SpinLock2

// Example06_SpinLock2.cpp : 콘솔 응용 프로그램에 대한 진입점을 정의합니다.
//
#include "stdafx.h"

#include<windows.h>
#include<process.h>

#include<string>
#include<iostream>
using namespace std;

unsigned int WINAPI writeCharacter(LPVOID param);

string g_string;
int const MAX_THREAD = 5;
long g_key =1;

int _tmain(int argc, _TCHAR* argv[])
{
 

 DWORD threadIDs[MAX_THREAD];
 HANDLE threadHandles[MAX_THREAD];
 char alphas[MAX_THREAD];

 for(int i =0; i<MAX_THREAD; ++i)
 {
  alphas[i] = 'a' + i;

  threadHandles[i] = (HANDLE) ::_beginthreadex( NULL, 0 , writeCharacter,(LPVOID*)(&alphas[i]),0,(unsigned int *)&threadIDs[i]);
 }
 
 DWORD result = ::WaitForMultipleObjects(MAX_THREAD, &threadHandles[0],TRUE,INFINITE);
 if(result == WAIT_OBJECT_0)
 {
  
  cout<<g_string;
  
 }
 for(int i = 0; i< MAX_THREAD; ++i)
 {
  CloseHandle(threadHandles[i]);
 }

 return 0;
}

unsigned int WINAPI writeCharacter(LPVOID param)
{
 char ch = *((char *)param);
 
 LONG key = g_key;
 while(1 != ::InterlockedCompareExchange(&g_key, 0 ,1));  //( 조건 ? 참 : 거짓)과 같다
 /***************임계영역 *************************/
 for(int i = 0; i< 1000; ++i)
 {
  g_string += ch;
 }
 /**************************************************/
 g_key = 1; 
 
 return 0;
}