目的: バンカーのアルゴリズムを使用して、システム リソースの動的な割り当てを実現し、セキュリティ ステータスの検出問題を処理します。
プロセスによって行われたリソース要求を判断し、計算されたセキュリティ シーケンスを出力できるバンカー アルゴリズム プログラムを作成します。
#include <iostream>
#include<cstring>
using namespace std;
#define False 0
#define True 1
//主要数据结构
int N = 50;//进程的最大数
int M = 100;//资源的最大数
char NAME[100] = { 0 };//资源的名称
int Max[50][100] = { 0 };//最大需求矩阵
int Avaliable[100] = { 0 };//可用资源矩阵
int Allocation[50][100] = { 0 };//系统已分配矩阵
int Need[50][100] = { 0 };//还需要资源矩阵
int Request[100] = { 0 };//请求资源向量
int Security[100] = { 0 };//存放安全序列
int Work[100] = { 0 };//存放系统可提供资源
/********
初始化数据：输入进程数量、资源种类、
各种资源可利用数量、
各进程的资源已分配数量、
各进程对资源最大需求量等。
********/
void chushihua()
{
/* n为进程个数，即矩阵行数，m为资源个数，即矩阵列数。*/
int i, j, n, m;
int number, flag;
char name;//输入资源名称
cout << "系统可用资源个数为:";
cin >> m;
M = m;
for (i = 0; i < m; i++)
{
cout << "资源" << i << "的名称:";
cin >> name;
NAME[i] = name;
cout << "资源" << name << "的初始个数为:";
cin >> number;
Avaliable[i] = number;
}
cout << endl;
cout << "请输入进程的数量:";
cin >> n;
N = n;
cout << "请输入各进程的最大需求矩阵的值(" << n << "*" << m << "矩阵)[Max]:" << endl;
for (i = 0; i < n; i++)
for (j = 0; j < m; j++)
cin >> Max[i][j];
int temp[100] = { 0 };
do
{
flag = 0;
cout << "请输入各进程已经分配的资源量(" << n << "*" << m << "矩阵)[Allocation]:" << endl;
for (i = 0; i < n; i++)
for (j = 0; j < m; j++)
{
cin >> Allocation[i][j];
if (Allocation[i][j] > Max[i][j]) flag = 1;
Need[i][j] = Max[i][j] - Allocation[i][j];
temp[j] += Allocation[i][j];
}
if (flag == 1)
cout << "申请的资源大于最大需求量，请重新输入!";
cout << endl;
} while (flag);
for (j = 0; j < m; j++)
Avaliable[j] = Avaliable[j] - temp[j];
}
/********
显示资源分配矩阵
********/
void showdata()
{
int i, j;
cout << "*************************************************************" << endl;
cout << "系统目前可用的资源[Avaliable]:" << endl;
for (i = 0; i < M; i++)
cout << NAME[i] << " ";
cout << endl;
for (j = 0; j < M; j++)
cout << Avaliable[j] << " ";//输出分配资源
cout << endl;
cout << "系统当前的资源分配情况如下：" << endl;
cout << " Max Allocation Need" << endl;
cout << "进程名 ";
for (j = 0; j < 3; j++)
{
for (i = 0; i < M; i++)
cout << NAME[i] << " ";
cout << " ";
}
cout << endl;
for (i = 0; i < N; i++)
{
cout << " P" << i << " ";
for (j = 0; j < M; j++)
cout << Max[i][j] << " ";
cout << " ";
for (j = 0; j < M; j++)
cout << Allocation[i][j] << " ";
cout << " ";
for (j = 0; j < M; j++)
cout << Need[i][j] << " ";
cout << endl;
}
}
/********
安全性算法
********/
int safe()
{
int i, j, k = 0, n, apply;
int Finish[100] = { 0 };
for (j = 0; j < N; j++)
Work[j] = Avaliable[j];
for (i = 0; i < N; i++)
{
apply = 0;
for (j = 0; j < M; j++)
{
if (Finish[i] == False && Need[i][j] <= Work[j])
{
apply++;
if (apply == M)
{
for (n = 0; n < M; n++)
Work[n] = Work[n] + Allocation[i][n];//变分配数
Finish[i] = True;
Security[k] = i;
i = -1;
k++;
}
}
}
}
for (i = 0; i < N; i++)
{
if (Finish[i] == False)
{
cout << "系统不安全，已瘫痪" << endl;//不成功系统不安全
return -1;
}
}
cout << "系统是安全的!" << endl;//如果安全，输出成功
cout << "存在一个安全序列:";
for (i = 0; i < N; i++)
{//输出运行进程数组
cout << "P" << Security[i];
if (i < N - 1) cout << "->";
}
cout << endl;
return 0;
}
/********
尝试分配资源
********/
int test(int i)//进行资源分配
{
int j;
for (j = 0; j < N; j++)
{
Avaliable[j] = Avaliable[j] - Request[j];
Allocation[i][j] = Allocation[i][j] + Request[j];
Need[i][j] = Need[i][j] - Request[j];
}
return 1;
}
/********
利用银行家算法对申请资源对进行试分配
********/
void bank()
{
char ch;
int i, j;
ch = 'y';
cout << "请输入请求分配资源的进程号(0-" << N - 1 << "):";
cin >> i;//输入须申请资源的进程号
cout << "请输入进程P" << i << "要申请的资源个数:" << endl;
for (j = 0; j < M; j++)
{
cout << NAME[j] << ":";
cin >> Request[j];//输入需要申请的资源
}
for (j = 0; j < M; j++)
{
if (Request[j] > Need[i][j])//判断申请是否大于需求，若大于则出错
{
cout << "进程P" << i << "申请的资源大于它需要的资源";
cout << " 分配不合理，不予分配！" << endl;
ch = 'm';
break;
}
else
{
if (Request[j] > Avaliable[j])//判断申请是否大于当前可分配资源，若大于则出错
{
cout << "进程" << i << "申请的资源大于系统现在可利用的资源";
cout << endl;
cout << " 系统尚无足够资源，不予分配!" << endl;
ch = 'm';
break;
}
}
}
if (ch == 'y')
{
test(i);//根据进程需求量变换资源
showdata();//根据进程需求量显示变换后的资源
safe();//根据进程需求量进行银行家算法判断
}
}
int main()//主函数
{
char choice=1;
cout << "\t---------------------------------------------------" << endl;
cout << "\t|| ||" << endl;
cout << "\t|| 银行家算法的实现 ||" << endl;
cout << "\t|| ||" << endl;
cout << "\t|| 班级：xxx ||" << endl;
cout << "\t|| 学生： xxx xxx xxx ||" << endl;
cout << "\t|| 学号: 11 12 13 ||" << endl;
cout << "\t---------------------------------------------------" << endl;
chushihua();//初始化数据
showdata();//显示各种资源
safe();//用银行家算法判定系统是否安全
while (choice)
{
cout << "*************************************************************" << endl;
cout << endl;
cout << endl;
cout << "\t-------------------银行家算法演示------------------" << endl;
cout << " R(r):请求分配 " << endl;
cout << " E(e):退出 " << endl;
cout << "\t---------------------------------------------------" << endl;
cout << "请选择：";
cin >> choice;
switch (choice)
{
case 'r':
case 'R':
bank(); break;
case 'e':
case 'E':
choice = 0; break;
default: cout << "请正确选择!" << endl; break;
}
}
}