feb1682814
* update terminology
- "regular update" to "cached resource"
- "interval" to "ttl"
- move file and update imports
* set a default TTL, don't explicitly pass params if we want the default
* add tests
* update docs
68 lines
1.7 KiB
JavaScript
68 lines
1.7 KiB
JavaScript
/**
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* @module
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*/
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import { InvalidResponse } from './errors.js'
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import { fetch } from './got.js'
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import checkErrorResponse from './check-error-response.js'
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const oneDay = 24 * 3600 * 1000 // 1 day in milliseconds
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// Map from URL to { timestamp: last fetch time, data: data }.
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let resourceCache = Object.create(null)
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/**
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* Make a HTTP request using an in-memory cache
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*
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* @param {object} attrs Refer to individual attrs
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* @param {string} attrs.url URL to request
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* @param {number} attrs.ttl Number of milliseconds to keep cached value for
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* @param {boolean} [attrs.json=true] True if we expect to parse the response as JSON
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* @param {Function} [attrs.scraper=buffer => buffer] Function to extract value from the response
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* @param {object} [attrs.options={}] Options to pass to got
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* @param {Function} [attrs.requestFetcher=fetch] Custom fetch function
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* @returns {*} Parsed response
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*/
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async function getCachedResource({
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url,
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ttl = oneDay,
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json = true,
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scraper = buffer => buffer,
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options = {},
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requestFetcher = fetch,
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}) {
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const timestamp = Date.now()
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const cached = resourceCache[url]
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if (cached != null && timestamp - cached.timestamp < ttl) {
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return cached.data
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}
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const { buffer } = await checkErrorResponse({})(
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await requestFetcher(url, options)
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)
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let reqData
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if (json) {
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try {
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reqData = JSON.parse(buffer)
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} catch (e) {
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throw new InvalidResponse({
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prettyMessage: 'unparseable intermediate json response',
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underlyingError: e,
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})
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}
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} else {
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reqData = buffer
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}
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const data = scraper(reqData)
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resourceCache[url] = { timestamp, data }
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return data
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}
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function clearResourceCache() {
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resourceCache = Object.create(null)
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}
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export { getCachedResource, clearResourceCache }
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