt(Object, long)
 643      */
 644     @Deprecated(since="18")
 645     @ForceInline
 646     public long objectFieldOffset(Field f) {
 647         if (f == null) {
 648             throw new NullPointerException();
 649         }
 650         Class<?> declaringClass = f.getDeclaringClass();
 651         if (declaringClass.isHidden()) {
 652             throw new UnsupportedOperationException("can't get field offset on a hidden class: " + f);
 653         }
 654         if (PrimitiveClass.isPrimitiveClass(f.getDeclaringClass())) {
 655             throw new UnsupportedOperationException("can't get field offset on a primitive class: " + f);
 656         }
 657         if (declaringClass.isRecord()) {
 658             throw new UnsupportedOperationException("can't get field offset on a record class: " + f);
 659         }
 660         return theInternalUnsafe.objectFieldOffset(f);
 661     }
 662 
 663     /**
 664      * Reports the location of a given static field, in conjunction with {@link
 665      * #staticFieldBase}.
 666      * <p>Do not expect to perform any sort of arithmetic on this offset;
 667      * it is just a cookie which is passed to the unsafe heap memory accessors.
 668      *
 669      * <p>Any given field will always have the same offset, and no two distinct
 670      * fields of the same class will ever have the same offset.
 671      *
 672      * <p>As of 1.4.1, offsets for fields are represented as long values,
 673      * although the Sun JVM does not use the most significant 32 bits.
 674      * It is hard to imagine a JVM technology which needs more than
 675      * a few bits to encode an offset within a non-array object,
 676      * However, for consistency with other methods in this class,
 677      * this method reports its result as a long value.
 678      *
 679      * @deprecated The guarantee that a field will always have the same offset
 680      * and base may not be true in a future release. The ability to provide an
 681      * offset and object reference to a heap memory accessor will be removed
 682      * in a future release. Use {@link java.lang.invoke.VarHandle} instead.
 683      *
 684      * @see #getInt(Object, long)
 685      */
 686     @Deprecated(since="18")
 687     @ForceInline
 688     public long staticFieldOffset(Field f) {
 689         if (f == null) {
 690             throw new NullPointerException();
 691         }
 692         Class<?> declaringClass = f.getDeclaringClass();
 693         if (declaringClass.isHidden()) {
 694             throw new UnsupportedOperationException("can't get field offset on a hidden class: " + f);
 695         }
 696         if (PrimitiveClass.isPrimitiveClass(f.getDeclaringClass())) {
 697             throw new UnsupportedOperationException("can't get static field offset on a primitive class: " + f);
 698         }
 699         if (declaringClass.isRecord()) {
 700             throw new UnsupportedOperationException("can't get field offset on a record class: " + f);
 701         }
 702         return theInternalUnsafe.staticFieldOffset(f);
 703     }
 704 
 705     /**
 706      * Reports the location of a given static field, in conjunction with {@link
 707      * #staticFieldOffset}.
 708      * <p>Fetch the base "Object", if any, with which static fields of the
 709      * given class can be accessed via methods like {@link #getInt(Object,
 710      * long)}.  This value may be null.  This value may refer to an object
 711      * which is a "cookie", not guaranteed to be a real Object, and it should
 712      * not be used in any way except as argument to the get and put routines in
 713      * this class.
 714      *
 715      * @deprecated The guarantee that a field will always have the same offset
 716      * and base may not be true in a future release. The ability to provide an
 717      * offset and object reference to a heap memory accessor will be removed
 718      * in a future release. Use {@link java.lang.invoke.VarHandle} instead.
