C# IOCP完成端口模型（简单实用高效）

1、在C#中，不用去面对完成端口的操作系统内核对象，Microsoft已经为我们提供了SocketAsyncEventArgs类，它封装了IOCP的使用。请参考：http://msdn.microsoft.com/zh-cn/library/system.net.sockets.socketasynceventargs.aspx?cs-save-lang=1&cs-lang=cpp#code-snippet-1。

2、我的SocketAsyncEventArgsPool类使用List对象来存储对客户端来通信的SocketAsyncEventArgs对象，它相当于直接使用内核对象时的IoContext。我这样设计比用堆栈来实现的好处理是，我可以在SocketAsyncEventArgsPool池中找到任何一个与服务器连接的客户，主动向它发信息。而用堆栈来实现的话，要主动给客户发信息，则还要设计一个结构来存储已连接上服务器的客户。

3、对每一个客户端不管还发送还是接收，我使用同一个SocketAsyncEventArgs对象，对每一个客户端来说，通信是同步进行的，也就是说服务器高度保证同一个客户连接上要么在投递发送请求，并等待；或者是在投递接收请求，等待中。本例只做echo服务器，还未考虑由服务器主动向客户发送信息。

4、SocketAsyncEventArgs的UserToken被直接设定为被接受的客户端Socket。

5、没有使用BufferManager 类，因为我在初始化时给每一个SocketAsyncEventArgsPool中的对象分配一个缓冲区，发送时使用Arrary.Copy来进行字符拷贝，不去改变缓冲区的位置，只改变使用的长度，因此在下次投递接收请求时恢复缓冲区长度就可以了！如果要主动给客户发信息的话，可以new一个SocketAsyncEventArgs对象，或者在初始化中建立几个来专门用于主动发送信息，因为这种需求一般是进行信息群发，建立一个对象可以用于很多次信息发送，总体来看，这种花销不大，还减去了字符拷贝和消耗。
demo下载地址： http://files.cnblogs.com/files/airtcp/IocpServer.zip

经典代码IOCP(完成端口)的C#.Net实现----解读

感谢原作者

经典代码IOCP(完成端口)的C#.Net实现

重复造轮子的意义在于深刻的理解和学习---

main.cs:

/*using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace c2iocp
{
    class Program
    {
        static void Main(string[] args)
        {
        }
    }
}
*/
using System;
using System.Threading;  // Included for the Thread.Sleep call
using Continuum.Threading;
namespace Sample
{
    //============================================
    ///  Sample class for the threading class
    public class UtilThreadingSample
    {
        //*******************************************
        ///  Test Method
        static void Main()
        {
            // Create the MSSQL IOCP Thread Pool
            IOCPThreadPool pThreadPool = new IOCPThreadPool(0, 5, 10, new IOCPThreadPool.USER_FUNCTION(IOCPThreadFunction));
            pThreadPool.PostEvent(10);
            Thread.Sleep(10000);
            pThreadPool.Dispose();
        }
        //*****************************************
        ///  Function to be called by the IOCP thread pool.  Called when
        ///           a command is posted for processing by the SocketManager
        ///  The value provided by the thread posting the event
        static public void IOCPThreadFunction(Int32 iValue)
        {
            try
            {
                Console.WriteLine("Value: {0}", iValue);
            }
            catch (Exception pException)
            {
                Console.WriteLine(pException.Message);
            }
        }
    }
}

