线程池
Windows API的线程池函数 > 示例

示例程序1如下：
#include <windows.h>
#include <tchar.h>
#include <stdio.h>

//
// Thread pool wait callback function template
//
VOID CALLBACK MyWaitCallback(PTP_CALLBACK_INSTANCE Instance, PVOID Parameter, PTP_WAIT Wait, TP_WAIT_RESULT WaitResult)
{
	// Instance, Parameter, Wait, and WaitResult not used in this example.
	UNREFERENCED_PARAMETER(Instance); 	UNREFERENCED_PARAMETER(Parameter);	UNREFERENCED_PARAMETER(Wait); 	UNREFERENCED_PARAMETER(WaitResult);

	// Do something when the wait is over.
	_tprintf(_T("MyWaitCallback: wait is over.\n"));
}


//
// Thread pool timer callback function template
//
VOID CALLBACK MyTimerCallback(PTP_CALLBACK_INSTANCE Instance, PVOID Parameter, PTP_TIMER Timer)
{
	// Instance, Parameter, and Timer not used in this example.
	UNREFERENCED_PARAMETER(Instance); UNREFERENCED_PARAMETER(Parameter); UNREFERENCED_PARAMETER(Timer);

	// Do something when the timer fires.
	_tprintf(_T("MyTimerCallback: timer has fired.\n"));
}


//
// This is the thread pool work callback function.
//
VOID CALLBACK MyWorkCallback( PTP_CALLBACK_INSTANCE Instance, PVOID Parameter, PTP_WORK Work)
{
	// Instance, Parameter, and Work not used in this example.
	UNREFERENCED_PARAMETER(Instance);UNREFERENCED_PARAMETER(Parameter);UNREFERENCED_PARAMETER(Work);

	// Do something when the work callback is invoked.
	_tprintf(_T("MyWorkCallback: Task performed.\n"));
}

 

int main(void)
{
	PTP_WAIT Wait = NULL;
	PTP_WAIT_CALLBACK waitcallback = MyWaitCallback;
	HANDLE hEvent = NULL;
	UINT i = 0;
	UINT rollback = 0;

	// Create an auto-reset event and initialized as nonsignaled.
	hEvent = CreateEvent(NULL, FALSE, FALSE, NULL);

	if (NULL == hEvent) {
		// Error Handling
		return 0;
	}

	rollback = 1; // CreateEvent succeeded

	Wait = CreateThreadpoolWait(waitcallback,
		NULL,     // 回调函数的输入参数
		NULL);    // 使用缺省的回调环境

	if (NULL == Wait) {
		_tprintf(_T("CreateThreadpoolWait failed. LastError: %u\n"),GetLastError());
		goto new_wait_cleanup;
	}

	rollback = 2; // CreateThreadpoolWait succeeded

				  // must re-register the event with the wait object before signaling it each time to trigger the wait callback
				  // each time before signaling the event to trigger the wait callback.
	for (i = 0; i < 5; i++) {
		SetThreadpoolWait(Wait, //线程池等待对象
			hEvent,             //内核等待对象
			NULL);              //超时设定

		SetEvent(hEvent);       //触发内核等待对象

		// Delay for the waiter thread to act if necessary.
		Sleep(500);

		// Block here until the callback function is done executing.
		WaitForThreadpoolWaitCallbacks(Wait, FALSE);
	}

new_wait_cleanup:
	switch (rollback) {
	case 2:
		// Unregister the wait by setting the event to NULL.
		SetThreadpoolWait(Wait, NULL, NULL); //the wait object will cease to queue new callbacks (but callbacks already queued will still occur

		// Close the wait.
		CloseThreadpoolWait(Wait);

	case 1:
		// Close the event.
		CloseHandle(hEvent);

	default:
		break;
	}
	

	BOOL bRet = FALSE;
	PTP_WORK work = NULL;
	PTP_TIMER timer = NULL;
	PTP_POOL pool = NULL;
	PTP_WORK_CALLBACK workcallback = MyWorkCallback;
	PTP_TIMER_CALLBACK timercallback = MyTimerCallback;
	TP_CALLBACK_ENVIRON CallBackEnviron;
	PTP_CLEANUP_GROUP cleanupgroup = NULL;
	FILETIME FileDueTime;
	ULARGE_INTEGER ulDueTime;
	rollback = 0;

	InitializeThreadpoolEnvironment(&CallBackEnviron); //不使用缺省的线程池与缺省的回调环境

	// Create a custom, dedicated thread pool.
	pool = CreateThreadpool(NULL);

	if (NULL == pool) {
		_tprintf(_T("CreateThreadpool failed. LastError: %u\n"), GetLastError());
		goto main_cleanup;
	}

	rollback = 1; // pool creation succeeded

				  // The thread pool is made persistent simply by setting both the minimum and maximum threads to 1.
	SetThreadpoolThreadMaximum(pool, 1);
	bRet = SetThreadpoolThreadMinimum(pool, 1);

	if (FALSE == bRet) {
		_tprintf(_T("SetThreadpoolThreadMinimum failed. LastError: %u\n"),GetLastError());
		goto main_cleanup;
	}

