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| 1 | +/* | |
| 2 | + * Copyright (c) 2000, 2009, 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 java.security.*; | |
| 29 | +import java.lang.reflect.*; | |
| 30 | + | |
| 31 | + | |
| 32 | +/** | |
| 33 | + * A collection of methods for performing low-level, unsafe operations. | |
| 34 | + * Although the class and all methods are public, use of this class is | |
| 35 | + * limited because only trusted code can obtain instances of it. | |
| 36 | + * | |
| 37 | + * @author John R. Rose | |
| 38 | + * @see #getUnsafe | |
| 39 | + */ | |
| 40 | + | |
| 41 | +public final class Unsafe { | |
| 42 | + | |
| 43 | + private static native void registerNatives(); | |
| 44 | + static { | |
| 45 | + registerNatives(); | |
| 46 | + sun.reflect.Reflection.registerMethodsToFilter(Unsafe.class, "getUnsafe"); | |
| 47 | + } | |
| 48 | + | |
| 49 | + private Unsafe() {} | |
| 50 | + | |
| 51 | + private static final Unsafe theUnsafe = new Unsafe(); | |
| 52 | + | |
| 53 | + /** | |
| 54 | + * Provides the caller with the capability of performing unsafe | |
| 55 | + * operations. | |
| 56 | + * | |
| 57 | + * <p> The returned <code>Unsafe</code> object should be carefully guarded | |
| 58 | + * by the caller, since it can be used to read and write data at arbitrary | |
| 59 | + * memory addresses. It must never be passed to untrusted code. | |
| 60 | + * | |
| 61 | + * <p> Most methods in this class are very low-level, and correspond to a | |
| 62 | + * small number of hardware instructions (on typical machines). Compilers | |
| 63 | + * are encouraged to optimize these methods accordingly. | |
| 64 | + * | |
| 65 | + * <p> Here is a suggested idiom for using unsafe operations: | |
| 66 | + * | |
| 67 | + * <blockquote><pre> | |
| 68 | + * class MyTrustedClass { | |
| 69 | + * private static final Unsafe unsafe = Unsafe.getUnsafe(); | |
| 70 | + * ... | |
| 71 | + * private long myCountAddress = ...; | |
| 72 | + * public int getCount() { return unsafe.getByte(myCountAddress); } | |
| 73 | + * } | |
| 74 | + * </pre></blockquote> | |
| 75 | + * | |
| 76 | + * (It may assist compilers to make the local variable be | |
| 77 | + * <code>final</code>.) | |
| 78 | + * | |
| 79 | + * @exception SecurityException if a security manager exists and its | |
| 80 | + * <code>checkPropertiesAccess</code> method doesn't allow | |
| 81 | + * access to the system properties. | |
| 82 | + */ | |
| 83 | + public static Unsafe getUnsafe() { | |
| 84 | + Class cc = sun.reflect.Reflection.getCallerClass(2); | |
| 85 | + if (cc.getClassLoader() != null) | |
| 86 | + throw new SecurityException("Unsafe"); | |
| 87 | + return theUnsafe; | |
| 88 | + } | |
| 89 | + | |
| 90 | + /// peek and poke operations | |
| 91 | + /// (compilers should optimize these to memory ops) | |
| 92 | + | |
| 93 | + // These work on object fields in the Java heap. | |
| 94 | + // They will not work on elements of packed arrays. | |
| 95 | + | |
| 96 | + /** | |
| 97 | + * Fetches a value from a given Java variable. | |
| 98 | + * More specifically, fetches a field or array element within the given | |
| 99 | + * object <code>o</code> at the given offset, or (if <code>o</code> is | |
| 100 | + * null) from the memory address whose numerical value is the given | |
| 101 | + * offset. | |
| 102 | + * <p> | |
| 103 | + * The results are undefined unless one of the following cases is true: | |
| 104 | + * <ul> | |
| 105 | + * <li>The offset was obtained from {@link #objectFieldOffset} on | |
| 106 | + * the {@link java.lang.reflect.Field} of some Java field and the object | |
| 107 | + * referred to by <code>o</code> is of a class compatible with that | |
| 108 | + * field's class. | |
| 109 | + * | |
| 110 | + * <li>The offset and object reference <code>o</code> (either null or | |
| 111 | + * non-null) were both obtained via {@link #staticFieldOffset} | |
| 112 | + * and {@link #staticFieldBase} (respectively) from the | |
| 113 | + * reflective {@link Field} representation of some Java field. | |
| 114 | + * | |
| 115 | + * <li>The object referred to by <code>o</code> is an array, and the offset | |
| 116 | + * is an integer of the form <code>B+N*S</code>, where <code>N</code> is | |
| 117 | + * a valid index into the array, and <code>B</code> and <code>S</code> are | |
| 118 | + * the values obtained by {@link #arrayBaseOffset} and {@link | |
| 119 | + * #arrayIndexScale} (respectively) from the array's class. The value | |
| 120 | + * referred to is the <code>N</code><em>th</em> element of the array. | |
| 121 | + * | |
| 122 | + * </ul> | |
| 123 | + * <p> | |
| 124 | + * If one of the above cases is true, the call references a specific Java | |
| 125 | + * variable (field or array element). However, the results are undefined | |
| 126 | + * if that variable is not in fact of the type returned by this method. | |
| 127 | + * <p> | |
| 128 | + * This method refers to a variable by means of two parameters, and so | |
| 129 | + * it provides (in effect) a <em>double-register</em> addressing mode | |
| 130 | + * for Java variables. When the object reference is null, this method | |
| 131 | + * uses its offset as an absolute address. This is similar in operation | |
| 132 | + * to methods such as {@link #getInt(long)}, which provide (in effect) a | |
| 133 | + * <em>single-register</em> addressing mode for non-Java variables. | |
| 134 | + * However, because Java variables may have a different layout in memory | |
| 135 | + * from non-Java variables, programmers should not assume that these | |
| 136 | + * two addressing modes are ever equivalent. Also, programmers should | |
| 137 | + * remember that offsets from the double-register addressing mode cannot | |
| 138 | + * be portably confused with longs used in the single-register addressing | |
| 139 | + * mode. | |
