SynchronizationContextScheduler.cs

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// 
// SynchronizationContextScheduler.cs
//  
// Author:
//       Jérémie "Garuma" Laval <jeremie.laval@gmail.com>
// 
// Copyright (c) 2011 Novell
// 
// 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

using System;
using System.Threading;

namespace System.Threading.Tasks
{
    sealed class SynchronizationContextScheduler : TaskScheduler
    {
        readonly SynchronizationContext ctx;
        readonly SendOrPostCallback callback;

        public SynchronizationContextScheduler (SynchronizationContext ctx)
        {
            this.ctx = ctx;
            this.callback = TaskLaunchWrapper;
        }

        protected internal override void QueueTask (Task task)
        {
            ctx.Post (callback, task);
        }

        void TaskLaunchWrapper (object obj)
        {
            TryExecuteTask ((Task)obj);
        }

        protected override System.Collections.Generic.IEnumerable<Task> GetScheduledTasks ()
        {
            throw new System.NotImplementedException();
        }

        protected internal override bool TryDequeue (Task task)
        {
            return false;
        }

        protected override bool TryExecuteTaskInline (Task task, bool taskWasPreviouslyQueued)
        {
            ctx.Send (callback, task);
            return true;
        }

        public override int MaximumConcurrencyLevel {
            get {
                return base.MaximumConcurrencyLevel;
            }
        }
    }
}

#endif