Question

Round Robin Simulation in C++ using queue

Description: 
Write a program that utilizes STL queue that simulates the round robin process scheduling algorithm. 

Requirement: 
- write a class Process that holds following integer information: id, arrival_time, time_needed, finished_time.
- read and initiate 5 Process objects from associated file (round_robin.txt)
- file format: id, arrival_time, time_needed
- once a process is finished, mark its finished_time accordingly. 
- CPU time frame: 4. 
- utilize a queue for process scheduling.
- store finished processes into a vector (first finished, first stored)
- output: print information about finished processes from the vector, in the finished order. 

round_robin.txt:

1 0 10
2 1 12
3 5 6
4 6 10
5 7 4

Answer 1

Here is the code:

#include <iostream>
#include <vector>
#include <fstream>

using namespace std;

int main(){
int i,time,remain,temps=0;
int cpu_timeframe = 4;
int wt=0,tat=0;
ifstream file;
vector<int> at;
vector<int> bt;
vector<int> rt;
vector<int> fp; // finished processes
  
file.open("round_robin.txt");
int tmp;
while(! file.eof()) {
file >> tmp; // false read not , not used in code
file >> tmp; // arrival_time
at.push_back(tmp);
file >> tmp; // time needed
bt.push_back(tmp);
rt.push_back(tmp);
}

cout << "finished processes from the vector, in the finished order";
cout<<"\nProcess\t: Turnaround Time: Waiting Time\n";
remain=at.size();
// In round robin simulation,the job scheduler saves current state of the job
// and moves to the another job in the queue.
for(time=0,i=0;remain!=0;) {

if(rt[i]<=cpu_timeframe && rt[i]>0) {
time += rt[i];
rt[i] = 0;
temps = 1;
} else if(rt[i]>0) {
// Every process gets an equal time of execution the CPU timeframe.
rt[i] -= cpu_timeframe;
time += cpu_timeframe;
}
  
if(rt[i]==0 && temps==1) {
remain--;
printf("Process# %d:\t%d\t:\t%d\n",i+1,time-at[i],time-at[i]-bt[i]);
fp.push_back(i+1);
wt += time-at[i]-bt[i];
tat += time-at[i];
temps=0;
}
  
if(i == at.size()-1)
i=0;
else if(at[i+1] <= time)
i++;
else
i=0;
}

cout<<"Average waiting time "<<wt*1.0/at.size()<<endl;
cout<<"Average turn around time "<<tat*1.0/at.size()<<endl;;

return 0;
}

The content of round_robit.txt
1 0 10
2 1 12
3 5 6
4 6 10
5 7 4

The program output: