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 jdk.internal.misc;
27
28 import jdk.internal.vm.annotation.AOTRuntimeSetup;
29 import jdk.internal.vm.annotation.AOTSafeClassInitializer;
30 import jdk.internal.vm.annotation.ForceInline;
31 import jdk.internal.vm.annotation.IntrinsicCandidate;
32 import sun.nio.Cleaner;
33 import sun.nio.ch.DirectBuffer;
34
35 import java.lang.reflect.Field;
36 import java.security.ProtectionDomain;
37
38 import static jdk.internal.misc.UnsafeConstants.*;
39
40 /**
41 * A collection of methods for performing low-level, unsafe operations.
42 * Although the class and all methods are public, use of this class is
43 * limited because only trusted code can obtain instances of it.
44 *
45 * <em>Note:</em> It is the responsibility of the caller to make sure
46 * arguments are checked before methods of this class are
47 * called. While some rudimentary checks are performed on the input,
169 * The first two parameters are interpreted exactly as with
170 * {@link #getInt(Object, long)} to refer to a specific
171 * Java variable (field or array element). The given value
172 * is stored into that variable.
173 * <p>
174 * The variable must be of the same type as the method
175 * parameter {@code x}.
176 *
177 * @param o Java heap object in which the variable resides, if any, else
178 * null
179 * @param offset indication of where the variable resides in a Java heap
180 * object, if any, else a memory address locating the variable
181 * statically
182 * @param x the value to store into the indicated Java variable
183 * @throws RuntimeException No defined exceptions are thrown, not even
184 * {@link NullPointerException}
185 */
186 @IntrinsicCandidate
187 public native void putInt(Object o, long offset, int x);
188
189 /**
190 * Fetches a reference value from a given Java variable.
191 * @see #getInt(Object, long)
192 */
193 @IntrinsicCandidate
194 public native Object getReference(Object o, long offset);
195
196 /**
197 * Stores a reference value into a given Java variable.
198 * <p>
199 * Unless the reference {@code x} being stored is either null
200 * or matches the field type, the results are undefined.
201 * If the reference {@code o} is non-null, card marks or
202 * other store barriers for that object (if the VM requires them)
203 * are updated.
204 * @see #putInt(Object, long, int)
205 */
206 @IntrinsicCandidate
207 public native void putReference(Object o, long offset, Object x);
208
209 /** @see #getInt(Object, long) */
210 @IntrinsicCandidate
211 public native boolean getBoolean(Object o, long offset);
212
213 /** @see #putInt(Object, long, int) */
214 @IntrinsicCandidate
215 public native void putBoolean(Object o, long offset, boolean x);
216
217 /** @see #getInt(Object, long) */
218 @IntrinsicCandidate
219 public native byte getByte(Object o, long offset);
220
221 /** @see #putInt(Object, long, int) */
222 @IntrinsicCandidate
223 public native void putByte(Object o, long offset, byte x);
224
225 /** @see #getInt(Object, long) */
226 @IntrinsicCandidate
227 public native short getShort(Object o, long offset);
228
1178 }
1179
1180 /**
1181 * Ensures the given class has been initialized (see JVMS-5.5 for details).
1182 * This is often needed in conjunction with obtaining the static field base
1183 * of a class.
1184 *
1185 * The call returns when either class {@code c} is fully initialized or
1186 * class {@code c} is being initialized and the call is performed from
1187 * the initializing thread. In the latter case a subsequent call to
1188 * {@link #shouldBeInitialized} will return {@code true}.
1189 */
1190 public void ensureClassInitialized(Class<?> c) {
1191 if (c == null) {
1192 throw new NullPointerException();
1193 }
1194
1195 ensureClassInitialized0(c);
1196 }
1197
1198 /**
1199 * Reports the offset of the first element in the storage allocation of a
1200 * given array class. If {@link #arrayIndexScale} returns a non-zero value
1201 * for the same class, you may use that scale factor, together with this
1202 * base offset, to form new offsets to access elements of arrays of the
1203 * given class.
1204 * <p>
1205 * The return value is in the range of a {@code int}. The return type is
1206 * {@code long} to emphasize that long arithmetic should always be used
1207 * for offset calculations to avoid overflows.
1208 *
1209 * @see #getInt(Object, long)
1210 * @see #putInt(Object, long, int)
1211 */
1212 public long arrayBaseOffset(Class<?> arrayClass) {
1213 if (arrayClass == null) {
1214 throw new NullPointerException();
1215 }
1216
1217 return arrayBaseOffset0(arrayClass);
1218 }
1219
1220
1221 /** The value of {@code arrayBaseOffset(boolean[].class)} */
1222 public static final long ARRAY_BOOLEAN_BASE_OFFSET
1223 = theUnsafe.arrayBaseOffset(boolean[].class);
1224
1225 /** The value of {@code arrayBaseOffset(byte[].class)} */
1226 public static final long ARRAY_BYTE_BASE_OFFSET
1227 = theUnsafe.arrayBaseOffset(byte[].class);
1228
1229 /** The value of {@code arrayBaseOffset(short[].class)} */
1230 public static final long ARRAY_SHORT_BASE_OFFSET
1231 = theUnsafe.arrayBaseOffset(short[].class);
1232
1233 /** The value of {@code arrayBaseOffset(char[].class)} */
1234 public static final long ARRAY_CHAR_BASE_OFFSET
1235 = theUnsafe.arrayBaseOffset(char[].class);
1236
1237 /** The value of {@code arrayBaseOffset(int[].class)} */
1238 public static final long ARRAY_INT_BASE_OFFSET
1239 = theUnsafe.arrayBaseOffset(int[].class);
1246 public static final long ARRAY_FLOAT_BASE_OFFSET
1247 = theUnsafe.arrayBaseOffset(float[].class);
1248
1249 /** The value of {@code arrayBaseOffset(double[].class)} */
1250 public static final long ARRAY_DOUBLE_BASE_OFFSET
1251 = theUnsafe.arrayBaseOffset(double[].class);
1252
1253 /** The value of {@code arrayBaseOffset(Object[].class)} */
1254 public static final long ARRAY_OBJECT_BASE_OFFSET
1255 = theUnsafe.arrayBaseOffset(Object[].class);
1256
1257 /**
1258 * Reports the scale factor for addressing elements in the storage
1259 * allocation of a given array class. However, arrays of "narrow" types
1260 * will generally not work properly with accessors like {@link
1261 * #getByte(Object, long)}, so the scale factor for such classes is reported
1262 * as zero.
1263 * <p>
1264 * The computation of the actual memory offset should always use {@code
1265 * long} arithmetic to avoid overflows.
1266 *
1267 * @see #arrayBaseOffset
1268 * @see #getInt(Object, long)
1269 * @see #putInt(Object, long, int)
1270 */
1271 public int arrayIndexScale(Class<?> arrayClass) {
1272 if (arrayClass == null) {
1273 throw new NullPointerException();
1274 }
1275
1276 return arrayIndexScale0(arrayClass);
1277 }
1278
1279
1280 /** The value of {@code arrayIndexScale(boolean[].class)} */
1281 public static final int ARRAY_BOOLEAN_INDEX_SCALE
1282 = theUnsafe.arrayIndexScale(boolean[].class);
1283
1284 /** The value of {@code arrayIndexScale(byte[].class)} */
1285 public static final int ARRAY_BYTE_INDEX_SCALE
1286 = theUnsafe.arrayIndexScale(byte[].class);
1287
1288 /** The value of {@code arrayIndexScale(short[].class)} */
1289 public static final int ARRAY_SHORT_INDEX_SCALE
1290 = theUnsafe.arrayIndexScale(short[].class);
1291
1292 /** The value of {@code arrayIndexScale(char[].class)} */
1293 public static final int ARRAY_CHAR_INDEX_SCALE
1294 = theUnsafe.arrayIndexScale(char[].class);
1295
1296 /** The value of {@code arrayIndexScale(int[].class)} */
1297 public static final int ARRAY_INT_INDEX_SCALE
1298 = theUnsafe.arrayIndexScale(int[].class);
1437 return null;
1438 }
1439
1440 /** Throws the exception without telling the verifier. */
1441 public native void throwException(Throwable ee);
1442
1443 /**
1444 * Atomically updates Java variable to {@code x} if it is currently
1445 * holding {@code expected}.
