PKHeX/PKHeX.Core/Util/RandUtil.cs
Kurt c301ce88ab Update Random to be a bit more thread safe
Random isn't thread safe; users of PKHeX.Core.dll might run multithreaded operations (see PKSM + ALM), so we need to have a thread-specific RNG available.

Thread Local get; to improve performance, save the random object locally whenever it is used more than once in the method.

https://docs.microsoft.com/en-us/dotnet/api/system.threading.threadlocal-1?redirectedfrom=MSDN&view=netframework-4.8
https://stackoverflow.com/questions/18333885/threadstatic-v-s-threadlocalt-is-generic-better-than-attribute/18337158#18337158
2020-01-25 21:49:52 -08:00

43 lines
1.5 KiB
C#

using System;
using System.Collections.Generic;
using System.Threading;
namespace PKHeX.Core
{
public static partial class Util
{
// Multithread safe rand, ha
public static Random Rand => _local.Value;
private static readonly ThreadLocal<Random> _local = new ThreadLocal<Random>(() => new Random());
public static uint Rand32() => Rand32(Rand);
public static uint Rand32(Random rnd) => (uint)rnd.Next(1 << 30) << 2 | (uint)rnd.Next(1 << 2);
/// <summary>
/// Shuffles the order of items within a collection of items.
/// </summary>
/// <typeparam name="T">Item type</typeparam>
/// <param name="items">Item collection</param>
public static void Shuffle<T>(IList<T> items) => Shuffle(items, 0, items.Count, Rand);
/// <summary>
/// Shuffles the order of items within a collection of items.
/// </summary>
/// <typeparam name="T">Item type</typeparam>
/// <param name="items">Item collection</param>
/// <param name="start">Starting position</param>
/// <param name="end">Ending position</param>
/// <param name="rnd">RNG object to use</param>
public static void Shuffle<T>(IList<T> items, int start, int end, Random rnd)
{
for (int i = start; i < end; i++)
{
int index = i + rnd.Next(end - i);
T t = items[index];
items[index] = items[i];
items[i] = t;
}
}
}
}