 719      */
 720     @Deprecated(since="18")
 721     @ForceInline
 722     public Object staticFieldBase(Field f) {
 723         if (f == null) {
 724             throw new NullPointerException();
 725         }
 726         Class<?> declaringClass = f.getDeclaringClass();
 727         if (declaringClass.isHidden()) {
 728             throw new UnsupportedOperationException("can't get base address on a hidden class: " + f);
 729         }
 730         if (PrimitiveClass.isPrimitiveClass(f.getDeclaringClass())) {
 731             throw new UnsupportedOperationException("can't get base address on a primitive class: " + f);
 732         }
 733         if (declaringClass.isRecord()) {
 734             throw new UnsupportedOperationException("can't get base address on a record class: " + f);
 735         }
 736         return theInternalUnsafe.staticFieldBase(f);
 737     }
 738 
 739     /**
 740      * Detects if the given class may need to be initialized. This is often
 741      * needed in conjunction with obtaining the static field base of a
 742      * class.
 743      *
 744      * @deprecated No replacement API for this method.  As multiple threads
 745      * may be trying to initialize the same class or interface at the same time.
 746      * The only reliable result returned by this method is {@code false}
 747      * indicating that the given class has been initialized.  Instead, simply
 748      * call {@link java.lang.invoke.MethodHandles.Lookup#ensureInitialized(Class)}
 749      * that does nothing if the given class has already been initialized.
 750      * This method is subject to removal in a future version of JDK.
 751      *
 752      * @return false only if a call to {@code ensureClassInitialized} would have no effect
 753      *
 754      */
 755     @Deprecated(since = "15", forRemoval = true)
 756     @ForceInline
 757     public boolean shouldBeInitialized(Class<?> c) {
 758         return theInternalUnsafe.shouldBeInitialized(c);
 759     }
 760 
 761     /**
 762      * Ensures the given class has been initialized. This is often
 763      * needed in conjunction with obtaining the static field base of a
 764      * class.
 765      *
 766      * @deprecated Use the {@link java.lang.invoke.MethodHandles.Lookup#ensureInitialized(Class)}
 767      * method instead.  This method is subject to removal in a future version of JDK.
 768      */
 769     @Deprecated(since = "15", forRemoval = true)
 770     @ForceInline
 771     public void ensureClassInitialized(Class<?> c) {
 772         theInternalUnsafe.ensureClassInitialized(c);
 773     }
 774 
 775     /**
 776      * Reports the offset of the first element in the storage allocation of a
 777      * given array class.  If {@link #arrayIndexScale} returns a non-zero value
 778      * for the same class, you may use that scale factor, together with this
 779      * base offset, to form new offsets to access elements of arrays of the
 780      * given class.
 781      *
 782      * @see #getInt(Object, long)
 783      * @see #putInt(Object, long, int)
 784      */
 785     @ForceInline
 786     public int arrayBaseOffset(Class<?> arrayClass) {
 787         return theInternalUnsafe.arrayBaseOffset(arrayClass);
 788     }
 789 
 790     /** The value of {@code arrayBaseOffset(boolean[].class)} */
 791     public static final int ARRAY_BOOLEAN_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_BOOLEAN_BASE_OFFSET;
 792 
 793     /** The value of {@code arrayBaseOffset(byte[].class)} */
 794     public static final int ARRAY_BYTE_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_BYTE_BASE_OFFSET;
 795 
 796     /** The value of {@code arrayBaseOffset(short[].class)} */
 797     public static final int ARRAY_SHORT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_SHORT_BASE_OFFSET;
 798 
 799     /** The value of {@code arrayBaseOffset(char[].class)} */
 800     public static final int ARRAY_CHAR_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_CHAR_BASE_OFFSET;
 801 
 802     /** The value of {@code arrayBaseOffset(int[].class)} */
 803     public static final int ARRAY_INT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_INT_BASE_OFFSET;
 804 
 805     /** The value of {@code arrayBaseOffset(long[].class)} */
 806     public static final int ARRAY_LONG_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_LONG_BASE_OFFSET;
 807 
 808     /** The value of {@code arrayBaseOffset(float[].class)} */
 809     public static final int ARRAY_FLOAT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_FLOAT_BASE_OFFSET;
 810 
 811     /** The value of {@code arrayBaseOffset(double[].class)} */
 812     public static final int ARRAY_DOUBLE_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_DOUBLE_BASE_OFFSET;
 813 
 814     /** The value of {@code arrayBaseOffset(Object[].class)} */
 815     public static final int ARRAY_OBJECT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_OBJECT_BASE_OFFSET;
 816 
 817     /**
 818      * Reports the scale factor for addressing elements in the storage
 819      * allocation of a given array class.  However, arrays of "narrow" types
 820      * will generally not work properly with accessors like {@link
 821      * #getByte(Object, long)}, so the scale factor for such classes is reported
 822      * as zero.