1446 *
1447 * <p>This operation has memory semantics of a {@code volatile} read
1448 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1449 *
1450 * @return {@code true} if successful
1451 */
1452 @IntrinsicCandidate
1453 public final native boolean compareAndSetReference(Object o, long offset,
1454 Object expected,
1455 Object x);
1456
1457 @IntrinsicCandidate
1458 public final native Object compareAndExchangeReference(Object o, long offset,
1459 Object expected,
1460 Object x);
1461
1462 @IntrinsicCandidate
1463 public final Object compareAndExchangeReferenceAcquire(Object o, long offset,
1464 Object expected,
1465 Object x) {
1466 return compareAndExchangeReference(o, offset, expected, x);
1467 }
1468
1469 @IntrinsicCandidate
1470 public final Object compareAndExchangeReferenceRelease(Object o, long offset,
1471 Object expected,
1472 Object x) {
1473 return compareAndExchangeReference(o, offset, expected, x);
1474 }
1475
1476 @IntrinsicCandidate
1477 public final boolean weakCompareAndSetReferencePlain(Object o, long offset,
1478 Object expected,
1479 Object x) {
1480 return compareAndSetReference(o, offset, expected, x);
1481 }
1482
1483 @IntrinsicCandidate
1484 public final boolean weakCompareAndSetReferenceAcquire(Object o, long offset,
1485 Object expected,
1486 Object x) {
1487 return compareAndSetReference(o, offset, expected, x);
1488 }
1489
1490 @IntrinsicCandidate
1491 public final boolean weakCompareAndSetReferenceRelease(Object o, long offset,
1492 Object expected,
1493 Object x) {
1494 return compareAndSetReference(o, offset, expected, x);
1495 }
1496
1497 @IntrinsicCandidate
1498 public final boolean weakCompareAndSetReference(Object o, long offset,
1499 Object expected,
1500 Object x) {
1501 return compareAndSetReference(o, offset, expected, x);
1502 }
1503
1504 /**
1505 * Atomically updates Java variable to {@code x} if it is currently
1506 * holding {@code expected}.
1507 *
1508 * <p>This operation has memory semantics of a {@code volatile} read
1509 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1510 *
1511 * @return {@code true} if successful
1512 */
1513 @IntrinsicCandidate
1514 public final native boolean compareAndSetInt(Object o, long offset,
1515 int expected,
1516 int x);
1517
1518 @IntrinsicCandidate
1519 public final native int compareAndExchangeInt(Object o, long offset,
1520 int expected,
1521 int x);
1522
1523 @IntrinsicCandidate
2099 public final boolean weakCompareAndSetLongRelease(Object o, long offset,
2100 long expected,
2101 long x) {
2102 return compareAndSetLong(o, offset, expected, x);
2103 }
2104
2105 @IntrinsicCandidate
2106 public final boolean weakCompareAndSetLong(Object o, long offset,
2107 long expected,
2108 long x) {
2109 return compareAndSetLong(o, offset, expected, x);
2110 }
2111
2112 /**
2113 * Fetches a reference value from a given Java variable, with volatile
2114 * load semantics. Otherwise identical to {@link #getReference(Object, long)}
2115 */
2116 @IntrinsicCandidate
2117 public native Object getReferenceVolatile(Object o, long offset);
2118
2119 /**
2120 * Stores a reference value into a given Java variable, with
2121 * volatile store semantics. Otherwise identical to {@link #putReference(Object, long, Object)}
2122 */
2123 @IntrinsicCandidate
2124 public native void putReferenceVolatile(Object o, long offset, Object x);
2125
2126 /** Volatile version of {@link #getInt(Object, long)} */
2127 @IntrinsicCandidate
2128 public native int getIntVolatile(Object o, long offset);
2129
2130 /** Volatile version of {@link #putInt(Object, long, int)} */
2131 @IntrinsicCandidate
2132 public native void putIntVolatile(Object o, long offset, int x);
2133
2134 /** Volatile version of {@link #getBoolean(Object, long)} */
2135 @IntrinsicCandidate
2136 public native boolean getBooleanVolatile(Object o, long offset);
2137
2138 /** Volatile version of {@link #putBoolean(Object, long, boolean)} */
2139 @IntrinsicCandidate
2140 public native void putBooleanVolatile(Object o, long offset, boolean x);
2141
2142 /** Volatile version of {@link #getByte(Object, long)} */
2143 @IntrinsicCandidate
2144 public native byte getByteVolatile(Object o, long offset);
2145
2178 /** Volatile version of {@link #putFloat(Object, long, float)} */
2179 @IntrinsicCandidate
2180 public native void putFloatVolatile(Object o, long offset, float x);
2181
2182 /** Volatile version of {@link #getDouble(Object, long)} */
2183 @IntrinsicCandidate
2184 public native double getDoubleVolatile(Object o, long offset);
2185
2186 /** Volatile version of {@link #putDouble(Object, long, double)} */
2187 @IntrinsicCandidate
2188 public native void putDoubleVolatile(Object o, long offset, double x);
2189
2190
2191
2192 /** Acquire version of {@link #getReferenceVolatile(Object, long)} */
2193 @IntrinsicCandidate
2194 public final Object getReferenceAcquire(Object o, long offset) {
2195 return getReferenceVolatile(o, offset);
2196 }
2197
2198 /** Acquire version of {@link #getBooleanVolatile(Object, long)} */
2199 @IntrinsicCandidate
2200 public final boolean getBooleanAcquire(Object o, long offset) {
2201 return getBooleanVolatile(o, offset);
2202 }
2203
2204 /** Acquire version of {@link #getByteVolatile(Object, long)} */
2205 @IntrinsicCandidate
2206 public final byte getByteAcquire(Object o, long offset) {
2207 return getByteVolatile(o, offset);
2208 }
2209
2210 /** Acquire version of {@link #getShortVolatile(Object, long)} */
2211 @IntrinsicCandidate
2212 public final short getShortAcquire(Object o, long offset) {
2213 return getShortVolatile(o, offset);
2214 }
2215
2216 /** Acquire version of {@link #getCharVolatile(Object, long)} */
2217 @IntrinsicCandidate
2242 public final double getDoubleAcquire(Object o, long offset) {
2243 return getDoubleVolatile(o, offset);
2244 }
2245
2246 /*
2247 * Versions of {@link #putReferenceVolatile(Object, long, Object)}
2248 * that do not guarantee immediate visibility of the store to
2249 * other threads. This method is generally only useful if the
2250 * underlying field is a Java volatile (or if an array cell, one
2251 * that is otherwise only accessed using volatile accesses).
2252 *
2253 * Corresponds to C11 atomic_store_explicit(..., memory_order_release).
2254 */
2255
2256 /** Release version of {@link #putReferenceVolatile(Object, long, Object)} */
2257 @IntrinsicCandidate
2258 public final void putReferenceRelease(Object o, long offset, Object x) {
2259 putReferenceVolatile(o, offset, x);
2260 }
2261
2262 /** Release version of {@link #putBooleanVolatile(Object, long, boolean)} */
2263 @IntrinsicCandidate
2264 public final void putBooleanRelease(Object o, long offset, boolean x) {
2265 putBooleanVolatile(o, offset, x);
2266 }
2267
2268 /** Release version of {@link #putByteVolatile(Object, long, byte)} */
2269 @IntrinsicCandidate
2270 public final void putByteRelease(Object o, long offset, byte x) {
2271 putByteVolatile(o, offset, x);
2272 }
2273
2274 /** Release version of {@link #putShortVolatile(Object, long, short)} */
2275 @IntrinsicCandidate
2276 public final void putShortRelease(Object o, long offset, short x) {
2277 putShortVolatile(o, offset, x);
2278 }
2279
2280 /** Release version of {@link #putCharVolatile(Object, long, char)} */
2281 @IntrinsicCandidate
2298 /** Release version of {@link #putLongVolatile(Object, long, long)} */
2299 @IntrinsicCandidate
2300 public final void putLongRelease(Object o, long offset, long x) {
2301 putLongVolatile(o, offset, x);
2302 }
2303
2304 /** Release version of {@link #putDoubleVolatile(Object, long, double)} */
2305 @IntrinsicCandidate
2306 public final void putDoubleRelease(Object o, long offset, double x) {
2307 putDoubleVolatile(o, offset, x);
2308 }
2309
2310 // ------------------------------ Opaque --------------------------------------
2311
2312 /** Opaque version of {@link #getReferenceVolatile(Object, long)} */
2313 @IntrinsicCandidate
2314 public final Object getReferenceOpaque(Object o, long offset) {
2315 return getReferenceVolatile(o, offset);
2316 }
2317
2318 /** Opaque version of {@link #getBooleanVolatile(Object, long)} */
2319 @IntrinsicCandidate
2320 public final boolean getBooleanOpaque(Object o, long offset) {
2321 return getBooleanVolatile(o, offset);
2322 }
2323
2324 /** Opaque version of {@link #getByteVolatile(Object, long)} */
2325 @IntrinsicCandidate
2326 public final byte getByteOpaque(Object o, long offset) {
2327 return getByteVolatile(o, offset);
2328 }
2329
2330 /** Opaque version of {@link #getShortVolatile(Object, long)} */
2331 @IntrinsicCandidate
2332 public final short getShortOpaque(Object o, long offset) {
