Package org.jboss.netty.util.internal

Class ThreadLocalRandom

  • All Implemented Interfaces:
    java.io.Serializable
    public final class ThreadLocalRandom
extends java.util.Random
    A random number generator isolated to the current thread. Like the global Random generator used by the 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. Use of ThreadLocalRandom is particularly appropriate when multiple tasks use random numbers in parallel in thread pools.

    Usages of this class should typically be of the form: ThreadLocalRandom.current().nextX(...) (where X is Int, Long, etc). When all usages are of this form, it is never possible to accidently share a ThreadLocalRandom across multiple threads.

    This class also provides additional commonly used bounded random generation methods.

    Since:
    1.7
    See Also:
    Serialized Form

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private static long addend  
      private boolean initialized
      Initialization flag to permit the first and only allowed call to setSeed (inside Random constructor) to succeed.
      private static java.lang.ThreadLocal<ThreadLocalRandom> localRandom
      The actual ThreadLocal
      private static long mask  
      private static long multiplier  
      private long pad0  
      private long pad1  
      private long pad2  
      private long pad3  
      private long pad4  
      private long pad5  
      private long pad6  
      private long pad7  
      private long rnd
      The random seed.
      private static long serialVersionUID  

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static ThreadLocalRandom current()
      Returns the current thread's ThreadLocalRandom.
      protected int next​(int bits)  
      void setSeed​(long seed)
      Throws UnsupportedOperationException.

      • Methods inherited from class java.util.Random

        doubles, doubles, doubles, doubles, ints, ints, ints, ints, longs, longs, longs, longs, nextBoolean, nextBytes, nextDouble, nextFloat, nextGaussian, nextInt, nextInt, nextLong

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • rnd

        private long rnd
        The random seed. We can't use super.seed.

      • initialized

        private boolean initialized
        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.

      • pad0

        private long pad0

      • pad1

        private long pad1

      • pad2

        private long pad2

      • pad3

        private long pad3

      • pad4

        private long pad4

      • pad5

        private long pad5

      • pad6

        private long pad6

      • pad7

        private long pad7

      • localRandom

        private static final java.lang.ThreadLocal<ThreadLocalRandom> localRandom
        The actual ThreadLocal

    • Constructor Detail

      • ThreadLocalRandom

        public ThreadLocalRandom()

    • Method Detail

      • current

        public static ThreadLocalRandom current()
        Returns the current thread's ThreadLocalRandom.
        Returns:
        the current thread's ThreadLocalRandom

      • setSeed

        public void setSeed​(long seed)
        Throws UnsupportedOperationException. Setting seeds in this generator is not supported.
        Overrides:
        setSeed in class java.util.Random
        Throws:
        java.lang.UnsupportedOperationException - always

      • next

        protected int next​(int bits)
        Overrides:
        next in class java.util.Random