银行家算法

/* --------------------------------------------------|| |||| 模拟银行家算法|||| |||| 张培乐||-------------------------------------------------- */#include <iostream>#include <stdio.h>#include <stdlib.h>using namespace std;#define processNum 5 //定义进程数量int distributeTime=0; //定义资源分配次数bool flag=false; //标志是否存在安全序列int safeSequence[5]={0,0,0,0,0}; //存储安全序列int proWaitTime=1; //进程开始等待的时间struct source{int A;int B;int C;}Max[processNum], //存储各进程对各类资源的最大需求Allocation[processNum], //存储各进程中每一类资源当前已分配的资源数Need[processNum], //存储各进程尚需的各类资源数Available; //存储当前可利用的资源数struct waitingQueue //进程等待队列{int ifWait; //进程是否等待int waitTime; //进程开始等待的时间int A;int B;int C;}queue[processNum];//打印算法标题void printTitle(){cout<<" --------------------------------------------------"<<endl;cout<<" || ||"<<endl;cout<<" || 模拟银行家算法||"<<endl;cout<<" || ||"<<endl;cout<<" --------------------------------------------------"<<endl;}//初始化T0时刻的资源分配表void InitSourceDistributionTable(){//初始化各进程对各类资源的最大需求Max[0].A=7; Max[0].B=5; Max[0].C=3;Max[1].A=3; Max[1].B=2; Max[1].C=2;Max[2].A=9; Max[2].B=0; Max[2].C=2;Max[3].A=2; Max[3].B=2; Max[3].C=2;Max[4].A=4; Max[4].B=3; Max[4].C=3;//初始化各进程中每一类资源当前已分配的资源数Allocation[0].A=0; Allocation[0].B=1; Allocation[0].C=0;Allocation[1].A=2; Allocation[1].B=0; Allocation[1].C=0;Allocation[2].A=3; Allocation[2].B=0; Allocation[2].C=2;Allocation[3].A=2; Allocation[3].B=1; Allocation[3].C=1;Allocation[4].A=0; Allocation[4].B=0; Allocation[4].C=2;//初始化各进程尚需的各类资源数Need[0].A=7; Need[0].B=4; Need[0].C=3;Need[1].A=1; Need[1].B=2; Need[1].C=2;Need[2].A=6; Need[2].B=0; Need[2].C=0;Need[3].A=0; Need[3].B=1; Need[3].C=1;Need[4].A=4; Need[4].B=3; Need[4].C=1;//存储当前可利用的资源数Available.A=3;Available.B=3;Available.C=2;}//打印T 时刻的资源分配表void printSourceDistributionTable(){cout<<"\n T"<<distributeTime<<" 时刻的资源分配表"<<endl;cout<<"----------------------------------------------------------------------\n";cout<<"| | Max | Allocation | Need | Available |\n";cout<<"| | A B C | A B C | A B C | A B C |\n";cout<<"|--------------------------------------------------------------------|\n";for(int i=0; i<5; i++){cout<<"| P"<<i<<" | "<<Max[i].A<<" "<<Max[i].B<<" "<<Max[i].C<<" ";cout<<"| "<<Allocation[i].A<<" "<<Allocation[i].B<<" "<<Allocation[i].C<<" ";cout<<"| "<<Need[i].A<<" "<<Need[i].B<<" "<<Need[i].C<<" ";if(i!=0)cout<<"| |\n";if(i==0)cout<<"| "<<Available.A<<" "<<Available.B<<" "<<Available.C<<" |\n";}cout<<"----------------------------------------------------------------------\n";}//打印T 时刻的安全序列void printSafeSequence(){cout<<"\n T"<<distributeTime<<" 时刻的安全序列"<<endl;cout<<"-----------------------------------------------------------------------------\n";cout<<"| | Work | Allocation | Need | Work+Available|Finish|\n";cout<<"| | A B C | A B C | A B C | A B C | |\n";cout<<"|---------------------------------------------------------------------------|\n";source Work ; //取当前可利用资源数Work.A=Available.A;Work.B=Available.B;Work.C=Available.C;for(int i=0; i<5; i++){int p=safeSequence[i];cout<<"| P"<<p<<" | "<<Work.A<<" "<<Work.B<<" "<<Work.C<<" ";cout<<"| "<<Allocation[p].A<<" "<<Allocation[p].B<<" "<<Allocation[p].C<<" ";cout<<"| "<<Need[p].A<<" "<<Need[p].B<<" "<<Need[p].C<<" ";cout<<"| "<<Work.A+Allocation[p].A<<" "<<Work.B+Allocation[p].B<<""<<Work.C+Allocation[p].C<<" | true |\n";Work.A+=Allocation[p].A;Work.B+=Allocation[p].B;Work.C+=Allocation[p].C;}cout<<"-----------------------------------------------------------------------------\n";cout<<"存在安全序列{";for(int i=0; i<5; i++){cout<<(i==0?"":",");cout<<"P"<<safeSequence[i];}cout<<"}"<<endl;}//打印试分配时的资源分配表void printTrySourceDistributionTable(){cout<<"\n T"<<distributeTime<<" 时刻试分配的资源分配表"<<endl;cout<<"------------------------------------------------------\n";cout<<"| | Allocation | Need | Available |\n";cout<<"| | A B C | A B C | A B C |\n";cout<<"|----------------------------------------------------|\n";for(int i=0; i<5; i++){cout<<"| P"<<i<<" ";cout<<"| "<<Allocation[i].A<<" "<<Allocation[i].B<<" "<<Allocation[i].C<<" ";cout<<"| "<<Need[i].A<<" "<<Need[i].B<<" "<<Need[i].C<<" ";if(i!=0)cout<<"| |\n";if(i==0)cout<<"| "<<Available.A<<" "<<Available.B<<" "<<Available.C<<" |\n";}cout<<"-----------------------------------------------------\n";}//判断T 时刻是否存在安全序列int *IfExistSafeSequence(){flag=false;int init[5]={1,1,1,1,1}; //存储寻找安全序列过程中各个进程是否已经分配了资源int i=0,j=0;source nowAvailable; //取当前可利用资源数nowAvailable.A=Available.A;nowAvailable.B=Available.B;nowAvailable.C=Available.C;while(i<5){if(nowAvailable.A>=Need[i].A && nowAvailable.B>=Need[i].B && nowAvailable.C>=Need[i].C && init[i]==1){init[i]=0;safeSequence[j++]=i;nowAvailable.A+=Allocation[i].A;nowAvailable.B+=Allocation[i].B;nowAvailable.C+=Allocation[i].C;i=0;}else{i++;}}if(j==5)flag=true;return safeSequence;}//进程进入等待队列等待分配资源void enqueue(int processNumber, int A, int B, int C){queue[processNumber].ifWait=1;queue[processNumber].waitTime=proWaitTime;queue[processNumber].A=A;queue[processNumber].B=B;queue[processNumber].C=C;proWaitTime++;}//进程完成执行，回收资源void reclaimResource(int processNumber, int A, int B, int C){//可用资源增加Available.A+=A;Available.B+=B;Available.C+=C;//已分配资源置为零Allocation[processNumber].A=0;Allocation[processNumber].B=0;Allocation[processNumber].C=0;}//为进程试分配请求的资源void distributeSource(int processNumber, int A, int B, int C){Available.A-=A;Available.B-=B;Available.C-=C;Allocation[processNumber].A+=A;Allocation[processNumber].B+=B;Allocation[processNumber].C+=C;Need[processNumber].A-=A;Need[processNumber].B-=B;Need[processNumber].C-=C;//打印试分配资源给当前进程时的资源分配表printTrySourceDistributionTable();IfExistSafeSequence(); //判断试分配后是否存在安全序列if(flag){printSafeSequence(); //如果存在安全序列，则打印该时刻的安全序列cout<<"\n请求能被满足，分配资源！