2333 return getShortVolatile(o, offset);
2334 }
2335
2336 /** Opaque version of {@link #getCharVolatile(Object, long)} */
2337 @IntrinsicCandidate
2352 }
2353
2354 /** Opaque version of {@link #getLongVolatile(Object, long)} */
2355 @IntrinsicCandidate
2356 public final long getLongOpaque(Object o, long offset) {
2357 return getLongVolatile(o, offset);
2358 }
2359
2360 /** Opaque version of {@link #getDoubleVolatile(Object, long)} */
2361 @IntrinsicCandidate
2362 public final double getDoubleOpaque(Object o, long offset) {
2363 return getDoubleVolatile(o, offset);
2364 }
2365
2366 /** Opaque version of {@link #putReferenceVolatile(Object, long, Object)} */
2367 @IntrinsicCandidate
2368 public final void putReferenceOpaque(Object o, long offset, Object x) {
2369 putReferenceVolatile(o, offset, x);
2370 }
2371
2372 /** Opaque version of {@link #putBooleanVolatile(Object, long, boolean)} */
2373 @IntrinsicCandidate
2374 public final void putBooleanOpaque(Object o, long offset, boolean x) {
2375 putBooleanVolatile(o, offset, x);
2376 }
2377
2378 /** Opaque version of {@link #putByteVolatile(Object, long, byte)} */
2379 @IntrinsicCandidate
2380 public final void putByteOpaque(Object o, long offset, byte x) {
2381 putByteVolatile(o, offset, x);
2382 }
2383
2384 /** Opaque version of {@link #putShortVolatile(Object, long, short)} */
2385 @IntrinsicCandidate
2386 public final void putShortOpaque(Object o, long offset, short x) {
2387 putShortVolatile(o, offset, x);
2388 }
2389
2390 /** Opaque version of {@link #putCharVolatile(Object, long, char)} */
2391 @IntrinsicCandidate
2400 }
2401
2402 /** Opaque version of {@link #putFloatVolatile(Object, long, float)} */
2403 @IntrinsicCandidate
2404 public final void putFloatOpaque(Object o, long offset, float x) {
2405 putFloatVolatile(o, offset, x);
2406 }
2407
2408 /** Opaque version of {@link #putLongVolatile(Object, long, long)} */
2409 @IntrinsicCandidate
2410 public final void putLongOpaque(Object o, long offset, long x) {
2411 putLongVolatile(o, offset, x);
2412 }
2413
2414 /** Opaque version of {@link #putDoubleVolatile(Object, long, double)} */
2415 @IntrinsicCandidate
2416 public final void putDoubleOpaque(Object o, long offset, double x) {
2417 putDoubleVolatile(o, offset, x);
2418 }
2419
2420 /**
2421 * Unblocks the given thread blocked on {@code park}, or, if it is
2422 * not blocked, causes the subsequent call to {@code park} not to
2423 * block. Note: this operation is "unsafe" solely because the
2424 * caller must somehow ensure that the thread has not been
2425 * destroyed. Nothing special is usually required to ensure this
2426 * when called from Java (in which there will ordinarily be a live
2427 * reference to the thread) but this is not nearly-automatically
2428 * so when calling from native code.
2429 *
2430 * @param thread the thread to unpark.
2431 */
2432 @IntrinsicCandidate
2433 public native void unpark(Object thread);
2434
2435 /**
2436 * Blocks current thread, returning when a balancing
2437 * {@code unpark} occurs, or a balancing {@code unpark} has
2438 * already occurred, or the thread is interrupted, or, if not
2439 * absolute and time is not zero, the given time nanoseconds have
2786 /**
2787 * Atomically exchanges the given reference value with the current
2788 * reference value of a field or array element within the given
2789 * object {@code o} at the given {@code offset}.
2790 *
2791 * @param o object/array to update the field/element in
2792 * @param offset field/element offset
2793 * @param newValue new value
2794 * @return the previous value
2795 * @since 1.8
2796 */
2797 @IntrinsicCandidate
2798 public final Object getAndSetReference(Object o, long offset, Object newValue) {
2799 Object v;
2800 do {
2801 v = getReferenceVolatile(o, offset);
2802 } while (!weakCompareAndSetReference(o, offset, v, newValue));
2803 return v;
2804 }
2805
2806 @ForceInline
2807 public final Object getAndSetReferenceRelease(Object o, long offset, Object newValue) {
2808 Object v;
2809 do {
2810 v = getReference(o, offset);
2811 } while (!weakCompareAndSetReferenceRelease(o, offset, v, newValue));
2812 return v;
2813 }
2814
2815 @ForceInline
2816 public final Object getAndSetReferenceAcquire(Object o, long offset, Object newValue) {
2817 Object v;
2818 do {
2819 v = getReferenceAcquire(o, offset);
2820 } while (!weakCompareAndSetReferenceAcquire(o, offset, v, newValue));
2821 return v;
2822 }
2823
2824 @IntrinsicCandidate
2825 public final byte getAndSetByte(Object o, long offset, byte newValue) {
2826 byte v;
2827 do {
2828 v = getByteVolatile(o, offset);
2829 } while (!weakCompareAndSetByte(o, offset, v, newValue));
2830 return v;
2831 }
2832
2833 @ForceInline
2834 public final byte getAndSetByteRelease(Object o, long offset, byte newValue) {
2835 byte v;
2836 do {
2837 v = getByte(o, offset);
2838 } while (!weakCompareAndSetByteRelease(o, offset, v, newValue));
2839 return v;
2840 }
2841
2842 @ForceInline
2843 public final byte getAndSetByteAcquire(Object o, long offset, byte newValue) {
3859 private static short convEndian(boolean big, short n) { return big == BIG_ENDIAN ? n : Short.reverseBytes(n) ; }
3860 private static int convEndian(boolean big, int n) { return big == BIG_ENDIAN ? n : Integer.reverseBytes(n) ; }
3861 private static long convEndian(boolean big, long n) { return big == BIG_ENDIAN ? n : Long.reverseBytes(n) ; }
3862
3863
3864
3865 private native long allocateMemory0(long bytes);
3866 private native long reallocateMemory0(long address, long bytes);
3867 private native void freeMemory0(long address);
3868 @IntrinsicCandidate
3869 private native void setMemory0(Object o, long offset, long bytes, byte value);
3870 @IntrinsicCandidate
3871 private native void copyMemory0(Object srcBase, long srcOffset, Object destBase, long destOffset, long bytes);
3872 private native void copySwapMemory0(Object srcBase, long srcOffset, Object destBase, long destOffset, long bytes, long elemSize);
3873 private native long objectFieldOffset0(Field f); // throws IAE
3874 private native long knownObjectFieldOffset0(Class<?> c, String name); // error code: -1 not found, -2 static
3875 private native long staticFieldOffset0(Field f); // throws IAE
3876 private native Object staticFieldBase0(Field f); // throws IAE
3877 private native boolean shouldBeInitialized0(Class<?> c);
3878 private native void ensureClassInitialized0(Class<?> c);
3879 private native int arrayBaseOffset0(Class<?> arrayClass); // public version returns long to promote correct arithmetic
3880 private native int arrayIndexScale0(Class<?> arrayClass);
3881 private native int getLoadAverage0(double[] loadavg, int nelems);
3882
3883
3884 /**
3885 * Invokes the given direct byte buffer's cleaner, if any.
3886 *
3887 * @param directBuffer a direct byte buffer
3888 * @throws NullPointerException if {@code directBuffer} is null
3889 * @throws IllegalArgumentException if {@code directBuffer} is non-direct,
3890 * or is a {@link java.nio.Buffer#slice slice}, or is a
3891 * {@link java.nio.Buffer#duplicate duplicate}
3892 */
3893 public void invokeCleaner(java.nio.ByteBuffer directBuffer) {
3894 if (!directBuffer.isDirect())
3895 throw new IllegalArgumentException("buffer is non-direct");
3896
3897 DirectBuffer db = (DirectBuffer) directBuffer;
3898 if (db.attachment() != null)
3899 throw new IllegalArgumentException("duplicate or slice");
3900
|
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 jdk.internal.misc;
27
28 import jdk.internal.value.ValueClass;
29 import jdk.internal.vm.annotation.AOTRuntimeSetup;
30 import jdk.internal.vm.annotation.AOTSafeClassInitializer;
31 import jdk.internal.vm.annotation.ForceInline;
32 import jdk.internal.vm.annotation.IntrinsicCandidate;
33 import sun.nio.Cleaner;
34 import sun.nio.ch.DirectBuffer;
35
36 import java.lang.reflect.Field;
37 import java.security.ProtectionDomain;
38
39 import static jdk.internal.misc.UnsafeConstants.*;
40
41 /**
42 * A collection of methods for performing low-level, unsafe operations.
43 * Although the class and all methods are public, use of this class is
44 * limited because only trusted code can obtain instances of it.
45 *
46 * <em>Note:</em> It is the responsibility of the caller to make sure
47 * arguments are checked before methods of this class are
48 * called. While some rudimentary checks are performed on the input,
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 @IntrinsicCandidate
188 public native void putInt(Object o, long offset, int x);
189
190
191 /**
192 * Returns true if the given field is flattened.