/*using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace c2iocp
{
    class Program
    {
        static void Main(string[] args)
        {
        }
    }
}
*/
using System;
using System.Threading;  // Included for the Thread.Sleep call
using Continuum.Threading;
namespace Sample
{
    //============================================
    /// 
 Sample class for the threading class 
    public class UtilThreadingSample
    {
        //******************************************* 
        /// 
 Test Method 
        static void Main()
        {
            // Create the MSSQL IOCP Thread Pool
            IOCPThreadPool pThreadPool = new IOCPThreadPool(0, 5, 10, new IOCPThreadPool.USER_FUNCTION(IOCPThreadFunction));
            pThreadPool.PostEvent(10);
            Thread.Sleep(10000);
            pThreadPool.Dispose();
        }
        //*****************************************
        /// 
 Function to be called by the IOCP thread pool.  Called when
        ///           a command is posted for processing by the SocketManager 
        ///  The value provided by the thread posting the event 
        static public void IOCPThreadFunction(Int32 iValue)
        {
            try
            {
                Console.WriteLine("Value: {0}", iValue);
            }
            catch (Exception pException)
            {
                Console.WriteLine(pException.Message);
            }
        }
    }
}

continuum.cs

using System;
using System.Threading;
using System.Runtime.InteropServices;

namespace Continuum.Threading
{

    // Structures
    //==========================================
    ///  This is the WIN32 OVERLAPPED structure
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    public unsafe struct OVERLAPPED
    {
        UInt32* ulpInternal;
        UInt32* ulpInternalHigh;
        Int32 lOffset;
        Int32 lOffsetHigh;
        UInt32 hEvent;
    }

    // Classes
    //============================================
    ///  This class provides the ability to create a thread pool to manage work.  The
    ///           class abstracts the Win32 IOCompletionPort API so it requires the use of
    ///           unmanaged code.  Unfortunately the .NET framework does not provide this functionality
    public sealed class IOCPThreadPool
    {

        // Win32 Function Prototypes
        ///  Win32Func: Create an IO Completion Port Thread Pool
        [DllImport("Kernel32", CharSet = CharSet.Auto)]
        private unsafe static extern UInt32 CreateIoCompletionPort(UInt32 hFile, UInt32 hExistingCompletionPort, UInt32* puiCompletionKey, UInt32 uiNumberOfConcurrentThreads);

        ///  Win32Func: Closes an IO Completion Port Thread Pool
        [DllImport("Kernel32", CharSet = CharSet.Auto)]
        private unsafe static extern Boolean CloseHandle(UInt32 hObject);

        ///  Win32Func: Posts a context based event into an IO Completion Port Thread Pool
        [DllImport("Kernel32", CharSet = CharSet.Auto)]
        private unsafe static extern Boolean PostQueuedCompletionStatus(UInt32 hCompletionPort, UInt32 uiSizeOfArgument, UInt32* puiUserArg, OVERLAPPED* pOverlapped);

        ///  Win32Func: Waits on a context based event from an IO Completion Port Thread Pool.
        ///           All threads in the pool wait in this Win32 Function
        [DllImport("Kernel32", CharSet = CharSet.Auto)]
        private unsafe static extern Boolean GetQueuedCompletionStatus(UInt32 hCompletionPort, UInt32* pSizeOfArgument, UInt32* puiUserArg, OVERLAPPED** ppOverlapped, UInt32 uiMilliseconds);

        // Constants
        ///  SimTypeConst: This represents the Win32 Invalid Handle Value Macro
        private const UInt32 INVALID_HANDLE_VALUE = 0xffffffff;

        ///  SimTypeConst: This represents the Win32 INFINITE Macro
        private const UInt32 INIFINITE = 0xffffffff;

        ///  SimTypeConst: This tells the IOCP Function to shutdown
        private const Int32 SHUTDOWN_IOCPTHREAD = 0x7fffffff;



        // Delegate Function Types
        ///  DelType: This is the type of user function to be supplied for the thread pool
        public delegate void USER_FUNCTION(Int32 iValue);