\n";//如果进程得到了所需的最大资源，则已执行完，回收资源if(Need[processNumber].A==0 && Need[processNumber].B==0 && Need[processNumber].C==0){reclaimResource(processNumber,Allocation[processNumber].A,Allocation[processNumber].B, Allocation[processNumber].C);cout<<"\n进程P"<<processNumber<<"得到了所需的最大资源，执行完毕，回收资源！\n";}printSourceDistributionTable(); //打印该时刻的资源分配表}else{cout<<"\n不存在安全序列，不予以分配资源，该进程请求进入等待队列！\n";//不存在安全序列，则进程进入等待队列等待enqueue(processNumber,A,B,C);//还原试分配的资源数Available.A+=A;Available.B+=B;Available.C+=C;Allocation[processNumber].A-=A;Allocation[processNumber].B-=B;Allocation[processNumber].C-=C;Need[processNumber].A+=A;Need[processNumber].B+=B;Need[processNumber].C+=C;printSourceDistributionTable(); //打印该时刻的资源分配表}}//遍历等待队列，查找是否有进程的请求可被满足void searchQueue(){int a[5]={0,0,0,0,0}; //记录等待的进程是否已经试分配资源//找出等待最久的进程while(1){bool find=false;int waitTime=100000,processNumber=0;for(int i=0; i<5; i++){if(queue[i].ifWait==1 && queue[i].waitTime<waitTime && a[i]==0){processNumber=i;waitTime=queue[i].waitTime;find=true;}}if(find){//如果进程请求的资源数大于当前可利用的资源数，则进程进入等待队列等待if(queue[processNumber].A<=Available.A && queue[processNumber].B<=Available.B && queue[processNumber].C<=Available.C){cout<<"\n等待进程P"<<processNumber<<"所请求的资源数<"<<queue[processNumber].A<<","<<queue[processNumber].B<<","<<queue[processNumber].C<<">小于等于可利用资源数，予以试分配资源！\n";distributeTime++;distributeSource(processNumber, queue[processNumber].A, queue[processNumber].B, queue[processNumber].C);//如果分配资源成功，则从等待队列中去除该进程的等待记录if(flag){queue[processNumber].A=0;queue[processNumber].B=0;queue[processNumber].C=0;queue[processNumber].ifWait=0;queue[processNumber].waitTime=0;}}a[processNumber]=1;}elsebreak;}}//开始银行家算法void BankerAlgorithm(){//初始化等待队列for(int i=0; i<5; i++){queue[i].ifWait=0;queue[i].waitTime=0;queue[i].A=0;queue[i].B=0;queue[i].C=0;}while(1){if(Available.A==10 && Available.B==5 && Available.C==7)cout<<"\n所有进程完成，退出系统！\n\n";break;}int processNumber;int A,B,C;while(1){cout<<"\n请选择需分配资源的进程号：";cin>>processNumber; //输入需分配资源的进程号if(processNumber>4)cout<<"\n进程号不正确，请输入正确的进程号！\n";else{if(queue[processNumber].ifWait==1)cout<<"\n该进程处于等待状态，不能请求资源，请输入进程号！\n";else{if(Need[processNumber].A==0 && Need[processNumber].B==0 && Need[processNumber].C==0)cout<<"\n该进程已执行完毕，不需要请求资源，请输入进程号！\n";elsebreak;}}}while(1){cout<<"\n请输入三个整数，分别代表P"<<processNumber<<"所请求的A、B、C的资源数：";cin>>A>>B>>C; //输入进程请求的资源数if(A>Need[processNumber].A || B>Need[processNumber].B || C>Need[processNumber].C )cout<<"\n错误！请求的资源数超出进程所需的最大资源数\n";elsebreak;}if(A>Available.A || B>Available.B || C>Available.C) //如果进程请求的资源数大于当前可利用的资源数，则进程进入等待队列等待enqueue(processNumber,A,B,C);cout<<"\n进程请求的资源数<"<<A<<","<<B<<","<<C<<">大于当前可利用的资源数，进程进入等待队列等待!\n";}else{distributeTime++;//试分配资源distributeSource(processNumber,A,B,C);if(flag){//遍历等待队列，查找是否有进程的请求可被满足searchQueue();}}}}int main(){printTitle(); //打印算法标题InitSourceDistributionTable(); //初始化T0时刻的资源分配表printSourceDistributionTable(); //打印T0时刻的资源分配表IfExistSafeSequence(); //判断T0 时刻是否存在安全序列if(flag)printSafeSequence(); //打印T0 时刻的安全序列BankerAlgorithm(); //开始分配请求的资源system("pause");}。