d78bb6fe46
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>
119 lines
3.4 KiB
TypeScript
119 lines
3.4 KiB
TypeScript
import { IncrementalCache } from './incremental-cache'
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import RenderResult from './render-result'
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interface CachedRedirectValue {
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kind: 'REDIRECT'
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props: Object
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}
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interface CachedPageValue {
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kind: 'PAGE'
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html: RenderResult
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pageData: Object
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}
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export type ResponseCacheValue = CachedRedirectValue | CachedPageValue
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export type ResponseCacheEntry = {
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revalidate?: number | false
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value: ResponseCacheValue | null
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}
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type ResponseGenerator = (
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hasResolved: boolean
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) => Promise<ResponseCacheEntry | null>
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export default class ResponseCache {
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incrementalCache: IncrementalCache
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pendingResponses: Map<string, Promise<ResponseCacheEntry | null>>
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constructor(incrementalCache: IncrementalCache) {
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this.incrementalCache = incrementalCache
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this.pendingResponses = new Map()
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}
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public get(
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key: string | null,
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responseGenerator: ResponseGenerator
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): Promise<ResponseCacheEntry | null> {
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const pendingResponse = key ? this.pendingResponses.get(key) : null
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if (pendingResponse) {
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return pendingResponse
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}
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let resolver: (cacheEntry: ResponseCacheEntry | null) => void = () => {}
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let rejecter: (error: Error) => void = () => {}
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const promise: Promise<ResponseCacheEntry | null> = new Promise(
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(resolve, reject) => {
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resolver = resolve
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rejecter = reject
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}
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)
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if (key) {
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this.pendingResponses.set(key, promise)
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}
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let resolved = false
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const resolve = (cacheEntry: ResponseCacheEntry | null) => {
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if (key) {
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// Ensure all reads from the cache get the latest value.
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this.pendingResponses.set(key, Promise.resolve(cacheEntry))
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}
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if (!resolved) {
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resolved = true
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resolver(cacheEntry)
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}
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}
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// We wait to do any async work until after we've added our promise to
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// `pendingResponses` to ensure that any any other calls will reuse the
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// same promise until we've fully finished our work.
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;(async () => {
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try {
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const cachedResponse = key ? await this.incrementalCache.get(key) : null
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if (cachedResponse) {
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resolve({
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revalidate: cachedResponse.curRevalidate,
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value:
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cachedResponse.value?.kind === 'PAGE'
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? {
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kind: 'PAGE',
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html: RenderResult.fromStatic(cachedResponse.value.html),
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pageData: cachedResponse.value.pageData,
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}
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: cachedResponse.value,
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})
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if (!cachedResponse.isStale) {
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// The cached value is still valid, so we don't need
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// to update it yet.
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return
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}
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}
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const cacheEntry = await responseGenerator(resolved)
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resolve(cacheEntry)
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if (key && cacheEntry && typeof cacheEntry.revalidate !== 'undefined') {
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await this.incrementalCache.set(
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key,
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cacheEntry.value?.kind === 'PAGE'
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? {
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kind: 'PAGE',
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html: cacheEntry.value.html.toUnchunkedString(),
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pageData: cacheEntry.value.pageData,
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}
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: cacheEntry.value,
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cacheEntry.revalidate
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)
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}
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} catch (err) {
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rejecter(err as Error)
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} finally {
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if (key) {
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this.pendingResponses.delete(key)
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}
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}
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})()
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return promise
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}
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}
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