mcs/class/corlib/System.Threading.Tasks/TaskCompletionSource.cs

   1 //
   2 // TaskCompletionSource.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;
  31 using System.Collections.Generic;
  32
  33 namespace System.Threading.Tasks
  34 {
  35         public class TaskCompletionSource<TResult>
  36         {
  37                 static readonly Func<TResult> emptyFunction = () => default (TResult);
  38                 static readonly Func<object, TResult> emptyParamFunction = (_) => default (TResult);
  39
  40                 static readonly Action<Task<TResult>, TResult> setResultAction = SetResultAction;
  41                 static readonly Action<Task<TResult>, AggregateException> setExceptionAction = SetExceptionAction;
  42                 static readonly Action<Task<TResult>, object> setCanceledAction = SetCanceledAction;
  43
  44                 readonly Task<TResult> source;
  45                 SpinLock opLock = new SpinLock (false);
  46
  47                 public TaskCompletionSource ()
  48                 {
  49                         source = new Task<TResult> (emptyFunction);
  50                         source.SetupScheduler (TaskScheduler.Current);
  51                 }
  52
  53                 public TaskCompletionSource (object state)
  54                 {
  55                         source = new Task<TResult> (emptyParamFunction, state);
  56                         source.SetupScheduler (TaskScheduler.Current);
  57                 }
  58
  59                 public TaskCompletionSource (TaskCreationOptions creationOptions)
  60                         : this (null, creationOptions)
  61                 {
  62                 }
  63
  64                 public TaskCompletionSource (object state, TaskCreationOptions creationOptions)
  65                 {
  66                         if ((creationOptions & System.Threading.Tasks.Task.WorkerTaskNotSupportedOptions) != 0)
  67                                 throw new ArgumentOutOfRangeException ("creationOptions");
  68
  69                         source = new Task<TResult> (emptyParamFunction, state, creationOptions);
  70                         source.SetupScheduler (TaskScheduler.Current);
  71                 }
  72
  73                 public void SetCanceled ()
  74                 {
  75                         if (!TrySetCanceled ())
  76                                 ThrowInvalidException ();
  77                 }
  78
  79                 public void SetException (Exception exception)
  80                 {
  81                         if (exception == null)
  82                                 throw new ArgumentNullException ("exception");
  83
  84                         SetException (new Exception[] { exception });
  85                 }
  86
  87                 public void SetException (IEnumerable<Exception> exceptions)
  88                 {
  89                         if (!TrySetException (exceptions))
  90                                 ThrowInvalidException ();
  91                 }
  92
  93                 public void SetResult (TResult result)
  94                 {
  95                         if (!TrySetResult (result))
  96                                 ThrowInvalidException ();
  97                 }
  98
  99                 static void ThrowInvalidException ()
 100                 {
 101                         throw new InvalidOperationException ("The underlying Task is already in one of the three final states: RanToCompletion, Faulted, or Canceled.");
 102                 }
 103
 104                 public bool TrySetCanceled ()
 105                 {
 106                         return ApplyOperation (setCanceledAction, null);
 107                 }
 108
 109                 public bool TrySetException (Exception exception)
 110                 {
 111                         if (exception == null)
 112                                 throw new ArgumentNullException ("exception");
 113
 114                         return TrySetException (new Exception[] { exception });
 115                 }
 116
 117                 public bool TrySetException (IEnumerable<Exception> exceptions)
 118                 {
 119                         if (exceptions == null)
 120                                 throw new ArgumentNullException ("exceptions");
 121
 122                         var aggregate = new AggregateException (exceptions);
 123                         if (aggregate.InnerExceptions.Count == 0)
 124                                 throw new ArgumentNullException ("exceptions");
 125
 126                         return ApplyOperation (setExceptionAction, aggregate);
 127                 }
 128
 129                 public bool TrySetResult (TResult result)
 130                 {
 131                         return ApplyOperation (setResultAction, result);
 132                 }
 133
 134                 bool ApplyOperation<TState> (Action<Task<TResult>, TState> action, TState state)
 135                 {
 136                         bool taken = false;
 137                         try {
 138                                 opLock.Enter (ref taken);
 139                                 if (CheckInvalidState ())
 140                                         return false;
 141
 142                                 source.Status = TaskStatus.Running;
 143
 144                                 if (action != null)
 145                                         action (source, state);
 146
 147                                 source.Finish ();
 148
 149                                 return true;
 150                         } finally {
 151                                 if (taken)
 152                                         opLock.Exit ();
 153                         }
 154                 }
 155
 156                 bool CheckInvalidState ()
 157                 {
 158                         return source.Status == TaskStatus.RanToCompletion ||
 159                                    source.Status == TaskStatus.Faulted ||
 160                                    source.Status == TaskStatus.Canceled;
 161                 }
 162
 163                 static void SetResultAction (Task<TResult> source, TResult result)
 164                 {
 165                         source.Result = result;
 166                 }
 167
 168                 static void SetExceptionAction (Task<TResult> source, AggregateException aggregate)
 169                 {
 170                         source.HandleGenericException (aggregate);
 171                 }
 172
 173                 static void SetCanceledAction (Task<TResult> source, object unused)
 174                 {
 175                         source.CancelReal ();
 176                 }
 177
 178                 public Task<TResult> Task {
 179                         get {
 180                                 return source;
 181                         }
 182                 }
 183         }
 184 }
 185 #endif