193 */
194 public boolean isFlatField(Field f) {
195 if (f == null) {
196 throw new NullPointerException();
197 }
198 return isFlatField0(f);
199 }
200
201 private native boolean isFlatField0(Object o);
202
203 /* Returns true if the given field has a null marker
204 * <p>
205 * Nullable flat fields are stored in a flattened representation
206 * and have an associated null marker to indicate if the the field value is
207 * null or the one stored with the flat representation
208 */
209
210 public boolean hasNullMarker(Field f) {
211 if (f == null) {
212 throw new NullPointerException();
213 }
214 return hasNullMarker0(f);
215 }
216
217 private native boolean hasNullMarker0(Object o);
218
219 /* Returns the offset of the null marker of the field,
220 * or -1 if the field doesn't have a null marker
221 */
222
223 public int nullMarkerOffset(Field f) {
224 if (f == null) {
225 throw new NullPointerException();
226 }
227 return nullMarkerOffset0(f);
228 }
229
230 private native int nullMarkerOffset0(Object o);
231
232 public static final int NON_FLAT_LAYOUT = 0;
233
234 /* Reports the kind of layout used for an element in the storage
235 * allocation of the given array. Do not expect to perform any logic
236 * or layout control with this value, it is just an opaque token
237 * used for performance reasons.
238 *
239 * A layout of 0 indicates this array is not flat.
240 */
241 public int arrayLayout(Object[] array) {
242 if (array == null) {
243 throw new NullPointerException();
244 }
245 return arrayLayout0(array);
246 }
247
248 private native int arrayLayout0(Object[] array);
249
250
251 /* Reports the kind of layout used for a given field in the storage
252 * allocation of its class. Do not expect to perform any logic
253 * or layout control with this value, it is just an opaque token
254 * used for performance reasons.
255 *
256 * A layout of 0 indicates this field is not flat.
257 */
258 public int fieldLayout(Field f) {
259 if (f == null) {
260 throw new NullPointerException();
261 }
262 return fieldLayout0(f);
263 }
264
265 private native int fieldLayout0(Object o);
266
267 public native Object[] newSpecialArray(Class<?> componentType,
268 int length, int layoutKind);
269
270 /**
271 * Fetches a reference value from a given Java variable.
272 * This method can return a reference to either an object or value
273 * or a null reference.
274 *
275 * @see #getInt(Object, long)
276 */
277 @IntrinsicCandidate
278 public native Object getReference(Object o, long offset);
279
280 /**
281 * Stores a reference value into a given Java variable.
282 * This method can store a reference to either an object or value
283 * or a null reference.
284 * <p>
285 * Unless the reference {@code x} being stored is either null
286 * or matches the field type, the results are undefined.
287 * If the reference {@code o} is non-null, card marks or
288 * other store barriers for that object (if the VM requires them)
289 * are updated.
290 * @see #putInt(Object, long, int)
291 */
292 @IntrinsicCandidate
293 public native void putReference(Object o, long offset, Object x);
294
295 /**
296 * Fetches a value of type {@code <V>} from a given Java variable.
297 * More specifically, fetches a field or array element within the given
298 * {@code o} object at the given offset, or (if {@code o} is null)
299 * from the memory address whose numerical value is the given offset.
300 *
301 * @param o Java heap object in which the variable resides, if any, else
302 * null
303 * @param offset indication of where the variable resides in a Java heap
304 * object, if any, else a memory address locating the variable
305 * statically
306 * @param valueType value type
307 * @param <V> the type of a value
308 * @return the value fetched from the indicated Java variable
309 * @throws RuntimeException No defined exceptions are thrown, not even
310 * {@link NullPointerException}
311 */
312 @IntrinsicCandidate
313 public native <V> V getValue(Object o, long offset, Class<?> valueType);
314
315 /**
316 * Fetches a value of type {@code <V>} from a given Java variable.
317 * More specifically, fetches a field or array element within the given
318 * {@code o} object at the given offset, or (if {@code o} is null)
319 * from the memory address whose numerical value is the given offset.
320 *
321 * @param o Java heap object in which the variable resides, if any, else
322 * null
323 * @param offset indication of where the variable resides in a Java heap
324 * object, if any, else a memory address locating the variable
325 * statically
326 * @param layoutKind opaque value used by the VM to know the layout
327 * the field or array element. This value must be retrieved with
328 * {@link #fieldLayout} or {@link #arrayLayout}.
329 * @param valueType value type
330 * @param <V> the type of a value
331 * @return the value fetched from the indicated Java variable
332 * @throws RuntimeException No defined exceptions are thrown, not even
333 * {@link NullPointerException}
334 */
335 @IntrinsicCandidate
336 public native <V> V getFlatValue(Object o, long offset, int layoutKind, Class<?> valueType);
337
338
339 /**
340 * Stores the given value into a given Java variable.
341 *
342 * Unless the reference {@code o} being stored is either null
343 * or matches the field type, the results are undefined.
344 *
345 * @param o Java heap object in which the variable resides, if any, else
346 * null
347 * @param offset indication of where the variable resides in a Java heap
348 * object, if any, else a memory address locating the variable
349 * statically
350 * @param valueType value type
351 * @param v the value to store into the indicated Java variable
352 * @param <V> the type of a value
353 * @throws RuntimeException No defined exceptions are thrown, not even
354 * {@link NullPointerException}
355 */
356 @IntrinsicCandidate
357 public native <V> void putValue(Object o, long offset, Class<?> valueType, V v);
358
359 /**
360 * Stores the given value into a given Java variable.
361 *
362 * Unless the reference {@code o} being stored is either null
363 * or matches the field type, the results are undefined.
364 *
365 * @param o Java heap object in which the variable resides, if any, else
366 * null
367 * @param offset indication of where the variable resides in a Java heap
368 * object, if any, else a memory address locating the variable
369 * statically
370 * @param layoutKind opaque value used by the VM to know the layout
371 * the field or array element. This value must be retrieved with
372 * {@link #fieldLayout} or {@link #arrayLayout}.
373 * @param valueType value type
374 * @param v the value to store into the indicated Java variable
375 * @param <V> the type of a value
376 * @throws RuntimeException No defined exceptions are thrown, not even
377 * {@link NullPointerException}
378 */
379 @IntrinsicCandidate
380 public native <V> void putFlatValue(Object o, long offset, int layoutKind, Class<?> valueType, V v);
381
382 /**
383 * Returns an object instance with a private buffered value whose layout
384 * and contents is exactly the given value instance. The return object
385 * is in the larval state that can be updated using the unsafe put operation.
386 *
387 * @param value a value instance
388 * @param <V> the type of the given value instance
389 */
390 @IntrinsicCandidate
391 public native <V> V makePrivateBuffer(V value);
392
393 /**
394 * Exits the larval state and returns a value instance.
395 *
396 * @param value a value instance
397 * @param <V> the type of the given value instance
398 */
399 @IntrinsicCandidate
400 public native <V> V finishPrivateBuffer(V value);
401
402 /**
403 * Returns the header size of the given value type.
404 *
405 * @param valueType value type
406 * @return the header size of the value type
407 */
408 public native <V> long valueHeaderSize(Class<V> valueType);
409
410 /** @see #getInt(Object, long) */
411 @IntrinsicCandidate
412 public native boolean getBoolean(Object o, long offset);
413
414 /** @see #putInt(Object, long, int) */
415 @IntrinsicCandidate
416 public native void putBoolean(Object o, long offset, boolean x);
417
418 /** @see #getInt(Object, long) */
419 @IntrinsicCandidate
420 public native byte getByte(Object o, long offset);
421
422 /** @see #putInt(Object, long, int) */
423 @IntrinsicCandidate
424 public native void putByte(Object o, long offset, byte x);
425
426 /** @see #getInt(Object, long) */
427 @IntrinsicCandidate
428 public native short getShort(Object o, long offset);
429
1379 }
1380
1381 /**
1382 * Ensures the given class has been initialized (see JVMS-5.5 for details).
1383 * This is often needed in conjunction with obtaining the static field base
1384 * of a class.
1385 *
1386 * The call returns when either class {@code c} is fully initialized or
1387 * class {@code c} is being initialized and the call is performed from
1388 * the initializing thread. In the latter case a subsequent call to
1389 * {@link #shouldBeInitialized} will return {@code true}.
1390 */
1391 public void ensureClassInitialized(Class<?> c) {
1392 if (c == null) {
1393 throw new NullPointerException();
1394 }
1395
1396 ensureClassInitialized0(c);
1397 }
1398
1399 /**
1400 * The reading or writing of strict static fields may require
1401 * special processing. Notify the VM that such an event is about
1402 * to happen. The VM may respond by throwing an exception, in the
1403 * case of a read of an uninitialized field. If the VM allows the
1404 * method to return normally, no further calls are needed, with
1405 * the same arguments.
