srtf.py

class Process:
    def __init__(self, pid, at, bt, priority=None):
        self.pid = pid
        self.at = at
        self.bt = bt
        self.priority = priority
        self.ct = None
        self.tat = None
        self.wt = None
        self.bt_remaining = bt
        self.completed = 0
        self.start_time = None
        self.rt = None


def runScheduler(processes: "list[Process]"):
    n = len(processes)
    completed = 0
    current_time = 0
    current_p = -1
    while completed != n:
        current_p = -1
        mn = 1000000000
        for i in range(n):
            if processes[i].at <= current_time and processes[i].completed == 0:
                if processes[i].bt_remaining < mn:
                    mn = processes[i].bt_remaining
                    current_p = i
                if processes[i].bt_remaining == mn:
                    if processes[i].at < processes[current_p].at:
                        mn = processes[i].bt_remaining
                        current_p = i
        if current_p != -1:
            if processes[current_p].bt_remaining == processes[current_p].bt:
                processes[current_p].start_time = current_time
            processes[current_p].bt_remaining = processes[current_p].bt_remaining - 1
            current_time = current_time + 1
            if processes[current_p].bt_remaining == 0:
                processes[current_p].ct = current_time
                processes[current_p].completed = 1
                completed = completed + 1
        else:
            current_time = current_time + 1



def findTurnAroundTime(processes):
    total_tat = 0
    for i in range(len(processes)):
        # tat = ct[i] - at[i]
        tat = processes[i].ct - processes[i].at
        total_tat = total_tat + tat
        processes[i].tat = tat
    return total_tat


def findWaitingTime(processes):
    total_wait = 0
    for i in range(len(processes)):
        # wt[i] = tat[i] - bt[i]
        wt = processes[i].tat - processes[i].bt
        processes[i].wt = wt
        total_wait = total_wait + wt

    return total_wait


def findAvgTime(processes):
    n = len(processes)
    # # run scheduling algorithm: priority scheduling

    runScheduler(processes)
    processes.sort(key=lambda x: x.ct)
    # Function to find turn around time for all processes
    total_tat = findTurnAroundTime(processes)
    # Function to find wait time for all processes
    total_wt = findWaitingTime(processes)
    # Display processes along with all details
    print("PID\tAT\tBT" + "\tCT" + "\tTAT\tWT")

    for i in range(n):
        print(str(processes[i].pid) + "\t" + str(processes[i].at) + "\t" + str(processes[i].bt) + "\t" + str(
            processes[i].ct) + "\t" + str(processes[i].tat) + "\t" + str(processes[i].wt) + "\t"
              # str(processes[i].priority) + "\t"
              )
    print("Average waiting time = " + str(total_wt / n))
    print("Average turn around time = " + str(total_tat / n))


if __name__ == "__main__":
    process_list = [
        Process(pid=1, at=2, bt=6),
        Process(pid=2, at=5, bt=2),
        Process(pid=3, at=1, bt=8),
        Process(pid=4, at=0, bt=3),
        Process(pid=5, at=4, bt=4)
    ]
    findAvgTime(process_list)