        // Private Properties
        private UInt32 m_hHandle;
        ///  SimType: Contains the IO Completion Port Thread Pool handle for this instance
        private UInt32 GetHandle { get { return m_hHandle; } set { m_hHandle = value; } }

        private Int32 m_uiMaxConcurrency;
        ///  SimType: The maximum number of threads that may be running at the same time
        private Int32 GetMaxConcurrency { get { return m_uiMaxConcurrency; } set { m_uiMaxConcurrency = value; } }

        private Int32 m_iMinThreadsInPool;
        ///  SimType: The minimal number of threads the thread pool maintains
        private Int32 GetMinThreadsInPool { get { return m_iMinThreadsInPool; } set { m_iMinThreadsInPool = value; } }

        private Int32 m_iMaxThreadsInPool;
        ///  SimType: The maximum number of threads the thread pool maintains
        private Int32 GetMaxThreadsInPool { get { return m_iMaxThreadsInPool; } set { m_iMaxThreadsInPool = value; } }

        private Object m_pCriticalSection;
        ///  RefType: A serialization object to protect the class state
        private Object GetCriticalSection { get { return m_pCriticalSection; } set { m_pCriticalSection = value; } }

        private USER_FUNCTION m_pfnUserFunction;
        ///  DelType: A reference to a user specified function to be call by the thread pool
        private USER_FUNCTION GetUserFunction { get { return m_pfnUserFunction; } set { m_pfnUserFunction = value; } }

        private Boolean m_bDisposeFlag;
        ///  SimType: Flag to indicate if the class is disposing
        private Boolean IsDisposed { get { return m_bDisposeFlag; } set { m_bDisposeFlag = value; } }

        // Public Properties
        private Int32 m_iCurThreadsInPool;
        ///  SimType: The current number of threads in the thread pool
        public Int32 GetCurThreadsInPool { get { return m_iCurThreadsInPool; } set { m_iCurThreadsInPool = value; } }
        ///  SimType: Increment current number of threads in the thread pool
        private Int32 IncCurThreadsInPool() { return Interlocked.Increment(ref m_iCurThreadsInPool); }
        ///  SimType: Decrement current number of threads in the thread pool
        private Int32 DecCurThreadsInPool() { return Interlocked.Decrement(ref m_iCurThreadsInPool); }
        private Int32 m_iActThreadsInPool;
        ///  SimType: The current number of active threads in the thread pool
        public Int32 GetActThreadsInPool { get { return m_iActThreadsInPool; } set { m_iActThreadsInPool = value; } }
        ///  SimType: Increment current number of active threads in the thread pool
        private Int32 IncActThreadsInPool() { return Interlocked.Increment(ref m_iActThreadsInPool); }
        ///  SimType: Decrement current number of active threads in the thread pool
        private Int32 DecActThreadsInPool() { return Interlocked.Decrement(ref m_iActThreadsInPool); }
        private Int32 m_iCurWorkInPool;
        ///  SimType: The current number of Work posted in the thread pool
        public Int32 GetCurWorkInPool { get { return m_iCurWorkInPool; } set { m_iCurWorkInPool = value; } }
        ///  SimType: Increment current number of Work posted in the thread pool
        private Int32 IncCurWorkInPool() { return Interlocked.Increment(ref m_iCurWorkInPool); }
        ///  SimType: Decrement current number of Work posted in the thread pool
        private Int32 DecCurWorkInPool() { return Interlocked.Decrement(ref m_iCurWorkInPool); }