| 140 | + * | |
| 141 | + * @param o Java heap object in which the variable resides, if any, else | |
| 142 | + * null | |
| 143 | + * @param offset indication of where the variable resides in a Java heap | |
| 144 | + * object, if any, else a memory address locating the variable | |
| 145 | + * statically | |
| 146 | + * @return the value fetched from the indicated Java variable | |
| 147 | + * @throws RuntimeException No defined exceptions are thrown, not even | |
| 148 | + * {@link NullPointerException} | |
| 149 | + */ | |
| 150 | + public native int getInt(Object o, long offset); | |
| 151 | + | |
| 152 | + /** | |
| 153 | + * Stores a value into a given Java variable. | |
| 154 | + * <p> | |
| 155 | + * The first two parameters are interpreted exactly as with | |
| 156 | + * {@link #getInt(Object, long)} to refer to a specific | |
| 157 | + * Java variable (field or array element). The given value | |
| 158 | + * is stored into that variable. | |
| 159 | + * <p> | |
| 160 | + * The variable must be of the same type as the method | |
| 161 | + * parameter <code>x</code>. | |
| 162 | + * | |
| 163 | + * @param o Java heap object in which the variable resides, if any, else | |
| 164 | + * null | |
| 165 | + * @param offset indication of where the variable resides in a Java heap | |
| 166 | + * object, if any, else a memory address locating the variable | |
| 167 | + * statically | |
| 168 | + * @param x the value to store into the indicated Java variable | |
| 169 | + * @throws RuntimeException No defined exceptions are thrown, not even | |
| 170 | + * {@link NullPointerException} | |
| 171 | + */ | |
| 172 | + public native void putInt(Object o, long offset, int x); | |
| 173 | + | |
| 174 | + /** | |
| 175 | + * Fetches a reference value from a given Java variable. | |
| 176 | + * @see #getInt(Object, long) | |
| 177 | + */ | |
| 178 | + public native Object getObject(Object o, long offset); | |
| 179 | + | |
| 180 | + /** | |
| 181 | + * Stores a reference value into a given Java variable. | |
| 182 | + * <p> | |
| 183 | + * Unless the reference <code>x</code> being stored is either null | |
| 184 | + * or matches the field type, the results are undefined. | |
| 185 | + * If the reference <code>o</code> is non-null, car marks or | |
| 186 | + * other store barriers for that object (if the VM requires them) | |
| 187 | + * are updated. | |
| 188 | + * @see #putInt(Object, int, int) | |
| 189 | + */ | |
| 190 | + public native void putObject(Object o, long offset, Object x); | |
| 191 | + | |
| 192 | + /** @see #getInt(Object, long) */ | |
| 193 | + public native boolean getBoolean(Object o, long offset); | |
| 194 | + /** @see #putInt(Object, int, int) */ | |
| 195 | + public native void putBoolean(Object o, long offset, boolean x); | |
| 196 | + /** @see #getInt(Object, long) */ | |
| 197 | + public native byte getByte(Object o, long offset); | |
| 198 | + /** @see #putInt(Object, int, int) */ | |
| 199 | + public native void putByte(Object o, long offset, byte x); | |
| 200 | + /** @see #getInt(Object, long) */ | |
| 201 | + public native short getShort(Object o, long offset); | |
| 202 | + /** @see #putInt(Object, int, int) */ | |
| 203 | + public native void putShort(Object o, long offset, short x); | |
| 204 | + /** @see #getInt(Object, long) */ | |
| 205 | + public native char getChar(Object o, long offset); | |
| 206 | + /** @see #putInt(Object, int, int) */ | |
| 207 | + public native void putChar(Object o, long offset, char x); | |
| 208 | + /** @see #getInt(Object, long) */ | |
| 209 | + public native long getLong(Object o, long offset); | |
| 210 | + /** @see #putInt(Object, int, int) */ | |
| 211 | + public native void putLong(Object o, long offset, long x); | |
| 212 | + /** @see #getInt(Object, long) */ | |
| 213 | + public native float getFloat(Object o, long offset); | |
| 214 | + /** @see #putInt(Object, int, int) */ | |
| 215 | + public native void putFloat(Object o, long offset, float x); | |
| 216 | + /** @see #getInt(Object, long) */ | |
| 217 | + public native double getDouble(Object o, long offset); | |
| 218 | + /** @see #putInt(Object, int, int) */ | |
| 219 | + public native void putDouble(Object o, long offset, double x); | |
| 220 | + | |
| 221 | + /** | |
| 222 | + * This method, like all others with 32-bit offsets, was native | |
| 223 | + * in a previous release but is now a wrapper which simply casts | |
| 224 | + * the offset to a long value. It provides backward compatibility | |
| 225 | + * with bytecodes compiled against 1.4. | |
| 226 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 227 | + * See {@link #staticFieldOffset}. | |
| 228 | + */ | |
| 229 | + @Deprecated | |
| 230 | + public int getInt(Object o, int offset) { | |
| 231 | + return getInt(o, (long)offset); | |
| 232 | + } | |
| 233 | + | |
| 234 | + /** | |
| 235 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 236 | + * See {@link #staticFieldOffset}. | |
| 237 | + */ | |
| 238 | + @Deprecated | |
| 239 | + public void putInt(Object o, int offset, int x) { | |
| 240 | + putInt(o, (long)offset, x); | |
| 241 | + } | |
| 242 | + | |
| 243 | + /** | |
| 244 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 245 | + * See {@link #staticFieldOffset}. | |
| 246 | + */ | |
| 247 | + @Deprecated | |
| 248 | + public Object getObject(Object o, int offset) { | |
| 249 | + return getObject(o, (long)offset); | |
| 250 | + } | |
| 251 | + | |
| 252 | + /** | |
| 253 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 254 | + * See {@link #staticFieldOffset}. | |
| 255 | + */ | |
| 256 | + @Deprecated | |
| 257 | + public void putObject(Object o, int offset, Object x) { | |
| 258 | + putObject(o, (long)offset, x); | |
| 259 | + } | |
| 260 | + | |
| 261 | + /** | |
| 262 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 263 | + * See {@link #staticFieldOffset}. | |
