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A DelegateQueue Class

, 13 Mar 2007
An implementation of the ISynchronizeInvoke interface.
#region License

/* Copyright (c) 2006 Leslie Sanford
 * 
 * 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.
 */

#endregion

#region Contact

/*
 * Leslie Sanford
 * Email: jabberdabber@hotmail.com
 */

#endregion

using System;
using System.Threading;

namespace Sanford.Threading
{
    /// <summary>
    /// Provides basic implementation of the IAsyncResult interface.
    /// </summary>
    public class AsyncResult : IAsyncResult
    {
        #region AsyncResult Members

        #region Fields

        // The owner of this AsyncResult object.
        private object owner;

        // The callback to be invoked when the operation completes.
        private AsyncCallback callback;

        // User state information.
        private object state;

        // For signaling when the operation has completed.
        private ManualResetEvent waitHandle = new ManualResetEvent(false);

        // A value indicating whether the operation completed synchronously.
        private bool completedSynchronously;

        // A value indicating whether the operation has completed.
        private bool isCompleted = false;

        // The ID of the thread this AsyncResult object originated on.
        private int threadId;

        #endregion

        #region Construction

        /// <summary>
        /// Initializes a new instance of the AsyncResult object with the
        /// specified owner of the AsyncResult object, the optional callback
        /// delegate, and optional state object.
        /// </summary>
        /// <param name="owner">
        /// The owner of the AsyncResult object.
        /// </param>
        /// <param name="callback">
        /// An optional asynchronous callback, to be called when the 
        /// operation is complete. 
        /// </param>
        /// <param name="state">
        /// A user-provided object that distinguishes this particular 
        /// asynchronous request from other requests. 
        /// </param>
        public AsyncResult(object owner, AsyncCallback callback, object state)
        {
            this.owner = owner;
            this.callback = callback;
            this.state = state;

            // Get the current thread ID. This will be used later to determine
            // if the operation completed synchronously.
            threadId = Thread.CurrentThread.ManagedThreadId;
        }

        #endregion

        #region Methods

        /// <summary>
        /// Signals that the operation has completed.
        /// </summary>
        public void Signal()
        {
            isCompleted = true;

            completedSynchronously = threadId == Thread.CurrentThread.ManagedThreadId;

            waitHandle.Set();

            if(callback != null)
            {
                callback(this);
            }
        }

        #endregion

        #region Properties

        /// <summary>
        /// Gets the owner of this AsyncResult object.
        /// </summary>
        public object Owner
        {
            get
            {
                return owner;
            }
        }

        #endregion

        #endregion

        #region IAsyncResult Members

        public object AsyncState
        {
            get             
            {
                return state;
            }
        }

        public WaitHandle AsyncWaitHandle
        {
            get 
            {
                return waitHandle;
            }
        }

        public bool CompletedSynchronously
        {
            get 
            {
                return completedSynchronously;
            }
        }

        public bool IsCompleted
        {
            get 
            { 
                return isCompleted; 
            }
        }

        #endregion
    }
}

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License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Leslie Sanford

United States United States
Aside from dabbling in BASIC on his old Atari 1040ST years ago, Leslie's programming experience didn't really begin until he discovered the Internet in the late 90s. There he found a treasure trove of information about two of his favorite interests: MIDI and sound synthesis.
 
After spending a good deal of time calculating formulas he found on the Internet for creating new sounds by hand, he decided that an easier way would be to program the computer to do the work for him. This led him to learn C. He discovered that beyond using programming as a tool for synthesizing sound, he loved programming in and of itself.
 
Eventually he taught himself C++ and C#, and along the way he immersed himself in the ideas of object oriented programming. Like many of us, he gotten bitten by the design patterns bug and a copy of GOF is never far from his hands.
 
Now his primary interest is in creating a complete MIDI toolkit using the C# language. He hopes to create something that will become an indispensable tool for those wanting to write MIDI applications for the .NET framework.
 
Besides programming, his other interests are photography and playing his Les Paul guitars.

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