 823      *
 824      * @see #arrayBaseOffset
 825      * @see #getInt(Object, long)
 826      * @see #putInt(Object, long, int)
 827      */
 828     @ForceInline
 829     public int arrayIndexScale(Class<?> arrayClass) {
 830         return theInternalUnsafe.arrayIndexScale(arrayClass);
 831     }
 832 
 833     /** The value of {@code arrayIndexScale(boolean[].class)} */
 834     public static final int ARRAY_BOOLEAN_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_BOOLEAN_INDEX_SCALE;
 835 
 836     /** The value of {@code arrayIndexScale(byte[].class)} */
 837     public static final int ARRAY_BYTE_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_BYTE_INDEX_SCALE;
 838 
 839     /** The value of {@code arrayIndexScale(short[].class)} */
 840     public static final int ARRAY_SHORT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_SHORT_INDEX_SCALE;
 841 
 842     /** The value of {@code arrayIndexScale(char[].class)} */
 843     public static final int ARRAY_CHAR_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_CHAR_INDEX_SCALE;
 844 
 845     /** The value of {@code arrayIndexScale(int[].class)} */
 846     public static final int ARRAY_INT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_INT_INDEX_SCALE;
 847 
 848     /** The value of {@code arrayIndexScale(long[].class)} */
 849     public static final int ARRAY_LONG_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_LONG_INDEX_SCALE;
 850 
 851     /** The value of {@code arrayIndexScale(float[].class)} */
 852     public static final int ARRAY_FLOAT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_FLOAT_INDEX_SCALE;
 853 
 854     /** The value of {@code arrayIndexScale(double[].class)} */
 855     public static final int ARRAY_DOUBLE_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_DOUBLE_INDEX_SCALE;
 856 
 857     /** The value of {@code arrayIndexScale(Object[].class)} */
 858     public static final int ARRAY_OBJECT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_OBJECT_INDEX_SCALE;
 859 
 860     /**
 861      * Reports the size in bytes of a native pointer, as stored via {@link
 862      * #putAddress}.  This value will be either 4 or 8.  Note that the sizes of
 863      * other primitive types (as stored in native memory blocks) is determined
 864      * fully by their information content.
 865      */
 866     @ForceInline
 867     public int addressSize() {
 868         return theInternalUnsafe.addressSize();
 869     }
 870 
 871     /** The value of {@code addressSize()} */
 872     public static final int ADDRESS_SIZE = theInternalUnsafe.addressSize();
 873 
 874     /**
 875      * Reports the size in bytes of a native memory page (whatever that is).
 876      * This value will always be a power of two.
 877      */
 878     @ForceInline
 879     public int pageSize() {
 880         return theInternalUnsafe.pageSize();
 881     }
 882 
 883 
 884     /// random trusted operations from JNI:
 885 
 886     /**
 887      * Allocates an instance but does not run any constructor.
 888      * Initializes the class if it has not yet been.
 889      */
 890     @ForceInline
 891     public Object allocateInstance(Class<?> cls)
 892         throws InstantiationException {
 893         return theInternalUnsafe.allocateInstance(cls);
 894     }
 895 
 896     /** Throws the exception without telling the verifier. */
 897     @ForceInline
 898     public void throwException(Throwable ee) {
 899         theInternalUnsafe.throwException(ee);
 900     }
 901 
 902     /**
 903      * Atomically updates Java variable to {@code x} if it is currently
 904      * holding {@code expected}.
