철학자 식사 문제 코드

// Test.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include 
using namespace std;

#define LEFT(n)  ((n+4)%5)
#define RIGHT(n) ((n+1)%5)

class MySemaphore
{
public:
	MySemaphore::MySemaphore(long nInitCount)
	{
		m_sem = CreateSemaphore(NULL,nInitCount,MAXLONG32,NULL);
	}

	bool down(DWORD dwMilliseconds)
	{
		if (m_sem)
		{
			DWORD dwRet = WaitForSingleObject(m_sem,dwMilliseconds);

			if (WAIT_OBJECT_0 == dwRet)
			{
				return true;
			}
		}
		
		return false;
	}

	bool up()
	{
		if (m_sem)
		{
			return ReleaseSemaphore(m_sem,1,NULL) ? true : false;
		}

		return false;
	}
private:
	HANDLE m_sem;
};

enum PersonState
{
	STATE_THINKING,
	STATE_WAITING,
	STATE_EATING,
};

MySemaphore personArr[5] = {0,0,0,0,0};
PersonState  stateArr[5] = {STATE_THINKING,STATE_THINKING,STATE_THINKING,STATE_THINKING,STATE_THINKING};
MySemaphore mutex = 1;

void test(int nIndex)
{
	if (stateArr[nIndex] == STATE_WAITING &&
		stateArr[LEFT(nIndex)] != STATE_EATING&&
		stateArr[RIGHT(nIndex)] != STATE_EATING)
	{
		stateArr[nIndex] = STATE_EATING;
		personArr[nIndex].up();
	}
}

void take_fork(int nIndex)
{
	mutex.down(INFINITE);
	stateArr[nIndex] = STATE_WAITING;
	test(nIndex);
	mutex.up();

	personArr[nIndex].down(INFINITE);
}

void put_fork(int nIndex)
{
	mutex.down(INFINITE);
	stateArr[nIndex] = STATE_THINKING;
	printf("person %d put fork and thinking
",nIndex+1);
	test(LEFT(nIndex));
	test(RIGHT(nIndex));
	mutex.up();
}

DWORD WINAPI PersonProc( LPVOID lpParam )
{
	int nThreadIndex = (int)lpParam;

	for(;;)
	{
		take_fork(nThreadIndex);
		printf("person %d take fork and eating
",nThreadIndex+1);
		Sleep(1000); //eating;
		put_fork(nThreadIndex);
	}

	return 0;
}

int _tmain(int argc, _TCHAR* argv[])
{
	HANDLE aThread[5];
	
	for(int i=0; i < 5; i++ )
	{
		aThread[i] = CreateThread( 
			NULL,       // default security attributes
			0,          // default stack size
			(LPTHREAD_START_ROUTINE) PersonProc, 
			(void*)i,       // no thread function arguments
			0,          // default creation flags
			NULL); // receive thread identifier

		if( aThread[i] == NULL )
		{
			printf("CreateThread error: %d
", GetLastError());
			return 1;
		}
	}

	Sleep(-1);
	return 0;
}

구체적인 분석은 관련 장과 절을 참고한다.