1406 */
1407 public void notifyStrictStaticAccess(Class<?> c, long staticFieldOffset, boolean writing) {
1408 if (c == null) {
1409 throw new NullPointerException();
1410 }
1411 notifyStrictStaticAccess0(c, staticFieldOffset, writing);
1412 }
1413
1414 /**
1415 * Reports the offset of the first element in the storage allocation of a
1416 * given array class. If {@link #arrayIndexScale} returns a non-zero value
1417 * for the same class, you may use that scale factor, together with this
1418 * base offset, to form new offsets to access elements of arrays of the
1419 * given class.
1420 * <p>
1421 * The return value is in the range of a {@code int}. The return type is
1422 * {@code long} to emphasize that long arithmetic should always be used
1423 * for offset calculations to avoid overflows.
1424 * <p>
1425 * This method doesn't support arrays with an element type that is
1426 * a value class, because this type of array can have multiple layouts.
1427 * For these arrays, {@code arrayInstanceBaseOffset(Object[] array)}
1428 * must be used instead.
1429 *
1430 * @see #getInt(Object, long)
1431 * @see #putInt(Object, long, int)
1432 */
1433 public long arrayBaseOffset(Class<?> arrayClass) {
1434 if (arrayClass == null) {
1435 throw new NullPointerException();
1436 }
1437
1438 return arrayBaseOffset0(arrayClass);
1439 }
1440
1441 public long arrayInstanceBaseOffset(Object[] array) {
1442 if (array == null) {
1443 throw new NullPointerException();
1444 }
1445
1446 return arrayInstanceBaseOffset0(array);
1447 }
1448
1449 /** The value of {@code arrayBaseOffset(boolean[].class)} */
1450 public static final long ARRAY_BOOLEAN_BASE_OFFSET
1451 = theUnsafe.arrayBaseOffset(boolean[].class);
1452
1453 /** The value of {@code arrayBaseOffset(byte[].class)} */
1454 public static final long ARRAY_BYTE_BASE_OFFSET
1455 = theUnsafe.arrayBaseOffset(byte[].class);
1456
1457 /** The value of {@code arrayBaseOffset(short[].class)} */
1458 public static final long ARRAY_SHORT_BASE_OFFSET
1459 = theUnsafe.arrayBaseOffset(short[].class);
1460
1461 /** The value of {@code arrayBaseOffset(char[].class)} */
1462 public static final long ARRAY_CHAR_BASE_OFFSET
1463 = theUnsafe.arrayBaseOffset(char[].class);
1464
1465 /** The value of {@code arrayBaseOffset(int[].class)} */
1466 public static final long ARRAY_INT_BASE_OFFSET
1467 = theUnsafe.arrayBaseOffset(int[].class);
1474 public static final long ARRAY_FLOAT_BASE_OFFSET
1475 = theUnsafe.arrayBaseOffset(float[].class);
1476
1477 /** The value of {@code arrayBaseOffset(double[].class)} */
1478 public static final long ARRAY_DOUBLE_BASE_OFFSET
1479 = theUnsafe.arrayBaseOffset(double[].class);
1480
1481 /** The value of {@code arrayBaseOffset(Object[].class)} */
1482 public static final long ARRAY_OBJECT_BASE_OFFSET
1483 = theUnsafe.arrayBaseOffset(Object[].class);
1484
1485 /**
1486 * Reports the scale factor for addressing elements in the storage
1487 * allocation of a given array class. However, arrays of "narrow" types
1488 * will generally not work properly with accessors like {@link
1489 * #getByte(Object, long)}, so the scale factor for such classes is reported
1490 * as zero.
1491 * <p>
1492 * The computation of the actual memory offset should always use {@code
1493 * long} arithmetic to avoid overflows.
1494 * <p>
1495 * This method doesn't support arrays with an element type that is
1496 * a value class, because this type of array can have multiple layouts.
1497 * For these arrays, {@code arrayInstanceIndexScale(Object[] array)}
1498 * must be used instead.
1499 *
1500 * @see #arrayBaseOffset
1501 * @see #getInt(Object, long)
1502 * @see #putInt(Object, long, int)
1503 */
1504 public int arrayIndexScale(Class<?> arrayClass) {
1505 if (arrayClass == null) {
1506 throw new NullPointerException();
1507 }
1508
1509 return arrayIndexScale0(arrayClass);
1510 }
1511
1512 public int arrayInstanceIndexScale(Object[] array) {
1513 if (array == null) {
1514 throw new NullPointerException();
1515 }
1516
1517 return arrayInstanceIndexScale0(array);
1518 }
1519
1520 /**
1521 * Return the size of the object in the heap.
1522 * @param o an object
1523 * @return the objects's size
1524 * @since Valhalla
1525 */
1526 public long getObjectSize(Object o) {
1527 if (o == null)
1528 throw new NullPointerException();
1529 return getObjectSize0(o);
1530 }
1531
1532 /** The value of {@code arrayIndexScale(boolean[].class)} */
1533 public static final int ARRAY_BOOLEAN_INDEX_SCALE
1534 = theUnsafe.arrayIndexScale(boolean[].class);
1535
1536 /** The value of {@code arrayIndexScale(byte[].class)} */
1537 public static final int ARRAY_BYTE_INDEX_SCALE
1538 = theUnsafe.arrayIndexScale(byte[].class);
1539
1540 /** The value of {@code arrayIndexScale(short[].class)} */
1541 public static final int ARRAY_SHORT_INDEX_SCALE
1542 = theUnsafe.arrayIndexScale(short[].class);
1543
1544 /** The value of {@code arrayIndexScale(char[].class)} */
1545 public static final int ARRAY_CHAR_INDEX_SCALE
1546 = theUnsafe.arrayIndexScale(char[].class);
1547
1548 /** The value of {@code arrayIndexScale(int[].class)} */
1549 public static final int ARRAY_INT_INDEX_SCALE
1550 = theUnsafe.arrayIndexScale(int[].class);
1689 return null;
1690 }
1691
1692 /** Throws the exception without telling the verifier. */
1693 public native void throwException(Throwable ee);
1694
1695 /**
1696 * Atomically updates Java variable to {@code x} if it is currently
1697 * holding {@code expected}.
1698 *
1699 * <p>This operation has memory semantics of a {@code volatile} read
1700 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1701 *
1702 * @return {@code true} if successful
1703 */
1704 @IntrinsicCandidate
1705 public final native boolean compareAndSetReference(Object o, long offset,
1706 Object expected,
1707 Object x);
1708
1709 private final boolean isValueObject(Object o) {
1710 return o != null && o.getClass().isValue();
1711 }
1712
1713 /*
1714 * For value type, CAS should do substitutability test as opposed
1715 * to two pointers comparison.
