fcfsprocessschedule.java~35~

来自「进程调度和存储管理模拟」· JAVA~35~ 代码 · 共 92 行

package cn.edu.cauc.crab.ossimulate;

import java.util.*;
import javax.swing.*;

/**
 * <p>Title: OS simulate</p>
 * <p>Description: This is my home work.</p>
 * <p>Copyright: Copyleft (c) 2004</p>
 * <p>Company: CAUC</p>
 * @author Crab
 * @version 0.1
 */

/**
 * To simulate first come first serve process scheduling.
 *
 * @author Crab
 * @version 0.1
 * @see cn.edu.cauc.crab.ossimulate.ProcessSchdule
 */
public class FCFSProcessSchedule extends ProcessSchedule {

    JTextArea out;

    /**
     * extends from ProcessSchedule a List named PCBs
     */
    public FCFSProcessSchedule() {
        super();
    }

    public FCFSProcessSchedule(JTextArea out) {
        super();
        this.out = out;
    }

    /**
     * extends from ProcessSchedule
     * After addProcess() is calling,
     * use to start scheduling.
     */
    public void start() {
        int time = 0;//set the beging time

        while (!PCBs.isEmpty()) {
            PCB pcb = (PCB)PCBs.get(0);//get the fist come process
            PCBs.remove(0);// because the process will finish at once, so remove it.

            if (time >= pcb.arriveTime) {// the process must run >= arrive time
                pcb.beginTime = time;
                time += pcb.serveTime;
                pcb.finishTime = time;
                pcb.rollTime = pcb.finishTime - pcb.arriveTime;
                // use tr ts to rise the precesion.
                float tr = pcb.rollTime;
                float ts = pcb.serveTime;
                pcb.nullWorkRate =  tr / ts;
                if (out == null) {
                    System.out.println("PID: " + pcb.pid
                                       +" Arrive: " + pcb.arriveTime
                                       + " Serve: " + pcb.serveTime
                                       + " Begin: " + pcb.beginTime
                                       + " Finish: " + pcb.finishTime
                                       + " Roll: " + pcb.rollTime
                                       + " nullWorkRate: " + pcb.nullWorkRate);
                } else {
                    out.append("PID: " + pcb.pid
                                       +" Arrive: " + pcb.arriveTime
                                       + " Serve: " + pcb.serveTime
                                       + " Begin: " + pcb.beginTime
                                       + " Finish: " + pcb.finishTime
                                       + " Roll: " + pcb.rollTime
                                       + " nullWorkRate: " + pcb.nullWorkRate
                                       + "\n");
                }
            }
            time = pcb.arriveTime;
        }
    }

    public static void main(String[] args) {
        ProcessSchedule pSch = new FCFSProcessSchedule();

        //pSch.addProcess(new Process(4), 0);
        pSch.addProcess(new Process(3), 1);
        pSch.addProcess(new Process(5), 2);
        pSch.addProcess(new Process(2), 3);
        pSch.addProcess(new Process(4), 4);
        pSch.start();
    }
}