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

   1 #if 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                 protected TaskScheduler ()
  45                 {
  46                         this.id = Interlocked.Increment (ref lastId);
  47                 }
  48
  49           // FIXME: Probably not correct
  50                 public static TaskScheduler FromCurrentSynchronizationContext ()
  51                 {
  52                         return Current;
  53                 }
  54
  55                 public static TaskScheduler Default  {
  56                         get {
  57                                 return defaultScheduler;
  58                         }
  59                 }
  60
  61                 public static TaskScheduler Current  {
  62                         get {
  63                                 if (Task.Current != null && currentScheduler != null)
  64                                         return currentScheduler;
  65
  66                                 return defaultScheduler;
  67                         }
  68                         internal set {
  69                                 currentScheduler = value;
  70                         }
  71                 }
  72
  73                 public int Id {
  74                         get {
  75                                 return id;
  76                         }
  77                 }
  78
  79                 public virtual int MaximumConcurrencyLevel {
  80                         get {
  81                                 return Environment.ProcessorCount;
  82                         }
  83                 }
  84
  85                 protected abstract IEnumerable<Task> GetScheduledTasks ();
  86                 protected internal abstract void QueueTask (Task task);
  87                 protected internal virtual bool TryDequeue (Task task)
  88                 {
  89                         throw new NotSupportedException ();
  90                 }
  91
  92                 internal protected bool TryExecuteTask (Task task)
  93                 {
  94                         throw new NotSupportedException ();
  95                 }
  96
  97                 protected abstract bool TryExecuteTaskInline (Task task, bool taskWasPreviouslyQueued);
  98         }
  99 }
 100 #endif