Add ReturnToMainThread, ReturnToSynchronizationContext, ReturnToCurrentSynchronizationContext

src/UniTask/Assets/Plugins/UniTask/Runtime/UniTask.Threading.cs

@@ -17,7 +17,31 @@ namespace Cysharp.Threading.Tasks
         /// </summary>
         public static SwitchToMainThreadAwaitable SwitchToMainThread()
         {
-            return new SwitchToMainThreadAwaitable();
+            return new SwitchToMainThreadAwaitable(PlayerLoopTiming.Update);
+        }
+
+        /// <summary>
+        /// If running on mainthread, do nothing. Otherwise, same as UniTask.Yield(timing).
+        /// </summary>
+        public static SwitchToMainThreadAwaitable SwitchToMainThread(PlayerLoopTiming timing)
+        {
+            return new SwitchToMainThreadAwaitable(timing);
+        }
+
+        /// <summary>
+        /// Return to mainthread(same as await SwitchToMainThread) after using scope is closed.
+        /// </summary>
+        public static ReturnToMainThread ReturnToMainThread()
+        {
+            return new ReturnToMainThread(PlayerLoopTiming.Update);
+        }
+
+        /// <summary>
+        /// Return to mainthread(same as await SwitchToMainThread) after using scope is closed.
+        /// </summary>
+        public static ReturnToMainThread ReturnToMainThread(PlayerLoopTiming timing)
+        {
+            return new ReturnToMainThread(timing);
         }
 
 #endif
@@ -27,15 +51,28 @@ namespace Cysharp.Threading.Tasks
             return new SwitchToThreadPoolAwaitable();
         }
 
+        /// <summary>
+        /// Note: use SwitchToThreadPool is recommended.
+        /// </summary>
         public static SwitchToTaskPoolAwaitable SwitchToTaskPool()
         {
             return new SwitchToTaskPoolAwaitable();
         }
 
-        public static SwitchToSynchronizationContextAwaitable SwitchToSynchronizationContext(SynchronizationContext syncContext)
+        public static SwitchToSynchronizationContextAwaitable SwitchToSynchronizationContext(SynchronizationContext synchronizationContext)
         {
-            Error.ThrowArgumentNullException(syncContext, nameof(syncContext));
-            return new SwitchToSynchronizationContextAwaitable(syncContext);
+            Error.ThrowArgumentNullException(synchronizationContext, nameof(synchronizationContext));
+            return new SwitchToSynchronizationContextAwaitable(synchronizationContext);
+        }
+
+        public static ReturnToSynchronizationContext ReturnToSynchronizationContext(SynchronizationContext synchronizationContext)
+        {
+            return new ReturnToSynchronizationContext(synchronizationContext);
+        }
+
+        public static ReturnToSynchronizationContext ReturnToCurrentSynchronizationContext()
+        {
+            return new ReturnToSynchronizationContext(SynchronizationContext.Current);
         }
     }
 
@@ -43,10 +80,24 @@ namespace Cysharp.Threading.Tasks
 
     public struct SwitchToMainThreadAwaitable
     {
-        public Awaiter GetAwaiter() => new Awaiter();
+        readonly PlayerLoopTiming playerLoopTiming;
+
+        public SwitchToMainThreadAwaitable(PlayerLoopTiming playerLoopTiming)
+        {
+            this.playerLoopTiming = playerLoopTiming;
+        }
+
+        public Awaiter GetAwaiter() => new Awaiter(playerLoopTiming);
 
         public struct Awaiter : ICriticalNotifyCompletion
         {
+            readonly PlayerLoopTiming playerLoopTiming;
+
+            public Awaiter(PlayerLoopTiming playerLoopTiming)
+            {
+                this.playerLoopTiming = playerLoopTiming;
+            }
+
             public bool IsCompleted
             {
                 get
@@ -67,12 +118,53 @@ namespace Cysharp.Threading.Tasks
 
             public void OnCompleted(Action continuation)
             {
-                PlayerLoopHelper.AddContinuation(PlayerLoopTiming.Update, continuation);
+                PlayerLoopHelper.AddContinuation(playerLoopTiming, continuation);
             }
 
             public void UnsafeOnCompleted(Action continuation)
             {
-                PlayerLoopHelper.AddContinuation(PlayerLoopTiming.Update, continuation);
+                PlayerLoopHelper.AddContinuation(playerLoopTiming, continuation);
+            }
+        }
+    }
+
+    public struct ReturnToMainThread
+    {
+        readonly PlayerLoopTiming playerLoopTiming;
+
+        public ReturnToMainThread(PlayerLoopTiming playerLoopTiming)
+        {
+            this.playerLoopTiming = playerLoopTiming;
+        }
+
+        public Awaiter DisposeAsync()
+        {
+            return new Awaiter(playerLoopTiming); // run immediate.
+        }
+
+        public readonly struct Awaiter : ICriticalNotifyCompletion
+        {
+            readonly PlayerLoopTiming timing;
+
+            public Awaiter(PlayerLoopTiming timing)
+            {
+                this.timing = timing;
+            }
+
+            public Awaiter GetAwaiter() => this;
+
+            public bool IsCompleted => PlayerLoopHelper.MainThreadId == System.Threading.Thread.CurrentThread.ManagedThreadId;
+
+            public void GetResult() { }
+
+            public void OnCompleted(Action continuation)
+            {
+                PlayerLoopHelper.AddContinuation(timing, continuation);
+            }
+
+            public void UnsafeOnCompleted(Action continuation)
+            {
+                PlayerLoopHelper.AddContinuation(timing, continuation);
             }
         }
     }
@@ -92,12 +184,16 @@ namespace Cysharp.Threading.Tasks
 