	// Create a cleanup group for this thread pool.
	cleanupgroup = CreateThreadpoolCleanupGroup();

	if (NULL == cleanupgroup) {
		_tprintf(_T("CreateThreadpoolCleanupGroup failed. LastError: %u\n"),GetLastError());
		goto main_cleanup;
	}

	rollback = 2;  // Cleanup group creation succeeded

				   // Associate the callback environment with our thread pool.
	SetThreadpoolCallbackPool(&CallBackEnviron, pool);

	// Associate the cleanup group with our thread pool.
	// Objects created with the same callback environment as the cleanup group become members of the cleanup group.
	SetThreadpoolCallbackCleanupGroup(&CallBackEnviron, //回调环境
		cleanupgroup,                                   //Cleanup Group
		NULL);                                          //Cleanup Group的回调函数，当释放其所包含的对象之前先调用该回调函数


	// Create work with the callback environment.
	work = CreateThreadpoolWork(workcallback, //回调函数
		NULL,                                 //回调函数的输入参数
		&CallBackEnviron);                    //回调环境

	if (NULL == work) {
		_tprintf(_T("CreateThreadpoolWork failed. LastError: %u\n"), GetLastError());
		goto main_cleanup;
	}

	rollback = 3;  // Creation of work succeeded


				   // Submit the work to the pool. Because this was a pre-allocated work item (using CreateThreadpoolWork), it is guaranteed to execute.
	SubmitThreadpoolWork(work);	

	// Create a timer with the same callback environment.
	timer = CreateThreadpoolTimer(timercallback, //回调函数
		NULL,                                    //回调函数的输入参数
		&CallBackEnviron);                       //回调环境


	if (NULL == timer) {
		_tprintf(_T("CreateThreadpoolTimer failed. LastError: %u\n"), GetLastError());
		goto main_cleanup;
	}

	rollback = 4;  // Timer creation succeeded

				   // Set the timer to fire in one second.
	ulDueTime.QuadPart = (ULONGLONG)-(1 * 10 * 1000 * 1000);
	FileDueTime.dwHighDateTime = ulDueTime.HighPart;
	FileDueTime.dwLowDateTime = ulDueTime.LowPart;

	SetThreadpoolTimer(timer, //线程池定时器对象
		&FileDueTime,         //到期时间
		0,                    //周期时期，为0则表示一次性定时器
		0);                   //操作系统调用回调函数的最大延迟时间


	// Delay for the timer to be fired
	Sleep(1500);


	// Wait for all callbacks to finish.
	// CloseThreadpoolCleanupGroupMembers also releases objects that are members of the cleanup group, 
	// so it is not necessary to call close functions on individual objects after calling CloseThreadpoolCleanupGroupMembers.
	CloseThreadpoolCleanupGroupMembers(cleanupgroup, //Cleanup Group
		FALSE,                                       //为真则取消还未开始执行的pending的回调函数
		NULL);                                       //CleanupGroup回调函数的输入参数

	// Already cleaned up the work item with the
	// CloseThreadpoolCleanupGroupMembers, so set rollback to 2.
	rollback = 2;
	goto main_cleanup;

main_cleanup:
	// Clean up any individual pieces manually
	// Notice the fall-through structure of the switch.
	// Clean up in reverse order.

	switch (rollback) {
	case 4:
	case 3:
		// Clean up the cleanup group members.
		CloseThreadpoolCleanupGroupMembers(cleanupgroup,FALSE, NULL);
	case 2:
		// Clean up the cleanup group.
		CloseThreadpoolCleanupGroup(cleanupgroup);
	case 1:
		// Clean up the pool.
		CloseThreadpool(pool);
	default:
		break;
	}

	return 0;
}
关于IO线程池的一个示例：
#include <windows.h>
#include <tchar.h>
#include <strsafe.h>
#include <locale.h> 
#include <iostream>
#include <limits>
 

void PressEnterToContinue()
{
	std::cout << "Press ENTER to continue... " << std::flush;
	std::cin.ignore( (std::numeric_limits<std::streamsize>::max)( ), '\n');
}
//////////////////////////////////////////////////////////////////////////
#define  QMLX_ALLOC(sz)    HeapAlloc(GetProcessHeap(),0,sz)   
#define  QMLX_CALLOC(sz)   HeapAlloc(GetProcessHeap(),HEAP_ZERO_MEMORY,sz)
#define  QMLX_SAFEFREE(p)  if(NULL != p){HeapFree(GetProcessHeap(),0,p);p=NULL;}

