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main.js
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main.js
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/**
* @file 项目JS文件
* @author wenhui-huang(wenhui-huang@qq.com)
*/
//磁道序列数组
let trackSequence = [];
/**
* 磁盘磁道总个数
* @type {Number}
*/
const track = 150;
/**
* 需要生成的磁道序列个数
* @type {Number}
*/
const trackNumber = 40;
/**
* 生成[minNum,maxNum]的随机整数
*
* @param {number} minNum 最小的数
* @param {number} maxNum 最大数
* @return {number} 产生的随机数
*/
function randomNum(minNum,maxNum) {
switch(arguments.length){
case 1:
return parseInt(Math.random() * minNum + 1, 10);
break;
case 2:
return parseInt(Math.random() * (maxNum - minNum + 1) + minNum, 10);
break;
default:
return 0;
break;
}
}
/**
* 生成num个磁道号序列
* 其中50%位于 0~49,25%分布在 50~99,25%分布在 100~149
*
* @param {number} num 磁道号序列个数
* @return {Array} trackSequence 磁道号序列数组
*/
function generateTrackNumberSequence(num) {
trackSequence = [];
const firstSequence = num * 0.5;
const secondSequence = num * 0.25;
const thirdSequence = num * 0.25;
for(let i = 0; i <= firstSequence; i++) {
trackSequence.push(randomNum(0,49));
}
for(let i = 0; i <= secondSequence; i++) {
trackSequence.push(randomNum(50,99));
}
for(let i = 0; i <= thirdSequence; i++) {
trackSequence.push(randomNum(100,149));
}
//将数字顺序打乱
for (let i = 1; i < trackSequence.length; i++) {
const random = Math.floor(Math.random() * (i + 1));
[trackSequence[i], trackSequence[random]] = [trackSequence[random], trackSequence[i]];
}
return trackSequence;
}
/**
* 算法选项数组
* @type {Array}
*/
const algorithms = Array.from(document.querySelectorAll('.btn-group > button'));
//用户选择的算法
let algorithmValue = null;
/**
* 记录用户选择的算法选项,并改变该选项的css样式
*
* @param {Object} btn 用户选择的事件对象
*/
function selectAlgorithm(btn) {
algorithmValue = this.dataset.algorithm;
algorithms.forEach(key => key.classList.remove('button-active'));
btn.target.classList.add('button-active');
}
algorithms.forEach(key => key.addEventListener('click', selectAlgorithm));
/**
* 提示信息
*
* @param {String} tips 信息文本
* @param {boolean} bool 是否要提示信息
*/
function showErrorMessage(tips, bool) {
const promptBox = document.querySelector('.error-message');
promptBox.innerHTML = tips;
if(bool) {
promptBox.classList.add('show-error-message');
} else {
promptBox.classList.remove('show-error-message');
}
}
/**
* 检查用户是否选择了算法和输入了磁头初始位置
* 错误时输出相应提示,正确时返回磁头初始位置
*
* @return {string | boolean}
*/
function check() {
const headInitalPosition = document.querySelector('.head-position').value;
if(!algorithmValue) {
showErrorMessage('请选择算法!', true);
return false;
} else if(!headInitalPosition) {
showErrorMessage('请输入磁头初始位置!', true);
return false;
} else {
showErrorMessage('', false);
return headInitalPosition;
}
}
/**
* 先来先服务算法
*
* @param {Array} headPath 磁头路径数组,传入时只包含磁头初始位置
* @return {Array} 磁头将要走过的路径数组
*/
function fcfs(headInitalPosition) {
let headPath = [];
headPath.push(headInitalPosition);
return headPath.concat(trackSequence);
}
/**
* 找到数组最小值并返回下标
*
* @return {number} coor 数组最小值下标
*/
Array.prototype.min = function () {
var min = this[0];
var coor = 0;
this.forEach((ele, index,arr) => {
if(ele < min) {
min = ele;
coor = index;
}
})
return coor;
}
/**
* 最短寻道时间算法
*
* @param {String} headInitalPosition 磁头初始位置
* @return {Array} headPath 磁头路径数组
*/
function sstf(headInitalPosition) {
let headPath = [];
headPath.push(headInitalPosition);
let trackSequenceCopy = trackSequence.concat();
for(let i = 0; i < trackSequence.length; i++) {
let distance = trackSequenceCopy.map(key => Math.abs(key - headPath[i]));
let minCoor = distance.min();
headPath.push(trackSequenceCopy[minCoor]);
trackSequenceCopy.splice(minCoor, 1);
}
return headPath;
}
/**
* 电梯调度算法
*
* @param {number} headInitalPosition 磁头初始位置
* @return {Array} 磁头路径数组
*/
function scan(headInitalPosition) {
let headPath = [];
headPath.push(headInitalPosition);
headPath = headPath.concat((trackSequence.filter(key => key <= headInitalPosition)).sort((a, b) => b - a));
headPath = headPath.concat((trackSequence.filter(key => key > headInitalPosition)).sort((a, b) => a - b));