| 264 | + */ | |
| 265 | + @Deprecated | |
| 266 | + public boolean getBoolean(Object o, int offset) { | |
| 267 | + return getBoolean(o, (long)offset); | |
| 268 | + } | |
| 269 | + | |
| 270 | + /** | |
| 271 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 272 | + * See {@link #staticFieldOffset}. | |
| 273 | + */ | |
| 274 | + @Deprecated | |
| 275 | + public void putBoolean(Object o, int offset, boolean x) { | |
| 276 | + putBoolean(o, (long)offset, x); | |
| 277 | + } | |
| 278 | + | |
| 279 | + /** | |
| 280 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 281 | + * See {@link #staticFieldOffset}. | |
| 282 | + */ | |
| 283 | + @Deprecated | |
| 284 | + public byte getByte(Object o, int offset) { | |
| 285 | + return getByte(o, (long)offset); | |
| 286 | + } | |
| 287 | + | |
| 288 | + /** | |
| 289 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 290 | + * See {@link #staticFieldOffset}. | |
| 291 | + */ | |
| 292 | + @Deprecated | |
| 293 | + public void putByte(Object o, int offset, byte x) { | |
| 294 | + putByte(o, (long)offset, x); | |
| 295 | + } | |
| 296 | + | |
| 297 | + /** | |
| 298 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 299 | + * See {@link #staticFieldOffset}. | |
| 300 | + */ | |
| 301 | + @Deprecated | |
| 302 | + public short getShort(Object o, int offset) { | |
| 303 | + return getShort(o, (long)offset); | |
| 304 | + } | |
| 305 | + | |
| 306 | + /** | |
| 307 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 308 | + * See {@link #staticFieldOffset}. | |
| 309 | + */ | |
| 310 | + @Deprecated | |
| 311 | + public void putShort(Object o, int offset, short x) { | |
| 312 | + putShort(o, (long)offset, x); | |
| 313 | + } | |
| 314 | + | |
| 315 | + /** | |
| 316 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 317 | + * See {@link #staticFieldOffset}. | |
| 318 | + */ | |
| 319 | + @Deprecated | |
| 320 | + public char getChar(Object o, int offset) { | |
| 321 | + return getChar(o, (long)offset); | |
| 322 | + } | |
| 323 | + | |
| 324 | + /** | |
| 325 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 326 | + * See {@link #staticFieldOffset}. | |
| 327 | + */ | |
| 328 | + @Deprecated | |
| 329 | + public void putChar(Object o, int offset, char x) { | |
| 330 | + putChar(o, (long)offset, x); | |
| 331 | + } | |
| 332 | + | |
| 333 | + /** | |
| 334 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 335 | + * See {@link #staticFieldOffset}. | |
| 336 | + */ | |
| 337 | + @Deprecated | |
| 338 | + public long getLong(Object o, int offset) { | |
| 339 | + return getLong(o, (long)offset); | |
| 340 | + } | |
| 341 | + | |
| 342 | + /** | |
| 343 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 344 | + * See {@link #staticFieldOffset}. | |
| 345 | + */ | |
| 346 | + @Deprecated | |
| 347 | + public void putLong(Object o, int offset, long x) { | |
| 348 | + putLong(o, (long)offset, x); | |
| 349 | + } | |
| 350 | + | |
| 351 | + /** | |
| 352 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 353 | + * See {@link #staticFieldOffset}. | |
| 354 | + */ | |
| 355 | + @Deprecated | |
| 356 | + public float getFloat(Object o, int offset) { | |
| 357 | + return getFloat(o, (long)offset); | |
| 358 | + } | |
| 359 | + | |
| 360 | + /** | |
| 361 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 362 | + * See {@link #staticFieldOffset}. | |
| 363 | + */ | |
| 364 | + @Deprecated | |
| 365 | + public void putFloat(Object o, int offset, float x) { | |
| 366 | + putFloat(o, (long)offset, x); | |
| 367 | + } | |
| 368 | + | |
| 369 | + /** | |
| 370 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 371 | + * See {@link #staticFieldOffset}. | |
| 372 | + */ | |
| 373 | + @Deprecated | |
| 374 | + public double getDouble(Object o, int offset) { | |
| 375 | + return getDouble(o, (long)offset); | |
| 376 | + } | |
| 377 | + | |
| 378 | + /** | |
| 379 | + * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. | |
| 380 | + * See {@link #staticFieldOffset}. | |
| 381 | + */ | |
| 382 | + @Deprecated | |
| 383 | + public void putDouble(Object o, int offset, double x) { | |
| 384 | + putDouble(o, (long)offset, x); | |
| 385 | + } | |
| 386 | + | |
| 387 | + // These work on values in the C heap. | |
| 388 | + | |
| 389 | + /** | |
| 390 | + * Fetches a value from a given memory address. If the address is zero, or | |
| 391 | + * does not point into a block obtained from {@link #allocateMemory}, the | |
| 392 | + * results are undefined. | |
| 393 | + * | |
| 394 | + * @see #allocateMemory | |
| 395 | + */ | |
| 396 | + public native byte getByte(long address); | |
| 397 | + | |
| 398 | + /** | |
| 399 | + * Stores a value into a given memory address. If the address is zero, or | |
| 400 | + * does not point into a block obtained from {@link #allocateMemory}, the | |
| 401 | + * results are undefined. | |
| 402 | + * | |
| 403 | + * @see #getByte(long) | |
| 404 | + */ | |
| 405 | + public native void putByte(long address, byte x); | |
| 406 | + | |
| 407 | + /** @see #getByte(long) */ | |
| 408 | + public native short getShort(long address); | |
| 409 | + /** @see #putByte(long, byte) */ | |
| 410 | + public native void putShort(long address, short x); | |
| 411 | + /** @see #getByte(long) */ | |
| 412 | + public native char getChar(long address); | |
| 413 | + /** @see #putByte(long, byte) */ | |
| 414 | + public native void putChar(long address, char x); | |
| 415 | + /** @see #getByte(long) */ | |
| 416 | + public native int getInt(long address); | |
| 417 | + /** @see #putByte(long, byte) */ | |
| 418 | + public native void putInt(long address, int x); | |
| 419 | + /** @see #getByte(long) */ | |
| 420 | + public native long getLong(long address); | |
| 421 | + /** @see #putByte(long, byte) */ | |
| 422 | + public native void putLong(long address, long x); | |
