87 lines
2.6 KiB
JavaScript
87 lines
2.6 KiB
JavaScript
const redis = require("../redis/init")
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const { doWithDB } = require("../db")
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const { DocumentType } = require("../db/constants")
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const AppState = {
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INVALID: "invalid",
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}
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const EXPIRY_SECONDS = 3600
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/**
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* The default populate app metadata function
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*/
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const populateFromDB = async appId => {
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return doWithDB(
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appId,
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db => {
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return db.get(DocumentType.APP_METADATA)
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},
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{ skip_setup: true }
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)
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}
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const isInvalid = metadata => {
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return !metadata || metadata.state === AppState.INVALID
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}
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/**
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* Get the requested app metadata by id.
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* Use redis cache to first read the app metadata.
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* If not present fallback to loading the app metadata directly and re-caching.
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* @param {string} appId the id of the app to get metadata from.
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* @returns {object} the app metadata.
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*/
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exports.getAppMetadata = async appId => {
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const client = await redis.getAppClient()
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// try cache
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let metadata = await client.get(appId)
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if (!metadata) {
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let expiry = EXPIRY_SECONDS
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try {
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metadata = await populateFromDB(appId)
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} catch (err) {
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// app DB left around, but no metadata, it is invalid
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if (err && err.status === 404) {
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metadata = { state: AppState.INVALID }
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// don't expire the reference to an invalid app, it'll only be
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// updated if a metadata doc actually gets stored (app is remade/reverted)
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expiry = undefined
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} else {
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throw err
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}
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}
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// needed for cypress/some scenarios where the caching happens
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// so quickly the requests can get slightly out of sync
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// might store its invalid just before it stores its valid
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if (isInvalid(metadata)) {
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const temp = await client.get(appId)
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if (temp) {
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metadata = temp
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}
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}
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await client.store(appId, metadata, expiry)
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}
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// we've stored in the cache an object to tell us that it is currently invalid
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if (isInvalid(metadata)) {
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throw { status: 404, message: "No app metadata found" }
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}
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return metadata
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}
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/**
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* Invalidate/reset the cached metadata when a change occurs in the db.
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* @param appId {string} the cache key to bust/update.
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* @param newMetadata {object|undefined} optional - can simply provide the new metadata to update with.
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* @return {Promise<void>} will respond with success when cache is updated.
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*/
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exports.invalidateAppMetadata = async (appId, newMetadata = null) => {
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if (!appId) {
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throw "Cannot invalidate if no app ID provided."
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}
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const client = await redis.getAppClient()
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await client.delete(appId)
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if (newMetadata) {
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await client.store(appId, newMetadata, EXPIRY_SECONDS)
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}
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}
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