developer/Samples/NET Standard/ParallelExtensionsExtras/Extensions/TaskFactoryExtensions/TaskFactoryExtensions_FromAsync.cs

   1 //--------------------------------------------------------------------------
   2 //
   3 //  Copyright (c) Microsoft Corporation.  All rights reserved.
   4 //
   5 //  File: TaskFactoryExtensions_FromAsync.cs
   6 //
   7 //--------------------------------------------------------------------------
   8
   9 namespace System.Threading.Tasks
  10 {
  11     /// <summary>Extensions for TaskFactory.</summary>
  12     public static partial class TaskFactoryExtensions
  13     {
  14         /// <summary>Creates a Task that will be completed when the specified WaitHandle is signaled.</summary>
  15         /// <param name="factory">The target factory.</param>
  16         /// <param name="waitHandle">The WaitHandle.</param>
  17         /// <returns>The created Task.</returns>
  18         public static Task FromAsync(this TaskFactory factory, WaitHandle waitHandle)
  19         {
  20             if (factory == null) throw new ArgumentNullException("factory");
  21             if (waitHandle == null) throw new ArgumentNullException("waitHandle");
  22
  23             var tcs = new TaskCompletionSource<object>();
  24             var rwh = ThreadPool.RegisterWaitForSingleObject(waitHandle, delegate { tcs.TrySetResult(null); }, null, -1, true);
  25             var t = tcs.Task;
  26             t.ContinueWith(_ => rwh.Unregister(null), TaskContinuationOptions.ExecuteSynchronously);
  27             return t;
  28         }
  29     }
  30 }