利用关键代码段实现多线程同步

利用关键代码段实现多线程同步

关键代码段又叫临界区，是指一个小代码段，在代码能够执行前，它必须对具有对资源的独中权。如一次只能一个人打电话的公用电话厅，开始时要建个 电话厅（初始化临界区：InitializeCriticalSection),一个人打电话(EnterCiticalSection)，打完电话离 开，便于别人打（LeaveCriticalSection),电话厅不用时，拆掉，释放资源（DeleteCriticalSection);

如下程序实现多线程同步：

#include <windows.h>
#include <iostream>

using namespace std;

DWORD WINAPI ThreadProc1(
  LPVOID lpParameter
);//define a thread function
DWORD WINAPI ThreadProc2(
  LPVOID lpParameter
);//define a thread function

int tickets=100;//the total of tickets
HANDLE g_hEvent;//define a handle of event
CRITICAL_SECTION g_cs;//define a ciritical section
int main(int argc,char** argv)
{
 HANDLE handle1;//a thread handle
 HANDLE handle2;//a thread handle
 handle1=CreateThread(NULL,0,ThreadProc1,NULL,0,NULL);//create a thread
 handle2=CreateThread(NULL,0,ThreadProc2,NULL,0,NULL);//creat a thread
    CloseHandle(handle1);//close a thread handle
 CloseHandle(handle2);//close a thread handle
 InitializeCriticalSection(&g_cs);

    Sleep(4000);
    DeleteCriticalSection(&g_cs);
 return 0;
}
DWORD WINAPI ThreadProc1(
  LPVOID lpParameter
)
{
   while(TRUE)
   {
    EnterCriticalSection(&g_cs);
    if(tickets>0)
    {
     Sleep(2);
     cout<<"Thread1 Ticket:"<<tickets--<<endl;
    
    }
    else
     break;
    LeaveCriticalSection(&g_cs);
   }
     
 return 0;
}
DWORD WINAPI ThreadProc2(
  LPVOID lpParameter
)
{
 while(TRUE)
   {
   EnterCriticalSection(&g_cs);
    if(tickets>0)
    { 
     Sleep(2);
     cout<<"Thread2 Ticket:"<<tickets--<<endl;
    
    }
    else
     break;
    LeaveCriticalSection(&g_cs);
   }
 return 0;
}

WINAPI是函数调用的一种约定,等同于__stdcall,该调用约定规定,按从右至左的顺序压参数入栈,由被调用者把参数弹出栈!