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

   1 #if NET_4_0 || BOOTSTRAP_NET_4_0
   2 //
   3 // TaskScheduler.cs
   4 //
   5 // Author:
   6 //       Jérémie "Garuma" Laval <jeremie.laval@gmail.com>
   7 //
   8 // Copyright (c) 2009 Jérémie "Garuma" Laval
   9 //
  10 // Permission is hereby granted, free of charge, to any person obtaining a copy
  11 // of this software and associated documentation files (the "Software"), to deal
  12 // in the Software without restriction, including without limitation the rights
  13 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  14 // copies of the Software, and to permit persons to whom the Software is
  15 // furnished to do so, subject to the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be included in
  18 // all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  23 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  25 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  26 // THE SOFTWARE.
  27
  28 using System;
  29 using System.Threading;
  30 using System.Collections.Generic;
  31
  32 namespace System.Threading.Tasks
  33 {
  34         public abstract class TaskScheduler
  35         {
  36                 static TaskScheduler defaultScheduler = new Scheduler ();
  37
  38                 [ThreadStatic]
  39                 static TaskScheduler currentScheduler;
  40
  41                 int id;
  42                 static int lastId = int.MinValue;
  43
  44                 public static event EventHandler<UnobservedTaskExceptionEventArgs> UnobservedTaskException;
  45
  46                 protected TaskScheduler ()
  47                 {
  48                         this.id = Interlocked.Increment (ref lastId);
  49                 }
  50
  51                 // FIXME: Probably not correct
  52                 public static TaskScheduler FromCurrentSynchronizationContext ()
  53                 {
  54                         return Current;
  55                 }
  56
  57                 public static TaskScheduler Default  {
  58                         get {
  59                                 return defaultScheduler;
  60                         }
  61                 }
  62
  63                 public static TaskScheduler Current  {
  64                         get {
  65                                 if (currentScheduler != null)
  66                                         return currentScheduler;
  67
  68                                 return defaultScheduler;
  69                         }
  70                         internal set {
  71                                 currentScheduler = value;
  72                         }
  73                 }
  74
  75                 public int Id {
  76                         get {
  77                                 return id;
  78                         }
  79                 }
  80
  81                 public virtual int MaximumConcurrencyLevel {
  82                         get {
  83                                 return Environment.ProcessorCount;
  84                         }
  85                 }
  86
  87                 protected abstract IEnumerable<Task> GetScheduledTasks ();
  88                 protected internal abstract void QueueTask (Task task);
  89                 protected internal virtual bool TryDequeue (Task task)
  90                 {
  91                         throw new NotSupportedException ();
  92                 }
  93
  94                 internal protected bool TryExecuteTask (Task task)
  95                 {
  96                         throw new NotSupportedException ();
  97                 }
  98
  99                 protected abstract bool TryExecuteTaskInline (Task task, bool taskWasPreviouslyQueued);
 100
 101                 internal UnobservedTaskExceptionEventArgs FireUnobservedEvent (AggregateException e)
 102                 {
 103                         UnobservedTaskExceptionEventArgs args = new UnobservedTaskExceptionEventArgs (e);
 104
 105                         EventHandler<UnobservedTaskExceptionEventArgs> temp = UnobservedTaskException;
 106                         if (temp == null)
 107                                 return args;
 108
 109                         temp (this, args);
 110
 111                         return args;
 112                 }
 113         }
 114 }
 115 #endif