org.jboss.netty.util.internal

Class ThreadLocalRandom

java.lang.Object

java.util.Random

org.jboss.netty.util.internal.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 and 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

Constructor Summary

Constructors

Constructor and Description
ThreadLocalRandom()

Method Summary

Modifier and Type	Method and 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

multiplier

private static final long multiplier

See Also:

Constant Field Values

addend

private static final long addend

See Also:

Constant Field Values

mask

private static final long mask

See Also:

Constant Field Values

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

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

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