mirror of https://git.sr.ht/~cadence/bibliogram
67 lines
1.2 KiB
JavaScript
67 lines
1.2 KiB
JavaScript
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class InstaCache {
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/**
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* @property {number} ttl time to keep each resource in milliseconds
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*/
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constructor(ttl) {
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this.ttl = ttl
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/** @type {Map<string, {data: any, time: number}>} */
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this.cache = new Map()
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}
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clean() {
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for (const key of this.cache.keys()) {
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const value = this.cache.get(key)
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if (Date.now() > value.time + this.ttl) this.cache.delete(key)
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}
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}
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/**
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* @param {string} key
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*/
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get(key) {
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return this.cache.get(key).data
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}
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/**
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* @param {string} key
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* @param {any} data
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*/
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set(key, data) {
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this.cache.set(key, {data, time: Date.now()})
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}
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/**
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* @param {string} key
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* @param {() => Promise<T>} callback
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* @returns {Promise<T>}
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* @template T
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*/
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getOrFetch(key, callback) {
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this.clean()
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if (this.cache.has(key)) return Promise.resolve(this.get(key))
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else {
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const pending = callback().then(result => {
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this.set(key, result)
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return result
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})
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this.set(key, pending)
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return pending
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}
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}
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/**
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* @param {string} key
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* @param {() => Promise<T>} callback
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* @returns {Promise<T>}
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* @template T
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*/
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getOrFetchPromise(key, callback) {
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return this.getOrFetch(key, callback).then(result => {
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this.cache.delete(key)
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return result
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})
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}
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}
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module.exports = InstaCache
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