From 91ba9466596bd94e1e6a868f293abbb32cb6e99d Mon Sep 17 00:00:00 2001
From: Laszlo Paillat <laszlo.paillat@gmail.com>
Date: Fri, 3 Dec 2021 22:24:18 +0100
Subject: [PATCH] Revert "changed DefaultParallelRunner implementation to rely
 on Thread for targets above netstandard1.1 (may help with #145)"

This reverts commit 6e539f24ab0eca9e1d6fd5ff97d38a2782082d94.
---
 .../Internal/Helper/DefaultThread.cs          | 40 -------------------
 .../Threading/DefaultParallelRunner.cs        | 26 ++++++------
 2 files changed, 13 insertions(+), 53 deletions(-)
 delete mode 100644 source/DefaultEcs/Internal/Helper/DefaultThread.cs

diff --git a/source/DefaultEcs/Internal/Helper/DefaultThread.cs b/source/DefaultEcs/Internal/Helper/DefaultThread.cs
deleted file mode 100644
index e3f11d81..00000000
--- a/source/DefaultEcs/Internal/Helper/DefaultThread.cs
+++ /dev/null
@@ -1,40 +0,0 @@
-#if NETSTANDARD1_1
-using System;
-using System.Threading.Tasks;
-#else
-using System.Threading;
-#endif
-
-namespace DefaultEcs.Internal.Helper
-{
-    internal sealed class DefaultThread
-    {
-#if NETSTANDARD1_1
-        private readonly Task _task;
-
-        public DefaultThread(Action<object> action, object state)
-        {
-            _task = new Task(action, state, TaskCreationOptions.LongRunning);
-        }
-
-        public void Start() => _task.Start(TaskScheduler.Default);
-
-        public void Wait() => _task.Wait();
-#else
-        private readonly Thread _thread;
-        private readonly object _state;
-
-        public DefaultThread(ParameterizedThreadStart action, object state)
-        {
-            _thread = new Thread(action);
-            _state = state;
-
-            _thread.Name = $"{nameof(DefaultThread)} {state}";
-        }
-
-        public void Start() => _thread.Start(_state);
-
-        public void Wait() => _thread.Join();
-#endif
-    }
-}
diff --git a/source/DefaultEcs/Threading/DefaultParallelRunner.cs b/source/DefaultEcs/Threading/DefaultParallelRunner.cs
index 38031192..592e3f4e 100644
--- a/source/DefaultEcs/Threading/DefaultParallelRunner.cs
+++ b/source/DefaultEcs/Threading/DefaultParallelRunner.cs
@@ -3,7 +3,6 @@
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using DefaultEcs.Internal.Helper;
 using DefaultEcs.Internal.Threading;
 
 namespace DefaultEcs.Threading
@@ -19,7 +18,7 @@ public sealed class DefaultParallelRunner : IParallelRunner
 
         private readonly CancellationTokenSource _disposeHandle;
         private readonly WorkerBarrier _barrier;
-        private readonly DefaultThread[] _threads;
+        private readonly Task[] _tasks;
 
         private IParallelRunnable _currentRunnable;
 
@@ -37,12 +36,12 @@ public DefaultParallelRunner(int degreeOfParallelism)
             IEnumerable<int> indices = degreeOfParallelism >= 1 ? Enumerable.Range(0, degreeOfParallelism - 1) : throw new ArgumentException("Argument cannot be inferior to one", nameof(degreeOfParallelism));
 
             _disposeHandle = new CancellationTokenSource();
-            _threads = indices.Select(index => new DefaultThread(Update, index)).ToArray();
-            _barrier = degreeOfParallelism > 1 ? new WorkerBarrier(_threads.Length) : null;
+            _tasks = indices.Select(index => new Task(Update, index, TaskCreationOptions.LongRunning)).ToArray();
+            _barrier = degreeOfParallelism > 1 ? new WorkerBarrier(_tasks.Length) : null;
 
-            foreach (DefaultThread thread in _threads)
+            foreach (Task task in _tasks)
             {
-                thread.Start();
+                task.Start(TaskScheduler.Default);
             }
         }
 
@@ -54,10 +53,14 @@ private void Update(object state)
         {
             int index = (int)state;
 
+#if !NETSTANDARD1_1
+            Thread.CurrentThread.Name = $"{nameof(DefaultParallelRunner)} worker {index + 1}";
+#endif
+
             goto Start;
 
         Work:
-            Volatile.Read(ref _currentRunnable).Run(index, _threads.Length);
+            Volatile.Read(ref _currentRunnable).Run(index, _tasks.Length);
 
             _barrier.Signal();
 
@@ -77,7 +80,7 @@ private void Update(object state)
         /// <summary>
         /// Gets the degree of parallelism used to run an <see cref="IParallelRunnable"/>.
         /// </summary>
-        public int DegreeOfParallelism => _threads.Length + 1;
+        public int DegreeOfParallelism => _tasks.Length + 1;
 
         /// <summary>
         /// Runs the provided <see cref="IParallelRunnable"/>.
@@ -89,7 +92,7 @@ public void Run(IParallelRunnable runnable)
 
             _barrier?.StartWorkers();
 
-            runnable.Run(_threads.Length, _threads.Length);
+            runnable.Run(_tasks.Length, _tasks.Length);
 
             _barrier?.WaitForWorkers();
         }
@@ -107,10 +110,7 @@ public void Dispose()
 
             _barrier?.StartWorkers();
 
-            foreach (DefaultThread thread in _threads)
-            {
-                thread.Wait();
-            }
+            Task.WaitAll(_tasks);
 
             _barrier?.Dispose();
             _disposeHandle.Dispose();