Semaphore

// Example03_Semaphore.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;
HANDLE g_semaphoreHandle;

int _tmain(int argc, _TCHAR* argv[])
{
 g_semaphoreHandle = ::CreateSemaphore(NULL,1, 1 , NULL);
 g_string.reserve(MAX_THREAD * 1000 +1);  //가용공간 예약부분

 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]);
 }
 CloseHandle(g_semaphoreHandle);

 return 0;
}

unsigned int WINAPI writeCharacter(LPVOID param)
{
 char ch = *((char *)param);
 DWORD result = ::WaitForSingleObject(g_semaphoreHandle,INFINITE);
 for(int i = 0; i< 1000; ++i)
 {
  g_string += ch;
 }
 ::ReleaseSemaphore(g_semaphoreHandle,1,NULL);
 
 return 0;
}