1716 */
1717 @ForceInline
1718 public final <V> boolean compareAndSetReference(Object o, long offset,
1719 Class<?> type,
1720 V expected,
1721 V x) {
1722 if (type.isValue() || isValueObject(expected)) {
1723 while (true) {
1724 Object witness = getReferenceVolatile(o, offset);
1725 if (witness != expected) {
1726 return false;
1727 }
1728 if (compareAndSetReference(o, offset, witness, x)) {
1729 return true;
1730 }
1731 }
1732 } else {
1733 return compareAndSetReference(o, offset, expected, x);
1734 }
1735 }
1736
1737 @ForceInline
1738 public final <V> boolean compareAndSetFlatValue(Object o, long offset,
1739 int layout,
1740 Class<?> valueType,
1741 V expected,
1742 V x) {
1743 while (true) {
1744 Object witness = getFlatValueVolatile(o, offset, layout, valueType);
1745 if (witness != expected) {
1746 return false;
1747 }
1748 if (compareAndSetFlatValueAsBytes(o, offset, layout, valueType, witness, x)) {
1749 return true;
1750 }
1751 }
1752 }
1753
1754 @IntrinsicCandidate
1755 public final native Object compareAndExchangeReference(Object o, long offset,
1756 Object expected,
1757 Object x);
1758
1759 @ForceInline
1760 public final <V> Object compareAndExchangeReference(Object o, long offset,
1761 Class<?> valueType,
1762 V expected,
1763 V x) {
1764 if (valueType.isValue() || isValueObject(expected)) {
1765 while (true) {
1766 Object witness = getReferenceVolatile(o, offset);
1767 if (witness != expected) {
1768 return witness;
1769 }
1770 if (compareAndSetReference(o, offset, witness, x)) {
1771 return witness;
1772 }
1773 }
1774 } else {
1775 return compareAndExchangeReference(o, offset, expected, x);
1776 }
1777 }
1778
1779 @ForceInline
1780 public final <V> Object compareAndExchangeFlatValue(Object o, long offset,
1781 int layout,
1782 Class<?> valueType,
1783 V expected,
1784 V x) {
1785 while (true) {
1786 Object witness = getFlatValueVolatile(o, offset, layout, valueType);
1787 if (witness != expected) {
1788 return witness;
1789 }
1790 if (compareAndSetFlatValueAsBytes(o, offset, layout, valueType, witness, x)) {
1791 return witness;
1792 }
1793 }
1794 }
1795
1796 @IntrinsicCandidate
1797 public final Object compareAndExchangeReferenceAcquire(Object o, long offset,
1798 Object expected,
1799 Object x) {
1800 return compareAndExchangeReference(o, offset, expected, x);
1801 }
1802
1803 public final <V> Object compareAndExchangeReferenceAcquire(Object o, long offset,
1804 Class<?> valueType,
1805 V expected,
1806 V x) {
1807 return compareAndExchangeReference(o, offset, valueType, expected, x);
1808 }
1809
1810 @ForceInline
1811 public final <V> Object compareAndExchangeFlatValueAcquire(Object o, long offset,
1812 int layout,
1813 Class<?> valueType,
1814 V expected,
1815 V x) {
1816 return compareAndExchangeFlatValue(o, offset, layout, valueType, expected, x);
1817 }
1818
1819 @IntrinsicCandidate
1820 public final Object compareAndExchangeReferenceRelease(Object o, long offset,
1821 Object expected,
1822 Object x) {
1823 return compareAndExchangeReference(o, offset, expected, x);
1824 }
1825
1826 public final <V> Object compareAndExchangeReferenceRelease(Object o, long offset,
1827 Class<?> valueType,
1828 V expected,
1829 V x) {
1830 return compareAndExchangeReference(o, offset, valueType, expected, x);
1831 }
1832
1833 @ForceInline
1834 public final <V> Object compareAndExchangeFlatValueRelease(Object o, long offset,
1835 int layout,
1836 Class<?> valueType,
1837 V expected,
1838 V x) {
1839 return compareAndExchangeFlatValue(o, offset, layout, valueType, expected, x);
1840 }
1841
1842 @IntrinsicCandidate
1843 public final boolean weakCompareAndSetReferencePlain(Object o, long offset,
1844 Object expected,
1845 Object x) {
1846 return compareAndSetReference(o, offset, expected, x);
1847 }
1848
1849 public final <V> boolean weakCompareAndSetReferencePlain(Object o, long offset,
1850 Class<?> valueType,
1851 V expected,
1852 V x) {
1853 if (valueType.isValue() || isValueObject(expected)) {
1854 return compareAndSetReference(o, offset, valueType, expected, x);
1855 } else {
1856 return weakCompareAndSetReferencePlain(o, offset, expected, x);
1857 }
1858 }
1859
1860 @ForceInline
1861 public final <V> boolean weakCompareAndSetFlatValuePlain(Object o, long offset,
1862 int layout,
1863 Class<?> valueType,
1864 V expected,
1865 V x) {
1866 return compareAndSetFlatValue(o, offset, layout, valueType, expected, x);
1867 }
1868
1869 @IntrinsicCandidate
1870 public final boolean weakCompareAndSetReferenceAcquire(Object o, long offset,
1871 Object expected,
1872 Object x) {
1873 return compareAndSetReference(o, offset, expected, x);
1874 }
1875
1876 public final <V> boolean weakCompareAndSetReferenceAcquire(Object o, long offset,
1877 Class<?> valueType,
1878 V expected,
1879 V x) {
1880 if (valueType.isValue() || isValueObject(expected)) {
1881 return compareAndSetReference(o, offset, valueType, expected, x);
1882 } else {
1883 return weakCompareAndSetReferencePlain(o, offset, expected, x);
1884 }
1885 }
1886
1887 @ForceInline
1888 public final <V> boolean weakCompareAndSetFlatValueAcquire(Object o, long offset,
1889 int layout,
1890 Class<?> valueType,
1891 V expected,
1892 V x) {
1893 return compareAndSetFlatValue(o, offset, layout, valueType, expected, x);
1894 }
1895
1896 @IntrinsicCandidate
1897 public final boolean weakCompareAndSetReferenceRelease(Object o, long offset,
1898 Object expected,
1899 Object x) {
1900 return compareAndSetReference(o, offset, expected, x);
1901 }
1902
1903 public final <V> boolean weakCompareAndSetReferenceRelease(Object o, long offset,
1904 Class<?> valueType,
1905 V expected,
1906 V x) {
1907 if (valueType.isValue() || isValueObject(expected)) {
1908 return compareAndSetReference(o, offset, valueType, expected, x);
1909 } else {
1910 return weakCompareAndSetReferencePlain(o, offset, expected, x);
1911 }
1912 }
1913
1914 @ForceInline
1915 public final <V> boolean weakCompareAndSetFlatValueRelease(Object o, long offset,
1916 int layout,
1917 Class<?> valueType,
1918 V expected,
1919 V x) {
1920 return compareAndSetFlatValue(o, offset, layout, valueType, expected, x);
1921 }
1922
1923 @IntrinsicCandidate
1924 public final boolean weakCompareAndSetReference(Object o, long offset,
1925 Object expected,
1926 Object x) {
1927 return compareAndSetReference(o, offset, expected, x);
1928 }
1929
1930 public final <V> boolean weakCompareAndSetReference(Object o, long offset,
1931 Class<?> valueType,
1932 V expected,
1933 V x) {
1934 if (valueType.isValue() || isValueObject(expected)) {
1935 return compareAndSetReference(o, offset, valueType, expected, x);
1936 } else {
1937 return weakCompareAndSetReferencePlain(o, offset, expected, x);
1938 }
1939 }
1940
1941 @ForceInline
1942 public final <V> boolean weakCompareAndSetFlatValue(Object o, long offset,
1943 int layout,
1944 Class<?> valueType,
1945 V expected,
1946 V x) {
1947 return compareAndSetFlatValue(o, offset, layout, valueType, expected, x);
1948 }
1949
1950 /**
1951 * Atomically updates Java variable to {@code x} if it is currently
1952 * holding {@code expected}.
1953 *
1954 * <p>This operation has memory semantics of a {@code volatile} read
1955 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1956 *
1957 * @return {@code true} if successful
1958 */
1959 @IntrinsicCandidate
1960 public final native boolean compareAndSetInt(Object o, long offset,
1961 int expected,
1962 int x);
1963
1964 @IntrinsicCandidate
1965 public final native int compareAndExchangeInt(Object o, long offset,
1966 int expected,
1967 int x);
1968
1969 @IntrinsicCandidate
2545 public final boolean weakCompareAndSetLongRelease(Object o, long offset,
2546 long expected,
2547 long x) {
2548 return compareAndSetLong(o, offset, expected, x);
2549 }
2550
2551 @IntrinsicCandidate
2552 public final boolean weakCompareAndSetLong(Object o, long offset,
2553 long expected,
2554 long x) {
2555 return compareAndSetLong(o, offset, expected, x);
2556 }
2557
2558 /**
2559 * Fetches a reference value from a given Java variable, with volatile
2560 * load semantics. Otherwise identical to {@link #getReference(Object, long)}
2561 */
2562 @IntrinsicCandidate
2563 public native Object getReferenceVolatile(Object o, long offset);
2564
2565 @ForceInline
2566 public final <V> Object getFlatValueVolatile(Object o, long offset, int layout, Class<?> valueType) {
2567 // we translate using fences (see: https://gee.cs.oswego.edu/dl/html/j9mm.html)
2568 Object res = getFlatValue(o, offset, layout, valueType);
2569 fullFence();
2570 return res;
2571 }
2572
2573 /**
2574 * Stores a reference value into a given Java variable, with
2575 * volatile store semantics. Otherwise identical to {@link #putReference(Object, long, Object)}
2576 */
2577 @IntrinsicCandidate
2578 public native void putReferenceVolatile(Object o, long offset, Object x);
2579
2580 @ForceInline
2581 public final <V> void putFlatValueVolatile(Object o, long offset, int layout, Class<?> valueType, V x) {
2582 // we translate using fences (see: https://gee.cs.oswego.edu/dl/html/j9mm.html)
2583 putFlatValueRelease(o, offset, layout, valueType, x);
2584 fullFence();
2585 }
2586
2587 /** Volatile version of {@link #getInt(Object, long)} */
2588 @IntrinsicCandidate
2589 public native int getIntVolatile(Object o, long offset);
2590
2591 /** Volatile version of {@link #putInt(Object, long, int)} */
2592 @IntrinsicCandidate
2593 public native void putIntVolatile(Object o, long offset, int x);
2594
2595 /** Volatile version of {@link #getBoolean(Object, long)} */
2596 @IntrinsicCandidate
2597 public native boolean getBooleanVolatile(Object o, long offset);
2598
2599 /** Volatile version of {@link #putBoolean(Object, long, boolean)} */
2600 @IntrinsicCandidate
2601 public native void putBooleanVolatile(Object o, long offset, boolean x);
2602
2603 /** Volatile version of {@link #getByte(Object, long)} */
2604 @IntrinsicCandidate
2605 public native byte getByteVolatile(Object o, long offset);
2606
2639 /** Volatile version of {@link #putFloat(Object, long, float)} */
2640 @IntrinsicCandidate
2641 public native void putFloatVolatile(Object o, long offset, float x);
2642
2643 /** Volatile version of {@link #getDouble(Object, long)} */
2644 @IntrinsicCandidate
2645 public native double getDoubleVolatile(Object o, long offset);
2646
2647 /** Volatile version of {@link #putDouble(Object, long, double)} */
2648 @IntrinsicCandidate
2649 public native void putDoubleVolatile(Object o, long offset, double x);
2650
2651
2652
2653 /** Acquire version of {@link #getReferenceVolatile(Object, long)} */
2654 @IntrinsicCandidate
2655 public final Object getReferenceAcquire(Object o, long offset) {
2656 return getReferenceVolatile(o, offset);
2657 }
2658
2659 @ForceInline
2660 public final <V> Object getFlatValueAcquire(Object o, long offset, int layout, Class<?> valueType) {
2661 // we translate using fences (see: https://gee.cs.oswego.edu/dl/html/j9mm.html)
2662 Object res = getFlatValue(o, offset, layout, valueType);
2663 loadFence();
2664 return res;
2665 }
2666
2667 /** Acquire version of {@link #getBooleanVolatile(Object, long)} */
2668 @IntrinsicCandidate
2669 public final boolean getBooleanAcquire(Object o, long offset) {
2670 return getBooleanVolatile(o, offset);
2671 }
2672
2673 /** Acquire version of {@link #getByteVolatile(Object, long)} */
2674 @IntrinsicCandidate
2675 public final byte getByteAcquire(Object o, long offset) {
2676 return getByteVolatile(o, offset);
2677 }
2678
2679 /** Acquire version of {@link #getShortVolatile(Object, long)} */
2680 @IntrinsicCandidate
2681 public final short getShortAcquire(Object o, long offset) {
2682 return getShortVolatile(o, offset);
2683 }
2684
2685 /** Acquire version of {@link #getCharVolatile(Object, long)} */
2686 @IntrinsicCandidate
2711 public final double getDoubleAcquire(Object o, long offset) {
2712 return getDoubleVolatile(o, offset);
2713 }
2714
2715 /*
2716 * Versions of {@link #putReferenceVolatile(Object, long, Object)}
2717 * that do not guarantee immediate visibility of the store to
2718 * other threads. This method is generally only useful if the
2719 * underlying field is a Java volatile (or if an array cell, one
2720 * that is otherwise only accessed using volatile accesses).
