tencentcloud-edgeone-migration-nodejs-v2
Version:
tencentcloud cdn config copy to edgeone
81 lines • 2.64 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.WRRLoadBalancer = void 0;
const utils_1 = require("../../utils");
const base_1 = require("./base");
/**
* Weighted Round-Robin Load Balancer
*
* @description
* Algorithm:
* 1. `S` = {S0, S1, S2, ..., Sn}, `W(Si)` = Si.weight
* 2. CW(Si) = W(Si) / GCD(W(S))
* 3. remaining_value = total_calls % Sum(CW(S))
* 4. Sx = Pick(remaining_value ∈ [Sum(CW(S0)...CW(Si-1)), Sum(CW(S0)...CW(Si))))
* 5. total_calls = total_calls + 1
* 6. return Sx
*/
class WRRLoadBalancer extends base_1.StatelessLoadBalancer {
constructor() {
super(...arguments);
this.name = "WRRLoadBalancer";
this.callStat = Object.create(null);
}
choose(namespace, service, instances) {
// #region Round 1, 预处理
/**
* 当前服务被调用次数
*/
let count = this.callStat[`${namespace}.${service}`];
if (count >= 0) {
count += 1;
}
else {
count = 0;
this.randomChoose(namespace, service, instances);
}
this.callStat[`${namespace}.${service}`] = count;
/**
* 各节点实际权重
*/
let weights = instances.map(instance => ~~this.instanceWeight(instance));
// #endregion
// #region Round 2
/*
* Round 2:
* 1. 计算所有权重的最大最大公约数 `gcd`
* 2. 选取每个权重的互质数 `mpn` 作为新权重
* 3. 计算新权重合
*/
let totalWeight = 0;
const gcd = (0, utils_1.GreatestCommonDivisor)(...weights.filter(weight => weight !== 0));
if (!Number.isNaN(gcd)) {
weights = weights.map((weight) => {
const mpn = weight / gcd;
totalWeight += mpn;
return mpn;
});
}
// #endregion
// #region Round 3, 根据 WRR 算法选取目标节点
if (!Number.isNaN(gcd)) {
const remaining = count % totalWeight;
for (let i = 0, effect = 0; i < weights.length; i += 1) {
effect += weights[i];
if (remaining < effect) {
return instances[i];
}
}
}
else {
/**
* 当所有权重均为 0(gcd = NaN) 时，退化为 RR
*/
return instances[count % instances.length];
}
(0, utils_1.UNREACHABLE)();
// #endregion
}
}
exports.WRRLoadBalancer = WRRLoadBalancer;
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