日期：2005-04-13
从William Kennedy那里整理过来的,不同之处在于他自己定义了一个Overlapped，而我们这里直接使用
System.Threading.NativeOverlapped：。
附一段我以前的Win32下的IOCP文档，如果您了解IOCP也可以直接跳过看后面的C#测试示范：
我们采用的是I/O Complete Port（以下简称IOCP）处理机制。
简单的讲，当服务应用程序初始化时，它应该先创建一个I/O CP。我们在请求到来后，将得到的数据打包用PostQueuedCompletionStatus发送到IOCP中。这时需要创建一些个线程(7个线程/每CPU，再多就没有意义了)来处理发送到IOCP端口的消息。实现步骤大致如下：
1 先在主线程中调用CreateIoCompletionPort创建IOCP。
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。
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。
需要注意的是：
第一， 线程池的数目是有限制的，和CPU数目有关系。
第二， IOCP是一种较为完美的睡眠/唤醒 线程机制；线程当前没有任务要处理时，就进入睡眠状态，从而不占用CPU资源，直到被内核唤醒；
第三， 最近一次刚执行完的线程，下次任务来的时候还会唤醒它；所以有可能比较少被调用的线程以后被调用的几率也少。
测试代码：
using System;
using System.Threading; // Included for the Thread.Sleep call
using Continuum.Threading;
using System.Runtime.InteropServices;
namespace IOCPDemo
{
//=============================================================================
/// <summary> Sample class for the threading class </summary>
public class UtilThreadingSample
{
//*****************************************************************************
/// <summary> Test Method </summary>
static void Main()
{
// Create the MSSQL IOCP Thread Pool
IOCPThreadPool pThreadPool = new IOCPThreadPool(0, 10, 20, new IOCPThreadPool.USER_FUNCTION(IOCPThreadFunction));
//for(int i =1;i<10000;i++)
{
pThreadPool.PostEvent(1234);
}
Thread.Sleep(100);
pThreadPool.Dispose();
}
//********************************************************************
/// <summary> Function to be called by the IOCP thread pool. Called when
/// a command is posted for processing by the SocketManager </summary>
/// <param name="iValue"> The value provided by the thread posting the event </param>
static public void IOCPThreadFunction(int iValue)
{
try
{
Console.WriteLine("Value: {0}", iValue.ToString());
Thread.Sleep(3000);
}
catch (Exception pException)
{
Console.WriteLine(pException.Message);
}
}
}
}
类代码：
using System;
using System.Threading;
using System.Runtime.InteropServices;
namespace IOCPThreading
{
[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Auto)]
public sealed class IOCPThreadPool
{
[DllImport("Kernel32", CharSet=CharSet.Auto)]
private unsafe static extern UInt32 CreateIoCompletionPort(UInt32 hFile, UInt32 hExistingCompletionPort, UInt32* puiCompletionKey, UInt32 uiNumberOfConcurrentThreads);
[DllImport("Kernel32", CharSet=CharSet.Auto)]
private unsafe static extern Boolean CloseHandle(UInt32 hObject);
[DllImport("Kernel32", CharSet=CharSet.Auto)]
private unsafe static extern Boolean PostQueuedCompletionStatus(UInt32 hCompletionPort, UInt32 uiSizeOfArgument, UInt32* puiUserArg, System.Threading.NativeOverlapped* pOverlapped);
[DllImport("Kernel32", CharSet=CharSet.Auto)]
private unsafe static extern Boolean GetQueuedCompletionStatus(UInt32 hCompletionPort, UInt32* pSizeOfArgument, UInt32* puiUserArg, System.Threading.NativeOverlapped** ppOverlapped, UInt32 uiMilliseconds);
private const UInt32 INVALID_HANDLE_VALUE = 0xffffffff;
private const UInt32 INIFINITE = 0xffffffff;
private const Int32 SHUTDOWN_IOCPTHREAD = 0x7fffffff;
public delegate void USER_FUNCTION(int iValue);
private UInt32 m_hHandle;
private UInt32 GetHandle { get { return m_hHandle; } set { m_hHandle = value; } }
private Int32 m_uiMaxConcurrency;
private Int32 GetMaxConcurrency { get { return m_uiMaxConcurrency; } set { m_uiMaxConcurrency = value; } }
private Int32 m_iMinThreadsInPool;
private Int32 GetMinThreadsInPool { get { return m_iMinThreadsInPool; } set { m_iMinThreadsInPool = value; } }
private Int32 m_iMaxThreadsInPool;
private Int32 GetMaxThreadsInPool { get { return m_iMaxThreadsInPool; } set { m_iMaxThreadsInPool = value; } }
private Object m_pCriticalSection;
private Object GetCriticalSection { get { return m_pCriticalSection; } set { m_pCriticalSection = value; } }
private USER_FUNCTION m_pfnUserFunction;
private USER_FUNCTION GetUserFunction { get { return m_pfnUserFunction; } set { m_pfnUserFunction = value; } }
private Boolean m_bDisposeFlag;
/// <summary> SimType: Flag to indicate if the class is disposing </summary>
private Boolean IsDisposed { get { return m_bDisposeFlag; } set { m_bDisposeFlag = value; } }