 905      *
 906      * <p>This operation has memory semantics of a {@code volatile} read
 907      * and write.  Corresponds to C11 atomic_compare_exchange_strong.
 908      *
 909      * @return {@code true} if successful
 910      */
 911     @ForceInline
 912     public final boolean compareAndSwapObject(Object o, long offset,
 913                                               Object expected,
 914                                               Object x) {
 915         return theInternalUnsafe.compareAndSetReference(o, offset, expected, x);
 916     }
 917 
 918     /**
 919      * Atomically updates Java variable to {@code x} if it is currently
 920      * holding {@code expected}.
 921      *
 922      * <p>This operation has memory semantics of a {@code volatile} read
 923      * and write.  Corresponds to C11 atomic_compare_exchange_strong.
 924      *
 925      * @return {@code true} if successful
 926      */
 927     @ForceInline
 928     public final boolean compareAndSwapInt(Object o, long offset,
 929                                            int expected,
 930                                            int x) {
 931         return theInternalUnsafe.compareAndSetInt(o, offset, expected, x);
 932     }
 933 
 934     /**
 935      * Atomically updates Java variable to {@code x} if it is currently
 936      * holding {@code expected}.
 937      *
 938      * <p>This operation has memory semantics of a {@code volatile} read
 939      * and write.  Corresponds to C11 atomic_compare_exchange_strong.
 940      *
 941      * @return {@code true} if successful
 942      */
 943     @ForceInline
 944     public final boolean compareAndSwapLong(Object o, long offset,
 945                                             long expected,
 946                                             long x) {
 947         return theInternalUnsafe.compareAndSetLong(o, offset, expected, x);
 948     }
 949 
 950     /**
 951      * Fetches a reference value from a given Java variable, with volatile
 952      * load semantics. Otherwise identical to {@link #getObject(Object, long)}
 953      */
 954     @ForceInline
 955     public Object getObjectVolatile(Object o, long offset) {
 956         return theInternalUnsafe.getReferenceVolatile(o, offset);
 957     }
 958 
 959     /**
 960      * Stores a reference value into a given Java variable, with
 961      * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)}
 962      */
 963     @ForceInline
 964     public void putObjectVolatile(Object o, long offset, Object x) {
 965         theInternalUnsafe.putReferenceVolatile(o, offset, x);
 966     }
 967 
 968     /** Volatile version of {@link #getInt(Object, long)}  */
 969     @ForceInline
 970     public int getIntVolatile(Object o, long offset) {
 971         return theInternalUnsafe.getIntVolatile(o, offset);
 972     }
 973 
 974     /** Volatile version of {@link #putInt(Object, long, int)}  */
 975     @ForceInline
 976     public void putIntVolatile(Object o, long offset, int x) {
 977         theInternalUnsafe.putIntVolatile(o, offset, x);
 978     }
 979 
 980     /** Volatile version of {@link #getBoolean(Object, long)}  */
 981     @ForceInline
 982     public boolean getBooleanVolatile(Object o, long offset) {
 983         return theInternalUnsafe.getBooleanVolatile(o, offset);
 984     }
 985 
 986     /** Volatile version of {@link #putBoolean(Object, long, boolean)}  */
 987     @ForceInline
 988     public void putBooleanVolatile(Object o, long offset, boolean x) {
 989         theInternalUnsafe.putBooleanVolatile(o, offset, x);
 990     }
 991 
 992     /** Volatile version of {@link #getByte(Object, long)}  */
 993     @ForceInline
 994     public byte getByteVolatile(Object o, long offset) {
 995         return theInternalUnsafe.getByteVolatile(o, offset);
 996     }
 997 
 998     /** Volatile version of {@link #putByte(Object, long, byte)}  */
 999     @ForceInline
1000     public void putByteVolatile(Object o, long offset, byte x) {
1001         theInternalUnsafe.putByteVolatile(o, offset, x);
1002     }
1003 
1004     /** Volatile version of {@link #getShort(Object, long)}  */