| 423 | + /** @see #getByte(long) */ | |
| 424 | + public native float getFloat(long address); | |
| 425 | + /** @see #putByte(long, byte) */ | |
| 426 | + public native void putFloat(long address, float x); | |
| 427 | + /** @see #getByte(long) */ | |
| 428 | + public native double getDouble(long address); | |
| 429 | + /** @see #putByte(long, byte) */ | |
| 430 | + public native void putDouble(long address, double x); | |
| 431 | + | |
| 432 | + /** | |
| 433 | + * Fetches a native pointer from a given memory address. If the address is | |
| 434 | + * zero, or does not point into a block obtained from {@link | |
| 435 | + * #allocateMemory}, the results are undefined. | |
| 436 | + * | |
| 437 | + * <p> If the native pointer is less than 64 bits wide, it is extended as | |
| 438 | + * an unsigned number to a Java long. The pointer may be indexed by any | |
| 439 | + * given byte offset, simply by adding that offset (as a simple integer) to | |
| 440 | + * the long representing the pointer. The number of bytes actually read | |
| 441 | + * from the target address maybe determined by consulting {@link | |
| 442 | + * #addressSize}. | |
| 443 | + * | |
| 444 | + * @see #allocateMemory | |
| 445 | + */ | |
| 446 | + public native long getAddress(long address); | |
| 447 | + | |
| 448 | + /** | |
| 449 | + * Stores a native pointer into a given memory address. If the address is | |
| 450 | + * zero, or does not point into a block obtained from {@link | |
| 451 | + * #allocateMemory}, the results are undefined. | |
| 452 | + * | |
| 453 | + * <p> The number of bytes actually written at the target address maybe | |
| 454 | + * determined by consulting {@link #addressSize}. | |
| 455 | + * | |
| 456 | + * @see #getAddress(long) | |
| 457 | + */ | |
| 458 | + public native void putAddress(long address, long x); | |
| 459 | + | |
| 460 | + /// wrappers for malloc, realloc, free: | |
| 461 | + | |
| 462 | + /** | |
| 463 | + * Allocates a new block of native memory, of the given size in bytes. The | |
| 464 | + * contents of the memory are uninitialized; they will generally be | |
| 465 | + * garbage. The resulting native pointer will never be zero, and will be | |
| 466 | + * aligned for all value types. Dispose of this memory by calling {@link | |
| 467 | + * #freeMemory}, or resize it with {@link #reallocateMemory}. | |
| 468 | + * | |
| 469 | + * @throws IllegalArgumentException if the size is negative or too large | |
| 470 | + * for the native size_t type | |
| 471 | + * | |
| 472 | + * @throws OutOfMemoryError if the allocation is refused by the system | |
| 473 | + * | |
| 474 | + * @see #getByte(long) | |
| 475 | + * @see #putByte(long, byte) | |
| 476 | + */ | |
| 477 | + public native long allocateMemory(long bytes); | |
| 478 | + | |
| 479 | + /** | |
| 480 | + * Resizes a new block of native memory, to the given size in bytes. The | |
| 481 | + * contents of the new block past the size of the old block are | |
| 482 | + * uninitialized; they will generally be garbage. The resulting native | |
| 483 | + * pointer will be zero if and only if the requested size is zero. The | |
| 484 | + * resulting native pointer will be aligned for all value types. Dispose | |
| 485 | + * of this memory by calling {@link #freeMemory}, or resize it with {@link | |
| 486 | + * #reallocateMemory}. The address passed to this method may be null, in | |
| 487 | + * which case an allocation will be performed. | |
| 488 | + * | |
| 489 | + * @throws IllegalArgumentException if the size is negative or too large | |
| 490 | + * for the native size_t type | |
| 491 | + * | |
| 492 | + * @throws OutOfMemoryError if the allocation is refused by the system | |
| 493 | + * | |
| 494 | + * @see #allocateMemory | |
| 495 | + */ | |
| 496 | + public native long reallocateMemory(long address, long bytes); | |
| 497 | + | |
| 498 | + /** | |
| 499 | + * Sets all bytes in a given block of memory to a fixed value | |
| 500 | + * (usually zero). | |
| 501 | + * | |
| 502 | + * <p>This method determines a block's base address by means of two parameters, | |
| 503 | + * and so it provides (in effect) a <em>double-register</em> addressing mode, | |
| 504 | + * as discussed in {@link #getInt(Object,long)}. When the object reference is null, | |
| 505 | + * the offset supplies an absolute base address. | |
| 506 | + * | |
| 507 | + * <p>The stores are in coherent (atomic) units of a size determined | |
| 508 | + * by the address and length parameters. If the effective address and | |
| 509 | + * length are all even modulo 8, the stores take place in 'long' units. | |
| 510 | + * If the effective address and length are (resp.) even modulo 4 or 2, | |
| 511 | + * the stores take place in units of 'int' or 'short'. | |
| 512 | + * | |
| 513 | + * @since 1.7 | |
| 514 | + */ | |
| 515 | + public native void setMemory(Object o, long offset, long bytes, byte value); | |
| 516 | + | |
| 517 | + /** | |
| 518 | + * Sets all bytes in a given block of memory to a fixed value | |
| 519 | + * (usually zero). This provides a <em>single-register</em> addressing mode, | |
| 520 | + * as discussed in {@link #getInt(Object,long)}. | |
| 521 | + * | |
| 522 | + * <p>Equivalent to <code>setMemory(null, address, bytes, value)</code>. | |
| 523 | + */ | |
| 524 | + public void setMemory(long address, long bytes, byte value) { | |
| 525 | + setMemory(null, address, bytes, value); | |
| 526 | + } | |
| 527 | + | |
| 528 | + /** | |
| 529 | + * Sets all bytes in a given block of memory to a copy of another | |
| 530 | + * block. | |
| 531 | + * | |
| 532 | + * <p>This method determines each block's base address by means of two parameters, | |
| 533 | + * and so it provides (in effect) a <em>double-register</em> addressing mode, | |
| 534 | + * as discussed in {@link #getInt(Object,long)}. When the object reference is null, | |