             public void OnCompleted(Action continuation)
             {
-                ThreadPool.UnsafeQueueUserWorkItem(switchToCallback, continuation);
+                ThreadPool.QueueUserWorkItem(switchToCallback, continuation);
             }
 
             public void UnsafeOnCompleted(Action continuation)
             {
+#if NETCOREAPP3_1
+                ThreadPool.UnsafeQueueUserWorkItem(ThreadPoolWorkItem.Create(continuation), false);
+#else
                 ThreadPool.UnsafeQueueUserWorkItem(switchToCallback, continuation);
+#endif
             }
 
             static void Callback(object state)
@@ -106,6 +202,47 @@ namespace Cysharp.Threading.Tasks
                 continuation();
             }
         }
+
+#if NETCOREAPP3_1
+
+        sealed class ThreadPoolWorkItem : IThreadPoolWorkItem, ITaskPoolNode<ThreadPoolWorkItem>
+        {
+            static TaskPool<ThreadPoolWorkItem> pool;
+            public ThreadPoolWorkItem NextNode { get; set; }
+
+            static ThreadPoolWorkItem()
+            {
+                TaskPool.RegisterSizeGetter(typeof(ThreadPoolWorkItem), () => pool.Size);
+            }
+
+            Action continuation;
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            public static ThreadPoolWorkItem Create(Action continuation)
+            {
+                if (!pool.TryPop(out var item))
+                {
+                    item = new ThreadPoolWorkItem();
+                }
+
+                item.continuation = continuation;
+                return item;
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            public void Execute()
+            {
+                var call = continuation;
+                continuation = null;
+                if (call != null)
+                {
+                    pool.TryPush(this);
+                    call.Invoke();
+                }
+            }
+        }
+
+#endif
     }
 
     public struct SwitchToTaskPoolAwaitable
@@ -178,5 +315,19 @@ namespace Cysharp.Threading.Tasks
             }
         }
     }
+
+    public struct ReturnToSynchronizationContext
+    {
+        readonly SynchronizationContext syncContext;
+
+        public ReturnToSynchronizationContext(SynchronizationContext syncContext)
+        {
+            this.syncContext = syncContext;
         }
 
+        public SwitchToSynchronizationContextAwaitable DisposeAsync()
+        {
+            return UniTask.SwitchToSynchronizationContext(syncContext);
+        }
+    }
+}

src/UniTask/Assets/Scenes/SandboxMain.cs

@@ -1,4 +1,5 @@
 using Cysharp.Threading.Tasks;
+using System.Linq;
 using Cysharp.Threading.Tasks.Linq;
 using Cysharp.Threading.Tasks.Triggers;
 using System;
@@ -10,6 +11,7 @@ using System.Threading.Tasks;
 using Unity.Collections;
 using Unity.Jobs;
 using UnityEngine;
+using UnityEngine.LowLevel;
 using UnityEngine.Networking;
 using UnityEngine.UI;
 
@@ -320,43 +322,132 @@ public class SandboxMain : MonoBehaviour
         //Debug.Log("AGAIN END MOVE");
 
 
+
+
+
+
+
+
+        //// DOTween.To(
+
+        //var cts = new CancellationTokenSource();
+
+        ////var tween = okButton.GetComponent<RectTransform>().DOLocalMoveX(100, 5.0f);
+
+        //cancelButton.OnClickAsAsyncEnumerable().ForEachAsync(_ =>
+        //{
+        //    cts.Cancel();
+        //}).Forget();
+
+
+        //// await tween.ToUniTask(TweenCancelBehaviour.KillAndCancelAwait, cts.Token);
+
+        ////tween.SetRecyclable(true);
+
+        //Debug.Log("END");
+
+        //// tween.Play();
+
+        //// DOTween.
+
+        //// DOVirtual.Float(0, 1, 1, x => { }).ToUniTask();
+
+
+        //await foreach (var _ in UniTaskAsyncEnumerable.EveryUpdate())
+        //{
+        //    Debug.Log("Update() " + Time.frameCount);
+        //}
+
+
+
+        //await okButton.OnClickAsAsyncEnumerable().Where((x, i) => i % 2 == 0).ForEachAsync(_ =>
+        //{
+        //});
+
+
+        //okButton.OnClickAsAsyncEnumerable().ForEachAsync(_ =>
+        //{
+
+
+
+
+
+        //}).Forget();
+
+        //CloseAsync(this.GetCancellationTokenOnDestroy()).Forget();
+
+        //okButton.onClick.AddListener(UniTask.UnityAction(async () => await UniTask.Yield()));
+
+        PlayerLoopInfo.Inject();
+
+        //UpdateUniTask().Forget();
+
+        //StartCoroutine(Coroutine());
+
+        //await UniTask.Delay(TimeSpan.FromSeconds(1));
+
+
+        _ = ReturnToMainThreadTest();
+
+        //GameObject.Destroy(this.gameObject);
+
+
+        SynchronizationContext.Current.Post(_ =>
+        {
+            //UnityEngine.Debug.Log("Post:" + PlayerLoopInfo.CurrentLoopType);
+        }, null);
+    }
+
+    async UniTaskVoid UpdateUniTask()
+    {
+        while (true)
+        {
             await UniTask.Yield();
-        // DOTween.To(
+            UnityEngine.Debug.Log("UniTaskYield:" + PlayerLoopInfo.CurrentLoopType);
+        }
+    }
 
