97 lines
2.9 KiB
TypeScript
97 lines
2.9 KiB
TypeScript
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import { RegExpWorker, TimeoutError } from "regexp-worker";
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import { CooldownManager } from "knub";
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import { MINUTES } from "./utils";
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import { EventEmitter } from "events";
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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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const REGEX_TIMEOUT = 100; // ms
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const REGEX_FAIL_TO_COOLDOWN_COUNT = 3; // If a regex fails this many times, it goes on cooldown...
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const REGEX_FAIL_COOLDOWN = 5 * MINUTES; // ...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;
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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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}
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private get worker(): RegExpWorker {
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if (!this._worker) {
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this._worker = new RegExpWorker(REGEX_TIMEOUT);
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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.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, REGEX_TIMEOUT, REGEX_FAIL_TO_COOLDOWN_COUNT);
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}
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this.emit("timeout", regex.source, REGEX_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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}
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}
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