        // Constructor, Finalize, and Dispose
        //***********************************************
        ///  Constructor
        ///  SimType: Max number of running threads allowed
        ///  SimType: Min number of threads in the pool
        ///  SimType: Max number of threads in the pool
        ///  DelType: Reference to a function to call to perform work
        ///  Unhandled Exception
        public IOCPThreadPool(Int32 iMaxConcurrency, Int32 iMinThreadsInPool, Int32 iMaxThreadsInPool, USER_FUNCTION pfnUserFunction)
        {
            try
            {
                // Set initial class state
                GetMaxConcurrency = iMaxConcurrency;//系统允许的最大线程数，如果为0，则和内核数一致，一般都是0，
                GetMinThreadsInPool = iMinThreadsInPool;//最小线程数目
                GetMaxThreadsInPool = iMaxThreadsInPool;//最大线程数目，都是设定给的参数
                GetUserFunction = pfnUserFunction;//传递过来的回调函数，或者说事件处理函数
                // Init the thread counters
                GetCurThreadsInPool = 0;//当前线程池里的线程数
                GetActThreadsInPool = 0;//活动的线程数，正在工作的线程数
                GetCurWorkInPool = 0;//被投递的事件数目
                // Initialize the Monitor Object
                GetCriticalSection = new Object();//来包含类状态的对象？？？？
                // Set the disposing flag to false
                IsDisposed = false;//是否资源释放标志
                unsafe//c#调用外面dll的时候，需要用这个unsafe
                {
                    // Create an IO Completion Port for Thread Pool use
                    //步骤1：创建iocp端口,
                    /*
                     * 参数说明编辑
FileHandle是有效的文件句柄或INVALID_HANDLE_VALUE。
ExistingCompletionPort是已经存在的完成端口。如果为NULL，则为新建一个IOCP。
CompletionKey是传送给处理函数的参数。
NumberOfConcurrentThreads是有多少个线程在访问这个消息队列。当参数ExistingCompletionPort不为0的时候，系统忽略该参数，当该参数为0表示允许同时相等数目于处理器个数的线程访问该消息队列。
返回值编辑
返回一个IOCP的句柄。若为NULL则创建失败，不为NULL则创建成功。
                     *
                     * CreateIoCompletionPort的前三个参数只在把设备同Complete Port相关联时才有用。
此时我们只需传递INVALID_HANDLE_VALUE,NULL和0即可。
第四个参数告诉端口同时能运行的最多线程数，这里设置为0，表示默认为当前计算机的CPU数目。
                     */
                    GetHandle = CreateIoCompletionPort(INVALID_HANDLE_VALUE, 0, null, (UInt32)GetMaxConcurrency);
                }
                // Test to make sure the IO Completion Port was created
                if (GetHandle == 0)
                    throw new Exception("Unable To Create IO Completion Port");
                // Allocate and start the Minimum number of threads specified
                Int32 iStartingCount = GetCurThreadsInPool;//当前线程池里的线程数目
                ThreadStart tsThread = new ThreadStart(IOCPFunction);//// 摘要: 表示在 System.Threading.Thread 上执行的方法。public delegate void ThreadStart();
                /*
                 * 2 我们的ThreadFun线程函数执行一些初始化之后，将进入一个循环，该循环会在服务进程终止时才结束。
 在循环中，调用GetQueuedCompletionStatus，这样就把当前线程的ID放入一个等待线程队列中，I/O CP内核对象就总能知道哪个线程在等待处理完成的I/O请求。
 如果在IDLE_THREAD_TIMEOUT规定的时间内I/O CP上还没有出现一个Completion Packet，则转入下一次循环。在这里我们设置的IDLE_THREAD_TIMEOUT为1秒。
 当端口的I/O完成队列中出现一项时，完成端口就唤醒等待线程队列中的这个线程，该线程将得到完成的I/O项中的信息： 传输的字节数、完成键和OVERLAPPED结构的地址。
 在我们的程序中可以用智能指针或者BSTR或者int来接受这个OVERLAPPED结构的地址的值，从而得到消息；然后在这个线程中处理消息。
 GetQueuedCompletionStatus的第一个参数hCompletionPort指出了要监视哪一个端口，这里我们传送先前从CreateIoCompletionPort返回的端口句柄。
                 */
                for (Int32 iThread = 0; iThread < GetMinThreadsInPool; ++iThread)
                {
                    // Create a thread and start it
                    Thread thThread = new Thread(tsThread);
                    thThread.Name = "IOCP " + thThread.GetHashCode();
                    thThread.Start();
                    // Increment the thread pool count
                    IncCurThreadsInPool();//原子操作+1初始为0
                    /*
                     * long m_dwRefCount..
InterlockedIncrement(&m_dwRefCount)
对m_dwRefCount加1
在对m_dwRefCount访问的时候其他线程不能访问这个变量
InterlockedIncrement实现的是原子性的加减，什么是原子性的加减呢？

