// There are plenty of packages for in-memory caching but each have their // own gotchas and often have extra complexity which makes it work in one // platform but not in another (for example, the use of long timeouts would // be fine in Node but not in React Native). // // So this class implements a simple in-memory cache with support for TTL. // Checking for expired keys is a bit inefficient since it doesn't rely on // timers, so it's checking every time a value is set or retrieved. But it // should be fine in most cases, as long as the class is not used at a massive // scale. interface Record { // eslint-disable-next-line @typescript-eslint/no-explicit-any -- Old code before rule was applied value: any; expiredTime: number; } interface Records { [key: string]: Record; } interface ExpirableKeys { [key: string]: boolean; } export default class Cache { private maxRecords_: number; private records_: Records = {}; private expirableKeys_: ExpirableKeys = {}; private recordKeyHistory_: string[] = []; public constructor(maxRecords = 50) { this.maxRecords_ = maxRecords; } private checkExpiredRecords() { const now = Date.now(); for (const key in this.expirableKeys_) { if (!this.records_[key]) { delete this.expirableKeys_[key]; } else { if (this.records_[key].expiredTime <= now) { delete this.records_[key]; delete this.expirableKeys_[key]; } } } while (this.recordKeyHistory_.length > this.maxRecords_) { const key = this.recordKeyHistory_[0]; delete this.records_[key]; delete this.expirableKeys_[key]; this.recordKeyHistory_.splice(0, 1); } } // eslint-disable-next-line @typescript-eslint/no-explicit-any -- Old code before rule was applied public value(key: string, defaultValue: any = undefined): any { this.checkExpiredRecords(); if (key in this.records_) return this.records_[key].value; return defaultValue; } // eslint-disable-next-line @typescript-eslint/no-explicit-any -- Old code before rule was applied public setValue(key: string, value: any, ttl = 0) { this.checkExpiredRecords(); this.records_[key] = { value: value, expiredTime: ttl ? Date.now() + ttl : 0, }; const idx = this.recordKeyHistory_.indexOf(key); if (idx >= 0) this.recordKeyHistory_.splice(idx, 1); this.recordKeyHistory_.push(key); if (ttl) { this.expirableKeys_[key] = true; } else { delete this.expirableKeys_[key]; } } }