标准IDispose模式浅析

 

#region 标准IDispose模式

Private bool disposed = false;

Public void Dispose()

{

         Dispose(true);

         GC.SuppressFinalize(this);

}

~XXXXClass()

{

         Dispose(false);

}

Protected virtual void Dispose(bool disposing)

{

         If(disposed)

         Return;

         If(disposing)

        {

                  If(Resource != null)

                  {

                            // Release managed resource

                  }

        }

         // Release unmanaged resource
        disposed = true;

}

#endregion 

/*************************************************************
 * Copyright @ BOCO Group
 * All Rights Reserved.
 * Author: Cui Yansong(STEPHEN-PC.Cuiyansong)
 * Mail: cuiyansong@boco.com.cn
 * Create Date: 5/23/2014 9:29:46 AM
 * File Name: DisposePatternBase
 * CLR Version: 4.0.30319.17929 
 * ***********************************************************/

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;

namespace BocodeProtobufTest.Common
{
 /* ******************************************************************************************
 * Note 1: 保证线程安全
 * System.Threading.Interlocked.CompareExchange(T,T,T)此方法是为了保证线程安全所执行的原子操作。
 * http://msdn.microsoft.com/en-us/library/bb297966.aspx
 * 首先将disposedMark标记为已释放，保证其他线程获得disposedMark值为已释放，其他线程将不执行该操作。
 * 然后判断disposedMark标记之前的值是否为未释放，如果是则执行Dispose。
 * 
 * Note 2: 区分托管资源和非托管资源的释放方法
 * 如果执行手动释放（直接调用类的Dispose方法），则需要将所有资源均释放调；
 * 如果程序执行析构函数，则无需释放托管资源，原因在于大多数情况下托管资源可自动释放并且当系统执行析
 * 构方法时，已无法手动调用Dispose方法。
 * ******************************************************************************************/
    public abstract class DisposePatternBase : IDisposable
    {
        #region Public Properties

        #endregion Public Properties

        #region Private Properties
        /// <summary>
        /// A private property indicate whether resource have been diposed.
        /// </summary>
        /// <remarks>
        /// 0 --- Not Released
        /// 1 --- Released 
        /// </remarks>
        private int disposedMark = 0;

        #endregion Private Properties

        #region Constructor
        /// <summary>
        /// 系统销毁对象时自动调用
        /// </summary>
        ~DisposePatternBase()
        {
            // 原子操作，保证线程安全。
            var original = System.Threading.Interlocked.CompareExchange(ref disposedMark, 1, 0);
            if (original != 0) return;
            Dispose(false); 
        }

        #endregion Constructor

        #region Public Method
        /// <summary>
        /// 外部调用（手动）Dispose方法
        /// </summary>
        public void Dispose()
        {
            // 原子操作，保证线程安全。
            var original = System.Threading.Interlocked.CompareExchange(ref disposedMark, 1, 0);
            if (original != 0) return;
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        protected abstract void Dispose(bool disposing);

        #endregion Public Method
    }

    public class DisposePatternDemo : DisposePatternBase
    {
        private SafeHandle handle;

        private IList<byte> source;

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                // Release managed resource
                if (source != null && source.Count != 0)
                {
                    source = null;
                }
            }

            // Release unmanaged resource
            if (handle != null)
                handle.Dispose();
        }
    }
}