2721 *
2722 * Corresponds to C11 atomic_store_explicit(..., memory_order_release).
2723 */
2724
2725 /** Release version of {@link #putReferenceVolatile(Object, long, Object)} */
2726 @IntrinsicCandidate
2727 public final void putReferenceRelease(Object o, long offset, Object x) {
2728 putReferenceVolatile(o, offset, x);
2729 }
2730
2731 @ForceInline
2732 public final <V> void putFlatValueRelease(Object o, long offset, int layout, Class<?> valueType, V x) {
2733 // we translate using fences (see: https://gee.cs.oswego.edu/dl/html/j9mm.html)
2734 storeFence();
2735 putFlatValue(o, offset, layout, valueType, x);
2736 }
2737
2738 /** Release version of {@link #putBooleanVolatile(Object, long, boolean)} */
2739 @IntrinsicCandidate
2740 public final void putBooleanRelease(Object o, long offset, boolean x) {
2741 putBooleanVolatile(o, offset, x);
2742 }
2743
2744 /** Release version of {@link #putByteVolatile(Object, long, byte)} */
2745 @IntrinsicCandidate
2746 public final void putByteRelease(Object o, long offset, byte x) {
2747 putByteVolatile(o, offset, x);
2748 }
2749
2750 /** Release version of {@link #putShortVolatile(Object, long, short)} */
2751 @IntrinsicCandidate
2752 public final void putShortRelease(Object o, long offset, short x) {
2753 putShortVolatile(o, offset, x);
2754 }
2755
2756 /** Release version of {@link #putCharVolatile(Object, long, char)} */
2757 @IntrinsicCandidate
2774 /** Release version of {@link #putLongVolatile(Object, long, long)} */
2775 @IntrinsicCandidate
2776 public final void putLongRelease(Object o, long offset, long x) {
2777 putLongVolatile(o, offset, x);
2778 }
2779
2780 /** Release version of {@link #putDoubleVolatile(Object, long, double)} */
2781 @IntrinsicCandidate
2782 public final void putDoubleRelease(Object o, long offset, double x) {
2783 putDoubleVolatile(o, offset, x);
2784 }
2785
2786 // ------------------------------ Opaque --------------------------------------
2787
2788 /** Opaque version of {@link #getReferenceVolatile(Object, long)} */
2789 @IntrinsicCandidate
2790 public final Object getReferenceOpaque(Object o, long offset) {
2791 return getReferenceVolatile(o, offset);
2792 }
2793
2794 @ForceInline
2795 public final <V> Object getFlatValueOpaque(Object o, long offset, int layout, Class<?> valueType) {
2796 // this is stronger than opaque semantics
2797 return getFlatValueAcquire(o, offset, layout, valueType);
2798 }
2799
2800 /** Opaque version of {@link #getBooleanVolatile(Object, long)} */
2801 @IntrinsicCandidate
2802 public final boolean getBooleanOpaque(Object o, long offset) {
2803 return getBooleanVolatile(o, offset);
2804 }
2805
2806 /** Opaque version of {@link #getByteVolatile(Object, long)} */
2807 @IntrinsicCandidate
2808 public final byte getByteOpaque(Object o, long offset) {
2809 return getByteVolatile(o, offset);
2810 }
2811
2812 /** Opaque version of {@link #getShortVolatile(Object, long)} */
2813 @IntrinsicCandidate
2814 public final short getShortOpaque(Object o, long offset) {
2815 return getShortVolatile(o, offset);
2816 }
2817
2818 /** Opaque version of {@link #getCharVolatile(Object, long)} */
2819 @IntrinsicCandidate
2834 }
2835
2836 /** Opaque version of {@link #getLongVolatile(Object, long)} */
2837 @IntrinsicCandidate
2838 public final long getLongOpaque(Object o, long offset) {
2839 return getLongVolatile(o, offset);
2840 }
2841
2842 /** Opaque version of {@link #getDoubleVolatile(Object, long)} */
2843 @IntrinsicCandidate
2844 public final double getDoubleOpaque(Object o, long offset) {
2845 return getDoubleVolatile(o, offset);
2846 }
2847
2848 /** Opaque version of {@link #putReferenceVolatile(Object, long, Object)} */
2849 @IntrinsicCandidate
2850 public final void putReferenceOpaque(Object o, long offset, Object x) {
2851 putReferenceVolatile(o, offset, x);
2852 }
2853
2854 @ForceInline
2855 public final <V> void putFlatValueOpaque(Object o, long offset, int layout, Class<?> valueType, V x) {
2856 // this is stronger than opaque semantics
2857 putFlatValueRelease(o, offset, layout, valueType, x);
2858 }
2859
2860 /** Opaque version of {@link #putBooleanVolatile(Object, long, boolean)} */
2861 @IntrinsicCandidate
2862 public final void putBooleanOpaque(Object o, long offset, boolean x) {
2863 putBooleanVolatile(o, offset, x);
2864 }
2865
2866 /** Opaque version of {@link #putByteVolatile(Object, long, byte)} */
2867 @IntrinsicCandidate
2868 public final void putByteOpaque(Object o, long offset, byte x) {
2869 putByteVolatile(o, offset, x);
2870 }
2871
2872 /** Opaque version of {@link #putShortVolatile(Object, long, short)} */
2873 @IntrinsicCandidate
2874 public final void putShortOpaque(Object o, long offset, short x) {
2875 putShortVolatile(o, offset, x);
2876 }
2877
2878 /** Opaque version of {@link #putCharVolatile(Object, long, char)} */
2879 @IntrinsicCandidate
2888 }
2889
2890 /** Opaque version of {@link #putFloatVolatile(Object, long, float)} */
2891 @IntrinsicCandidate
2892 public final void putFloatOpaque(Object o, long offset, float x) {
2893 putFloatVolatile(o, offset, x);
2894 }
2895
2896 /** Opaque version of {@link #putLongVolatile(Object, long, long)} */
2897 @IntrinsicCandidate
2898 public final void putLongOpaque(Object o, long offset, long x) {
2899 putLongVolatile(o, offset, x);
2900 }
2901
2902 /** Opaque version of {@link #putDoubleVolatile(Object, long, double)} */
2903 @IntrinsicCandidate
2904 public final void putDoubleOpaque(Object o, long offset, double x) {
2905 putDoubleVolatile(o, offset, x);
2906 }
2907
2908 @ForceInline
2909 private boolean compareAndSetFlatValueAsBytes(Object o, long offset, int layout, Class<?> valueType, Object expected, Object x) {
2910 // We turn the payload of an atomic value into a numeric value (of suitable type)
2911 // by storing the value into an array element (of matching layout) and by reading
2912 // back the array element as an integral value. After which we can implement the CAS
2913 // as a plain numeric CAS. Note: this only works if the payload contains no oops
2914 // (see VarHandles::isAtomicFlat).
