最终版本！！ 操作系统--磁头引臂调度 SCAN算法）

说明具体要求运行结果完整代码请求构造类磁盘构造类算法设计类

说明

前几次的磁头引臂调度博客写的跟小孩过家家似的，实现起来也并非题目的本意。这次的实现是借鉴了Hansen管程的思想，快抛弃前面的几篇，来看这个~

具体要求

运行结果

完整代码

请求构造类

package com.guangluo.OSDesign; import java.util.HashMap; import java.util.LinkedList; import java.util.Random; import java.util.Set; import java.util.concurrent.locks.LockSupport; public class Creator { public HashMap<Thread, Integer> create() { HashMap<Thread, Integer> hm = new HashMap<Thread, Integer>(); // 容器：存放 线程-请求 键值对 MyThread mt = new MyThread(); for(int i = 0; i < 8; i++) { int req = new Random().nextInt(200); Thread t = new Thread(mt, "Thread_"+i); t.start(); hm.put(t, req); } System.out.println("请求序列: 线程--请求"); Set<Thread> keys = hm.keySet(); for(Thread key: keys) { System.out.println(key.getName() + " -- " + hm.get(key)); } return hm; } } class MyThread implements Runnable{ @Override public void run() { LockSupport.park(); // 模拟调度的线程被创建后立即进入阻塞状态，等相应的调度算法按调度顺序将他们唤醒 } } }

磁盘构造类

package com.guangluo.OSDesign; public class Disk { private int currentDist = 100; private int requireNum = 0; private static float m = 1; // 跨越一个磁道所用的时间 单位 ms private int n; // 跨越的磁道数 private static float s = 0; // 启动时间 单位 ms private static float r = 100; // 磁盘转速 单位r/s private static int num = 100; // 扇区数 public void set(int rn, int n) { this.requireNum = rn; this.n = n; } public int getCurrentDist() { return currentDist; } public void setCurrentDist(int newCurrentDist) { this.currentDist = newCurrentDist; } public void showTime() { float t1 = m * n + s; float t2 = (float)(1 / (2*r)) * 1000 * requireNum; float t3 = (float)(1 / (r*num)) * 1000 * requireNum; float t = t1+ t2 + t3; System.out.println("----------------"); System.out.println("寻道时间：" + t1); System.out.println("旋转延迟：" + t2); System.out.println("传输时间：" + t3); System.out.println("总用时：" + t); // System.out.println("当前所在磁道：" + currentDist); System.out.println("================"); } }

算法设计类

package com.guangluo.OSDesign; import java.util.HashMap; import java.util.Set; import java.util.concurrent.locks.LockSupport; public class SCAN { private int direction = 1; // 1:up -1:down public static void main(String[] args) { Creator creator = new Creator(); HashMap<Thread, Integer> hm = creator.create(); int requireNum = hm.size(); Disk disk = new Disk(); SCAN s = new SCAN(); int n = s.scan(hm, disk); disk.set(requireNum, n); disk.showTime(); } public int scan(HashMap<Thread, Integer> hm, Disk disk) { System.out.println("----------------"); System.out.println("SCAN算法调度序列:"); System.out.println("磁头初始在100位置、移动方向为up"); int[] count = new int[200]; this.require(hm, count); int n = this.release(hm, count, disk); return n; } public void require(HashMap<Thread, Integer> hm, int[] count) { Set<Thread> keys = hm.keySet(); for(Thread key: keys) { // System.out.println(hm.get(key)); count[hm.get(key)] += 1; // System.out.println(count[hm.get(key)]); } } public int upscan(HashMap<Thread, Integer> hm, int[] count, Disk disk) { int i = disk.getCurrentDist(), num = 0, absNum = 0; Thread removeKey = null; while(i <= 199) { while(i <= 199 && count[i] == 0) { i += 1; absNum += 1; } if(i <= 199) { num += absNum; absNum = 0; count[i] -= 1; Set<Thread> keys = hm.keySet(); for(Thread key: keys) { if(hm.get(key) == i) { System.out.println(key.getName() + " -- " + hm.get(key)); // hm.remove(key); // 错误做法 removeKey = key; LockSupport.unpark(key); } } hm.remove(removeKey); disk.setCurrentDist(i); i = disk.getCurrentDist(); } } this.direction = -1; return num; } public int downscan(HashMap<Thread, Integer> hm, int[] count, Disk disk) { int i = disk.getCurrentDist(), num = 0, absNum = 0; Thread removeKey = null; while(i >= 0) { while(i >= 0 && count[i] == 0) { i -= 1; absNum += 1; } if(i >= 0) { num += absNum; absNum = 0; count[i] -= 1; Set<Thread> keys = hm.keySet(); for(Thread key: keys) { if(hm.get(key) == i) { System.out.println(key.getName() + " -- " + hm.get(key)); removeKey = key; LockSupport.unpark(key); } } hm.remove(removeKey); disk.setCurrentDist(i); i = disk.getCurrentDist(); } } this.direction = 1; return num; } public int release(HashMap<Thread, Integer> hm, int[] count, Disk disk) { int n = 0; if(this.direction == 1) { n += this.upscan(hm, count, disk); n += this.downscan(hm, count, disk); } else if(this.direction == -1){ n += this.downscan(hm, count, disk); n += this.upscan(hm, count, disk); } return n; } }