private Process TryLoadProcessFromQueue()
{
if (ProcessesQueue.Count > 0)
{
if (Algorithm == SchedulerAlgorithm.FCFS)
{
var processFromQueue = ProcessesQueue[0];
//Process can be loaded from queue
if (processFromQueue.ArrivalTime <= CurrentTime && processFromQueue.LastEnterTime == -1 ||
processFromQueue.LastExitTime + processFromQueue.IOTime <= CurrentTime)
{
ProcessesQueue.RemoveAt(0);
processFromQueue.Status = ProcessStatus.OnCpu;
processFromQueue.LastEnterTime = CurrentTime;
return(processFromQueue);
}
}
else if (Algorithm == SchedulerAlgorithm.SJF)
{
int shortestJobAvailableDuration = int.MaxValue;
int it = 0;
int processFromQueuePosition = -1;
Process processFromQueue = null;
for (; it < ProcessesQueue.Count; it++)
{
Process p = ProcessesQueue[it];
if (((p.ArrivalTime <= CurrentTime && p.LastEnterTime == -1) || (p.LastExitTime + p.IOTime <= CurrentTime && p.LastExitTime != -1)) &&
(p.BurstTime < p.RemainingDuration ? p.BurstTime : p.RemainingDuration) < shortestJobAvailableDuration)
{
processFromQueue = CloneObject.CloneJson(p);
processFromQueuePosition = it;
shortestJobAvailableDuration = p.BurstTime < p.RemainingDuration ? p.BurstTime : p.RemainingDuration;
}
}
if (processFromQueue != null)
{
ProcessesQueue.RemoveAt(processFromQueuePosition);
processFromQueue.Status = ProcessStatus.OnCpu;
processFromQueue.LastEnterTime = CurrentTime;
return(processFromQueue);
}
}
}
return(null);
}
//SJF = Shortest Job First
public void solveSJF()
{
CurrentTime = 0;
Status = SchedulerStatus.On;
ProcessesQueue = ProcessesList;
//Queue Starts with ascending order of processes by Arrival Time.
ProcessesQueue = ProcessesQueue.OrderBy(c => c.ArrivalTime).ThenBy(c => c.BurstTime).ToList();
//Load first Process
while (ProcessesQueue[0].ArrivalTime > CurrentTime)
{
KeyTime keyTime = new KeyTime();
keyTime.CpuOnLoad = false;
keyTime.Process = null;
keyTime.OngoingProcess = null;
keyTime.OutgoingProcess = null;
keyTime.Timestamp = CurrentTime;
++CurrentTime;
KeyTimes.Add(keyTime);
}
//First process comes at moment zero (special scenario)
if (CurrentTime == 0 && ProcessesQueue[0].ArrivalTime == 0)
{
Process firstProcess = ProcessesQueue[0];
ProcessesQueue.RemoveAt(0); //Remove selected process from the queue
KeyTime keyTime = new KeyTime();
keyTime.CpuOnLoad = true;
keyTime.OutgoingProcess = null;
keyTime.Timestamp = CurrentTime;
firstProcess.LastEnterTime = CurrentTime;
firstProcess.Status = ProcessStatus.OnCpu;
keyTime.OngoingProcess = firstProcess;
KeyTimes.Add(keyTime);
++CurrentTime;
}
//Continue processing
KeyTime currentKeyTime = new KeyTime();
KeyTime lastKeyTime = KeyTimes[CurrentTime - 1];
while (ProcessesQueue.Count > 0 || lastKeyTime.OngoingProcess != null || currentKeyTime.OngoingProcess != null)
{
currentKeyTime = new KeyTime();
lastKeyTime = KeyTimes[CurrentTime - 1];
currentKeyTime.Timestamp = CurrentTime;
//Last process action on current moment
var lastOngoingProcessResult = CheckForProcessContinuity(CloneObject.CloneJson(lastKeyTime.OngoingProcess));
//Process ongoing on the CPU. No replacements actions needed
if (lastOngoingProcessResult != null && lastOngoingProcessResult.Item2 != null)
{
currentKeyTime.OutgoingProcess = null;
currentKeyTime.OngoingProcess = lastOngoingProcessResult.Item2;
currentKeyTime.CpuOnLoad = true;
if (currentKeyTime.OngoingProcess.ResponseTime == 0)
{
currentKeyTime.OngoingProcess.ResponseTime = CurrentTime;
}
++AverageCPUUtilisation;
}
else
{
if (lastOngoingProcessResult != null)
{
currentKeyTime.OutgoingProcess = lastOngoingProcessResult.Item1;
}
currentKeyTime.OngoingProcess = TryLoadProcessFromQueue();
if (currentKeyTime.OngoingProcess != null)
{
++AverageCPUUtilisation;
if (currentKeyTime.OngoingProcess.ResponseTime == 0)
{
currentKeyTime.OngoingProcess.ResponseTime = CurrentTime;
}
}
}
KeyTimes.Add(currentKeyTime);
AverageWaitingProcesses += ProcessesQueue.Count;
++CurrentTime;
}
Status = SchedulerStatus.Off;
}