1005     @ForceInline
1006     public short getShortVolatile(Object o, long offset) {
1007         return theInternalUnsafe.getShortVolatile(o, offset);
1008     }
1009 
1010     /** Volatile version of {@link #putShort(Object, long, short)}  */
1011     @ForceInline
1012     public void putShortVolatile(Object o, long offset, short x) {
1013         theInternalUnsafe.putShortVolatile(o, offset, x);
1014     }
1015 
1016     /** Volatile version of {@link #getChar(Object, long)}  */
1017     @ForceInline
1018     public char getCharVolatile(Object o, long offset) {
1019         return theInternalUnsafe.getCharVolatile(o, offset);
1020     }
1021 
1022     /** Volatile version of {@link #putChar(Object, long, char)}  */
1023     @ForceInline
1024     public void putCharVolatile(Object o, long offset, char x) {
1025         theInternalUnsafe.putCharVolatile(o, offset, x);
1026     }
1027 
1028     /** Volatile version of {@link #getLong(Object, long)}  */
1029     @ForceInline
1030     public long getLongVolatile(Object o, long offset) {
1031         return theInternalUnsafe.getLongVolatile(o, offset);
1032     }
1033 
1034     /** Volatile version of {@link #putLong(Object, long, long)}  */
1035     @ForceInline
1036     public void putLongVolatile(Object o, long offset, long x) {
1037         theInternalUnsafe.putLongVolatile(o, offset, x);
1038     }
1039 
1040     /** Volatile version of {@link #getFloat(Object, long)}  */
1041     @ForceInline
1042     public float getFloatVolatile(Object o, long offset) {
1043         return theInternalUnsafe.getFloatVolatile(o, offset);
1044     }
1045 
1046     /** Volatile version of {@link #putFloat(Object, long, float)}  */
1047     @ForceInline
1048     public void putFloatVolatile(Object o, long offset, float x) {
1049         theInternalUnsafe.putFloatVolatile(o, offset, x);
1050     }
1051 
1052     /** Volatile version of {@link #getDouble(Object, long)}  */
1053     @ForceInline
1054     public double getDoubleVolatile(Object o, long offset) {
1055         return theInternalUnsafe.getDoubleVolatile(o, offset);
1056     }
1057 
1058     /** Volatile version of {@link #putDouble(Object, long, double)}  */
1059     @ForceInline
1060     public void putDoubleVolatile(Object o, long offset, double x) {
1061         theInternalUnsafe.putDoubleVolatile(o, offset, x);
1062     }
1063 
1064     /**
1065      * Version of {@link #putObjectVolatile(Object, long, Object)}
1066      * that does not guarantee immediate visibility of the store to
1067      * other threads. This method is generally only useful if the
1068      * underlying field is a Java volatile (or if an array cell, one
1069      * that is otherwise only accessed using volatile accesses).
1070      *
1071      * Corresponds to C11 atomic_store_explicit(..., memory_order_release).
1072      */
1073     @ForceInline
1074     public void putOrderedObject(Object o, long offset, Object x) {
1075         theInternalUnsafe.putReferenceRelease(o, offset, x);
1076     }
1077 
1078     /** Ordered/Lazy version of {@link #putIntVolatile(Object, long, int)}  */
1079     @ForceInline
1080     public void putOrderedInt(Object o, long offset, int x) {
1081         theInternalUnsafe.putIntRelease(o, offset, x);
1082     }
1083 
1084     /** Ordered/Lazy version of {@link #putLongVolatile(Object, long, long)} */
1085     @ForceInline
1086     public void putOrderedLong(Object o, long offset, long x) {
1087         theInternalUnsafe.putLongRelease(o, offset, x);
1088     }
1089 
1090     /**
1091      * Unblocks the given thread blocked on {@code park}, or, if it is
1092      * not blocked, causes the subsequent call to {@code park} not to
1093      * block.  Note: this operation is "unsafe" solely because the
1094      * caller must somehow ensure that the thread has not been
1095      * destroyed. Nothing special is usually required to ensure this
1096      * when called from Java (in which there will ordinarily be a live
1097      * reference to the thread) but this is not nearly-automatically
1098      * so when calling from native code.
