（操作系统）编写进程调度算法程序

3.1 先来先服务算法3.1.1 算法思想 该算法思想是按照进入就绪队列的先后次序来分配处理机。FCFS采用非剥夺调度方式，即一旦某个进程占有处理机，就一直运行下去，直到该进程完成其工作或因等待某一事件而不能继续执行时才释放处理机。

#include<iostream>
#include<string>
#include<iomanip>
#include<windows.h>
using namespace std;
typedef struct Process
{ string id;
int arrive_time;
int sever_time;
int finish_time;
int turnover_time;
Process * next;
}Process,* Linkp; class FCFS_schedule
{ public: FCFS_schedule()
{
Creat_queue();
}
~FCFS_schedule();
void Creat_queue();
void Insert_queue();
void orderInsert_queue();
void Out_queue();
void Printall();
void Sort_queue();
Process Gethead();
private:
Linkp head,tail;
int num;
Process Creat_process();
};///////////////////////////////////////////////////////方法的具体实现void FCFS_schedule::Creat_queue()
{ head=new Process;
head->next=0;
tail=head;
num=0;
}
ostream& operator <<(ostream& out,Process& a) //对插入流运算符<<进行重载
{ out<<"process id:"<<a.id <<" arrivetime:"<<a.arrive_time
<<" severtime:"<<a.sever_time<<endl;
return(out);
}Process FCFS_schedule::Creat_process()
{ Process a;

cout<<"please input process id"<<num+1<<":";
cin>>a.id ;
cout<<"please input process arrivetime:";
cin>>a.arrive_time ;
cout<<"please input process severtime:";
cin>>a.sever_time ;
a.finish_time=0;
a.turnover_time=0;
a.next =0;
return(a);
} void FCFS_schedule::Insert_queue ()
{ Linkp p;
p=new Process;
*p=Creat_process();
if(num==0)
{p->finish_time=p->arrive_time+p->sever_time;<br> p->turnover_time=p->finish_time-p->arrive_time ;<br> }
else
{p->finish_time=tail->finish_time + p->sever_time ;<br> p->turnover_time=p->finish_time - p->arrive_time ;<br> }
tail->next=p;
tail=p;
num++;
}
void FCFS_schedule::Out_queue() //进程调度出队
{ Linkp p;
p=head->next;
if(!p) cout<<"empty!\n";
else
{ head->next=p->next;
if(p->next==NULL) tail=head;
cout<<"process id:"<<p->id<<" arrivetime:"<<p->arrive_time
<<" severtime:"<<p->sever_time<<" finishtime:"<<p->finish_time
<<" turnovertime:"<<p->turnover_time <<endl;
delete p;
num--;
}
}
Process FCFS_schedule::Gethead()throw(int)

{ Linkp p;
p=head->next;
if(p) return(*p);
else throw 1; //当队空无法返回Process类型返回值时抛出异常错误整形值1

}
void FCFS_schedule::Printall()
//打印进程队列所有进程信息
{ Linkp p;
float sum_wghtime=0;
p=head->next;
cout<<" Process Information\n";
cout<<"process id arrivetime severtime finishtime turnovertime weightime\n";
while(p)
{ cout<<p->id<<setw(14)<<p->arrive_time
<<setw(14)<<p->sever_time<<setw(14)<<p->finish_time<<setw(14)<<p->turnover_time
<<setw(14)<<float(p->turnover_time)/float(p->sever_time )<<endl;
sum_wghtime=sum_wghtime+(float)p->turnover_time/p->sever_time;
p=p->next;
}
cout<<"平均带权周转时间为:"<<sum_wghtime/num<<endl;
}
void FCFS_schedule::Sort_queue ()
//采用选择法将队列中的进程按servertime长短进行换值不换址的排序{ Linkp location,search,record,track;
Process temp;
track=head->next;
location=track->next ;
while(location && location->next )
{ record=search=location;

while(search)
{ if(search->sever_time <record->sever_time ) record=search;
search=search->next ;
} if(record!=location)
{
temp=*record;
record->arrive_time =location->arrive_time ;
record->id =location->id ;
record->sever_time =location->sever_time ;

location->id =temp.id;
location->sever_time =temp.sever_time ;
location->arrive_time =temp.arrive_time ;
location->finish_time =track->finish_time + location->sever_time ;
location->turnover_time =location->finish_time - location->arrive_time ;
}
track=location;
location=location->next ;
}
if(tail==location)
{tail->finish_time = track->finish_time +tail->sever_time ;<br> tail->turnover_time =tail->finish_time -tail->arrive_time ;<br> }}
FCFS_schedule::~FCFS_schedule ()
{ Linkp p;
while(p=head)
{
head=head->next ;
delete p;
}
cout<<"the storage of memory has been distory!\n";
} void FCFS_schedule::orderInsert_queue () //进程插入排序
{ Linkp p,pr;
p=new Process;
*p=Creat_process(); if(num==0)
{
head->next=p;
tail=p;
p->finish_time =p->arrive_time + p->sever_time ;
p->turnover_time =p->finish_time - p->arrive_time ;
}
else
{
pr=head->next ;
while(pr->next && p->sever_time >= pr->next->sever_time )
pr=pr->next;
if(pr->next==0)
{
p->finish_time = tail->finish_time + p->sever_time ;
p->turnover_time =p->finish_time - p->arrive_time ;
tail->next=p;
tail=p;
}
else
{
p->next =pr->next ;
pr->next=p;
while(p)
{
p->finish_time =pr->finish_time + p->sever_time ;
p->turnover_time = p->finish_time - p->arrive_time ;
pr=p;
p=p->next ;
}
}

}
num++;
} void main()
{
// DWORD start=GetTickCount();

FCFS_schedule os;
os.orderInsert_queue ();
os.orderInsert_queue ();
os.orderInsert_queue ();
os.orderInsert_queue ();
os.orderInsert_queue ();
// os.orderInsert_queue ();
// os.orderInsert_queue ();
os.Printall ();
// os.Sort_queue ();
os.Sort_queue ();
os.Printall ();
os.Out_queue ();
os.Out_queue ();
os.Out_queue ();
os.Out_queue ();
/* try{
cout<<os.Gethead () ;
}
catch(int i)
{ if(i==1) cout<<"empty!\n";
}*/
//
// DWORD end=GetTickCount();
// cout<<"spend time:"<<(end-start)<<endl;
/*

os.Out_queue ();
*/
}

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