#define  QMLX_ASSERT(s)    if(!(s)){DebugBreak();}
#define  QMLX_BEGINTHREAD(Fun,Param)  CreateThread(NULL,0,\
                                     (LPTHREAD_START_ROUTINE)Fun,Param,0,NULL);

//////////////////////////////////////////////////////////////////////////
#define MAXWRITEPERTHREAD 2  //每个线程最大写入次数
#define MAXWRITETHREAD    2   //写入线程的数量

#define OP_READ    0x01  //读操作
#define OP_WRITE   0x02  //写操作
//#pragma pack(show)
//单IO数据
typedef struct __declspec(align(16)) _tagPerIoData {
	OVERLAPPED  m_ol;
	HANDLE      m_hFile;   //操作的文件句柄
	DWORD       m_dwOp;    //操作类型，OP_READ或OP_WRITE
	LPVOID      m_pData;   //操作的数据
	UINT        m_nLen;    //操作的数据长度
	DWORD       m_dwWrite; //写入的字节数 
	DWORD       m_dwTimestamp; //起始操作的时间戳
}PER_IO_DATA, *PPER_IO_DATA;

//IOCP线程池回调函数，实际就是完成通知的响应函数
VOID CALLBACK IOCPCallback(PTP_CALLBACK_INSTANCE pInstance, PVOID pvContext, PVOID pOverlapped,
	ULONG IoResult, ULONG_PTR NumberOfBytesTransferred, PTP_IO pio);

//写文件的线程
DWORD WINAPI WriteThread(LPVOID lpParam);

//当前操作的文件对象的指针
LARGE_INTEGER  g_liFilePointer = { 0 };

//IOCP线程池
PTP_IO  g_pThreadpoolIo = NULL;

//////////////////////////////////////////////////////////////////////////
//获取可模块的路径名（路径后含‘\’)
VOID  GetAppPath(LPTSTR pszBuffer) {
	DWORD dwLen = 0;
	if (0 == (dwLen = GetModuleFileName(NULL, pszBuffer, MAX_PATH)))
		return;

	for (DWORD i = dwLen; i > 0; i--) {
		if ('\\' == pszBuffer[i]) {
			pszBuffer[i + 1] = '\0';
			break;
		}
	}
}

int _tmain() {
	 
	_tsetlocale(LC_ALL, _T("chs"));
	TCHAR pFileName[MAX_PATH] = {};
	GetAppPath(pFileName);
	StringCchCat(pFileName, MAX_PATH, _T("NewIOCPFile.txt"));

	HANDLE ahWThread[MAXWRITETHREAD] = {};
	DWORD dwWrited = 0;

	//创建文件
	HANDLE hTxtFile = CreateFile(pFileName, GENERIC_WRITE, 0, NULL,
		CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, NULL);
	if (INVALID_HANDLE_VALUE == hTxtFile) {
		_tprintf(_T("CreateFile(%s)失败，错误码：%u\n"), GetLastError());
		_tsystem(_T("PAUSE"));
		return 0;
	}

	//初始化线程池回调环境
	TP_CALLBACK_ENVIRON poolEnv = {};
	InitializeThreadpoolEnvironment(&poolEnv);

	//创建IOCP线程池
	g_pThreadpoolIo = CreateThreadpoolIo(hTxtFile, (PTP_WIN32_IO_CALLBACK)IOCPCallback, hTxtFile, &poolEnv);

	//启动IOCP线程池
	StartThreadpoolIo(g_pThreadpoolIo);

	//写入UNICODE文件的前缀码，以便正确打开
	PER_IO_DATA* pIo = (PPER_IO_DATA)QMLX_CALLOC(sizeof(PER_IO_DATA));
	QMLX_ASSERT(pIo != NULL);

	pIo->m_dwOp = OP_WRITE;
	pIo->m_hFile = hTxtFile;
	pIo->m_pData = QMLX_CALLOC(sizeof(WORD));
	QMLX_ASSERT(pIo->m_pData != NULL);
	*((WORD*)pIo->m_pData) = MAKEWORD(0xFF, 0xFE);
	pIo->m_nLen = sizeof(WORD);

	//偏移文件指针
	pIo->m_ol.Offset = g_liFilePointer.LowPart;
	pIo->m_ol.OffsetHigh = g_liFilePointer.HighPart;
	g_liFilePointer.QuadPart += pIo->m_nLen;
	pIo->m_dwTimestamp = GetTickCount(); //记录时间戳

	WriteFile(hTxtFile, pIo->m_pData, pIo->m_nLen,
		&pIo->m_dwWrite, (LPOVERLAPPED)&pIo->m_ol);

	//等待IOCP线程池完成操作
	WaitForThreadpoolIoCallbacks(g_pThreadpoolIo, FALSE);

