批处理系统的作业调度.cpp

操作系统C++编程——批处理系统的作业调度.c

//vc++ 6.0
#include <iostream>
#include <vector>
using namespace std;

int sysmemory=64*1024, sysprinter=4, systape=2;

typedef  struct  jcb
{

	char  name[5];				    //作业名
    int  length;					//作业长度，所需主存大小
    int  printer;					//作业执行所需打印机的数量
    int  tape;					    //作业执行所需磁带机的数量
    int  runtime;					//作业估计执行时间
    int  waittime;					//作业在系统中的等待时间
    int  next;						//指向下一个作业控制块的指针
} JCB   ;

//#define n 10					//假定系统中可容纳的作业数量为n
JCB  jobtable[10];				//作业表
//int  jobcount;

int  head;    //现在后备作业头；
int  runhead; //现在的运行作业；

struct Avaliable
{
	int mememory;
	int printer;
	int tape;
} cur;

void Done();
int Select();
void Init();
void FinishJob();
void FinishAll();

int main (void)
{
	Init();
	while(1)
	{
		Select();
	}
	return 0;
}    	

void Init()
{
	head = 0;
	runhead = -1;
	int jobcount = 0;
	cur.mememory = sysmemory;
	cur.printer  =sysprinter;
	cur.tape     = systape;
	cout << "Enter the number of jobs you want to put in( 2~10):\n";
	cin >> jobcount;
	while (jobcount >10 || jobcount <2)
	{
		cout << "Invaliad number of jobs.Please enter a new one (2~10):\n";
		cin >> jobcount;
	}
	for (int i =0;i<jobcount;i++)
	{
		cout<<"Enter the JOBNAME of NO."<<i+1<<endl;
		cin>>jobtable[i].name;
		jobtable[i].name[4]='\0';
		
		cout<<"Enter the job's LENGTH(1~65536)"<<endl;
		cin>>jobtable[i].length;
		while(jobtable[i].length<=0||jobtable[i].length>sysmemory){	
			cout<<"Enter error!"<<"\nInvaliad length.Please enter a new one (1～65536)：\n";
			cin>>jobtable[i].length;
		}
		
		cout<<"Enter how many PRINTERS the job need(<=4)"<<endl;
		cin>>jobtable[i].printer;
		while(jobtable[i].printer>4|| jobtable[i].printer<0){	
			cout<<"Enter error!"<<"\nInvaliad number of needed printers.Please enter a new one (0~4):\n";
			cin>>jobtable[i].printer;
		}
		
	
		cout<<"Enter how many TAPES the job need(<=2)"<<endl;
		cin>>jobtable[i].tape;
		while(jobtable[i].tape>2 || jobtable[i].tape<0){		
			cout<<"Enter error!"<<"\nInvaliad number of needed tapes.Please enter a new one (0~2):\n";
			cin>>jobtable[i].tape;
		}
		
		cout<<"Enter the RUNTIME that the job may run(>0):\n";
		cin>>jobtable[i].runtime;
		while(jobtable[i].runtime<1){		
			cout<<"Enter error!"<<"\nInvaliad runtime.Please enter a new one:\n";
			cin>>jobtable[i].runtime;
		}
		
		cout<<"Enter the time the job has waited(>=0):\n";
		cin>>jobtable[i].waittime;
		while(jobtable[i].waittime<0){		
			cout<<"Enter error!"<<"\nInvaliad waitingtime.Please enter a new one:\n";
			cin>>jobtable[i].waittime;
		}
		jobtable[i].next = i+1;
	}
	jobtable[jobcount-1].next = -1;
}

int Select()
{
	int now;
	vector<int> selected;
	if (head <0)
	{
		Done();
	}
	//selected.clear();
	for (now = head;now >=0;now = jobtable[now].next)
	{
		if (jobtable[now].length<=cur.mememory && jobtable[now].printer <=cur.printer && jobtable[now].tape <=cur.tape)
		{
			selected.push_back(now);
		}
	}
	if (selected.size()==0)
	{
		FinishJob();
		return 0;
	}
	int best=selected[0];
	float bestv = jobtable[best].waittime / jobtable[best].runtime;
	for (int i =1;i<selected.size();i++)
	{
		int tmp = selected[i];
		if (jobtable[tmp].waittime / jobtable[tmp].runtime > bestv)
		{
			bestv = jobtable[tmp].waittime / jobtable[tmp].runtime;
			best = tmp;
		}
	}
	cout << "Start doing job No." << best+1
		<< "  job name:" << jobtable[best].name
		<< "  used "  << jobtable[best].length << " of memeory ,"
		<<jobtable[best].printer <<" printers, "
		<<jobtable[best].tape    << " tapes."
		<<endl;
	if (runhead < 0)
	{		
		runhead = best;
		if (head == best)
		{
			head = jobtable[best].next;
		}else{
			int i;
			for(i= head;jobtable[i].next!=best;i=jobtable[i].next)
				;
			jobtable[i].next=jobtable[best].next;
		}
		jobtable[best].next = -1;
	}else{
		int i;
		for(i= runhead;jobtable[i].next>=0;i=jobtable[i].next)
			;
		jobtable[i].next=best;
		if (head == best)
		{
			head = jobtable[best].next;
		}else{
			for(i= head;jobtable[i].next!=best;i=jobtable[i].next)
				;
			jobtable[i].next=jobtable[best].next;
		}
		jobtable[best].next = -1;
	}
	cur.mememory -= jobtable[best].length;
	cur.printer -= jobtable[best].printer;
	cur.tape   -=  jobtable[best].tape;
	return 1;
}

void Done()
{
	FinishAll();
	cout << "All job has been done\n";
	exit(0);
}

void FinishJob()
{
	if (runhead <0)
	{
		cout << "Error!! There is a job can never be selected as limits to the resourse\n";
		Done();
	}
	int selected=runhead;
	int lesttime=jobtable[runhead].runtime;
	for (int i=runhead;i>=0;i=jobtable[i].next)
	{
		if (lesttime < jobtable[i].runtime)
		{
			lesttime = jobtable[i].runtime;
			selected = i;
		}
	}

	for (int m=runhead;m>=0;m=jobtable[m].next)
	{
		jobtable[m].runtime -= lesttime;
		jobtable[m].waittime += lesttime;
	}
	if (selected==runhead)
	{
		runhead = jobtable[runhead].next;
	}else
	{
		int m;
		for (m=runhead;jobtable[m].next!=selected;m=jobtable[m].next)
			;
		jobtable[m].next = jobtable[selected].next;
	}
	cur.mememory += jobtable[selected].length;
	cur.printer  +=jobtable[selected].printer;
	cur.tape     += jobtable[selected].tape;
	cout << "Finied job No."<<selected+1
		<< "Get "<<jobtable[selected].length << " memeory,"
		<<jobtable[selected].printer  << " printers, "
		<<jobtable[selected].tape     << " tapes."
		<<endl;
}

void FinishAll()
{
	for (int m=runhead;m>=0;m=jobtable[m].next)
	{
		cout << "Finied job No."<<m+1
			<< "Get "<<jobtable[m].length << " memeory,"
			<<jobtable[m].printer  << " printers, "
			<<jobtable[m].tape     << " tapes."
			<<endl;
	}
	cout << "请输入e结束程序：";
	char e;
	cin>>e;
}