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

// Scheduler.cs
//
// Copyright (c) 2008 Jérémie "Garuma" Laval
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
//

#if NET_4_0 || BOOTSTRAP_NET_4_0
using System;
using System.Collections.Concurrent;

namespace System.Threading.Tasks
{
	internal class Scheduler: TaskScheduler, IScheduler
	{
		IProducerConsumerCollection<Task> workQueue;
		ThreadWorker[]        workers;
		EventWaitHandle       pulseHandle = new AutoResetEvent (false);

		public Scheduler ()
			: this (Environment.ProcessorCount, 0, ThreadPriority.Normal)
		{
			
		}
		
		public Scheduler (int maxWorker, int maxStackSize, ThreadPriority priority)
		{
			workQueue = new ConcurrentQueue<Task> ();
			workers = new ThreadWorker [maxWorker];
			
			for (int i = 0; i < maxWorker; i++) {
				workers [i] = new ThreadWorker (this, workers, workQueue, maxStackSize, priority, pulseHandle);
				workers [i].Pulse ();
			}
		}
		
		public void AddWork (Task t)
		{
			// Add to the shared work pool
			workQueue.TryAdd (t);
			// Wake up some worker if they were asleep
			PulseAll ();
		}
		
		public void ParticipateUntil (Task task)
		{
			if (AreTasksFinished (task))
				return;
			
			ParticipateUntil (delegate {
				return AreTasksFinished (task);
			});
		}
		
		public bool ParticipateUntil (Task task, Func<bool> predicate)
		{
			if (AreTasksFinished (task))
				return false;
			
			bool isFromPredicate = false;
			
			ParticipateUntil (delegate {
				if (predicate ()) {
					isFromPredicate = true;
					return true;
				}
				return AreTasksFinished (task);	
			});
				
			return isFromPredicate;
		}
		
		// Called with Task.WaitAll(someTasks) or Task.WaitAny(someTasks) so that we can remove ourselves
		// also when our wait condition is ok
		public void ParticipateUntil (Func<bool> predicate)
		{	
			ThreadWorker.WorkerMethod (predicate, workQueue, workers);
		}
		
		public void PulseAll ()
		{
			pulseHandle.Set ();
		}
		
		public void Dispose ()
		{
			foreach (ThreadWorker w in workers) {
				w.Dispose ();
			}
		}
		
		bool AreTasksFinished (Task parent)
		{
			return parent.IsCompleted;
		}

		#region Scheduler dummy stubs
		protected override System.Collections.Generic.IEnumerable<Task> GetScheduledTasks ()
		{
			throw new System.NotImplementedException();
		}

		protected internal override void QueueTask (Task task)
		{
			throw new System.NotImplementedException();
		}

		protected internal override bool TryDequeue (Task task)
		{
			throw new System.NotImplementedException();
		}

		protected override bool TryExecuteTaskInline (Task task, bool taskWasPreviouslyQueued)
		{
			throw new System.NotImplementedException();
		}
		
		public override int MaximumConcurrencyLevel {
			get {
				return base.MaximumConcurrencyLevel;
			}
		}
		#endregion
	}
}
#endif