| 535 | + * the offset supplies an absolute base address. | |
| 536 | + * | |
| 537 | + * <p>The transfers are in coherent (atomic) units of a size determined | |
| 538 | + * by the address and length parameters. If the effective addresses and | |
| 539 | + * length are all even modulo 8, the transfer takes place in 'long' units. | |
| 540 | + * If the effective addresses and length are (resp.) even modulo 4 or 2, | |
| 541 | + * the transfer takes place in units of 'int' or 'short'. | |
| 542 | + * | |
| 543 | + * @since 1.7 | |
| 544 | + */ | |
| 545 | + public native void copyMemory(Object srcBase, long srcOffset, | |
| 546 | + Object destBase, long destOffset, | |
| 547 | + long bytes); | |
| 548 | + /** | |
| 549 | + * Sets all bytes in a given block of memory to a copy of another | |
| 550 | + * block. This provides a <em>single-register</em> addressing mode, | |
| 551 | + * as discussed in {@link #getInt(Object,long)}. | |
| 552 | + * | |
| 553 | + * Equivalent to <code>copyMemory(null, srcAddress, null, destAddress, bytes)</code>. | |
| 554 | + */ | |
| 555 | + public void copyMemory(long srcAddress, long destAddress, long bytes) { | |
| 556 | + copyMemory(null, srcAddress, null, destAddress, bytes); | |
| 557 | + } | |
| 558 | + | |
| 559 | + /** | |
| 560 | + * Disposes of a block of native memory, as obtained from {@link | |
| 561 | + * #allocateMemory} or {@link #reallocateMemory}. The address passed to | |
| 562 | + * this method may be null, in which case no action is taken. | |
| 563 | + * | |
| 564 | + * @see #allocateMemory | |
| 565 | + */ | |
| 566 | + public native void freeMemory(long address); | |
| 567 | + | |
| 568 | + /// random queries | |
| 569 | + | |
| 570 | + /** | |
| 571 | + * This constant differs from all results that will ever be returned from | |
| 572 | + * {@link #staticFieldOffset}, {@link #objectFieldOffset}, | |
| 573 | + * or {@link #arrayBaseOffset}. | |
| 574 | + */ | |
| 575 | + public static final int INVALID_FIELD_OFFSET = -1; | |
| 576 | + | |
| 577 | + /** | |
| 578 | + * Returns the offset of a field, truncated to 32 bits. | |
| 579 | + * This method is implemented as follows: | |
| 580 | + * <blockquote><pre> | |
| 581 | + * public int fieldOffset(Field f) { | |
| 582 | + * if (Modifier.isStatic(f.getModifiers())) | |
| 583 | + * return (int) staticFieldOffset(f); | |
| 584 | + * else | |
| 585 | + * return (int) objectFieldOffset(f); | |
| 586 | + * } | |
| 587 | + * </pre></blockquote> | |
| 588 | + * @deprecated As of 1.4.1, use {@link #staticFieldOffset} for static | |
| 589 | + * fields and {@link #objectFieldOffset} for non-static fields. | |
| 590 | + */ | |
| 591 | + @Deprecated | |
| 592 | + public int fieldOffset(Field f) { | |
| 593 | + if (Modifier.isStatic(f.getModifiers())) | |
| 594 | + return (int) staticFieldOffset(f); | |
| 595 | + else | |
| 596 | + return (int) objectFieldOffset(f); | |
| 597 | + } | |
| 598 | + | |
| 599 | + /** | |
| 600 | + * Returns the base address for accessing some static field | |
| 601 | + * in the given class. This method is implemented as follows: | |
| 602 | + * <blockquote><pre> | |
| 603 | + * public Object staticFieldBase(Class c) { | |
| 604 | + * Field[] fields = c.getDeclaredFields(); | |
| 605 | + * for (int i = 0; i < fields.length; i++) { | |
| 606 | + * if (Modifier.isStatic(fields[i].getModifiers())) { | |
| 607 | + * return staticFieldBase(fields[i]); | |
| 608 | + * } | |
| 609 | + * } | |
| 610 | + * return null; | |
| 611 | + * } | |
| 612 | + * </pre></blockquote> | |
| 613 | + * @deprecated As of 1.4.1, use {@link #staticFieldBase(Field)} | |
| 614 | + * to obtain the base pertaining to a specific {@link Field}. | |
| 615 | + * This method works only for JVMs which store all statics | |
| 616 | + * for a given class in one place. | |
| 617 | + */ | |
| 618 | + @Deprecated | |
| 619 | + public Object staticFieldBase(Class c) { | |
| 620 | + Field[] fields = c.getDeclaredFields(); | |
| 621 | + for (int i = 0; i < fields.length; i++) { | |
| 622 | + if (Modifier.isStatic(fields[i].getModifiers())) { | |
| 623 | + return staticFieldBase(fields[i]); | |
| 624 | + } | |
| 625 | + } | |
| 626 | + return null; | |
| 627 | + } | |
| 628 | + | |
| 629 | + /** | |
| 630 | + * Report the location of a given field in the storage allocation of its | |
| 631 | + * class. Do not expect to perform any sort of arithmetic on this offset; | |
| 632 | + * it is just a cookie which is passed to the unsafe heap memory accessors. | |
| 633 | + * | |
| 634 | + * <p>Any given field will always have the same offset and base, and no | |
| 635 | + * two distinct fields of the same class will ever have the same offset | |
| 636 | + * and base. | |
| 637 | + * | |
| 638 | + * <p>As of 1.4.1, offsets for fields are represented as long values, | |
| 639 | + * although the Sun JVM does not use the most significant 32 bits. | |
| 640 | + * However, JVM implementations which store static fields at absolute | |
| 641 | + * addresses can use long offsets and null base pointers to express | |
| 642 | + * the field locations in a form usable by {@link #getInt(Object,long)}. | |
| 643 | + * Therefore, code which will be ported to such JVMs on 64-bit platforms | |
| 644 | + * must preserve all bits of static field offsets. | |
| 645 | + * @see #getInt(Object, long) | |
| 646 | + */ | |
| 647 | + public native long staticFieldOffset(Field f); | |
| 648 | + | |
| 649 | + /** | |
| 650 | + * Report the location of a given static field, in conjunction with {@link | |
| 651 | + * #staticFieldBase}. | |
| 652 | + * <p>Do not expect to perform any sort of arithmetic on this offset; | |
| 653 | + * it is just a cookie which is passed to the unsafe heap memory accessors. | |
| 654 | + * | |
| 655 | + * <p>Any given field will always have the same offset, and no two distinct | |
