Package org.jboss.netty.util.internal
Class ThreadLocalRandom
- java.lang.Object
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- java.util.Random
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- org.jboss.netty.util.internal.ThreadLocalRandom
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- 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 globalRandom
generator used by theMath
class, aThreadLocalRandom
is initialized with an internally generated seed that may not otherwise be modified. When applicable, use ofThreadLocalRandom
rather than sharedRandom
objects in concurrent programs will typically encounter much less overhead and contention. Use ofThreadLocalRandom
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(...)
(whereX
isInt
,Long
, etc). When all usages are of this form, it is never possible to accidently share aThreadLocalRandom
across multiple threads.This class also provides additional commonly used bounded random generation methods.
- Since:
- 1.7
- See Also:
- Serialized Form
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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 ThreadLocalprivate 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
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Constructor Summary
Constructors Constructor Description ThreadLocalRandom()
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description static ThreadLocalRandom
current()
Returns the current thread'sThreadLocalRandom
.protected int
next(int bits)
void
setSeed(long seed)
ThrowsUnsupportedOperationException
.
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Field Detail
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multiplier
private static final long multiplier
- See Also:
- Constant Field Values
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addend
private static final long addend
- See Also:
- Constant Field Values
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mask
private static final long mask
- See Also:
- Constant Field Values
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rnd
private long rnd
The random seed. We can't use super.seed.
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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.
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pad0
private long pad0
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pad1
private long pad1
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pad2
private long pad2
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pad3
private long pad3
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pad4
private long pad4
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pad5
private long pad5
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pad6
private long pad6
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pad7
private long pad7
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localRandom
private static final java.lang.ThreadLocal<ThreadLocalRandom> localRandom
The actual ThreadLocal
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serialVersionUID
private static final long serialVersionUID
- See Also:
- Constant Field Values
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Method Detail
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current
public static ThreadLocalRandom current()
Returns the current thread'sThreadLocalRandom
.- Returns:
- the current thread's
ThreadLocalRandom
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setSeed
public void setSeed(long seed)
ThrowsUnsupportedOperationException
. Setting seeds in this generator is not supported.- Overrides:
setSeed
in classjava.util.Random
- Throws:
java.lang.UnsupportedOperationException
- always
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next
protected int next(int bits)
- Overrides:
next
in classjava.util.Random
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