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

   1 //
   2 // CancellationTokenSource.cs
   3 //
   4 // Authors:
   5 //       Jérémie "Garuma" Laval <jeremie.laval@gmail.com>
   6 //       Marek Safar (marek.safar@gmail.com)
   7 //
   8 // Copyright (c) 2009 Jérémie "Garuma" Laval
   9 // Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining a copy
  12 // of this software and associated documentation files (the "Software"), to deal
  13 // in the Software without restriction, including without limitation the rights
  14 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  15 // copies of the Software, and to permit persons to whom the Software is
  16 // furnished to do so, subject to the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be included in
  19 // all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  24 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  25 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  26 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  27 // THE SOFTWARE.
  28
  29 #if NET_4_0 || MOBILE
  30 using System.Collections.Generic;
  31
  32 namespace System.Threading
  33 {
  34 #if !NET_4_5
  35         sealed
  36 #endif
  37         public class CancellationTokenSource : IDisposable
  38         {
  39                 bool canceled;
  40                 bool processed;
  41                 bool disposed;
  42
  43                 int currId = int.MinValue;
  44
  45                 Dictionary<CancellationTokenRegistration, Action> callbacks;
  46
  47                 ManualResetEvent handle;
  48                 readonly object syncRoot = new object ();
  49
  50                 internal static readonly CancellationTokenSource NoneSource = new CancellationTokenSource ();
  51                 internal static readonly CancellationTokenSource CanceledSource = new CancellationTokenSource ();
  52
  53 #if NET_4_5
  54                 static readonly TimerCallback timer_callback;
  55                 Timer timer;
  56 #endif
  57
  58                 static CancellationTokenSource ()
  59                 {
  60                         CanceledSource.processed = true;
  61                         CanceledSource.canceled = true;
  62
  63 #if NET_4_5
  64                         timer_callback = token => {
  65                                 var cts = (CancellationTokenSource) token;
  66                                 cts.Cancel ();
  67                         };
  68 #endif
  69                 }
  70
  71                 public CancellationTokenSource ()
  72                 {
  73                         callbacks = new Dictionary<CancellationTokenRegistration, Action> ();
  74                         handle = new ManualResetEvent (false);
  75                 }
  76
  77 #if NET_4_5
  78                 public CancellationTokenSource (int millisecondsDelay)
  79                         : this ()
  80                 {
  81                         if (millisecondsDelay < -1)
  82                                 throw new ArgumentOutOfRangeException ("millisecondsDelay");
  83
  84                         if (millisecondsDelay != Timeout.Infinite)
  85                                 timer = new Timer (timer_callback, this, millisecondsDelay, Timeout.Infinite);
  86                 }
  87
  88                 public CancellationTokenSource (TimeSpan delay)
  89                         : this (CheckTimeout (delay))
  90                 {
  91                 }
  92 #endif
  93
  94                 public CancellationToken Token {
  95                         get {
  96                                 CheckDisposed ();
  97                                 return new CancellationToken (this);
  98                         }
  99                 }
 100
 101                 public bool IsCancellationRequested {
 102                         get {
 103                                 return canceled;
 104                         }
 105                 }
 106
 107                 internal WaitHandle WaitHandle {
 108                         get {
 109                                 CheckDisposed ();
 110                                 return handle;
 111                         }
 112                 }
 113
 114                 public void Cancel ()
 115                 {
 116                         Cancel (false);
 117                 }
 118
 119                 // If parameter is true we throw exception as soon as they appear otherwise we aggregate them
 120                 public void Cancel (bool throwOnFirstException)
 121                 {
 122                         CheckDisposed ();
 123
 124                         canceled = true;
 125                         handle.Set ();
 126
 127                         List<Exception> exceptions = null;
 128
 129                         lock (callbacks) {
 130                                 try {
 131                                         foreach (var item in callbacks) {
 132                                                 if (throwOnFirstException) {
 133                                                         item.Value ();
 134                                                 } else {
 135                                                         try {
 136                                                                 item.Value ();
 137                                                         } catch (Exception e) {
 138                                                                 if (exceptions == null)
 139                                                                         exceptions = new List<Exception> ();
 140
 141                                                                 exceptions.Add (e);
 142                                                         }
 143                                                 }
 144                                         }