1099      *
1100      * @param thread the thread to unpark.
1101      */
1102     @ForceInline
1103     public void unpark(Object thread) {
1104         theInternalUnsafe.unpark(thread);
1105     }
1106 
1107     /**
1108      * Blocks current thread, returning when a balancing
1109      * {@code unpark} occurs, or a balancing {@code unpark} has
1110      * already occurred, or the thread is interrupted, or, if not
1111      * absolute and time is not zero, the given time nanoseconds have
1112      * elapsed, or if absolute, the given deadline in milliseconds
1113      * since Epoch has passed, or spuriously (i.e., returning for no
1114      * "reason"). Note: This operation is in the Unsafe class only
1115      * because {@code unpark} is, so it would be strange to place it
1116      * elsewhere.
1117      */
1118     @ForceInline
1119     public void park(boolean isAbsolute, long time) {
1120         theInternalUnsafe.park(isAbsolute, time);
1121     }
1122 
1123     /**
1124      * Gets the load average in the system run queue assigned
1125      * to the available processors averaged over various periods of time.
1126      * This method retrieves the given {@code nelem} samples and
1127      * assigns to the elements of the given {@code loadavg} array.
1128      * The system imposes a maximum of 3 samples, representing
1129      * averages over the last 1,  5,  and  15 minutes, respectively.
1130      *
1131      * @param loadavg an array of double of size nelems
1132      * @param nelems the number of samples to be retrieved and
1133      *        must be 1 to 3.
1134      *
1135      * @return the number of samples actually retrieved; or -1
1136      *         if the load average is unobtainable.
1137      */
1138     @ForceInline
1139     public int getLoadAverage(double[] loadavg, int nelems) {
1140         return theInternalUnsafe.getLoadAverage(loadavg, nelems);
1141     }
1142 
1143     // The following contain CAS-based Java implementations used on
1144     // platforms not supporting native instructions
1145 
1146     /**
1147      * Atomically adds the given value to the current value of a field
1148      * or array element within the given object {@code o}
1149      * at the given {@code offset}.
1150      *
1151      * @param o object/array to update the field/element in
1152      * @param offset field/element offset
1153      * @param delta the value to add
1154      * @return the previous value
1155      * @since 1.8
1156      */
1157     @ForceInline
1158     public final int getAndAddInt(Object o, long offset, int delta) {
1159         return theInternalUnsafe.getAndAddInt(o, offset, delta);
1160     }
1161 
1162     /**
1163      * Atomically adds the given value to the current value of a field
1164      * or array element within the given object {@code o}
1165      * at the given {@code offset}.
1166      *
1167      * @param o object/array to update the field/element in
1168      * @param offset field/element offset
1169      * @param delta the value to add
1170      * @return the previous value
1171      * @since 1.8
1172      */
1173     @ForceInline
1174     public final long getAndAddLong(Object o, long offset, long delta) {
1175         return theInternalUnsafe.getAndAddLong(o, offset, delta);
1176     }
1177 
1178     /**
1179      * Atomically exchanges the given value with the current value of
1180      * a field or array element within the given object {@code o}
1181      * at the given {@code offset}.
