GEEKING

Client.LegacyAssemblies/Roblox.System/RandomExtensions.cs

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+using System;
+using System.Security.Cryptography;
+
+namespace Roblox
+{
+    /// <summary>
+    /// Inspired by: http://blogs.msdn.com/pfxteam/archive/2009/02/19/9434171.aspx
+    /// </summary>
+    public static class SeededRandom
+    {
+        private static readonly Random Seeder = new Random();
+        private static volatile int _seed = Seeder.Next();
+
+        [ThreadStatic]
+        private static Random _local;
+        private static readonly Random Global = new Random();
+        private static readonly RNGCryptoServiceProvider Crypto = new RNGCryptoServiceProvider();
+
+        // TODO: How/When to dispose?
+        private static readonly System.Threading.Timer Timer = new System.Threading.Timer(
+            (o) => _seed = Seeder.Next(), null, 100, 100);
+
+        /// <summary>
+        /// Creates a seeded Random number generator.
+        /// Avoids a clump of equally-seeded Random objects being created at the same time.
+        /// Use this if you spawn multiple threads at the same time and each creates a Random.
+        /// </summary>
+        public static Random Create()
+        {
+            // We simply increase the seed by 1 every time.
+            // The timer will change the seed to something more interesting in the future
+            return new Random(System.Threading.Interlocked.Increment(ref _seed));
+        }
+
+
+        /// <summary>
+        /// Creates and re-uses a single Random number object per thread.
+        /// Best used in situations where you re-use threads a lot.
+        /// </summary>
+        /// <returns></returns>
+        public static Random ThreadStaticCreate()
+        {
+            Random inst = _local;
+            if (inst == null)
+            {
+                int seed;
+                lock (Global)
+                    seed = Global.Next();
+                _local = inst = new Random(seed);
+            }
+            return inst;
+        }
+
+
+        /// <summary>
+        /// An alternate approach to SeededRandom that uses Crypto and no lock
+        /// TBD which one is faster
+        /// </summary>
+        public static Random CryptoThreadStaticCreate()
+        {
+            Random inst = _local;
+            if (inst == null)
+            {
+                var buffer = new byte[4];
+                Crypto.GetBytes(buffer);
+                _local = inst = new Random(BitConverter.ToInt32(buffer, 0));
+            }
+            return inst;
+        }
+    }
+}