#region
/* -----------------------------------------------------------------------
 * <copyright file="AsyncManualResetEvent.cs" company="GRNet">
 * 
 * Copyright 2011-2012 GRNET S.A. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 *   1. Redistributions of source code must retain the above
 *      copyright notice, this list of conditions and the following
 *      disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above
 *      copyright notice, this list of conditions and the following
 *      disclaimer in the documentation and/or other materials
 *      provided with the distribution.
 *
 *
 * THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * The views and conclusions contained in the software and
 * documentation are those of the authors and should not be
 * interpreted as representing official policies, either expressed
 * or implied, of GRNET S.A.
 * </copyright>
 * -----------------------------------------------------------------------
 */
#endregion
using System.Threading;
using System.Threading.Tasks;

namespace Pithos.Core.Agents
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;

    /// <summary>
    /// TODO: Update summary.
    /// </summary>
    public class AsyncManualResetEvent
    {
        private volatile TaskCompletionSource<bool> _tcs;

        public AsyncManualResetEvent()
        {
            _tcs = new TaskCompletionSource<bool>();
        }

        public AsyncManualResetEvent(bool signalled)
        {            
            _tcs = new TaskCompletionSource<bool>();
            if (signalled)
                _tcs.SetResult(true);
        }
        public Task WaitAsync() { return _tcs.Task; }

        public void Wait()
        {            
            _tcs.Task.Wait();
        }

        public void Set()
        {
            var tcs = _tcs;
            Task.Factory.StartNew(s => ((TaskCompletionSource<bool>)s).TrySetResult(true),
                tcs, CancellationToken.None, TaskCreationOptions.PreferFairness, TaskScheduler.Default);
            tcs.Task.Wait(); 
        }

        public void Reset()
        {
            while (true)
            {
                var tcs = _tcs;
                if (!tcs.Task.IsCompleted)
                    return;
#pragma warning disable 420
                if (Interlocked.CompareExchange(ref _tcs, new TaskCompletionSource<bool>(), tcs) == tcs)
#pragma warning restore 420
                    return;
            }
        }
    }
}