82 lines
2.8 KiB
TypeScript
82 lines
2.8 KiB
TypeScript
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import {TooManyRequestsHttpError} from "./HttpError";
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export default class Throttler {
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private static readonly throttles: { [throttleName: string]: Throttle } = {};
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/**
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* Throttle function; will throw a TooManyRequestsHttpError when the threshold is reached.
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*
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* This throttle is adaptive: it will slowly decrease (linear) until it reaches 0 after {@param resetPeriod} ms.
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* Threshold will hold for {@param holdPeriod} ms.
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*
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* @param action a unique action name (can be used multiple times, but it'll account for a single action).
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* @param max how many times this action can be triggered per id.
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* @param resetPeriod after how much time in ms the throttle will reach 0.
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* @param id an identifier of who triggered the action.
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* @param holdPeriod time in ms after each call before the threshold begins to decrease.
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* @param jailPeriod time in ms for which the throttle will throw when it is triggered.
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*/
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public static throttle(action: string, max: number, resetPeriod: number, id: string, holdPeriod: number = 100, jailPeriod: number = 30 * 1000) {
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let throttle = this.throttles[action];
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if (!throttle) throttle = this.throttles[action] = new Throttle(max, resetPeriod, holdPeriod, jailPeriod);
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throttle.trigger(id);
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}
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private constructor() {
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}
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}
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class Throttle {
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private readonly max: number;
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private readonly resetPeriod: number;
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private readonly holdPeriod: number;
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private readonly jailPeriod: number;
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private readonly triggers: {
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[id: string]: {
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count: number,
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lastTrigger?: number,
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jailed?: number;
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}
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} = {};
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constructor(max: number, resetPeriod: number, holdPeriod: number, jailPeriod: number) {
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this.max = max;
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this.resetPeriod = resetPeriod;
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this.holdPeriod = holdPeriod;
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this.jailPeriod = jailPeriod;
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}
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public trigger(id: string) {
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let trigger = this.triggers[id];
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if (!trigger) trigger = this.triggers[id] = {count: 0};
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let currentDate = new Date().getTime();
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if (trigger.jailed && currentDate - trigger.jailed > 0) {
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this.throw();
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return;
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}
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if (trigger.lastTrigger) {
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let timeDiff = currentDate - trigger.lastTrigger;
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if (timeDiff > this.holdPeriod) {
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timeDiff -= this.holdPeriod;
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trigger.count = Math.floor(Math.min(trigger.count, this.max * (1 - timeDiff / this.resetPeriod)));
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}
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}
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trigger.count++;
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trigger.lastTrigger = currentDate;
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if (trigger.count > this.max) {
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trigger.jailed = currentDate;
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this.throw();
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return;
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}
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}
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private throw() {
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throw new TooManyRequestsHttpError();
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}
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}
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