Windows核心编程学习九：利用内核对象进行线程同步

注：源码为学习《Windows核心编程》的一些尝试，非原创。若能有助于一二访客，幸甚。

1.程序框架

#include "Queue.h"
#include <tchar.h>
#include <windowsx.h>
#include <StrSafe.h>
#include <process.h>
#include "resource.h"

/************************************************************************/

#define chHANDLE_DLGMSG(hWnd, message, fn)                 \
   case (message): return (SetDlgMsgResult(hWnd, uMsg,     \
      HANDLE_##message((hWnd), (wParam), (lParam), (fn))))

// This macro function calls the C runtime's _beginthreadex function.
// The C runtime library doesn't want to have any reliance on Windows' data
// types such as HANDLE. This means that a Windows programmer needs to cast
// values when using _beginthreadex. Since this is terribly inconvenient,
// I created this macro to perform the casting.
typedef unsigned (__stdcall *PTHREAD_START) (void *);

#define chBEGINTHREADEX(psa, cbStackSize, pfnStartAddr, \
   pvParam, dwCreateFlags, pdwThreadId)                 \
        ((HANDLE)_beginthreadex(                        \
         (void *)        (psa),                         \
         (unsigned)      (cbStackSize),                 \
         (PTHREAD_START) (pfnStartAddr),                \
         (void *)        (pvParam),                     \
         (unsigned)      (dwCreateFlags),               \
         (unsigned *)    (pdwThreadId)))

// Sets the dialog box icons
inline void chSETDLGICONS(HWND hWnd, int idi)
{
   SendMessage(hWnd, WM_SETICON, ICON_BIG,  (LPARAM)
      LoadIcon((HINSTANCE) GetWindowLongPtr(hWnd, GWLP_HINSTANCE), MAKEINTRESOURCE(idi)));
   SendMessage(hWnd, WM_SETICON, ICON_SMALL, (LPARAM)
      LoadIcon((HINSTANCE) GetWindowLongPtr(hWnd, GWLP_HINSTANCE), MAKEINTRESOURCE(idi)));
}

BOOL Dlg_OnInitDialog(HWND hWnd, HWND hWndFocus, LPARAM lParam)
{
	chSETDLGICONS(hWnd, IDI_QUEUE);

	return TRUE;
}

void Dlg_OnCommand(HWND hWnd, int id, HWND hWndCtl, UINT codeNotify)
{
	switch (id)
	{
	case IDCANCEL:
		EndDialog(hWnd, id);
		break;
	}
}

INT_PTR WINAPI Dlg_Proc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
	switch (uMsg)
	{
		chHANDLE_DLGMSG(hWnd, WM_INITDIALOG, Dlg_OnInitDialog);
		chHANDLE_DLGMSG(hWnd, WM_COMMAND,	 Dlg_OnCommand);
	}

	return FALSE;
}

/*************************************************************************/

int WINAPI _tWinMain(HINSTANCE hInstExe, HINSTANCE, PTSTR pszCmdLine, int)
{
	DialogBox(hInstExe, MAKEINTRESOURCE(IDD_QUEUE), NULL, Dlg_Proc);

	return 0;
}

2.线程安全队列的实现

/*
 * File:	CQueue.h
 * Time:	2013-07-10
 * 描述：	学习《Windows核心编程》
 */

#ifndef _CQUEUE_H_
#define _CQUEUE_H_

#include <windows.h>

class CQueue
{
public:
	struct ELEMENT {
		int m_nThreadNum;				// 线程号
		int m_nRequestNum;				// 请求号
	};
	typedef ELEMENT* PELEMENT;

private:
	PELEMENT	m_pElements;			// 队列元素数组
	int			m_nMaxElements;			// 数组长度
	HANDLE		m_h[2];					// 两个内核对象，一个互斥量一个信号量
	HANDLE		&m_hmtxQ;				// 互斥量对象的引用
	HANDLE		&m_hsemNumElements;		// 信号量对象的引用

public:
	CQueue(int nMaxElements);
	~CQueue();

	BOOL Append(PELEMENT pElement, DWORD dwMilliseconds);
	BOOL Remove(PELEMENT pElement, DWORD dwMilliseconds);
};

#endif

/************************************************************************/

CQueue::CQueue(int nMaxElements) : m_hmtxQ(m_h[0]), m_hsemNumElements(m_h[1])
{
	// 初始化结构数组
	m_pElements = (PELEMENT)HeapAlloc(GetProcessHeap(), 0, sizeof(ELEMENT) * nMaxElements);

	// 初始化数组长度
	m_nMaxElements = nMaxElements;

	// 创建互斥量和信号量内核对象
	m_hmtxQ = CreateMutex(NULL, FALSE, NULL);
	m_hsemNumElements = CreateSemaphore(NULL, 0, nMaxElements, NULL);
}

CQueue::~CQueue()
{
	// 清理内核对象和内存
	CloseHandle(m_hsemNumElements);
	CloseHandle(m_hmtxQ);
	HeapFree(GetProcessHeap(), 0, m_pElements);
}

BOOL CQueue::Append(CQueue::PELEMENT pElement, DWORD dwTimeout)
{
	BOOL fOk = FALSE;

	// 等待互斥量内核对象
	DWORD dw = WaitForSingleObject(m_hmtxQ, dwTimeout);

	// 返回WAIT_OBJECT_0表示得到了队列的独占访问权
	if (dw == WAIT_OBJECT_0) {
		LONG lPrevCount;

		// 尝试向队列添加新元素
		fOk = ReleaseSemaphore(m_hsemNumElements, 1, &lPrevCount);

