mcs/class/corlib/System.Threading/ManualResetEventSlim.cs

   1 // ManualResetEventSlim.cs
   2 //
   3 // Authors:
   4 //    Marek Safar  <marek.safar@gmail.com>
   5 //
   6 // Copyright (c) 2008 Jérémie "Garuma" Laval
   7 // Copyright 2011 Xamarin Inc (http://www.xamarin.com).
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining a copy
  10 // of this software and associated documentation files (the "Software"), to deal
  11 // in the Software without restriction, including without limitation the rights
  12 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  13 // copies of the Software, and to permit persons to whom the Software is
  14 // furnished to do so, subject to the following conditions:
  15 //
  16 // The above copyright notice and this permission notice shall be included in
  17 // all copies or substantial portions of the Software.
  18 //
  19 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  22 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  23 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  24 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  25 // THE SOFTWARE.
  26 //
  27 //
  28
  29 #if NET_4_0 || MOBILE
  30
  31 namespace System.Threading
  32 {
  33         [System.Diagnostics.DebuggerDisplayAttribute ("Set = {IsSet}")]
  34         public class ManualResetEventSlim : IDisposable
  35         {
  36                 readonly int spinCount;
  37
  38                 ManualResetEvent handle;
  39                 internal AtomicBooleanValue disposed;
  40                 int used;
  41                 bool set;
  42
  43                 public ManualResetEventSlim ()
  44                         : this (false, 10)
  45                 {
  46                 }
  47
  48                 public ManualResetEventSlim (bool initialState)
  49                         : this (initialState, 10)
  50                 {
  51                 }
  52
  53                 public ManualResetEventSlim (bool initialState, int spinCount)
  54                 {
  55                         if (spinCount < 0 || spinCount > 2047)
  56                                 throw new ArgumentOutOfRangeException ("spinCount");
  57
  58                         this.set = initialState;
  59                         this.spinCount = spinCount;
  60                 }
  61
  62                 public bool IsSet {
  63                         get {
  64                                 return set;
  65                         }
  66                 }
  67
  68                 public int SpinCount {
  69                         get {
  70                                 return spinCount;
  71                         }
  72                 }
  73
  74                 public void Reset ()
  75                 {
  76                         ThrowIfDisposed ();
  77
  78                         set = false;
  79                         Thread.MemoryBarrier ();
  80                         if (handle != null) {
  81                                 Interlocked.Increment (ref used);
  82                                 var tmpHandle = handle;
  83                                 if (tmpHandle != null)
  84                                         tmpHandle.Reset ();
  85                                 Interlocked.Decrement (ref used);
  86                         }
  87                 }
  88
  89                 public void Set ()
  90                 {
  91                         set = true;
  92                         Thread.MemoryBarrier ();
  93                         if (handle != null) {
  94                                 Interlocked.Increment (ref used);
  95                                 var tmpHandle = handle;
  96                                 if (tmpHandle != null)
  97                                         tmpHandle.Set ();
  98                                 Interlocked.Decrement (ref used);
  99                         }
 100                 }
 101
 102                 public void Wait ()
 103                 {
 104                         Wait (CancellationToken.None);
 105                 }
 106
 107                 public bool Wait (int millisecondsTimeout)
 108                 {
 109                         return Wait (millisecondsTimeout, CancellationToken.None);
 110                 }
 111
 112                 public bool Wait (TimeSpan timeout)
 113                 {
 114                         return Wait (CheckTimeout (timeout), CancellationToken.None);
 115                 }
 116
 117                 public void Wait (CancellationToken cancellationToken)
 118                 {
 119                         Wait (Timeout.Infinite, cancellationToken);
 120                 }
 121
 122                 public bool Wait (int millisecondsTimeout, CancellationToken cancellationToken)
 123                 {
 124                         if (millisecondsTimeout < -1)
 125                                 throw new ArgumentOutOfRangeException ("millisecondsTimeout");
 126
 127                         ThrowIfDisposed ();
 128
 129                         if (!set) {
 130                                 SpinWait wait = new SpinWait ();
 131
 132                                 while (!set) {
 133                                         cancellationToken.ThrowIfCancellationRequested ();
 134
 135                                         if (wait.Count < spinCount) {
 136                                                 wait.SpinOnce ();
 137                                                 continue;
 138                                         }
 139
 140                                         break;
 141                                 }
 142
 143                                 if (set)
 144                                         return true;
 145
 146                                 WaitHandle handle = WaitHandle;
 147
 148                                 if (cancellationToken.CanBeCanceled) {
 149                                         if (WaitHandle.WaitAny (new[] { handle, cancellationToken.WaitHandle }, millisecondsTimeout, false) == 0)
 150                                                 return false;
 151
 152                                         cancellationToken.ThrowIfCancellationRequested ();
 153                                 } else {
 154                                         if (!handle.WaitOne (millisecondsTimeout, false))
 155                                                 return false;
 156                                 }
 157                         }
 158
 159                         return true;
 160                 }
 161
 162                 public bool Wait (TimeSpan timeout, CancellationToken cancellationToken)
 163                 {
 164                         return Wait (CheckTimeout (timeout), cancellationToken);
 165                 }
 166
 167                 public WaitHandle WaitHandle {
 168                         get {
 169                                 ThrowIfDisposed ();
 170
 171                                 if (handle != null)
 172                                         return handle;
 173
 174                                 var isSet = set;
 175                                 var mre = new ManualResetEvent (isSet);
 176                                 if (Interlocked.CompareExchange (ref handle, mre, null) == null) {
 177                                         //
 178                                         // Ensure the Set has not ran meantime
 179                                         //
 180                                         if (isSet != set) {
 181                                                 if (set) {
 182                                                         mre.Set ();
 183                                                 } else {
 184                                                         mre.Reset ();
 185                                                 }
 186                                         }
 187                                 } else {
 188                                         //
 189                                         // Release the event when other thread was faster
 190                                         //
 191                                         mre.Dispose ();
 192                                 }
 193
 194                                 return handle;
 195                         }
 196                 }
 197
 198                 public void Dispose ()
 199                 {
 200                         Dispose (true);
 201                 }
 202
 203                 protected virtual void Dispose (bool disposing)
 204                 {
 205                         if (!disposed.TryRelaxedSet ())
 206                                 return;
 207
 208                         if (handle != null) {
 209                                 var tmpHandle = Interlocked.Exchange (ref handle, null);
 210                                 if (used > 0) {
 211                                         // A tiny wait (just a few cycles normally) before releasing
 212                                         SpinWait wait = new SpinWait ();
 213                                         while (used > 0)
 214                                                 wait.SpinOnce ();
 215                                 }
 216                                 tmpHandle.Dispose ();
 217                         }
 218                 }
 219
 220                 void ThrowIfDisposed ()
 221                 {
 222                         if (disposed.Value)
 223                                 throw new ObjectDisposedException ("ManualResetEventSlim");
 224                 }
 225
 226                 static int CheckTimeout (TimeSpan timeout)
 227                 {
 228                         try {
 229                                 return checked ((int)timeout.TotalMilliseconds);
 230                         } catch (System.OverflowException) {
 231                                 throw new ArgumentOutOfRangeException ("timeout");
 232                         }
 233                 }
 234         }
 235 }
 236 #endif