1 files changed, 46 insertions, 35 deletions
diff --git a/src/forkjoin/scala/concurrent/forkjoin/ThreadLocalRandom.java b/src/forkjoin/scala/concurrent/forkjoin/ThreadLocalRandom.java
index 34e2e37f37..19237c9092 100644
--- a/src/forkjoin/scala/concurrent/forkjoin/ThreadLocalRandom.java
+++ b/src/forkjoin/scala/concurrent/forkjoin/ThreadLocalRandom.java
@@ -1,49 +1,53 @@
 /*
  * Written by Doug Lea with assistance from members of JCP JSR-166
  * Expert Group and released to the public domain, as explained at
- * http://creativecommons.org/licenses/publicdomain
+ * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
 package scala.concurrent.forkjoin;
-import java.util.*;
+
+import java.util.Random;
 
 /**
- * A random number generator with the same properties as class {@link
- * Random} but isolated to the current Thread.  Like the global
- * generator used by the {@link java.lang.Math} class, a
- * ThreadLocalRandom is initialized with an internally generated seed
- * that may not otherwise be modified. When applicable, use of
- * ThreadLocalRandom rather than shared Random objects in concurrent
- * programs will typically encounter much less overhead and
- * contention.  ThreadLocalRandoms are particularly appropriate when
- * multiple tasks (for example, each a {@link ForkJoinTask}), use
- * random numbers in parallel in thread pools.
+ * A random number generator isolated to the current thread.  Like the
+ * global {@link java.util.Random} generator used by the {@link
+ * java.lang.Math} class, a {@code ThreadLocalRandom} is initialized
+ * with an internally generated seed that may not otherwise be
+ * modified. When applicable, use of {@code ThreadLocalRandom} rather
+ * than shared {@code Random} objects in concurrent programs will
+ * typically encounter much less overhead and contention.  Use of
+ * {@code ThreadLocalRandom} is particularly appropriate when multiple
+ * tasks (for example, each a {@link ForkJoinTask}) use random numbers
+ * in parallel in thread pools.
  *
  * <p>Usages of this class should typically be of the form:
- * <code>ThreadLocalRandom.current().nextX(...)</code> (where
- * <code>X</code> is <code>Int</code>, <code>Long</code>, etc).
+ * {@code ThreadLocalRandom.current().nextX(...)} (where
+ * {@code X} is {@code Int}, {@code Long}, etc).
  * When all usages are of this form, it is never possible to
- * accidently share ThreadLocalRandoms across multiple threads.
+ * accidently share a {@code ThreadLocalRandom} across multiple threads.
  *
  * <p>This class also provides additional commonly used bounded random
  * generation methods.
+ *
+ * @since 1.7
+ * @author Doug Lea
  */
 public class ThreadLocalRandom extends Random {
     // same constants as Random, but must be redeclared because private
-    private final static long multiplier = 0x5DEECE66DL;
-    private final static long addend = 0xBL;
-    private final static long mask = (1L << 48) - 1;
+    private static final long multiplier = 0x5DEECE66DL;
+    private static final long addend = 0xBL;
+    private static final long mask = (1L << 48) - 1;
 
     /**
-     * The random seed. We can't use super.seed
+     * The random seed. We can't use super.seed.
      */
     private long rnd;
 
     /**
-     * Initialization flag to permit the first and only allowed call
-     * to setSeed (inside Random constructor) to succeed.  We can't
-     * allow others since it would cause setting seed in one part of a
-     * program to unintentionally impact other usages by the thread.
+     * Initialization flag to permit calls to setSeed to succeed only
+     * while executing the Random constructor.  We can't allow others
+     * since it would cause setting seed in one part of a program to
+     * unintentionally impact other usages by the thread.
      */
     boolean initialized;
 
@@ -65,40 +69,42 @@ public class ThreadLocalRandom extends Random {
 
     /**
      * Constructor called only by localRandom.initialValue.
-     * We rely on the fact that the superclass no-arg constructor
-     * invokes setSeed exactly once to initialize.
      */
     ThreadLocalRandom() {
         super();
+        initialized = true;
     }
 
     /**
-     * Returns the current Thread's ThreadLocalRandom
-     * @return the current Thread's ThreadLocalRandom
+     * Returns the current thread's {@code ThreadLocalRandom}.
+     *
+     * @return the current thread's {@code ThreadLocalRandom}
      */
     public static ThreadLocalRandom current() {
         return localRandom.get();
     }
 
     /**
-     * Throws UnsupportedOperationException. Setting seeds in this
-     * generator is unsupported.
+     * Throws {@code UnsupportedOperationException}.  Setting seeds in
+     * this generator is not supported.
+     *
      * @throws UnsupportedOperationException always
      */
     public void setSeed(long seed) {
         if (initialized)
             throw new UnsupportedOperationException();
-        initialized = true;
         rnd = (seed ^ multiplier) & mask;
     }
 
     protected int next(int bits) {
-        return (int)((rnd = (rnd * multiplier + addend) & mask) >>> (48-bits));
+        rnd = (rnd * multiplier + addend) & mask;
+        return (int) (rnd >>> (48-bits));
     }
 
     /**
      * Returns a pseudorandom, uniformly distributed value between the
      * given least value (inclusive) and bound (exclusive).
+     *
      * @param least the least value returned
      * @param bound the upper bound (exclusive)
      * @throws IllegalArgumentException if least greater than or equal
@@ -113,7 +119,8 @@ public class ThreadLocalRandom extends Random {
 
     /**
      * Returns a pseudorandom, uniformly distributed value
-     * between 0 (inclusive) and the specified value (exclusive)
+     * between 0 (inclusive) and the specified value (exclusive).
+     *
      * @param n the bound on the random number to be returned.  Must be
      *        positive.
      * @return the next value
@@ -131,17 +138,18 @@ public class ThreadLocalRandom extends Random {
         while (n >= Integer.MAX_VALUE) {
             int bits = next(2);
             long half = n >>> 1;
-            long nextn = ((bits & 2) == 0)? half : n - half;
+            long nextn = ((bits & 2) == 0) ? half : n - half;
             if ((bits & 1) == 0)
                 offset += n - nextn;
             n = nextn;
         }
-        return offset + nextInt((int)n);
+        return offset + nextInt((int) n);
     }
 
     /**
      * Returns a pseudorandom, uniformly distributed value between the
      * given least value (inclusive) and bound (exclusive).
+     *
      * @param least the least value returned
      * @param bound the upper bound (exclusive)
      * @return the next value
@@ -156,7 +164,8 @@ public class ThreadLocalRandom extends Random {
 
     /**
      * Returns a pseudorandom, uniformly distributed {@code double} value
-     * between 0 (inclusive) and the specified value (exclusive)
+     * between 0 (inclusive) and the specified value (exclusive).
+     *
      * @param n the bound on the random number to be returned.  Must be
      *        positive.
      * @return the next value
@@ -171,6 +180,7 @@ public class ThreadLocalRandom extends Random {
     /**
      * Returns a pseudorandom, uniformly distributed value between the
      * given least value (inclusive) and bound (exclusive).
+     *
      * @param least the least value returned
      * @param bound the upper bound (exclusive)
      * @return the next value
@@ -183,4 +193,5 @@ public class ThreadLocalRandom extends Random {
         return nextDouble() * (bound - least) + least;
     }
 
+    private static final long serialVersionUID = -5851777807851030925L;
 }