举例：如果一个变量long value = 0；
首先说一下正常情况下的加减操作，value+=1；
1.系统从value的空间取出值，并动态生成一个空间存储取出来的值；
2.将取出来的值和1做加法，并将和放入value的空间覆盖掉原值，操作结束；

如果此时有2个Thread，分别记作AThread，BThread
1.AThread将value从存储空间取出，为0；
2.BThread将value从存储空间取出，为0；
3.AThread将取出来的值和1做加法，并将和放入value的空间覆盖掉原值，加法结束，value = 1；
4.BThread将取出来的值和1做加法，并将和放入value的空间覆盖掉原值，加法结束，value = 1；
最后value应该是2，InterlockedIncrement保证一个线程访问变量时其他线程不能访问。

用于增减变量的并不是常用的Inc/Dec过程，而是用了InterlockedIncrement/InterlockedDecrement这一对过程，它们实现的功能完全一样，都是对变量加一或减一。
但它们有一个最大的区别，那就是InterlockedIncrement/InterlockedDecrement是线程安全的。
即它们在多线程下能保证执行结果正确，而Inc/Dec不能。
或者按操作系统理论中的术语来说，这是一对“原语”操作。
                     */
                }
            }
            catch
            {
                throw new Exception("Unhandled Exception");
            }
        }

        //***********************************************
        ///  Finalize called by the GC
        ~IOCPThreadPool()
        {
            /*
             * 这个类结束，应该也意味着是主线程了，所以只有主线程访问？，既然是主线程，为什么还要加标志位呢？？？？
             */
            if (!IsDisposed)//还没有释放资源，则释放，这个应该也是原子操作对isdisposeD吧
                Dispose();
        }

        //**********************************************
        ///  Called when the object will be shutdown.  This
        ///           function will wait for all of the work to be completed
        ///           inside the queue before completing
        public void Dispose()
        {
            try
            {
                // Flag that we are disposing this object
                IsDisposed = true;
                // Get the current number of threads in the pool
                Int32 iCurThreadsInPool = GetCurThreadsInPool;//现在生成的线程数，用原子操作实现的
                // Shutdown all thread in the pool
                for (Int32 iThread = 0; iThread < iCurThreadsInPool; ++iThread)
                {
                    unsafe
                    {
                        bool bret = PostQueuedCompletionStatus(GetHandle, 4, (UInt32*)SHUTDOWN_IOCPTHREAD, null);
                        /*
                         * PostQueuedCompletionStatus函数，向每个工作者线程都发送—个特殊的完成数据包。该函数会指示每个线程都“立即结束并退出”.
                         * 下面是PostQueuedCompletionStatus函数的定义：
[cpp] view plain copy
BOOL PostQueuedCompletionStatus(
    HANDLE CompletlonPort,
    DW0RD dwNumberOfBytesTrlansferred,
    DWORD dwCompletlonKey,
LPOVERLAPPED lpoverlapped,
);


