code.grnet.gr Git - pithos-ms-client/blob - trunk/Pithos.Core/Agents/AsyncAutoResetEvent.cs

   1 // -----------------------------------------------------------------------
   2 // <copyright file="AsyncAutoResetEvent.cs" company="Microsoft">
   3 // TODO: Update copyright text.
   4 // </copyright>
   5 // -----------------------------------------------------------------------
   6
   7 using System.Threading.Tasks;
   8
   9 namespace Pithos.Core.Agents
  10 {
  11     using System;
  12     using System.Collections.Generic;
  13     using System.Linq;
  14     using System.Text;
  15
  16     /// <summary>
  17     /// TODO: Update summary.
  18     /// </summary>
  19     public class AsyncAutoResetEvent
  20     {
  21         private readonly static Task Completed = TaskEx.FromResult(true);
  22         private readonly Queue<TaskCompletionSource<bool>> _waits = new Queue<TaskCompletionSource<bool>>();
  23         private bool _signaled;
  24
  25         public Task WaitAsync()
  26         {
  27             lock (_waits)
  28             {
  29                 if (_signaled)
  30                 {
  31                     _signaled = false;
  32                     return Completed;
  33                 }
  34                 else
  35                 {
  36                     var tcs = new TaskCompletionSource<bool>();
  37                     _waits.Enqueue(tcs);
  38                     return tcs.Task;
  39                 }
  40             }
  41         }
  42
  43         public void Set()
  44         {
  45             TaskCompletionSource<bool> toRelease = null;
  46             lock (_waits)
  47             {
  48                 if (_waits.Count > 0)
  49                     toRelease = _waits.Dequeue();
  50                 else if (!_signaled)
  51                     _signaled = true;
  52             }
  53             if (toRelease != null)
  54                 toRelease.SetResult(true);
  55         }
  56
  57     }
  58 }