const Consts = require("./consts");
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const Scheduler = require("./scheduler");
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/**
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* 负载均衡器
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* @intro 参考electron-re项目，并做了一些改动
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* @since 1.0.0
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*/
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class LoadBalancer {
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static Algorithm = Consts;
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/**
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* @param {Object} options
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* @param {Array } options.targets [ targets for load balancing calculation: [{id: 1, weight: 1}, {id: 2, weight: 2}] ]
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* @param {String} options.algorithm
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*/
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constructor(options) {
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this.targets = options.targets;
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this.algorithm = options.algorithm || Consts.polling;
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this.params = { // data for algorithm
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currentIndex: 0, // index
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weightIndex: 0, // index for weight alogrithm
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weightTotal: 0, // total weight
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connectionsMap: {}, // connections of each target
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cpuOccupancyMap: {}, // cpu occupancy of each target
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memoryOccupancyMap: {}, // cpu occupancy of each target
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};
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this.scheduler = new Scheduler(this.algorithm);
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this.memoParams = this.memorizedParams();
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this.calculateWeightIndex();
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}
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/**
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* 算法参数
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*/
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memorizedParams() {
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return {
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[Consts.random]: () => [],
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[Consts.polling]: () => [this.params.currentIndex, this.params],
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[Consts.weights]: () => [this.params.weightTotal, this.params],
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[Consts.specify]: (id) => [id],
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[Consts.weightsRandom]: () => [this.params.weightTotal],
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[Consts.weightsPolling]: () => [this.params.weightIndex, this.params.weightTotal, this.params],
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[Consts.minimumConnection]: () => [this.params.connectionsMap],
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[Consts.weightsMinimumConnection]: () => [this.params.weightTotal, this.params.connectionsMap, this.params],
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};
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}
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/**
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* 刷新参数
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*/
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refreshParams(pidMap) {
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const infos = Object.values(pidMap);
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for (let info of infos) {
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// this.params.connectionsMap[id] = connections;
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this.params.cpuOccupancyMap[info.pid] = info.cpu;
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this.params.memoryOccupancyMap[info.pid] = info.memory;
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}
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}
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/**
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* 选举出一个进程
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*/
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pickOne(...params) {
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return this.scheduler.calculate(
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this.targets, this.memoParams[this.algorithm](...params)
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);
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}
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/**
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* 选举出多个进程
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*/
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pickMulti(count = 1, ...params) {
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return new Array(count).fill().map(
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() => this.pickOne(...params)
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);
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}
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/**
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* 计算权重
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*/
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calculateWeightIndex() {
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this.params.weightTotal = this.targets.reduce((total, cur) => total + (cur.weight || 0), 0);
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if (this.params.weightIndex > this.params.weightTotal) {
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this.params.weightIndex = this.params.weightTotal;
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}
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}
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/**
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* 计算索引
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*/
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calculateIndex() {
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if (this.params.currentIndex >= this.targets.length) {
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this.params.currentIndex = (this.params.currentIndex - 1 >= 0) ? (this.params.currentIndex - 1) : 0;
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}
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}
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/**
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* 清除data
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*/
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clean(id) {
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if (id) {
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delete this.params.connectionsMap[id];
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delete this.params.cpuOccupancyMap[id];
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delete this.params.memoryOccupancyMap[id];
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} else {
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this.params = {
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currentIndex: 0,
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connectionsMap: {},
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cpuOccupancyMap: {},
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memoryOccupancyMap: {},
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};
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}
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}
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/**
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* 添加一个进程信息
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*/
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add(task) {
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if (this.targets.find(target => target.id === task.id)) {
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return console.warn(`Add Operation: the task ${task.id} already exists.`);
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}
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this.targets.push(task);
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this.calculateWeightIndex();
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}
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/**
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* 删除一个进程信息
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*/
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del(target) {
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let found = false;
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for (let i = 0; i < this.targets.length; i++) {
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if (this.targets[i].id === target.id) {
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this.targets.splice(i, 1);
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this.clean(target.id);
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this.calculateIndex();
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found = true;
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break;
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}
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}
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if (found) {
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this.calculateWeightIndex();
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} else {
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console.warn(`Del Operation: the task ${target.id} is not found.`, this.targets);
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}
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}
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/**
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* 擦除
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*/
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wipe() {
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this.targets = [];
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this.calculateWeightIndex();
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this.clean();
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}
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/**
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* 更新计算参数
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*/
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updateParams(object) {
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Object.entries(object).map(([key, value]) => {
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if (key in this.params) {
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this.params[key] = value;
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}
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});
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}
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/**
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* 设置targets
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*/
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setTargets(targets) {
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const targetsMap = targets.reduce((total, cur) => {
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total[cur.id] = 1;
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return total;
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}, {});
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this.targets.forEach(target => {
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if (!(target.id in targetsMap)) {
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this.clean(target.id);
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this.calculateIndex();
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}
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});
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this.targets = targets;
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this.calculateWeightIndex();
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}
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/**
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* 设置算法
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*/
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setAlgorithm = (algorithm) => {
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if (algorithm in Consts) {
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this.algorithm = algorithm;
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this.params.weightIndex = 0;
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this.scheduler.setAlgorithm(this.algorithm);
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} else {
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throw new Error(`Invalid algorithm: ${algorithm}, pick from ${Object.keys(Consts).join('|')}`);
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}
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}
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}
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module.exports = LoadBalancer;
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