bakery.cpp

/* AP   18-apr-05 bakery.c          */
/*  an implementation of critical       */
/*  sections based on bakery algorithm  */

# include "bakery.h"
# include <stdio.h>
# include <conio.h>
# include <windows.h>

# define MAX_THREAD 1024

MY_LPCRITICAL_SECTION *sec;
int count=0;
struct _crit_sec {
    volatile int choosing[MAX_THREAD];
    volatile int number[MAX_THREAD];
};

void My_InitializeCriticalSection( MY_LPCRITICAL_SECTION * sec ) {
    int i;

    *sec = (MY_LPCRITICAL_SECTION) malloc (sizeof(struct _crit_sec));
    for(i=0; i<MAX_THREAD; i++) {
        (*sec)->choosing[i] = 0;
        (*sec)->number[i] = 0;
    }
}

void My_DeleteCriticalSection( MY_LPCRITICAL_SECTION sec ) {
    if (sec) free( sec );
}

void My_EnterCriticalSection( int myId, MY_LPCRITICAL_SECTION sec ) {
    int max, j;
    sec->choosing[myId] = 1;
    max = 0;
    for (j=0; j<MAX_THREAD; j++) {
        if(max < sec->number[j]) max = sec->number[j];
    }
    sec->number[myId] = max + 1;
    sec->choosing[myId] = 0;
    for (j = 0; j < MAX_THREAD; j++) {
        while (sec->choosing[j]);
        while (sec->number[j] != 0 &&
            (sec->number[j] < sec->number[myId] ||
            (sec->number[j] == sec->number[myId] && j < myId)));
    }
}

void My_LeaveCriticalSection( int myId, MY_LPCRITICAL_SECTION sec ) {
    sec->number[myId] = 0;
}
DWORD WINAPI ThreadFunction(LPVOID n)
{
    do{
        My_EnterCriticalSection((int)n, sec);//Xin vào vùng tranh chấp
        if((int)n==0)//kiểm tra: là thread thứ nhất?
        {
            count++;//nếu đúng thì tăng biến count
            Sleep(2000);
        }
        else
        {
            count--;//Nếu không phải thì giảm biến count
            Sleep(2000);
        }
        printf("%d\n",count);//Hiển thị biến count
        My_LeaveCriticalSection((int)n, sec);//Ra khỏi vùng tranh chấp
    }while(1);
    return 0;
}

void main(void)
{
    HANDLE hThread[3];
    DWORD dwThreadID;
    int i;
    My_InitializeCriticalSection(&sec);//Khởi tạo vùng tranh chấp
    for(i=0;i<3;i++)
    {
        hThread[i]=CreateThread(NULL,0, ThreadFunction,(LPVOID)i,0, &dwThreadID);//Tạo Thread
        printf("Successful, ID=%d, hThread=%d\n", dwThreadID, hThread[i]);//Hiển thị thông tin Thread
    }
    Sleep(1000000);
}