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119 lines
4 KiB
TypeScript
119 lines
4 KiB
TypeScript
import { EventEmitter } from "events";
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import { CooldownManager } from "knub";
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import { RegExpWorker, TimeoutError } from "regexp-worker";
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import { MINUTES, SECONDS } from "./utils";
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import Timeout = NodeJS.Timeout;
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const isTimeoutError = (a): a is TimeoutError => {
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return a.message != null && a.elapsedTimeMs != null;
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};
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export class RegExpTimeoutError extends Error {
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constructor(message: string, public elapsedTimeMs: number) {
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super(message);
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}
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}
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export function allowTimeout(err: RegExpTimeoutError | Error) {
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if (err instanceof RegExpTimeoutError) {
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return null;
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}
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throw err;
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}
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// Regex timeout starts at a higher value while the bot loads initially, and gets lowered afterwards
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const INITIAL_REGEX_TIMEOUT = 5 * SECONDS;
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const INITIAL_REGEX_TIMEOUT_DURATION = 30 * SECONDS;
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const FINAL_REGEX_TIMEOUT = 5 * SECONDS;
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const regexTimeoutUpgradePromise = new Promise(resolve => setTimeout(resolve, INITIAL_REGEX_TIMEOUT_DURATION));
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let newWorkerTimeout = INITIAL_REGEX_TIMEOUT;
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regexTimeoutUpgradePromise.then(() => (newWorkerTimeout = FINAL_REGEX_TIMEOUT));
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const REGEX_FAIL_TO_COOLDOWN_COUNT = 5; // If a regex times out this many times...
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const REGEX_FAIL_DECAY_TIME = 2 * MINUTES; // ...in this interval...
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const REGEX_FAIL_COOLDOWN = 2 * MINUTES + 30 * SECONDS; // ...it goes on cooldown for this long
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export interface RegExpRunner {
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on(event: "timeout", listener: (regexSource: string, timeoutMs: number) => void);
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on(event: "repeatedTimeout", listener: (regexSource: string, timeoutMs: number, failTimes: number) => void);
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}
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/**
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* Leverages RegExpWorker to run regular expressions in worker threads with a timeout.
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* Repeatedly failing regexes are put on a cooldown where requests to execute them are ignored.
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*/
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export class RegExpRunner extends EventEmitter {
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private _worker: RegExpWorker | null;
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private readonly _failedTimesInterval: Timeout;
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private cooldown: CooldownManager;
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private failedTimes: Map<string, number>;
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constructor() {
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super();
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this.cooldown = new CooldownManager();
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this.failedTimes = new Map();
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this._failedTimesInterval = setInterval(() => {
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for (const [pattern, times] of this.failedTimes.entries()) {
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this.failedTimes.set(pattern, times - 1);
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}
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}, REGEX_FAIL_DECAY_TIME);
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}
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private get worker(): RegExpWorker {
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if (!this._worker) {
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this._worker = new RegExpWorker(newWorkerTimeout);
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if (newWorkerTimeout !== FINAL_REGEX_TIMEOUT) {
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regexTimeoutUpgradePromise.then(() => {
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if (!this._worker) return;
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this._worker.timeout = FINAL_REGEX_TIMEOUT;
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});
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}
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}
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return this._worker;
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}
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public async exec(regex: RegExp, str: string): Promise<null | RegExpExecArray[]> {
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if (this.cooldown.isOnCooldown(regex.source)) {
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return null;
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}
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try {
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const result = await this.worker.execRegExp(regex, str);
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return result.matches.length || regex.global ? result.matches : null;
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} catch (e) {
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if (isTimeoutError(e)) {
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if (this.failedTimes.has(regex.source)) {
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// Regex has failed before, increment fail counter
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this.failedTimes.set(regex.source, this.failedTimes.get(regex.source)! + 1);
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} else {
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// This is the first time this regex failed, init fail counter
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this.failedTimes.set(regex.source, 1);
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}
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if (this.failedTimes.has(regex.source) && this.failedTimes.get(regex.source)! >= REGEX_FAIL_TO_COOLDOWN_COUNT) {
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// Regex has failed too many times, set it on cooldown
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this.cooldown.setCooldown(regex.source, REGEX_FAIL_COOLDOWN);
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this.failedTimes.delete(regex.source);
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this.emit("repeatedTimeout", regex.source, this.worker.timeout, REGEX_FAIL_TO_COOLDOWN_COUNT);
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}
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this.emit("timeout", regex.source, this.worker.timeout);
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throw new RegExpTimeoutError(e.message, e.elapsedTimeMs);
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}
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throw e;
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}
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}
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public async dispose() {
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await this.worker.dispose();
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this._worker = null;
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clearInterval(this._failedTimesInterval);
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}
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}
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