EventLoop V1

src/Library/TerminalUI/EventLoop.cs

@@ -0,0 +1,130 @@
+using System.Buffers;
+using System.Collections.Concurrent;
+using TerminalUI.Controls;
+
+namespace TerminalUI;
+
+public class EventLoop : IEventLoop
+{
+    private readonly IApplicationContext _applicationContext;
+    private readonly object _lock = new();
+    private readonly ArrayPool<IView> _viewPool = ArrayPool<IView>.Shared;
+
+    private readonly ConcurrentBag<IView> _viewsToRenderInstantly = new();
+    private readonly LinkedList<IView> _viewsToRender = new();
+
+    public EventLoop(IApplicationContext applicationContext)
+    {
+        _applicationContext = applicationContext;
+    }
+
+    public void Run()
+    {
+        _applicationContext.IsRunning = true;
+        while (_applicationContext.IsRunning)
+        {
+            Render();
+            Thread.Sleep(10);
+        }
+    }
+
+    public void Render()
+    {
+        IView[]? viewsToRenderCopy = null;
+        IView[]? viewsAlreadyRendered = null;
+        try
+        {
+            int viewsToRenderCopyCount;
+            IView[]? viewsToRenderInstantly;
+
+            lock (_lock)
+            {
+                CleanViewsToRender();
+
+                viewsToRenderCopyCount = _viewsToRender.Count;
+                viewsToRenderCopy = _viewPool.Rent(_viewsToRender.Count);
+                _viewsToRender.CopyTo(viewsToRenderCopy, 0);
+
+                viewsToRenderInstantly = _viewsToRenderInstantly.ToArray();
+                _viewsToRenderInstantly.Clear();
+            }
+
+            viewsAlreadyRendered = _viewPool.Rent(viewsToRenderCopy.Length + viewsToRenderInstantly.Length);
+            var viewsAlreadyRenderedIndex = 0;
+
+            foreach (var view in viewsToRenderInstantly)
+            {
+                if (Contains(viewsAlreadyRendered, view, viewsAlreadyRenderedIndex)) continue;
+
+                view.Render();
+                viewsAlreadyRendered[viewsAlreadyRenderedIndex++] = view;
+            }
+
+            for (var i = 0; i < viewsToRenderCopyCount; i++)
+            {
+                var view = viewsToRenderCopy[i];
+                if (Contains(viewsAlreadyRendered, view, viewsAlreadyRenderedIndex)) continue;
+
+                view.Render();
+                viewsAlreadyRendered[viewsAlreadyRenderedIndex++] = view;
+            }
+        }
+        finally
+        {
+            if (viewsToRenderCopy is not null)
+                _viewPool.Return(viewsToRenderCopy);
+
+            if (viewsAlreadyRendered is not null)
+                _viewPool.Return(viewsAlreadyRendered);
+        }
+    }
+
+    private void CleanViewsToRender()
+    {
+        IView[]? viewsAlreadyProcessed = null;
+        try
+        {
+            viewsAlreadyProcessed = _viewPool.Rent(_viewsToRender.Count);
+            var viewsAlreadyProcessedIndex = 0;
+
+            var currentItem = _viewsToRender.First;
+            for (var i = 0; i < _viewsToRender.Count && currentItem is not null; i++)
+            {
+                if (Contains(viewsAlreadyProcessed, currentItem.Value, viewsAlreadyProcessedIndex))
+                {
+                    var itemToRemove = currentItem;
+                    currentItem = currentItem.Next;
+                    _viewsToRender.Remove(itemToRemove);
+                    continue;
+                }
+
+                viewsAlreadyProcessed[viewsAlreadyProcessedIndex++] = currentItem.Value;
+            }
+        }
+        finally
+        {
+            if (viewsAlreadyProcessed is not null)
+            {
+                _viewPool.Return(viewsAlreadyProcessed);
+            }
+        }
+    }
+
+    private static bool Contains(IView[] views, IView view, int max)
+    {
+        for (var i = 0; i < max; i++)
+        {
+            if (views[i] == view) return true;
+        }
+
+        return false;
+    }
+
+    public void AddViewToRender(IView view)
+    {
+        lock (_lock)
+        {
+            _viewsToRender.AddLast(view);
+        }
+    }
+}