-        var cts = new CancellationTokenSource();
 
-        //var tween = okButton.GetComponent<RectTransform>().DOLocalMoveX(100, 5.0f);
-
-        cancelButton.OnClickAsAsyncEnumerable().ForEachAsync(_ =>
+    async UniTaskVoid ReturnToMainThreadTest()
     {
-            cts.Cancel();
-        }).Forget();
-
-
-        // await tween.ToUniTask(TweenCancelBehaviour.KillAndCancelAwait, cts.Token);
-
-        //tween.SetRecyclable(true);
-
-        Debug.Log("END");
-
-        // tween.Play();
-
-        // DOTween.
-
-        // DOVirtual.Float(0, 1, 1, x => { }).ToUniTask();
-
-        okButton.OnClickAsAsyncEnumerable().ForEachAsync(_ =>
+        var d = UniTask.ReturnToCurrentSynchronizationContext();
+        try
         {
+            UnityEngine.Debug.Log("In MainThread?" + Thread.CurrentThread.ManagedThreadId);
+            UnityEngine.Debug.Log("SyncContext is null?" + (SynchronizationContext.Current == null));
+            await UniTask.SwitchToThreadPool();
+            UnityEngine.Debug.Log("In ThreadPool?" + Thread.CurrentThread.ManagedThreadId);
+            UnityEngine.Debug.Log("SyncContext is null?" + (SynchronizationContext.Current == null));
+        }
+        finally
+        {
+            await d.DisposeAsync();
+        }
+
+        UnityEngine.Debug.Log("In ThreadPool?" + Thread.CurrentThread.ManagedThreadId);
+        UnityEngine.Debug.Log("SyncContext is null2" + (SynchronizationContext.Current == null));
+    }
 
 
+    private void Update()
+    {
+        // UnityEngine.Debug.Log("Update:" + PlayerLoopInfo.CurrentLoopType);
+    }
 
-
-
-        }).Forget();
-
-        CloseAsync(this.GetCancellationTokenOnDestroy()).Forget();
-
-        okButton.onClick.AddListener(UniTask.UnityAction(async () => await UniTask.Yield()));
+    IEnumerator Coroutine()
+    {
+        try
+        {
+            while (true)
+            {
+                yield return null;
+                //UnityEngine.Debug.Log("Coroutine null:" + PlayerLoopInfo.CurrentLoopType);
+            }
+        }
+        finally
+        {
+            UnityEngine.Debug.Log("Coroutine Finally");
+        }
     }
 
     async UniTaskVoid CloseAsync(CancellationToken cancellationToken = default)
@@ -597,7 +688,7 @@ public class SandboxMain : MonoBehaviour
     }
 }
 
-public class ShowPlayerLoop
+public class PlayerLoopInfo
 {
     // [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.SubsystemRegistration)]
     static void Init()
@@ -628,4 +719,45 @@ public class ShowPlayerLoop
 
         UnityEngine.Debug.Log(sb.ToString());
     }
+
+    public static Type CurrentLoopType { get; private set; }
+
+    public static void Inject()
+    {
+        var system = PlayerLoop.GetCurrentPlayerLoop();
+
+        for (int i = 0; i < system.subSystemList.Length; i++)
+        {
+            var loop = system.subSystemList[i].subSystemList.SelectMany(x =>
+            {
+                var t = typeof(WrapLoop<>).MakeGenericType(x.type);
+                var instance = (ILoopRunner)Activator.CreateInstance(t, x.type);
+                return new[] { new PlayerLoopSystem { type = t, updateDelegate = instance.Run }, x };
+            }).ToArray();
+
+            system.subSystemList[i].subSystemList = loop;
+        }
+
+        PlayerLoop.SetPlayerLoop(system);
+    }
+
+    interface ILoopRunner
+    {
+        void Run();
+    }
+
+    class WrapLoop<T> : ILoopRunner
+    {
+        readonly Type type;
+
+        public WrapLoop(Type type)
+        {
+            this.type = type;
+        }
+
+        public void Run()
+        {
+            CurrentLoopType = type;
+        }
+    }
 }