		// fOk为TRUE表示队列没满，可以添加新元素
		if (fOk) {
			m_pElements[lPrevCount] = *pElement;
		}
		else {
			SetLastError(ERROR_DATABASE_FULL);
		}

		// 释放互斥量，允许其他线程访问队列
		ReleaseMutex(m_hmtxQ);
	}
	else {
		SetLastError(ERROR_TIMEOUT);
	}

	return fOk;
}

BOOL CQueue::Remove(CQueue::PELEMENT pElement, DWORD dwTimeout)
{
	// 确保对队列具有独占访问权，且要求队列中有元素可取
	// 等待信号量成功的副作用使它的计数减一，所以不需要显示调用ReleaseSemaphore()
	BOOL fOk = (WaitForMultipleObjects(_countof(m_h), m_h, TRUE, dwTimeout) == WAIT_OBJECT_0);

	if (fOk)
	{
		// 获取元素
		*pElement = m_pElements[0];

		// 取出索引为0 的元素，把数组中剩余元素向前挪一个位置
		MoveMemory(&m_pElements[0], &m_pElements[1], sizeof(ELEMENT) * (m_nMaxElements - 1));

		// 释放互斥量，允许其他线程访问队列
		ReleaseMutex(m_hmtxQ);
	}
	else
	{
		SetLastError(ERROR_TIMEOUT);
	}

	return fOk;
}

3.客户端线程

CQueue				g_q(10);
volatile LONG		g_fShutdown = FALSE;
HWND				g_hWnd;

// Handles to all reader/writer threads
HANDLE g_hThreads[MAXIMUM_WAIT_OBJECTS];

// Number of reader/writer threads
int    g_nNumThreads = 0;

/************************************************************************/

DWORD WINAPI ClientThread(PVOID pvParam)
{
	int nThreadNum = PtrToUlong(pvParam);			// 线程号
	HWND hWndLB = GetDlgItem(g_hWnd, IDC_CLIENT);

	int nRequestNum = 0;
	while (1 != InterlockedCompareExchange(&g_fShutdown, 0, 0))
	{
		nRequestNum++;

		TCHAR sz[1024];
		CQueue::ELEMENT e = { nThreadNum, nRequestNum };

		// 尝试添加元素到队列
		if (g_q.Append(&e, 200)) {
			StringCchPrintf(sz, _countof(sz), TEXT("客户线程%d 添加元素%d"), nThreadNum, nRequestNum);
		}
		else {
			StringCchPrintf(sz, _countof(sz), TEXT("客户线程%d 添加元素%d失败(%s)"), nThreadNum, nRequestNum,
				(GetLastError() == ERROR_TIMEOUT) ? TEXT("超时") : TEXT("队列已满"));
		}

		ListBox_SetCurSel(hWndLB, ListBox_AddString(hWndLB, sz));
		Sleep(2500);
	}

	return 0;
}

BOOL Dlg_OnInitDialog(HWND hWnd, HWND hWndFocus, LPARAM lParam)
{
	chSETDLGICONS(hWnd, IDI_QUEUE);

	g_hWnd = hWnd;

	DWORD dwThreadID;

	// 创建客户端线程
	for (int i = 0; i < 4; i++)
		g_hThreads[g_nNumThreads++] = chBEGINTHREADEX(NULL, 0, ClientThread, (PVOID)(INT_PTR) i, 0, &dwThreadID);

	return TRUE;
}

4.服务器端线程

DWORD WINAPI ServerThread(PVOID pvParam)
{
	int nThreadNum = PtrToUlong(pvParam);
	HWND hWndLB = GetDlgItem(g_hWnd, IDC_SERVER);

	while (1 != InterlockedCompareExchange(&g_fShutdown, 0, 0)) {
		TCHAR sz[1024];
		CQueue::ELEMENT e;

		// 尝试移除元素
		if (g_q.Remove(&e, 5000)) {
			StringCchPrintf(sz, _countof(sz), TEXT("服务器端线程%d移除客户端线程%d放入的元素%d"), nThreadNum, e.m_nThreadNum, e.m_nRequestNum);
			Sleep(2000 * e.m_nThreadNum);
		}
		else {
			StringCchPrintf(sz, _countof(sz), TEXT("服务器端线程%d 没有元素可取"), nThreadNum);
		}

		ListBox_SetCurSel(hWndLB, ListBox_AddString(hWndLB, sz));
	}

	return 0;
}

BOOL Dlg_OnInitDialog(HWND hWnd, HWND hWndFocus, LPARAM lParam)
{
	chSETDLGICONS(hWnd, IDI_QUEUE);

	g_hWnd = hWnd;

	DWORD dwThreadID;

	// 创建客户端线程
	for (int i = 0; i < 4; i++)
		g_hThreads[g_nNumThreads++] = chBEGINTHREADEX(NULL, 0, ClientThread, (PVOID)(INT_PTR) i, 0, &dwThreadID);

	// 创建读者线程
	for (int i = 0; i < 2; i++)
		g_hThreads[g_nNumThreads++] = chBEGINTHREADEX(NULL, 0, ServerThread, (PVOID)(INT_PTR) i, 0, &dwThreadID);

	return TRUE;
}

int WINAPI _tWinMain(HINSTANCE hInstExe, HINSTANCE, PTSTR pszCmdLine, int)
{
	DialogBox(hInstExe, MAKEINTRESOURCE(IDD_QUEUE), NULL, Dlg_Proc);

	InterlockedExchange(&g_fShutdown, TRUE);

	WaitForMultipleObjects(g_nNumThreads, g_hThreads, TRUE, INFINITE);
	while (g_nNumThreads--)
		CloseHandle(g_hThreads[g_nNumThreads]);

	return 0;
}