TaskScheduler.cs :  » 2.6.4-mono-.net-core » System.Threading » System » Threading » Tasks » C# / CSharp Open Source

#if NET_4_0 || BOOTSTRAP_NET_4_0
// 
// TaskScheduler.cs
//  
// Author:
//       Jrmie "Garuma" Laval <jeremie.laval@gmail.com>
// 
// Copyright (c) 2009 Jrmie "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.

using System;
using System.Threading;
using System.Collections.Generic;

namespace System.Threading.Tasks{
  public abstract class TaskScheduler
  {
    static TaskScheduler defaultScheduler = new Scheduler ();
    
    [ThreadStatic]
    static TaskScheduler currentScheduler;
    
    int id;
    static int lastId = int.MinValue;
    
    public static event EventHandler<UnobservedTaskExceptionEventArgs> UnobservedTaskException;
    
    protected TaskScheduler ()
    {
      this.id = Interlocked.Increment (ref lastId);
    }

    // FIXME: Probably not correct
    public static TaskScheduler FromCurrentSynchronizationContext ()
    {
      return Current;
    }
    
    public static TaskScheduler Default  {
      get {
        return defaultScheduler;
      }
    }
    
    public static TaskScheduler Current  {
      get {
        if (currentScheduler != null)
          return currentScheduler;
        
        return defaultScheduler;
      }
      internal set {
        currentScheduler = value;
      }
    }
    
    public int Id {
      get {
        return id;
      }
    }
    
    public virtual int MaximumConcurrencyLevel {
      get {
        return Environment.ProcessorCount;
      }
    }
    
    protected abstract IEnumerable<Task> GetScheduledTasks ();
    protected internal abstract void QueueTask (Task task);
    protected internal virtual bool TryDequeue (Task task)
    {
      throw new NotSupportedException ();
    }

    internal protected bool TryExecuteTask (Task task)
    {
      throw new NotSupportedException ();
    }

    protected abstract bool TryExecuteTaskInline (Task task, bool taskWasPreviouslyQueued);
    
    internal UnobservedTaskExceptionEventArgs FireUnobservedEvent (AggregateException e)
    {
      UnobservedTaskExceptionEventArgs args = new UnobservedTaskExceptionEventArgs (e);
      
      EventHandler<UnobservedTaskExceptionEventArgs> temp = UnobservedTaskException;
      if (temp == null)
        return args;
      
      temp (this, args);
      
      return args;
    }
  }
}
#endif