return headPath;
}
/**
* 循环扫描算法
*
* @param {number} headInitalPosition 磁头初始位置
* @return {Array} 磁头路径数组
*/
function cScan(headInitalPosition) {
let headPath = [];
headPath.push(headInitalPosition);
headPath = headPath.concat((trackSequence.filter(key => key <= headInitalPosition)).sort((a, b) => b - a));
headPath = headPath.concat((trackSequence.filter(key => key > headInitalPosition)).sort((a, b) => b - a));
return headPath;
}
const canvas = document.querySelector('#draw');
const ctx = canvas.getContext('2d');
/**
* 获取css样式
* 如果是height或者width,先去掉单位再返回该属性值
*
* @param {Object} obj 将要获取样式的元素
* @param {String} attr 样式的属性
* @return {Array} cssStyleNumber 属性值
*/
function getStyle(obj,attr){
const cssStyle = obj.currentStyle ? obj.currentStyle[attr] : getComputedStyle(obj)[attr];
if(attr == 'height' || attr == 'width') {
return cssStyle.slice(0, cssStyle.length - 2);
}
return cssStyle;
}
/**
* 画线的方法
*
* @param {number} x1 起点横坐标
* @param {number} y1 起点纵坐标
* @param {number} x2 终点横坐标
* @param {number} y2 终点纵坐标
*/
function drawLine(x1, y1, x2, y2) {
ctx.beginPath();
ctx.moveTo(x1, y1);
ctx.lineTo(x2, y2);
ctx.stroke();
ctx.closePath();
}
/**
* 显示坐标轴上的标记文本
*
* @param {String} text 要显示的文本
* @param {Number} xPos 横坐标
* @param {Number} yPos 纵坐标
*/
function drawText(text, xPos, yPos) {
ctx.textAlign = "center";
ctx.font = "20px Arial";
ctx.fillText(text, xPos, yPos);
}
/**
* 绘制X轴及标记点
*
* @param {Array} xCoorArray 按升序排好的横坐标数组
*/
function drawCoordinateAxis(xCoorArray) {
ctx.strokeStyle = '#566a80';
ctx.fillStyle = '#566a80';
ctx.lineWidth = 2;
for(let i = 0; i < xCoorArray.length; i++) {
const startXCoor = (xCoorArray[i] / track) * canvas.width;
const endYCoor = (xCoorArray[i + 1] / track) * canvas.width;
drawText(xCoorArray[i], startXCoor, 25);
drawLine(startXCoor, 40, endYCoor, 40);
drawLine(startXCoor, 40, startXCoor, 30);
}
}
/**
* 画点
*
* @param {Number} xPos 圆心横坐标
* @param {Number} yPos 圆心纵坐标
* @param {Number} size 圆半径
*/
function drawPoint(xPos, yPos, size) {
ctx.beginPath();
ctx.arc(xPos, yPos, size, 0, Math.PI * 2, true);
ctx.fill();
}
/**
* 绘制折线图
*
* @param {Array} headPath 磁头轨迹数组
*/
function drawLineChart(headPath) {
ctx.strokeStyle = '#566a80';
ctx.fillStyle = '#566a80';
ctx.lineWidth = 2;
ctx.lineJoin = 'round';
ctx.lineCap = 'round';
//起点和终点纵坐标
let startYCoor = 50;
let endYCoor = 60;
for(let i = 0; i < headPath.length; i++) {
//起点和终点横坐标
let startXCoor = (headPath[i] / track) * canvas.width;
let endXCoor = (headPath[i + 1] / track) * canvas.width;
if(startXCoor == endXCoor) {
endYCoor = startYCoor;
}
drawPoint(startXCoor, startYCoor, 5);
drawLine(startXCoor, startYCoor, endXCoor, endYCoor);
startYCoor = endYCoor;
endYCoor += 10;
}
}
/**
* 展示图
*
* @param {Array} headPath 磁头轨迹数组
*/
function showCanvas(headPath) {
//清除画布
ctx.clearRect(0, 0, canvas.width, canvas.height);
canvas.width = getStyle(canvas, 'width') * 2;
canvas.height = getStyle(canvas, 'height') * 2;
let xCoorArray = []
xCoorArray = xCoorArray.concat(headPath);
//横坐标数组
xCoorArray.sort((a, b) => a - b);
console.log(`横坐标数组:${xCoorArray}`);
drawCoordinateAxis(xCoorArray);
drawLineChart(headPath);
}
/**
* 显示磁头移动道数
*
* @param {Array} headPath 磁头移动路径
*/
function showMoveNumber(headPath) {
let moveNumber = [];
for(let i = 1; i < headPath.length; i++) {
moveNumber.push(Math.abs(headPath[i] - headPath[i - 1]));
}
showErrorMessage(`磁头移动道数:${moveNumber.reduce((a, b) => a + b)}`, true);
}
/**
* 生成随机磁道序列
* 根据用户选择的算法和磁头初始位置绘制效果图
*
*/
function start() {
const headInitalPosition = check();
if(headInitalPosition && algorithmValue) {
generateTrackNumberSequence(trackNumber);
console.log(`随机生成的磁道序列:${trackSequence}`);
let headPath = [];
switch(algorithmValue) {
case 'fcfs':
headPath = fcfs(headInitalPosition);
break;
case 'sstf':
headPath = sstf(headInitalPosition);
break;
case 'scan':
headPath = scan(headInitalPosition);
break;
case 'c-scan':
headPath = cScan(headInitalPosition);
break;
}
console.log(`磁头轨迹:${headPath}`);
showCanvas(headPath);
showMoveNumber(headPath);
}
}
document.querySelector('.start-btn').addEventListener('click', start);