| 656 | + * fields of the same class will ever have the same offset. | |
| 657 | + * | |
| 658 | + * <p>As of 1.4.1, offsets for fields are represented as long values, | |
| 659 | + * although the Sun JVM does not use the most significant 32 bits. | |
| 660 | + * It is hard to imagine a JVM technology which needs more than | |
| 661 | + * a few bits to encode an offset within a non-array object, | |
| 662 | + * However, for consistency with other methods in this class, | |
| 663 | + * this method reports its result as a long value. | |
| 664 | + * @see #getInt(Object, long) | |
| 665 | + */ | |
| 666 | + public native long objectFieldOffset(Field f); | |
| 667 | + | |
| 668 | + /** | |
| 669 | + * Report the location of a given static field, in conjunction with {@link | |
| 670 | + * #staticFieldOffset}. | |
| 671 | + * <p>Fetch the base "Object", if any, with which static fields of the | |
| 672 | + * given class can be accessed via methods like {@link #getInt(Object, | |
| 673 | + * long)}. This value may be null. This value may refer to an object | |
| 674 | + * which is a "cookie", not guaranteed to be a real Object, and it should | |
| 675 | + * not be used in any way except as argument to the get and put routines in | |
| 676 | + * this class. | |
| 677 | + */ | |
| 678 | + public native Object staticFieldBase(Field f); | |
| 679 | + | |
| 680 | + /** | |
| 681 | + * Ensure the given class has been initialized. This is often | |
| 682 | + * needed in conjunction with obtaining the static field base of a | |
| 683 | + * class. | |
| 684 | + */ | |
| 685 | + public native void ensureClassInitialized(Class c); | |
| 686 | + | |
| 687 | + /** | |
| 688 | + * Report the offset of the first element in the storage allocation of a | |
| 689 | + * given array class. If {@link #arrayIndexScale} returns a non-zero value | |
| 690 | + * for the same class, you may use that scale factor, together with this | |
| 691 | + * base offset, to form new offsets to access elements of arrays of the | |
| 692 | + * given class. | |
| 693 | + * | |
| 694 | + * @see #getInt(Object, long) | |
| 695 | + * @see #putInt(Object, long, int) | |
| 696 | + */ | |
| 697 | + public native int arrayBaseOffset(Class arrayClass); | |
| 698 | + | |
| 699 | + /** The value of {@code arrayBaseOffset(boolean[].class)} */ | |
| 700 | + public static final int ARRAY_BOOLEAN_BASE_OFFSET | |
| 701 | + = theUnsafe.arrayBaseOffset(boolean[].class); | |
| 702 | + | |
| 703 | + /** The value of {@code arrayBaseOffset(byte[].class)} */ | |
| 704 | + public static final int ARRAY_BYTE_BASE_OFFSET | |
| 705 | + = theUnsafe.arrayBaseOffset(byte[].class); | |
| 706 | + | |
| 707 | + /** The value of {@code arrayBaseOffset(short[].class)} */ | |
| 708 | + public static final int ARRAY_SHORT_BASE_OFFSET | |
| 709 | + = theUnsafe.arrayBaseOffset(short[].class); | |
| 710 | + | |
| 711 | + /** The value of {@code arrayBaseOffset(char[].class)} */ | |
| 712 | + public static final int ARRAY_CHAR_BASE_OFFSET | |
| 713 | + = theUnsafe.arrayBaseOffset(char[].class); | |
| 714 | + | |
| 715 | + /** The value of {@code arrayBaseOffset(int[].class)} */ | |
| 716 | + public static final int ARRAY_INT_BASE_OFFSET | |
| 717 | + = theUnsafe.arrayBaseOffset(int[].class); | |
| 718 | + | |
| 719 | + /** The value of {@code arrayBaseOffset(long[].class)} */ | |
| 720 | + public static final int ARRAY_LONG_BASE_OFFSET | |
| 721 | + = theUnsafe.arrayBaseOffset(long[].class); | |
| 722 | + | |
| 723 | + /** The value of {@code arrayBaseOffset(float[].class)} */ | |
| 724 | + public static final int ARRAY_FLOAT_BASE_OFFSET | |
| 725 | + = theUnsafe.arrayBaseOffset(float[].class); | |
| 726 | + | |
| 727 | + /** The value of {@code arrayBaseOffset(double[].class)} */ | |
| 728 | + public static final int ARRAY_DOUBLE_BASE_OFFSET | |
| 729 | + = theUnsafe.arrayBaseOffset(double[].class); | |
| 730 | + | |
| 731 | + /** The value of {@code arrayBaseOffset(Object[].class)} */ | |
| 732 | + public static final int ARRAY_OBJECT_BASE_OFFSET | |
| 733 | + = theUnsafe.arrayBaseOffset(Object[].class); | |
| 734 | + | |
| 735 | + /** | |
| 736 | + * Report the scale factor for addressing elements in the storage | |
| 737 | + * allocation of a given array class. However, arrays of "narrow" types | |
| 738 | + * will generally not work properly with accessors like {@link | |
| 739 | + * #getByte(Object, int)}, so the scale factor for such classes is reported | |
| 740 | + * as zero. | |
| 741 | + * | |
| 742 | + * @see #arrayBaseOffset | |
| 743 | + * @see #getInt(Object, long) | |
| 744 | + * @see #putInt(Object, long, int) | |
| 745 | + */ | |
| 746 | + public native int arrayIndexScale(Class arrayClass); | |
| 747 | + | |
| 748 | + /** The value of {@code arrayIndexScale(boolean[].class)} */ | |
| 749 | + public static final int ARRAY_BOOLEAN_INDEX_SCALE | |
| 750 | + = theUnsafe.arrayIndexScale(boolean[].class); | |
| 751 | + | |
| 752 | + /** The value of {@code arrayIndexScale(byte[].class)} */ | |
| 753 | + public static final int ARRAY_BYTE_INDEX_SCALE | |
| 754 | + = theUnsafe.arrayIndexScale(byte[].class); | |
| 755 | + | |
| 756 | + /** The value of {@code arrayIndexScale(short[].class)} */ | |
| 757 | + public static final int ARRAY_SHORT_INDEX_SCALE | |
| 758 | + = theUnsafe.arrayIndexScale(short[].class); | |
| 759 | + | |
| 760 | + /** The value of {@code arrayIndexScale(char[].class)} */ | |
| 761 | + public static final int ARRAY_CHAR_INDEX_SCALE | |
| 762 | + = theUnsafe.arrayIndexScale(char[].class); | |
| 763 | + | |
| 764 | + /** The value of {@code arrayIndexScale(int[].class)} */ | |
| 765 | + public static final int ARRAY_INT_INDEX_SCALE | |
| 766 | + = theUnsafe.arrayIndexScale(int[].class); | |
| 767 | + | |
| 768 | + /** The value of {@code arrayIndexScale(long[].class)} */ | |
| 769 | + public static final int ARRAY_LONG_INDEX_SCALE | |
