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

   1 // Scheduler.cs
   2 //
   3 // Copyright (c) 2008 Jérémie "Garuma" Laval
   4 //
   5 // Permission is hereby granted, free of charge, to any person obtaining a copy
   6 // of this software and associated documentation files (the "Software"), to deal
   7 // in the Software without restriction, including without limitation the rights
   8 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   9 // copies of the Software, and to permit persons to whom the Software is
  10 // furnished to do so, subject to the following conditions:
  11 //
  12 // The above copyright notice and this permission notice shall be included in
  13 // all copies or substantial portions of the Software.
  14 //
  15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  21 // THE SOFTWARE.
  22 //
  23 //
  24
  25 #if NET_4_0 || MOBILE
  26 using System;
  27 using System.Collections.Concurrent;
  28
  29 namespace System.Threading.Tasks
  30 {
  31         internal class Scheduler: TaskScheduler
  32         {
  33                 readonly IProducerConsumerCollection<Task> workQueue;
  34                 readonly ThreadWorker[]        workers;
  35                 readonly ManualResetEvent      pulseHandle = new ManualResetEvent (false);
  36
  37                 public Scheduler ()
  38                         : this (Environment.ProcessorCount, ThreadPriority.Normal)
  39                 {
  40
  41                 }
  42
  43                 public Scheduler (int maxWorker, ThreadPriority priority)
  44                 {
  45                         workQueue = new ConcurrentQueue<Task> ();
  46                         workers = new ThreadWorker [maxWorker];
  47
  48                         for (int i = 0; i < maxWorker; i++) {
  49                                 workers [i] = new ThreadWorker (workers, i, workQueue, new CyclicDeque<Task> (), priority, pulseHandle);
  50                                 workers [i].Pulse ();
  51                         }
  52                 }
  53
  54                 protected internal override void QueueTask (Task t)
  55                 {
  56                         // Add to the shared work pool
  57                         workQueue.TryAdd (t);
  58                         // Wake up some worker if they were asleep
  59                         PulseAll ();
  60                 }
  61
  62                 internal override void ParticipateUntil (Task task)
  63                 {
  64                         if (task.IsCompleted)
  65                                 return;
  66
  67                         ManualResetEventSlim evt = new ManualResetEventSlim (false);
  68                         task.ContinueWith (_ => evt.Set (), TaskContinuationOptions.ExecuteSynchronously);
  69                         if (evt.IsSet || task.IsCompleted)
  70                                 return;
  71
  72                         ParticipateUntilInternal (task, evt, -1);
  73                 }
  74
  75                 internal override bool ParticipateUntil (Task task, ManualResetEventSlim evt, int millisecondsTimeout)
  76                 {
  77                         if (task.IsCompleted)
  78                                 return false;
  79
  80                         bool isFromPredicate = true;
  81                         task.ContinueWith (_ => { isFromPredicate = false; evt.Set (); }, TaskContinuationOptions.ExecuteSynchronously);
  82
  83                         ParticipateUntilInternal (task, evt, millisecondsTimeout);
  84
  85                         if (task.IsCompleted)
  86                                 return false;
  87
  88                         return isFromPredicate;
  89                 }
  90
  91                 internal void ParticipateUntilInternal (Task self, ManualResetEventSlim evt, int millisecondsTimeout)
  92                 {
  93                         ThreadWorker.ParticipativeWorkerMethod (self, evt, millisecondsTimeout, workQueue, workers, pulseHandle);
  94                 }
  95
  96                 static bool TaskCompletedPredicate (Task self)
  97                 {
  98                         return self.IsCompleted;
  99                 }
 100
 101                 internal override void PulseAll ()
 102                 {
 103                         pulseHandle.Set ();
 104                 }
 105
 106                 public void Dispose ()
 107                 {
 108                         foreach (ThreadWorker w in workers)
 109                                 w.Dispose ();
 110                 }
 111                 #region Scheduler dummy stubs
 112                 protected override System.Collections.Generic.IEnumerable<Task> GetScheduledTasks ()
 113                 {
 114                         throw new System.NotImplementedException();
 115                 }
 116
 117                 protected internal override bool TryDequeue (Task task)
 118                 {
 119                         throw new System.NotImplementedException();
 120                 }
 121
 122                 protected override bool TryExecuteTaskInline (Task task, bool taskWasPreviouslyQueued)
 123                 {
 124                         task.Execute (null);
 125                         return true;
 126                 }
 127
 128                 public override int MaximumConcurrencyLevel {
 129                         get {
 130                                 return base.MaximumConcurrencyLevel;
 131                         }
 132                 }
 133                 #endregion
 134         }
 135 }
 136 #endif