操作系统–银行家算法c语言代码

#include <stdio.h>
#include <string.h>
#include "banker.h"
//试探分配
void ProbeAlloc(int process,RESOURCE *res)
{
    Available.A -= res->A;
    Available.B -= res->B;
    Available.C -= res->C;
    Available.D -= res->D;
    Allocation[process].A += res->A;
    Allocation[process].B += res->B;
    Allocation[process].C += res->C;
    Allocation[process].D += res->D;
    Need[process].A -= res->A;
    Need[process].B -= res->B;
    Need[process].C -= res->C;
    Need[process].D -= res->D;
}
//若试探分配后进入不安全状态，将分配回滚
void RollBack(int process,RESOURCE *res)
{
    Available.A += res->A;
    Available.B += res->B;
    Available.C += res->C;
    Available.D += res->D;
    Allocation[process].A -= res->A;
    Allocation[process].B -= res->B;
    Allocation[process].C -= res->C;
    Allocation[process].D -= res->D;
    Need[process].A += res->A;
    Need[process].B += res->B;
    Need[process].C += res->C;
    Need[process].D += res->D;
}
//安全性检查
bool SafeCheck()
{
    RESOURCE    Work = Available;
    bool        Finish[PROCESSES_NUMBER] = {false,false,false,false,false};
    int     i;
    int     j = 0;
    for (i = 0; i < PROCESSES_NUMBER; i++)
    {
        //是否已检查过
        if(Finish[i] == false)
        {
            //是否有足够的资源分配给该进程
            if(Need[i].A <= Work.A && Need[i].B <= Work.B && Need[i].C <= Work.C && Need[i].D <= Work.D)
            {
                //有则使其执行完成，并将已分配给该进程的资源全部回收
                Work.A += Allocation[i].A;
                Work.B += Allocation[i].B;
                Work.C += Allocation[i].C;
                Work.D += Allocation[i].D;
                Finish[i] = true;
                safe[j++] = i;
                i = -1;             //重新进行遍历
            }
        }
    }
    //如果所有进程的Finish向量都为true则处于安全状态，否则为不安全状态
    for (i = 0; i < PROCESSES_NUMBER; i++)
    {
        if (Finish[i] == false)
        {
            return false;
        }
    }
    return true;
}
//资源分配请求
bool request(int process,RESOURCE *res)
{
    //request向量需小于Need矩阵中对应的向量
    if(res->A <= Need[process].A && res->B <= Need[process].B && res->C <= Need[process].C&& res->D <= Need[process].D)
    {
        //request向量需小于Available向量
        if(res->A <= Available.A && res->B <= Available.B && res->C <= Available.C && res->D <= Available.D)
        {
            //试探分配
            ProbeAlloc(process,res);
            //如果安全检查成立，则请求成功，否则将分配回滚并返回失败
            if(SafeCheck())
            {
                return true;
            }
            else
            {
                printf("安全性检查失败。原因：系统将进入不安全状态，有可能引起死锁。\n");
                printf("正在回滚...\n");
                RollBack(process,res);
            }
        }
        else
        {
            printf("安全性检查失败。原因：请求向量大于可利用资源向量。\n");
        }
    }
    else
    {
        printf("安全性检查失败。原因：请求向量大于需求向量。\n");
    }
    return false;
}
//输出资源分配表
void PrintTable()
{
    printf("\t\t\t*********资源分配表*********\n");
    printf("Process Max Allocation Need Available\n");
    printf(" A B C D A B C D A B C D A B C D\n");
    printf(" P0 %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d\n",Max[0].A,Max[0].B,Max[0].C,Max[0].D,Allocation[0].A,Allocation[0].B,Allocation[0].C,Allocation[0].D,Need[0].A,Need[0].B,Need[0].C,Need[0].D,Available.A,Available.B,Available.C,Available.D);
    printf(" P1 %d %d %d %d %d %d %d %d %d %d %d %d\n",Max[1].A,Max[1].B,Max[1].C,Max[1].D,Allocation[1].A,Allocation[1].B,Allocation[1].C,Allocation[1].D,Need[1].A,Need[1].B,Need[1].C,Need[1].D);
    printf(" P2 %d %d %d %d %d %d %d %d %d %d %d %d\n",Max[2].A,Max[2].B,Max[2].C,Max[2].D,Allocation[2].A,Allocation[2].B,Allocation[2].C,Allocation[2].D,Need[2].A,Need[2].B,Need[2].C,Need[2].D);
    printf(" P3 %d %d %d %d %d %d %d %d %d %d %d %d\n",Max[3].A,Max[3].B,Max[3].C,Max[3].D,Allocation[3].A,Allocation[3].B,Allocation[3].C,Allocation[3].D,Need[3].A,Need[3].B,Need[3].C,Need[3].D);
    printf(" P4 %d %d %d %d %d %d %d %d %d %d %d %d\n",Max[4].A,Max[4].B,Max[4].C,Max[4].D,Allocation[4].A,Allocation[4].B,Allocation[4].C,Allocation[4].D,Need[4].A,Need[4].B,Need[4].C,Need[4].D);
    printf("\n");
}
int main()
{
    int ch;
    printf("先检查初始状态是否安全。\n");
    if (SafeCheck())
    {
        printf("系统处于安全状态。\n");
        printf("安全序列是{P%d,P%d,P%d,P%d,P%d}。\n",safe[0],safe[1],safe[2],safe[3],safe[4]);
    }
    else
    {
        printf("系统处于不安全状态。程序将退出...\n");
        goto over;
    }
    do
    {
        int     process;
        RESOURCE    res;
        PrintTable();
        printf("请依次输入请求分配的进程和对四类资源的请求数量：");
        scanf("%d%d%d%d%d",&process,&res.A,&res.B,&res.C,&res.D);
        if (request(process,&res))
        {
            printf("分配成功。\n");
            printf("安全序列是{P%d,P%d,P%d,P%d,P%d}。\n",safe[0],safe[1],safe[2],safe[3],safe[4]);
        }
        else
        {
            printf("分配失败。\n");
        }
        printf("是否继续分配？(Y/N):");
        fflush(stdin);              //虽然C标准不支持这种用法，但是VC++支持
        ch = getchar();
    } while (ch == 'Y' || ch == 'y');
over:
    printf("执行完毕。");
    return 0;
}

#pragma warning(disable:4996)
typedef int bool;
#define false 0
#define true !false
//系统中所有进程数量
#define PROCESSES_NUMBER 5
typedef struct {
    int A;
    int B;
    int C;
    int D;
}RESOURCE;
//最大需求矩阵 Max
RESOURCE Max[PROCESSES_NUMBER] =
{
    {
  
  4,1,1,1},
    {
  
  0,2,1,2},
    {
  
  4,2,1,0},
    {
  
  1,1,1,1},
    {
  
  2,1,1,0}
};
//已分配资源数矩阵 Allocation
RESOURCE Allocation[PROCESSES_NUMBER] =
{
    {
  
  3,0,1,1},
    {
  
  0,1,0,0},
    {
  
  1,1,1,0},
    {
  
  1,1,0,1},
    {
  
  0,0,0,0}
};
//需求矩阵
RESOURCE Need[PROCESSES_NUMBER] =
{
    {
  
  1,1,0,0},
    {
  
  0,1,1,2},
    {
  
  3,1,0,0},
    {
  
  0,0,1,0},
    {
  
  2,1,1,0}
};
//可用资源向量
RESOURCE Available = {
  
  1,0,2,0};
int safe[PROCESSES_NUMBER];