1182      *
1183      * @param o object/array to update the field/element in
1184      * @param offset field/element offset
1185      * @param newValue new value
1186      * @return the previous value
1187      * @since 1.8
1188      */
1189     @ForceInline
1190     public final int getAndSetInt(Object o, long offset, int newValue) {
1191         return theInternalUnsafe.getAndSetInt(o, offset, newValue);
1192     }
1193 
1194     /**
1195      * Atomically exchanges the given value with the current value of
1196      * a field or array element within the given object {@code o}
1197      * at the given {@code offset}.
1198      *
1199      * @param o object/array to update the field/element in
1200      * @param offset field/element offset
1201      * @param newValue new value
1202      * @return the previous value
1203      * @since 1.8
1204      */
1205     @ForceInline
1206     public final long getAndSetLong(Object o, long offset, long newValue) {
1207         return theInternalUnsafe.getAndSetLong(o, offset, newValue);
1208     }
1209 
1210     /**
1211      * Atomically exchanges the given reference value with the current
1212      * reference value of a field or array element within the given
1213      * object {@code o} at the given {@code offset}.
1214      *
1215      * @param o object/array to update the field/element in
1216      * @param offset field/element offset
1217      * @param newValue new value
1218      * @return the previous value
1219      * @since 1.8
1220      */
1221     @ForceInline
1222     public final Object getAndSetObject(Object o, long offset, Object newValue) {
1223         return theInternalUnsafe.getAndSetReference(o, offset, newValue);
1224     }
1225 
1226 
1227     /**
1228      * Ensures that loads before the fence will not be reordered with loads and
1229      * stores after the fence; a "LoadLoad plus LoadStore barrier".
1230      *
1231      * Corresponds to C11 atomic_thread_fence(memory_order_acquire)
1232      * (an "acquire fence").
1233      *
1234      * A pure LoadLoad fence is not provided, since the addition of LoadStore
1235      * is almost always desired, and most current hardware instructions that
1236      * provide a LoadLoad barrier also provide a LoadStore barrier for free.
1237      * @since 1.8
1238      */
1239     @ForceInline
1240     public void loadFence() {
1241         theInternalUnsafe.loadFence();
1242     }
1243 
1244     /**
1245      * Ensures that loads and stores before the fence will not be reordered with
1246      * stores after the fence; a "StoreStore plus LoadStore barrier".
1247      *
1248      * Corresponds to C11 atomic_thread_fence(memory_order_release)
1249      * (a "release fence").
1250      *
1251      * A pure StoreStore fence is not provided, since the addition of LoadStore
1252      * is almost always desired, and most current hardware instructions that
1253      * provide a StoreStore barrier also provide a LoadStore barrier for free.
1254      * @since 1.8
1255      */
1256     @ForceInline
1257     public void storeFence() {
1258         theInternalUnsafe.storeFence();
1259     }
1260 
1261     /**
1262      * Ensures that loads and stores before the fence will not be reordered
1263      * with loads and stores after the fence.  Implies the effects of both
1264      * loadFence() and storeFence(), and in addition, the effect of a StoreLoad
1265      * barrier.
1266      *
1267      * Corresponds to C11 atomic_thread_fence(memory_order_seq_cst).
1268      * @since 1.8
1269      */
1270     @ForceInline
1271     public void fullFence() {
1272         theInternalUnsafe.fullFence();
1273     }
1274 
1275     /**
1276      * Invokes the given direct byte buffer's cleaner, if any.
1277      *
1278      * @param directBuffer a direct byte buffer
1279      * @throws NullPointerException if {@code directBuffer} is null
1280      * @throws IllegalArgumentException if {@code directBuffer} is non-direct,
1281      * or is a {@link java.nio.Buffer#slice slice}, or is a
1282      * {@link java.nio.Buffer#duplicate duplicate}
1283      * @since 9
1284      */
1285     public void invokeCleaner(java.nio.ByteBuffer directBuffer) {
1286         if (!directBuffer.isDirect())
1287             throw new IllegalArgumentException("buffer is non-direct");
1288 
1289         theInternalUnsafe.invokeCleaner(directBuffer);
1290     }
1291 }