前面幾篇博文中， 我們一直在討論異質連結串列訊息佇列問題， 在本文中， 我們繼續來探討這一問題， 在多執行緒環境下， 考慮執行緒同步問題， 程式碼如下（我用Sleep(20);來故意搗亂）：

#include <windows.h>
#include <iostream>
using namespace std;

#define Rectangle MyRectangle  // 避免Rectangle與Windows中的Rectangle衝突

HANDLE g_hSemp = NULL;  // 訊號量handle

// 物件的id值
typedef enum
{
	ErrorId = -1,
	IntegerId = 1,
	PointId = 2,
	RectangeId = 3,
}ObjectID;


// 基類
struct Basic
{
	ObjectID id;
	virtual Basic *copy() = 0; // 純虛擬函式
};

// 整數類
struct Integer : public Basic
{
	int a;

	Basic *copy()
	{
		Integer *p = new Integer;
		p->a = ((Integer*)this)->a;
		p->id = ((Integer*)this)->id;

		return p;
	}
};

// 點類
struct Point : public Basic
{
	int x;
	int y;

	Basic *copy()
	{
		Point *p = new Point;
		p->x = ((Point*)this)->x;
		p->y = ((Point*)this)->y;
		p->id = ((Point*)this)->id;

		return p;
	}
};

// 矩形類
struct Rectangle : public Basic
{
	Point point;
	int width;
	int height;

	Basic *copy()
	{
		Rectangle *p = new Rectangle;
		p->point.x = ((Rectangle*)this)->point.x;
		p->point.y = ((Rectangle*)this)->point.y;
		p->width = ((Rectangle*)this)->width;
		p->height = ((Rectangle*)this)->height;
		p->id = ((Rectangle*)this)->id;

		return p;
	}
};

// 抽象物件的共同點， 構造成新的結點， 便於連結
typedef struct node
{
	node *next;
	Basic *pBasic;
}Node;


Node *head = NULL;  // 指向第一結點（採用不帶頭結點的連結串列）


// 往鏈式訊息佇列中塞訊息
Node *addToMsgQueue(Basic* pb)
{
	WaitForSingleObject(g_hSemp, INFINITE);
	printf("add\n");

	Node *pn = new Node;
	Node *qn = NULL;
	Basic *p = pb->copy(); // 多型性

	if(NULL == head)
	{
		Sleep(20);  
		head = pn;
	}
	else
	{
		qn = head;
		while(NULL != qn->next)
		{
			Sleep(20);  
			qn = qn->next;
		}

		Sleep(20);  
		qn->next = pn;
	}

	pn->pBasic = p;   // 千萬別忘記啊
	pn->next = NULL;  // 千萬別忘記啊

	
	ReleaseSemaphore(g_hSemp, 1, NULL);  

	return head;
}


// 從鏈式訊息佇列中取出訊息（結點）
Node *getMsgFromQueue()
{
	WaitForSingleObject(g_hSemp, INFINITE);  
	printf("get\n");


	if(NULL == head)
	{
		Sleep(20);  
		ReleaseSemaphore(g_hSemp, 1, NULL);  
		return NULL;
	}

	Node *pn = head;
	head = head->next;
	Sleep(20);  

	ReleaseSemaphore(g_hSemp, 1, NULL);  
	return pn;
} 


// 執行緒函式
DWORD WINAPI ThreadFun(LPVOID pM)
{
	Node *p = NULL;

	// 從訊息佇列中取出訊息
	while(1)
	{
		p = getMsgFromQueue();
		if(NULL == p)
		{
			Sleep(100);
			continue;
		}

		// 對指標進行還原
		switch(p->pBasic->id) 
		{
			case IntegerId:
			{
				cout << ((Integer*)(p->pBasic))->a << endl;
				break;
			}
			case PointId:
			{
			
				cout << ((Point *)(p->pBasic))->x << endl;
				cout << ((Point *)(p->pBasic))->y << endl;
				break;
			}
			case RectangeId:
			{
				cout << ((Rectangle *)(p->pBasic))->point.x << endl;
				cout << ((Rectangle *)(p->pBasic))->point.y << endl;
				cout << ((Rectangle *)(p->pBasic))->width << endl;
				cout << ((Rectangle *)(p->pBasic))->height << endl;
				break;
			}
			default:
			{
				break;
			}
		}
	}

	return 0;
}

// 主執行緒
int main()
{
	HANDLE handle = CreateThread(NULL, 0, ThreadFun, NULL, 0, NULL);
    CloseHandle(handle);

	g_hSemp = CreateSemaphore(NULL, 1, 10, NULL);  
	


	// 定義三個物件並賦值
	Integer i;
	Point po;
	Rectangle rect;

	i.id = IntegerId;
	po.id = PointId;
	rect.id = RectangeId;
	
	i.a = 11;
	po.x = 22;
	po.y = 33;

	rect.point.x = 44;
	rect.point.y = 55;
	rect.width = 66;
	rect.height = 77;

	// 塞入訊息佇列
	while(1)
	{	
		addToMsgQueue(&i);
		addToMsgQueue(&po);
		addToMsgQueue(&rect);
		Sleep(2000);
	}

	CloseHandle(g_hSemp);
	return 0;
}
 

       貌似該睡覺了啊。