// executes process' swap in the CPU based on the "ready processes list" and
// the routing algorithm(preemptive or non-preemptive)
public void SJF(int currentTime) {
Process cpuProcess = cpu.peekCpuProcess();
Process HeadofQueue =
getReadyList()
.getReadyList()
.peek(); // first process of the ready queue/the one with the lowest burst
if (!isPreemptive) {
if (cpuProcess != null) {
if (cpuProcess.getCpuRemainingTime() == 0) {
// zero remaining time means that the process is finished, therefore update number of
// finished processes and total waiting time
if (stats != null) {
stats.updatetotalwait(cpuProcess, currentTime); // total waiting time update
stats.updatemyfinished(); // update number of finished processes
}
cpu.removeProcessFromCpu();
if (stats != null) {
stats.updateFinishedNumber(1); // edit
stats.updateResponseTime(currentTime - cpuProcess.getArrivalTime()); // edit.
}
}
}
cpuProcess = cpu.peekCpuProcess();
if (cpuProcess == null) {
Process forCPU = getReadyList().getProcessToRunInCPU();
if (forCPU != null) {
cpu.addProcess(forCPU);
cpu.setLastProcessStartTime(currentTime);
}
}
}
// //////////////////PREEMPTIVE////////////////////
else if (isPreemptive) {
if (cpuProcess != null) {
if (cpuProcess.getCpuRemainingTime() == 0) { // same as non-preemptive
// zero remaining time means that the process is finished, therefore update number of
// finished processes and total waiting time
if (stats != null) {
stats.updatetotalwait(cpuProcess, currentTime); // total waiting time update
stats.updatemyfinished(); // update number of finished processes
}
cpu.removeProcessFromCpu();
if (stats != null) {
stats.updateFinishedNumber(1);
stats.updateResponseTime(currentTime - cpuProcess.getArrivalTime());
}
} else if ((HeadofQueue != null)
&& (cpuProcess.getCpuRemainingTime()
> HeadofQueue
.getCpuRemainingTime())) { // null check + compare the remaining CPU times
// between the current CPU process and the one on the
// top of the Queue
readyList.addProcess(
cpu.removeProcessFromCpu()); // remove current Process and put it again at ready list
Process forCPU =
getReadyList().getProcessToRunInCPU(); // add the one from the top of the queue
{
if (forCPU.getCpuTotalTime() == forCPU.getCpuTotalTime()) {
if (stats != null) stats.updateResponseTime(currentTime - forCPU.getArrivalTime());
}
cpu.addProcess(forCPU);
cpu.setLastProcessStartTime(currentTime);
}
}
}
cpuProcess = cpu.peekCpuProcess();
if (cpuProcess == null) { // if CPU isn't occupied
Process forCPU =
getReadyList().getProcessToRunInCPU(); // get process from the top of the Queue
if (forCPU != null) {
if (forCPU.getCpuTotalTime() == forCPU.getCpuTotalTime()) {
if (stats != null) stats.updateResponseTime(currentTime - forCPU.getArrivalTime());
}
cpu.addProcess(forCPU); // add to CPU
cpu.setLastProcessStartTime(currentTime);
}
}
}
if (stats != null) {
stats.updateTotalWaitingTime(getReadyList().lengthOfQueue());
stats.WriteStatistics2File(currentTime);
}
}