	//启动写入线程进行日志写入操作
	for (int i = 0; i < MAXWRITETHREAD; i++) {
		ahWThread[i] = QMLX_BEGINTHREAD(WriteThread, hTxtFile);
	}

	//让主线程等待这些写入线程结束
	WaitForMultipleObjects(MAXWRITETHREAD, ahWThread, TRUE, INFINITE);

	for (int i = 0; i < MAXWRITETHREAD; i++) {
		CloseHandle(ahWThread[i]);
	}

	//关闭IOCP线程池
	CloseThreadpoolIo(g_pThreadpoolIo);

	//关闭日志文件
	if (INVALID_HANDLE_VALUE != hTxtFile) {
		CloseHandle(hTxtFile);
		hTxtFile = INVALID_HANDLE_VALUE;
	}

	_tsystem(_T("PAUSE"));

	return 0;
}

//IOCP线程池回调函数，实际就是完成通知的响应函数
VOID CALLBACK IOCPCallback(PTP_CALLBACK_INSTANCE pInstance, PVOID pvContext, PVOID pOverlapped,
	ULONG IoResult, ULONG_PTR NumberOfBytesTransferred, PTP_IO pio)
{ 
 
	if (NO_ERROR != IoResult) {
		_tprintf(_T("I/O操作出错，错误码：%u\n"), IoResult);
		return;
	}

	PPER_IO_DATA pIo = CONTAINING_RECORD((LPOVERLAPPED)pOverlapped, PER_IO_DATA, m_ol);
	DWORD dwCurTimestamp = GetTickCount();

	switch (pIo->m_dwOp)
	{
	case OP_WRITE://写操作结束
	{//写入操作结束
		_tprintf(_T("线程[0x%x]得到IO完成通知,完成操作(%s),缓冲(0x%08x)长度(%ubytes),写入时间戳(%u)当前时间戳(%u)时差(%u)\n"),
			GetCurrentThreadId(), OP_WRITE == pIo->m_dwOp ? _T("Write") : _T("Read"),
			pIo->m_pData, pIo->m_nLen, pIo->m_dwTimestamp, dwCurTimestamp, dwCurTimestamp - pIo->m_dwTimestamp);

		QMLX_SAFEFREE(pIo->m_pData);
		QMLX_SAFEFREE(pIo);
	}
	break;

	case OP_READ: //读操作结束
		break;

	default:
		break;
	}
}

//写文件的线程
#define MAX_LOGLEN 256
DWORD WINAPI WriteThread(LPVOID lpParam)
{
	TCHAR pTxtContext[MAX_LOGLEN] = {};
	PPER_IO_DATA pIo = NULL;
	size_t szLen = 0;
	LPTSTR pWriteText = NULL;

	StringCchPrintf(pTxtContext, MAX_LOGLEN, _T("这是一条模拟的日志记录,由线程[0x%x]写入\r\n"),
		GetCurrentThreadId());
	StringCchLength(pTxtContext, MAX_LOGLEN, &szLen);

	szLen += 1;

	int i = 0;
	for (; i < MAXWRITEPERTHREAD; i++) {
		pWriteText = (LPTSTR)QMLX_CALLOC(szLen * sizeof(TCHAR));
		QMLX_ASSERT(NULL != pWriteText);
			StringCchCopy(pWriteText, szLen, pTxtContext);

		//为每个操作申请一个“单IO数据”结构体
		pIo = (PPER_IO_DATA)QMLX_CALLOC(sizeof(PER_IO_DATA));
		QMLX_ASSERT(pIo != NULL);

		pIo->m_dwOp = OP_WRITE;
		pIo->m_hFile = (HANDLE)lpParam;
		pIo->m_pData = pWriteText;
		pIo->m_nLen = (szLen - 1) * sizeof(TCHAR);

		//这里使用原子操作同步文件指针，写入不会相互覆盖
		//这个地方体现了lock-free算法的精髓,使用了基本的CAS操作控制文件指针
		//比传统的使用关键代码段并等待的方法,这里用的方法要轻巧的多,付出的代价也小
		*((LONGLONG*)&pIo->m_ol.Pointer) = InterlockedCompareExchange64(&g_liFilePointer.QuadPart,
			g_liFilePointer.QuadPart + pIo->m_nLen, g_liFilePointer.QuadPart);
		pIo->m_dwTimestamp = GetTickCount(); //记录时间戳

		StartThreadpoolIo(g_pThreadpoolIo);

		//写入
		WriteFile((HANDLE)lpParam, pIo->m_pData, pIo->m_nLen,
			&pIo->m_dwWrite, (LPOVERLAPPED)&pIo->m_ol);
		if (ERROR_IO_PENDING != GetLastError()) {
			CancelThreadpoolIo(g_pThreadpoolIo);
		}
	} 
	return i;
}