       其中，CompletionPort参数指定想向其发送一个完成数据包的完成端口对象。而就dwNumberOfBytesTransferred,dwCompletionKey和lpOverlapped
                         * 这三个参数来说.每—个都允许我们指定—个值,直接传递给GetQueuedCompletionStatus函数中对应的参数。这样—来。
                         * —个工作者线程收到传递过来的三个GetQueuedCompletionStatus函数参数后，便可根据由这三个参数的某一个设置的特殊值，
                         * 决定何时应该退出。例如,可用dwCompletionPort参数传递0值,而—个工作者线程会将其解释成中止指令。一旦所有工作者线程都已关闭,
                         * 便可使用CloseHandle函数,关闭完成端口。最终安全退出程序。
        PostQueuedCompletionStatus函数提供了一种方式来与线程池中的所有线程进行通信。如，当用户终止服务应用程序时，我们想要所有线程都完全利索地退出。
                         * 但是如果各线程还在等待完成端口而又没有已完成的I/O 请求，那么它们将无法被唤醒。
       通过为线程池中的每个线程都调用一次PostQueuedCompletionStatus，我们可以将它们都唤醒。每个线程会对GetQueuedCompletionStatus的返回值进行检查，
                         * 如果发现应用程序正在终止，那么它们就可以进行清理工作并正常地退出。
                         */
                    }
                }
                // Wait here until all the threads are gone
                while (GetCurThreadsInPool != 0) Thread.Sleep(100);
                unsafe
                {
                    // Close the IOCP Handle
                    CloseHandle(GetHandle);//便可使用CloseHandle函数,关闭完成端口。最终安全退出程序。
                }
            }
            catch
            {
            }
        }

        // Private Methods
        //*******************************************
        ///  IOCP Worker Function that calls the specified user function
        private void IOCPFunction()
        {
            UInt32 uiNumberOfBytes;
            Int32 iValue;
            try
            {
                while (true)
                {
                    unsafe
                    {
                        OVERLAPPED* pOv;
                        // Wait for an event
                        /*
                         * BOOL GetQueuedCompletionStatus(
HANDLE CompletionPort,
LPDWORD lpNumberOfBytes,
PULONG_PTR lpCompletionKey,
LPOVERLAPPED *lpOverlapped,
DWORD dwMilliseconds)；
调用参数：
CompletionPort：指定的IOCP，该值由CreateIoCompletionPort函数创建。
lpnumberofbytes：一次完成后的I/O操作所传送数据的字节数。
lpcompletionkey：当文件I/O操作完成后，用于存放与之关联的CK。
lpoverlapped：为调用IOCP机制所引用的OVERLAPPED结构。
dwmilliseconds：用于指定调用者等待CP的时间。
返回值：
调用成功，则返回非零数值，相关数据存于lpNumberOfBytes、lpCompletionKey、lpoverlapped变量中。失败则返回零值。
                         */
                        GetQueuedCompletionStatus(GetHandle, &uiNumberOfBytes, (UInt32*)&iValue, &pOv, INIFINITE);
                    }
                    // Decrement the number of events in queue
                    DecCurWorkInPool();//原子操作，减少一个io里面的任务数目
                    // Was this thread told to shutdown
                    if (iValue == SHUTDOWN_IOCPTHREAD)//关闭标志位，post传递一个io完成数据，这里读到，知道该结束了，提前约定
                        break;
                    // Increment the number of active threads
                    IncActThreadsInPool();//这个线程读到任务开始工作，增加活动线程数
                    try
                    {
                        // Call the user function
                        GetUserFunction(iValue);
                    }
                    catch
                    {
                    }
                    // Get a lock
                    Monitor.Enter(GetCriticalSection);
                    try
                    {
                        // If we have less than max threads currently in the pool
                        //当前已经生成了符合设定最小线程数目的线程，如果当前每到最大线程数，继续创建
                        if (GetCurThreadsInPool < GetMaxThreadsInPool)
                        {
                            // Should we add a new thread to the pool
                            //所有线程都已在工作
                            if (GetActThreadsInPool == GetCurThreadsInPool)
                            {
                                if (IsDisposed == false)//没有进行资源释放，标志位的作用在这里
                                {
                                    // Create a thread and start it
                                    ThreadStart tsThread = new ThreadStart(IOCPFunction);
                                    Thread thThread = new Thread(tsThread);
                                    thThread.Name = "IOCP " + thThread.GetHashCode();
                                    thThread.Start();
                                    // Increment the thread pool count
                                    IncCurThreadsInPool();//增加当前的活动总数，子线程还可以继续生成线程？？？？
                                }
                            }
                        }
                    }
                    catch
                    {
                    }
                    // Relase the lock
                    Monitor.Exit(GetCriticalSection);//这个是为了保证，比如当前进程为5都在工作了，最大上限设定10，
                    //发现都在工作只增加1个额外空闲线程，如果不用 Monitor 是不是会都发现不够一下增加太多，最后可能当前线程数超过10
                    // Increment the number of active threads
                    DecActThreadsInPool();//干活结束，减少忙碌状态的线程
                }
            }
            catch
            {
            }
            // Decrement the thread pool count
            DecCurThreadsInPool();//线程退出，减少当前进程数
        }

