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);
}
}
}
}
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");
}
}
}
}