| 770 | + = theUnsafe.arrayIndexScale(long[].class); | |
| 771 | + | |
| 772 | + /** The value of {@code arrayIndexScale(float[].class)} */ | |
| 773 | + public static final int ARRAY_FLOAT_INDEX_SCALE | |
| 774 | + = theUnsafe.arrayIndexScale(float[].class); | |
| 775 | + | |
| 776 | + /** The value of {@code arrayIndexScale(double[].class)} */ | |
| 777 | + public static final int ARRAY_DOUBLE_INDEX_SCALE | |
| 778 | + = theUnsafe.arrayIndexScale(double[].class); | |
| 779 | + | |
| 780 | + /** The value of {@code arrayIndexScale(Object[].class)} */ | |
| 781 | + public static final int ARRAY_OBJECT_INDEX_SCALE | |
| 782 | + = theUnsafe.arrayIndexScale(Object[].class); | |
| 783 | + | |
| 784 | + /** | |
| 785 | + * Report 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 | + public native int addressSize(); | |
| 791 | + | |
| 792 | + /** The value of {@code addressSize()} */ | |
| 793 | + public static final int ADDRESS_SIZE = theUnsafe.addressSize(); | |
| 794 | + | |
| 795 | + /** | |
| 796 | + * Report the size in bytes of a native memory page (whatever that is). | |
| 797 | + * This value will always be a power of two. | |
| 798 | + */ | |
| 799 | + public native int pageSize(); | |
| 800 | + | |
| 801 | + | |
| 802 | + /// random trusted operations from JNI: | |
| 803 | + | |
| 804 | + /** | |
| 805 | + * Tell the VM to define a class, without security checks. By default, the | |
| 806 | + * class loader and protection domain come from the caller's class. | |
| 807 | + */ | |
| 808 | + public native Class defineClass(String name, byte[] b, int off, int len, | |
| 809 | + ClassLoader loader, | |
| 810 | + ProtectionDomain protectionDomain); | |
| 811 | + | |
| 812 | + public native Class defineClass(String name, byte[] b, int off, int len); | |
| 813 | + | |
| 814 | + /** | |
| 815 | + * Define a class but do not make it known to the class loader or system dictionary. | |
| 816 | + * <p> | |
| 817 | + * For each CP entry, the corresponding CP patch must either be null or have | |
| 818 | + * the a format that matches its tag: | |
| 819 | + * <ul> | |
| 820 | + * <li>Integer, Long, Float, Double: the corresponding wrapper object type from java.lang | |
| 821 | + * <li>Utf8: a string (must have suitable syntax if used as signature or name) | |
| 822 | + * <li>Class: any java.lang.Class object | |
| 823 | + * <li>String: any object (not just a java.lang.String) | |
| 824 | + * <li>InterfaceMethodRef: (NYI) a method handle to invoke on that call site's arguments | |
| 825 | + * </ul> | |
| 826 | + * @params hostClass context for linkage, access control, protection domain, and class loader | |
| 827 | + * @params data bytes of a class file | |
| 828 | + * @params cpPatches where non-null entries exist, they replace corresponding CP entries in data | |
| 829 | + */ | |
| 830 | + public native Class defineAnonymousClass(Class hostClass, byte[] data, Object[] cpPatches); | |
| 831 | + | |
| 832 | + | |
| 833 | + /** Allocate an instance but do not run any constructor. | |
| 834 | + Initializes the class if it has not yet been. */ | |
| 835 | + public native Object allocateInstance(Class cls) | |
| 836 | + throws InstantiationException; | |
| 837 | + | |
| 838 | + /** Lock the object. It must get unlocked via {@link #monitorExit}. */ | |
| 839 | + public native void monitorEnter(Object o); | |
| 840 | + | |
| 841 | + /** | |
| 842 | + * Unlock the object. It must have been locked via {@link | |
| 843 | + * #monitorEnter}. | |
| 844 | + */ | |
| 845 | + public native void monitorExit(Object o); | |
| 846 | + | |
| 847 | + /** | |
| 848 | + * Tries to lock the object. Returns true or false to indicate | |
| 849 | + * whether the lock succeeded. If it did, the object must be | |
| 850 | + * unlocked via {@link #monitorExit}. | |
| 851 | + */ | |
| 852 | + public native boolean tryMonitorEnter(Object o); | |
| 853 | + | |
| 854 | + /** Throw the exception without telling the verifier. */ | |
| 855 | + public native void throwException(Throwable ee); | |
| 856 | + | |
| 857 | + | |
| 858 | + /** | |
| 859 | + * Atomically update Java variable to <tt>x</tt> if it is currently | |
| 860 | + * holding <tt>expected</tt>. | |
| 861 | + * @return <tt>true</tt> if successful | |
| 862 | + */ | |
| 863 | + public final native boolean compareAndSwapObject(Object o, long offset, | |
| 864 | + Object expected, | |
| 865 | + Object x); | |
| 866 | + | |
| 867 | + /** | |
| 868 | + * Atomically update Java variable to <tt>x</tt> if it is currently | |
| 869 | + * holding <tt>expected</tt>. | |
| 870 | + * @return <tt>true</tt> if successful | |
| 871 | + */ | |
| 872 | + public final native boolean compareAndSwapInt(Object o, long offset, | |
| 873 | + int expected, | |
| 874 | + int x); | |
| 875 | + | |
| 876 | + /** | |
| 877 | + * Atomically update Java variable to <tt>x</tt> if it is currently | |
| 878 | + * holding <tt>expected</tt>. | |
| 879 | + * @return <tt>true</tt> if successful | |
| 880 | + */ | |
| 881 | + public final native boolean compareAndSwapLong(Object o, long offset, | |
| 882 | + long expected, | |
| 883 | + long x); | |
| 884 | + | |
| 885 | + /** | |
| 886 | + * Fetches a reference value from a given Java variable, with volatile | |
| 887 | + * load semantics. Otherwise identical to {@link #getObject(Object, long)} | |
| 888 | + */ | |
| 889 | + public native Object getObjectVolatile(Object o, long offset); | |
| 890 | + | |
| 891 | + /** | |
| 892 | + * Stores a reference value into a given Java variable, with | |
| 893 | + * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)} | |
| 894 | + */ | |
| 895 | + public native void putObjectVolatile(Object o, long offset, Object x); | |
| 896 | + | |
| 897 | + /** Volatile version of {@link #getInt(Object, long)} */ | |
| 898 | + public native int getIntVolatile(Object o, long offset); | |
