FastRandomRandomization.cs

using System;
using System.Threading;
using SharpNeatLib.Maths;

namespace GeneticSharp
{
 /// <summary>
 /// An IRandomization using FastRandom has pseudo-number generator.
 /// <see href="http://www.codeproject.com/Articles/9187/A-fast-equivalent-for-System-Random"/>
 /// </summary>
 public class FastRandomRandomization : RandomizationBase
 {
 private static readonly FastRandom _globalRandom = new FastRandom(DateTime.Now.Millisecond);
 private static readonly object _globalLock = new object();
 private static int? _seed;

 /// <summary> 
 /// Random number generator 
 /// </summary> 
 private static ThreadLocal<FastRandom> _threadRandom = new ThreadLocal<FastRandom>(NewRandom);

 /// <summary> 
 /// Creates a new instance of FastRandom. The seed is derived 
 /// from a global (static) instance of Random, rather 
 /// than time. 
 /// </summary> 
 private static FastRandom NewRandom()
 {
 lock (_globalLock)
 {
 return new FastRandom(_seed ?? _globalRandom.Next(0, int.MaxValue));
 }
 }

 /// <summary> 
 /// Returns an instance of Random which can be used freely 
 /// within the current thread. 
 /// </summary> 
 private static FastRandom Instance { get { return _threadRandom.Value; } }

 /// <summary>
 /// Resets the pseudorandom number generator (SharpNeatLib.Maths.FastRandom) initial seed.
 /// </summary>
 /// <param name="seed">The seed. Use null to reset to default one.</param>
 /// <remarks>
 /// Can be useful on situation where you need to generate the same result with the same parameter.
 /// </remarks>
 public static void ResetSeed(int? seed)
 {
 _seed = seed; 
 _threadRandom = new ThreadLocal<FastRandom>(NewRandom);
 }

 /// <summary>
 /// Gets an integer value between minimum value (inclusive) and maximum value (exclusive).
 /// </summary>
 /// <returns>The integer.</returns>
 /// <param name="min">Minimum value (inclusive).</param>
 /// <param name="max">Maximum value (exclusive).</param>
 public override int GetInt(int min, int max)
 {
 return Instance.Next(min, max);
 }

 /// <summary>
 /// Gets a float value between 0.0 and 1.0.
 /// </summary>
 /// <returns>
 /// The float value.
 /// </returns>
 public override float GetFloat()
 {
 return (float)Instance.NextDouble();
 }

 /// <summary>
 /// Gets a double value between 0.0 and 1.0.
 /// </summary>
 /// <returns>The double value.</returns>
 public override double GetDouble()
 {
 return Instance.NextDouble();
 }
 }
}