src/java.base/share/classes/java/util/concurrent/locks/LockSupport.java

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rev 12972 : 8140606: Update library code to use internal Unsafe
Reviewed-by: duke


 377 
 378     /**
 379      * Returns the pseudo-randomly initialized or updated secondary seed.
 380      * Copied from ThreadLocalRandom due to package access restrictions.
 381      */
 382     static final int nextSecondarySeed() {
 383         int r;
 384         Thread t = Thread.currentThread();
 385         if ((r = U.getInt(t, SECONDARY)) != 0) {
 386             r ^= r << 13;   // xorshift
 387             r ^= r >>> 17;
 388             r ^= r << 5;
 389         }
 390         else if ((r = java.util.concurrent.ThreadLocalRandom.current().nextInt()) == 0)
 391             r = 1; // avoid zero
 392         U.putInt(t, SECONDARY, r);
 393         return r;
 394     }
 395 
 396     // Hotspot implementation via intrinsics API
 397     private static final sun.misc.Unsafe U = sun.misc.Unsafe.getUnsafe();
 398     private static final long PARKBLOCKER;
 399     private static final long SECONDARY;
 400     static {
 401         try {
 402             PARKBLOCKER = U.objectFieldOffset
 403                 (Thread.class.getDeclaredField("parkBlocker"));
 404             SECONDARY = U.objectFieldOffset
 405                 (Thread.class.getDeclaredField("threadLocalRandomSecondarySeed"));
 406         } catch (ReflectiveOperationException e) {
 407             throw new Error(e);
 408         }
 409     }
 410 
 411 }



 377 
 378     /**
 379      * Returns the pseudo-randomly initialized or updated secondary seed.
 380      * Copied from ThreadLocalRandom due to package access restrictions.
 381      */
 382     static final int nextSecondarySeed() {
 383         int r;
 384         Thread t = Thread.currentThread();
 385         if ((r = U.getInt(t, SECONDARY)) != 0) {
 386             r ^= r << 13;   // xorshift
 387             r ^= r >>> 17;
 388             r ^= r << 5;
 389         }
 390         else if ((r = java.util.concurrent.ThreadLocalRandom.current().nextInt()) == 0)
 391             r = 1; // avoid zero
 392         U.putInt(t, SECONDARY, r);
 393         return r;
 394     }
 395 
 396     // Hotspot implementation via intrinsics API
 397     private static final jdk.internal.misc.Unsafe U = jdk.internal.misc.Unsafe.getUnsafe();
 398     private static final long PARKBLOCKER;
 399     private static final long SECONDARY;
 400     static {
 401         try {
 402             PARKBLOCKER = U.objectFieldOffset
 403                 (Thread.class.getDeclaredField("parkBlocker"));
 404             SECONDARY = U.objectFieldOffset
 405                 (Thread.class.getDeclaredField("threadLocalRandomSecondarySeed"));
 406         } catch (ReflectiveOperationException e) {
 407             throw new Error(e);
 408         }
 409     }
 410 
 411 }