        // Public Methods
        //******************************************
        ///  IOCP Worker Function that calls the specified user function
        ///  SimType: A value to be passed with the event
        ///  Unhandled Exception
        public void PostEvent(Int32 iValue)
        {
            try
            {
                // Only add work if we are not disposing
                if (IsDisposed == false)
                {
                    unsafe
                    {
                        // Post an event into the IOCP Thread Pool
                        PostQueuedCompletionStatus(GetHandle, 4, (UInt32*)iValue, null);
                    }
                    // Increment the number of item of work
                    IncCurWorkInPool();
                    // Get a lock
                    Monitor.Enter(GetCriticalSection);
                    try
                    {
                        // If we have less than max threads currently in the pool
                        if (GetCurThreadsInPool < GetMaxThreadsInPool)
                        {
                            // Should we add a new thread to the pool
                            if (GetActThreadsInPool == GetCurThreadsInPool)
                            {
                                if (IsDisposed == false)
                                {
                                    // Create a thread and start it
                                    ThreadStart tsThread = new ThreadStart(IOCPFunction);
                                    Thread thThread = new Thread(tsThread);
                                    thThread.Name = "IOCP " + thThread.GetHashCode();
                                    thThread.Start();
                                    // Increment the thread pool count
                                    IncCurThreadsInPool();
                                }
                            }
                        }
                    }
                    catch
                    {
                    }
                    // Release the lock
                    Monitor.Exit(GetCriticalSection);
                }
            }
            catch (Exception e)
            {
                throw e;
            }
            catch
            {
                throw new Exception("Unhandled Exception");
            }
        }
        //*****************************************
        ///  IOCP Worker Function that calls the specified user function
        ///  Unhandled Exception
        public void PostEvent()
        {
            try
            {
                // Only add work if we are not disposing
                if (IsDisposed == false)
                {
                    unsafe
                    {
                        // Post an event into the IOCP Thread Pool
                        PostQueuedCompletionStatus(GetHandle, 0, null, null);
                    }
                    // Increment the number of item of work
                    IncCurWorkInPool();
                    // Get a lock
                    Monitor.Enter(GetCriticalSection);
                    try
                    {
                        // If we have less than max threads currently in the pool
                        if (GetCurThreadsInPool < GetMaxThreadsInPool)
                        {
                            // Should we add a new thread to the pool
                            if (GetActThreadsInPool == GetCurThreadsInPool)
                            {
                                if (IsDisposed == false)
                                {
                                    // Create a thread and start it
                                    ThreadStart tsThread = new ThreadStart(IOCPFunction);
                                    Thread thThread = new Thread(tsThread);
                                    thThread.Name = "IOCP " + thThread.GetHashCode();
                                    thThread.Start();
                                    // Increment the thread pool count
                                    IncCurThreadsInPool();
                                }
                            }
                        }
                    }
                    catch
                    {
                    }
                    // Release the lock
                    Monitor.Exit(GetCriticalSection);
                }
            }
            catch (Exception e)
            {
                throw e;
            }
            catch
            {
                throw new Exception("Unhandled Exception");
            }
        }
    }
}