 145                                 } finally {
 146                                         callbacks.Clear ();
 147                                 }
 148                         }
 149
 150                         Thread.MemoryBarrier ();
 151                         processed = true;
 152
 153                         if (exceptions != null)
 154                                 throw new AggregateException (exceptions);
 155                 }
 156
 157 #if NET_4_5
 158                 public void CancelAfter (TimeSpan delay)
 159                 {
 160                         CancelAfter (CheckTimeout (delay));
 161                 }
 162
 163                 public void CancelAfter (int millisecondsDelay)
 164                 {
 165                         if (millisecondsDelay < -1)
 166                                 throw new ArgumentOutOfRangeException ("millisecondsDelay");
 167
 168                         CheckDisposed ();
 169
 170                         if (canceled || millisecondsDelay == Timeout.Infinite)
 171                                 return;
 172
 173                         if (timer == null) {
 174                                 // Have to be carefull not to create secondary background timer
 175                                 var t = new Timer (timer_callback, this, Timeout.Infinite, Timeout.Infinite);
 176                                 if (Interlocked.CompareExchange (ref timer, t, null) != null)
 177                                         t.Dispose ();
 178                         }
 179
 180                         timer.Change (millisecondsDelay, Timeout.Infinite);
 181                 }
 182 #endif
 183
 184                 public static CancellationTokenSource CreateLinkedTokenSource (CancellationToken token1, CancellationToken token2)
 185                 {
 186                         return CreateLinkedTokenSource (new [] { token1, token2 });
 187                 }
 188
 189                 public static CancellationTokenSource CreateLinkedTokenSource (params CancellationToken[] tokens)
 190                 {
 191                         if (tokens == null)
 192                                 throw new ArgumentNullException ("tokens");
 193
 194                         if (tokens.Length == 0)
 195                                 throw new ArgumentException ("Empty tokens array");
 196
 197                         CancellationTokenSource src = new CancellationTokenSource ();
 198                         Action action = src.Cancel;
 199
 200                         foreach (CancellationToken token in tokens) {
 201                                 if (token.CanBeCanceled)
 202                                         token.Register (action);
 203                         }
 204
 205                         return src;
 206                 }
 207
 208                 static int CheckTimeout (TimeSpan delay)
 209                 {
 210                         try {
 211                                 return checked ((int) delay.TotalMilliseconds);
 212                         } catch (OverflowException) {
 213                                 throw new ArgumentOutOfRangeException ("delay");
 214                         }
 215                 }
 216
 217                 void CheckDisposed ()
 218                 {
 219                         if (disposed)
 220                                 throw new ObjectDisposedException (GetType ().Name);
 221                 }
 222
 223                 public void Dispose ()
 224                 {
 225                         Dispose (true);
 226                 }
 227
 228 #if NET_4_5
 229                 protected virtual
 230 #endif
 231                 void Dispose (bool disposing)
 232                 {
 233                         if (disposing && !disposed) {
 234                                 disposed = true;
 235
 236                                 callbacks = null;
 237 #if NET_4_5
 238                                 if (timer != null)
 239                                         timer.Dispose ();
 240 #endif
 241                                 handle.Dispose ();
 242                         }
 243                 }
 244
 245                 internal CancellationTokenRegistration Register (Action callback, bool useSynchronizationContext)
 246                 {
 247                         CheckDisposed ();
 248
 249                         var tokenReg = new CancellationTokenRegistration (Interlocked.Increment (ref currId), this);
 250
 251                         if (canceled) {
 252                                 callback ();
 253                         } else {
 254                                 bool temp = false;
 255                                 lock (syncRoot) {
 256                                         if (!(temp = canceled))
 257                                                 callbacks.Add (tokenReg, callback);
 258                                 }
 259                                 if (temp)
 260                                         callback ();
 261                         }
 262
 263                         return tokenReg;
 264                 }
 265
 266                 internal void RemoveCallback (CancellationTokenRegistration tokenReg)
 267                 {
 268                         if (!canceled) {
 269                                 lock (syncRoot) {
 270                                         if (!canceled) {
 271                                                 callbacks.Remove (tokenReg);
 272                                                 return;
 273                                         }
 274                                 }
 275                         }
 276
 277                         SpinWait sw = new SpinWait ();
 278                         while (!processed)
 279                                 sw.SpinOnce ();
 280
 281                 }
 282         }
 283 }
 284 #endif