[성현모] CPXV2 Init

SystemX.Net.CP.Platform/SystemX.Net.Platform/SystemX.Common/Event/PauseToken.cs

@@ -0,0 +1,63 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace SystemX.Net.Platform.Common.Event
+{
+    public class PauseTokenSource
+    {
+        private volatile TaskCompletionSource<bool> m_paused;
+        internal static readonly Task s_completedTask = Task.FromResult(true);
+
+        public void Pause()
+        {
+            Interlocked.CompareExchange(
+                ref m_paused, new TaskCompletionSource<bool>(), null);
+        }
+
+        public void Resume()
+        {
+            while (true)
+            {
+                var tcs = m_paused;
+                if (tcs == null) return;
+                if (Interlocked.CompareExchange(ref m_paused, null, tcs) == tcs)
+                {
+                    tcs.SetResult(true);
+                    break;
+                }
+            }
+        }
+
+        public bool IsPaused
+        {
+            get { return m_paused != null; }            
+        }
+
+        public PauseToken Token { get { return new PauseToken(this); } }
+
+        internal Task WaitWhilePausedAsync()
+        {
+            var cur = m_paused;
+            return cur != null ? cur.Task : s_completedTask;
+        }
+    }
+
+    public struct PauseToken
+    {
+        private readonly PauseTokenSource m_source;
+        internal PauseToken(PauseTokenSource source) { m_source = source; }
+
+        public bool IsPaused { get { return m_source != null && m_source.IsPaused; } }
+
+        public Task WaitWhilePausedAsync()
+        {
+            return IsPaused ?
+                m_source.WaitWhilePausedAsync() :
+                PauseTokenSource.s_completedTask;
+        }
+    }
+}