2915 Object[] expectedArray = newSpecialArray(valueType, 1, layout);
2916 Object xArray = newSpecialArray(valueType, 1, layout);
2917 long base = arrayInstanceBaseOffset(expectedArray);
2918 int scale = arrayInstanceIndexScale(expectedArray);
2919 putFlatValue(expectedArray, base, layout, valueType, expected);
2920 putFlatValue(xArray, base, layout, valueType, x);
2921 switch (scale) {
2922 case 1: {
2923 byte expectedByte = getByte(expectedArray, base);
2924 byte xByte = getByte(xArray, base);
2925 return compareAndSetByte(o, offset, expectedByte, xByte);
2926 }
2927 case 2: {
2928 short expectedShort = getShort(expectedArray, base);
2929 short xShort = getShort(xArray, base);
2930 return compareAndSetShort(o, offset, expectedShort, xShort);
2931 }
2932 case 4: {
2933 int expectedInt = getInt(expectedArray, base);
2934 int xInt = getInt(xArray, base);
2935 return compareAndSetInt(o, offset, expectedInt, xInt);
2936 }
2937 case 8: {
2938 long expectedLong = getLong(expectedArray, base);
2939 long xLong = getLong(xArray, base);
2940 return compareAndSetLong(o, offset, expectedLong, xLong);
2941 }
2942 default: {
2943 throw new UnsupportedOperationException();
2944 }
2945 }
2946 }
2947
2948 /**
2949 * Unblocks the given thread blocked on {@code park}, or, if it is
2950 * not blocked, causes the subsequent call to {@code park} not to
2951 * block. Note: this operation is "unsafe" solely because the
2952 * caller must somehow ensure that the thread has not been
2953 * destroyed. Nothing special is usually required to ensure this
2954 * when called from Java (in which there will ordinarily be a live
2955 * reference to the thread) but this is not nearly-automatically
2956 * so when calling from native code.
2957 *
2958 * @param thread the thread to unpark.
2959 */
2960 @IntrinsicCandidate
2961 public native void unpark(Object thread);
2962
2963 /**
2964 * Blocks current thread, returning when a balancing
2965 * {@code unpark} occurs, or a balancing {@code unpark} has
2966 * already occurred, or the thread is interrupted, or, if not
2967 * absolute and time is not zero, the given time nanoseconds have
3314 /**
3315 * Atomically exchanges the given reference value with the current
3316 * reference value of a field or array element within the given
3317 * object {@code o} at the given {@code offset}.
3318 *
3319 * @param o object/array to update the field/element in
3320 * @param offset field/element offset
3321 * @param newValue new value
3322 * @return the previous value
3323 * @since 1.8
3324 */
3325 @IntrinsicCandidate
3326 public final Object getAndSetReference(Object o, long offset, Object newValue) {
3327 Object v;
3328 do {
3329 v = getReferenceVolatile(o, offset);
3330 } while (!weakCompareAndSetReference(o, offset, v, newValue));
3331 return v;
3332 }
3333
3334 @ForceInline
3335 public final Object getAndSetReference(Object o, long offset, Class<?> valueType, Object newValue) {
3336 Object v;
3337 do {
3338 v = getReferenceVolatile(o, offset);
3339 } while (!compareAndSetReference(o, offset, valueType, v, newValue));
3340 return v;
3341 }
3342
3343 @ForceInline
3344 public Object getAndSetFlatValue(Object o, long offset, int layoutKind, Class<?> valueType, Object newValue) {
3345 Object v;
3346 do {
3347 v = getFlatValueVolatile(o, offset, layoutKind, valueType);
3348 } while (!compareAndSetFlatValue(o, offset, layoutKind, valueType, v, newValue));
3349 return v;
3350 }
3351
3352 @ForceInline
3353 public final Object getAndSetReferenceRelease(Object o, long offset, Object newValue) {
3354 Object v;
3355 do {
3356 v = getReference(o, offset);
3357 } while (!weakCompareAndSetReferenceRelease(o, offset, v, newValue));
3358 return v;
3359 }
3360
3361 @ForceInline
3362 public final Object getAndSetReferenceRelease(Object o, long offset, Class<?> valueType, Object newValue) {
3363 return getAndSetReference(o, offset, valueType, newValue);
3364 }
3365
3366 @ForceInline
3367 public Object getAndSetFlatValueRelease(Object o, long offset, int layoutKind, Class<?> valueType, Object x) {
3368 return getAndSetFlatValue(o, offset, layoutKind, valueType, x);
3369 }
3370
3371 @ForceInline
3372 public final Object getAndSetReferenceAcquire(Object o, long offset, Object newValue) {
3373 Object v;
3374 do {
3375 v = getReferenceAcquire(o, offset);
3376 } while (!weakCompareAndSetReferenceAcquire(o, offset, v, newValue));
3377 return v;
3378 }
3379
3380 @ForceInline
3381 public final Object getAndSetReferenceAcquire(Object o, long offset, Class<?> valueType, Object newValue) {
3382 return getAndSetReference(o, offset, valueType, newValue);
3383 }
3384
3385 @ForceInline
3386 public Object getAndSetFlatValueAcquire(Object o, long offset, int layoutKind, Class<?> valueType, Object x) {
3387 return getAndSetFlatValue(o, offset, layoutKind, valueType, x);
3388 }
3389
3390 @IntrinsicCandidate
3391 public final byte getAndSetByte(Object o, long offset, byte newValue) {
3392 byte v;
3393 do {
3394 v = getByteVolatile(o, offset);
3395 } while (!weakCompareAndSetByte(o, offset, v, newValue));
3396 return v;
3397 }
3398
3399 @ForceInline
3400 public final byte getAndSetByteRelease(Object o, long offset, byte newValue) {
3401 byte v;
3402 do {
3403 v = getByte(o, offset);
3404 } while (!weakCompareAndSetByteRelease(o, offset, v, newValue));
3405 return v;
3406 }
3407
3408 @ForceInline
3409 public final byte getAndSetByteAcquire(Object o, long offset, byte newValue) {
4425 private static short convEndian(boolean big, short n) { return big == BIG_ENDIAN ? n : Short.reverseBytes(n) ; }
4426 private static int convEndian(boolean big, int n) { return big == BIG_ENDIAN ? n : Integer.reverseBytes(n) ; }
4427 private static long convEndian(boolean big, long n) { return big == BIG_ENDIAN ? n : Long.reverseBytes(n) ; }
4428
4429
4430
4431 private native long allocateMemory0(long bytes);
4432 private native long reallocateMemory0(long address, long bytes);
4433 private native void freeMemory0(long address);
4434 @IntrinsicCandidate
4435 private native void setMemory0(Object o, long offset, long bytes, byte value);
4436 @IntrinsicCandidate
4437 private native void copyMemory0(Object srcBase, long srcOffset, Object destBase, long destOffset, long bytes);
4438 private native void copySwapMemory0(Object srcBase, long srcOffset, Object destBase, long destOffset, long bytes, long elemSize);
4439 private native long objectFieldOffset0(Field f); // throws IAE
4440 private native long knownObjectFieldOffset0(Class<?> c, String name); // error code: -1 not found, -2 static
4441 private native long staticFieldOffset0(Field f); // throws IAE
4442 private native Object staticFieldBase0(Field f); // throws IAE
4443 private native boolean shouldBeInitialized0(Class<?> c);
4444 private native void ensureClassInitialized0(Class<?> c);
4445 private native void notifyStrictStaticAccess0(Class<?> c, long staticFieldOffset, boolean writing);
4446 private native int arrayBaseOffset0(Class<?> arrayClass); // public version returns long to promote correct arithmetic
4447 private native int arrayInstanceBaseOffset0(Object[] array);
4448 private native int arrayIndexScale0(Class<?> arrayClass);
4449 private native int arrayInstanceIndexScale0(Object[] array);
4450 private native long getObjectSize0(Object o);
4451 private native int getLoadAverage0(double[] loadavg, int nelems);
4452
4453
4454 /**
4455 * Invokes the given direct byte buffer's cleaner, if any.
4456 *
4457 * @param directBuffer a direct byte buffer
4458 * @throws NullPointerException if {@code directBuffer} is null
4459 * @throws IllegalArgumentException if {@code directBuffer} is non-direct,
4460 * or is a {@link java.nio.Buffer#slice slice}, or is a
4461 * {@link java.nio.Buffer#duplicate duplicate}
4462 */
4463 public void invokeCleaner(java.nio.ByteBuffer directBuffer) {
4464 if (!directBuffer.isDirect())
4465 throw new IllegalArgumentException("buffer is non-direct");
4466
4467 DirectBuffer db = (DirectBuffer) directBuffer;
4468 if (db.attachment() != null)
4469 throw new IllegalArgumentException("duplicate or slice");
4470
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