private Int32 m_iCurThreadsInPool;
/// <summary> SimType: The current number of threads in the thread pool </summary>
public Int32 GetCurThreadsInPool { get { return m_iCurThreadsInPool; } set { m_iCurThreadsInPool = value; } }
/// <summary> SimType: Increment current number of threads in the thread pool </summary>
private Int32 IncCurThreadsInPool() { return Interlocked.Increment(ref m_iCurThreadsInPool); }
/// <summary> SimType: Decrement current number of threads in the thread pool </summary>
private Int32 DecCurThreadsInPool() { return Interlocked.Decrement(ref m_iCurThreadsInPool); }
private Int32 m_iActThreadsInPool;
/// <summary> SimType: The current number of active threads in the thread pool </summary>
public Int32 GetActThreadsInPool { get { return m_iActThreadsInPool; } set { m_iActThreadsInPool = value; } }
/// <summary> SimType: Increment current number of active threads in the thread pool </summary>
private Int32 IncActThreadsInPool() { return Interlocked.Increment(ref m_iActThreadsInPool); }
/// <summary> SimType: Decrement current number of active threads in the thread pool </summary>
private Int32 DecActThreadsInPool() { return Interlocked.Decrement(ref m_iActThreadsInPool); }
private Int32 m_iCurWorkInPool;
/// <summary> SimType: The current number of Work posted in the thread pool </summary>
public Int32 GetCurWorkInPool { get { return m_iCurWorkInPool; } set { m_iCurWorkInPool = value; } }
/// <summary> SimType: Increment current number of Work posted in the thread pool </summary>
private Int32 IncCurWorkInPool() { return Interlocked.Increment(ref m_iCurWorkInPool); }
/// <summary> SimType: Decrement current number of Work posted in the thread pool </summary>
private Int32 DecCurWorkInPool() { return Interlocked.Decrement(ref m_iCurWorkInPool); }
public IOCPThreadPool(Int32 iMaxConcurrency, Int32 iMinThreadsInPool, Int32 iMaxThreadsInPool, USER_FUNCTION pfnUserFunction)
{
try
{
// Set initial class state
GetMaxConcurrency = iMaxConcurrency;
GetMinThreadsInPool = iMinThreadsInPool;
GetMaxThreadsInPool = iMaxThreadsInPool;
GetUserFunction = pfnUserFunction;
// Init the thread counters
GetCurThreadsInPool = 0;
GetActThreadsInPool = 0;
GetCurWorkInPool = 0;
// Initialize the Monitor Object
GetCriticalSection = new Object();
// Set the disposing flag to false
IsDisposed = false;
unsafe
{
// Create an IO Completion Port for Thread Pool use
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;
ThreadStart tsThread = new ThreadStart(IOCPFunction);
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();
}
}
catch
{
throw new Exception("Unhandled Exception");
}
}
~IOCPThreadPool()
{
if (!IsDisposed)
Dispose();
}
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;
// Shutdown all thread in the pool
for (Int32 iThread = 0; iThread < iCurThreadsInPool; ++iThread)
{
unsafe
{
bool bret = PostQueuedCompletionStatus(GetHandle, 4, (UInt32*) SHUTDOWN_IOCPTHREAD, null);
}
}
// Wait here until all the threads are gone
while (GetCurThreadsInPool != 0) Thread.Sleep(100);
unsafe
{
// Close the IOCP Handle
CloseHandle(GetHandle);
}
}
catch
{
}
}
private void IOCPFunction()
{
UInt32 uiNumberOfBytes;
Int32 iValue;
try
{
while (true)
{
unsafe
{
System.Threading.NativeOverlapped* pOv;
// Wait for an event
GetQueuedCompletionStatus(GetHandle, &uiNumberOfBytes, (UInt32*) &iValue, &pOv, INIFINITE);
}
// Decrement the number of events in queue
DecCurWorkInPool();
// Was this thread told to shutdown
if (iValue == SHUTDOWN_IOCPTHREAD)
break;
// Increment the number of active threads
IncActThreadsInPool();
try
{
// Call the user function
GetUserFunction(iValue);
}
catch(Exception ex)
{
throw ex;
}
// 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
{
}
// Relase the lock
Monitor.Exit(GetCriticalSection);
// Increment the number of active threads
DecActThreadsInPool();
}
}
catch(Exception ex)
{
string str=ex.Message;
}
// Decrement the thread pool count
DecCurThreadsInPool();
}
//public void PostEvent(Int32 iValue
public void PostEvent(int 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");
}
}
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
{
throw new Exception("Unhandled Exception");
}
}
}
}