Created
December 10, 2018 16:30
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| interface Cache<T> { | |
| get: (id: string) => T | null; | |
| set: (id: string, item: T) => void; | |
| invalidate: (id: string) => void; | |
| }; | |
| interface CacheEntry<T> { | |
| // Unix timestamp Math.floor(new Date() / 1000) | |
| cachedAt: number; | |
| item: T; | |
| }; | |
| interface CacheMap<T> { | |
| [key: string]: CacheEntry<T> | |
| }; | |
| interface CacheOptions { | |
| // In seconds | |
| TTL: number | |
| }; | |
| const createCache<T> = ({ TTL }: CacheOptions): Cache<T> => { | |
| return { | |
| _cache: CacheMap<T> = {}, | |
| get: function(id:string) { | |
| const entry = this._cache[id]; | |
| if (!entry) { | |
| return null; | |
| } | |
| const now = Math.floor(new Date() / 1000); | |
| if (now - entry.cachedAt > TTL) { | |
| this.invalidate(id); | |
| return null; | |
| } | |
| return entry.item; | |
| }, | |
| invalidate(id: string) { | |
| if (this._cache[id]) { | |
| delete this._cache[id]; | |
| } | |
| }, | |
| set(id: string, item: T) { | |
| const now = Math.floor(new Date() / 1000); | |
| this._cache[id] = { | |
| cachedAt: now, | |
| item | |
| } | |
| } | |
| } | |
| }; |
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