From 97c5a3598acb8195fa3d021610dde1877b8b2ccb Mon Sep 17 00:00:00 2001
From: Mikhail <99481254+DCFApixels@users.noreply.github.com>
Date: Sun, 11 Jun 2023 23:09:46 +0800
Subject: [PATCH] Create ThreadRunner.cs

---
 src/ThreadRunner.cs | 101 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 src/ThreadRunner.cs

diff --git a/src/ThreadRunner.cs b/src/ThreadRunner.cs
new file mode 100644
index 0000000..8185208
--- /dev/null
+++ b/src/ThreadRunner.cs
@@ -0,0 +1,101 @@
+using DCFApixels.DragonECS;
+
+internal static class ThreadRunner
+{
+    private readonly static int _maxThreadsCount;
+    private static ThreadReacord[] _threads;
+
+    private static ThreadWorkerHandler _worker;
+    private static int[] _entities = new int[64];
+
+    private static void ThreadProc(object obj)
+    {
+        ref ThreadReacord record = ref _threads[(int)obj];
+        try
+        {
+            while (Thread.CurrentThread.IsAlive)
+            {
+                record.runWork.WaitOne();
+                record.runWork.Reset();
+                _worker.Invoke(new ReadOnlySpan<int>(_entities, record.start, record.size));
+
+                record.doneWork.Set();
+            }
+        }
+        catch { }
+    }
+
+    static ThreadRunner()
+    {
+        _maxThreadsCount = Environment.ProcessorCount;
+        _threads = new ThreadReacord[_maxThreadsCount];
+
+        for (int i = 0; i < _maxThreadsCount; i++)
+        {
+            _threads[i] = new ThreadReacord()
+            {
+                thread = new Thread(ThreadProc) { IsBackground = true },
+                runWork = new ManualResetEvent(false),
+                doneWork = new ManualResetEvent(true),
+            };
+            _threads[i].thread.Start(i);
+        }
+        _worker = delegate { };
+    }
+
+    public static void Run(ThreadWorkerHandler worker, EcsReadonlyGroup entities, int minSpanSize)
+    {
+        _worker = worker;
+        int entitiesCount = entities.Bake(ref _entities);
+
+        int threadsCount = entitiesCount / minSpanSize;
+        //if (entitiesCount % minSpanSize > 0)
+        //    threadsCount++;
+        if (threadsCount > _maxThreadsCount)
+            threadsCount = _maxThreadsCount;
+
+        if (threadsCount > 1)
+        {
+            int spanSize = entitiesCount / (threadsCount - 1);
+            for (int i = 0; i < threadsCount; i++)
+            {
+                ref var thread = ref _threads[i];
+                thread.start = i * spanSize;
+                thread.size = spanSize;
+            }
+            _threads[^1].size = entities.Count % (threadsCount - 1);
+        }
+        else
+        {
+            threadsCount = 1;
+            ref var thread = ref _threads[0];
+            thread.start = 0;
+            thread.size = entitiesCount;
+        }
+
+        for (int i = 0; i < threadsCount; i++)
+        {
+            ref var thread = ref _threads[i];
+            thread.runWork.Reset();
+            thread.runWork.Set();
+        }
+        for (int i = 0; i < threadsCount; i++)
+        {
+            _threads[i].doneWork.WaitOne();
+        }
+
+        _worker = null;
+    }
+
+    public delegate void ThreadWorkerHandler(ReadOnlySpan<int> entities);
+
+    private struct ThreadReacord
+    {
+        public Thread thread;
+        public ManualResetEvent runWork;
+        public ManualResetEvent doneWork;
+
+        public int start;
+        public int size;
+    }
+}
\ No newline at end of file