SimScheduler

A simple CPU scheduler simulator made in Java for learning purposes. There are two classes which shouldn't be altered, unless you're very certain of what you're doing: CPU and Process. One should implement his scehduling policy inside the Scheduler class.

Compiling

Before anything, you need to have a Java compiler installed (Go either Oracle's SDK or OpenJDK, or any Java SDK you like).

Just go to the root of this project and do (assuming your Java compiler is javac):

javac -d build src/*.java

Running

Go to the build directory and run the OS.class program:

cd build/
java OS

Documentation

Class Process

Constructor

The Process class contains all process related data, including status, execution data and time measuring statistics. The constructor function requires a integer PID and a already instatiated Random number generator (java.util.Random). The constructor will create a radomly generated process with several CPU-Bursts. To create a new process, do:

import java.util.Random;
Random gen = new Random();
Process p = new Process(1, gen);

The Process p will have a PID 1 and will bre ready for execution.

Public Methods

public int getPID()

Returns the Process' PID.

public int getStatus()

Returns the Process' current status:

• 0 - Ready
• 1 - Waiting
• 2 - Finished

public void setStatus (int s)

Sets the status of the process, following the rules above.

public int getNextBurstDuration()

Returns the amount of cycles of the next CPU Burst of the process.

public void executeBurst()

Execute the next CPU burst until the end. If it is the last burst, the process is finished, otherwise, it will wait for I/O.

public int getTurnaround()

Get the total amount of cycles passed since the process creation until its end (Process must be finished).

public void addTotalTime(int cycles)

Add elapsed cycles to the process' turnaround. (Added only when time passed while the process was waiting for I/O).

public double getAvgResponseTime()

Returns the average Response Time across all CPU-I/O Bursts of the process (Process must be finished)

public void addWaitingTime(int cycles)

Add elapsed cycles to the process' time count, only when the process is ready (on the Ready Queue). Adds to response time and waiting time.

public int getWaitingTime()

Returns the Waiting Time of the process (Process must be finished).