| 899 | + | |
| 900 | + /** Volatile version of {@link #putInt(Object, long, int)} */ | |
| 901 | + public native void putIntVolatile(Object o, long offset, int x); | |
| 902 | + | |
| 903 | + /** Volatile version of {@link #getBoolean(Object, long)} */ | |
| 904 | + public native boolean getBooleanVolatile(Object o, long offset); | |
| 905 | + | |
| 906 | + /** Volatile version of {@link #putBoolean(Object, long, boolean)} */ | |
| 907 | + public native void putBooleanVolatile(Object o, long offset, boolean x); | |
| 908 | + | |
| 909 | + /** Volatile version of {@link #getByte(Object, long)} */ | |
| 910 | + public native byte getByteVolatile(Object o, long offset); | |
| 911 | + | |
| 912 | + /** Volatile version of {@link #putByte(Object, long, byte)} */ | |
| 913 | + public native void putByteVolatile(Object o, long offset, byte x); | |
| 914 | + | |
| 915 | + /** Volatile version of {@link #getShort(Object, long)} */ | |
| 916 | + public native short getShortVolatile(Object o, long offset); | |
| 917 | + | |
| 918 | + /** Volatile version of {@link #putShort(Object, long, short)} */ | |
| 919 | + public native void putShortVolatile(Object o, long offset, short x); | |
| 920 | + | |
| 921 | + /** Volatile version of {@link #getChar(Object, long)} */ | |
| 922 | + public native char getCharVolatile(Object o, long offset); | |
| 923 | + | |
| 924 | + /** Volatile version of {@link #putChar(Object, long, char)} */ | |
| 925 | + public native void putCharVolatile(Object o, long offset, char x); | |
| 926 | + | |
| 927 | + /** Volatile version of {@link #getLong(Object, long)} */ | |
| 928 | + public native long getLongVolatile(Object o, long offset); | |
| 929 | + | |
| 930 | + /** Volatile version of {@link #putLong(Object, long, long)} */ | |
| 931 | + public native void putLongVolatile(Object o, long offset, long x); | |
| 932 | + | |
| 933 | + /** Volatile version of {@link #getFloat(Object, long)} */ | |
| 934 | + public native float getFloatVolatile(Object o, long offset); | |
| 935 | + | |
| 936 | + /** Volatile version of {@link #putFloat(Object, long, float)} */ | |
| 937 | + public native void putFloatVolatile(Object o, long offset, float x); | |
| 938 | + | |
| 939 | + /** Volatile version of {@link #getDouble(Object, long)} */ | |
| 940 | + public native double getDoubleVolatile(Object o, long offset); | |
| 941 | + | |
| 942 | + /** Volatile version of {@link #putDouble(Object, long, double)} */ | |
| 943 | + public native void putDoubleVolatile(Object o, long offset, double x); | |
| 944 | + | |
| 945 | + /** | |
| 946 | + * Version of {@link #putObjectVolatile(Object, long, Object)} | |
| 947 | + * that does not guarantee immediate visibility of the store to | |
| 948 | + * other threads. This method is generally only useful if the | |
| 949 | + * underlying field is a Java volatile (or if an array cell, one | |
| 950 | + * that is otherwise only accessed using volatile accesses). | |
| 951 | + */ | |
| 952 | + public native void putOrderedObject(Object o, long offset, Object x); | |
| 953 | + | |
| 954 | + /** Ordered/Lazy version of {@link #putIntVolatile(Object, long, int)} */ | |
| 955 | + public native void putOrderedInt(Object o, long offset, int x); | |
| 956 | + | |
| 957 | + /** Ordered/Lazy version of {@link #putLongVolatile(Object, long, long)} */ | |
| 958 | + public native void putOrderedLong(Object o, long offset, long x); | |
| 959 | + | |
| 960 | + /** | |
| 961 | + * Unblock the given thread blocked on <tt>park</tt>, or, if it is | |
| 962 | + * not blocked, cause the subsequent call to <tt>park</tt> not to | |
| 963 | + * block. Note: this operation is "unsafe" solely because the | |
| 964 | + * caller must somehow ensure that the thread has not been | |
| 965 | + * destroyed. Nothing special is usually required to ensure this | |
| 966 | + * when called from Java (in which there will ordinarily be a live | |
| 967 | + * reference to the thread) but this is not nearly-automatically | |
| 968 | + * so when calling from native code. | |
| 969 | + * @param thread the thread to unpark. | |
| 970 | + * | |
| 971 | + */ | |
| 972 | + public native void unpark(Object thread); | |
| 973 | + | |
| 974 | + /** | |
| 975 | + * Block current thread, returning when a balancing | |
| 976 | + * <tt>unpark</tt> occurs, or a balancing <tt>unpark</tt> has | |
| 977 | + * already occurred, or the thread is interrupted, or, if not | |
| 978 | + * absolute and time is not zero, the given time nanoseconds have | |
| 979 | + * elapsed, or if absolute, the given deadline in milliseconds | |
| 980 | + * since Epoch has passed, or spuriously (i.e., returning for no | |
| 981 | + * "reason"). Note: This operation is in the Unsafe class only | |
| 982 | + * because <tt>unpark</tt> is, so it would be strange to place it | |
| 983 | + * elsewhere. | |
| 984 | + */ | |
| 985 | + public native void park(boolean isAbsolute, long time); | |
| 986 | + | |
| 987 | + /** | |
| 988 | + * Gets the load average in the system run queue assigned | |
| 989 | + * to the available processors averaged over various periods of time. | |
| 990 | + * This method retrieves the given <tt>nelem</tt> samples and | |
| 991 | + * assigns to the elements of the given <tt>loadavg</tt> array. | |
| 992 | + * The system imposes a maximum of 3 samples, representing | |
| 993 | + * averages over the last 1, 5, and 15 minutes, respectively. | |
| 994 | + * | |
| 995 | + * @params loadavg an array of double of size nelems | |
| 996 | + * @params nelems the number of samples to be retrieved and | |
| 997 | + * must be 1 to 3. | |
| 998 | + * | |
| 999 | + * @return the number of samples actually retrieved; or -1 | |
| 1000 | + * if the load average is unobtainable. | |
| 1001 | + */ | |
| 1002 | + public native int getLoadAverage(double[] loadavg, int nelems); | |
| 1003 | +} | |