mirror of
https://github.com/vercel/next.js.git
synced 2026-09-20 02:25:18 +08:00
Zack Tanner
0d4649989d
When self-hosting Next.js, it's possible to customize a cache handler for ISR. Self-hosted Next.js also makes use of a similar cache interface for `next/image`, but there's no way to customize this cache handler. This plugs into the [existing ability](https://nextjs.org/docs/app/api-reference/config/next-config-js/incrementalCacheHandlerPath) to customize a `cacheHandler` to support the `IMAGE` type. This lets you implement whatever constraints you might have on your self-hosted environment, eg the need for an LRU cache, or storing optimized images outside of disk. This is currently opt-in because it's a breaking change for cache handlers to start receiving `IMAGE` cache types, which we'll make default in the next major.
106 lines
2.4 KiB
JavaScript
106 lines
2.4 KiB
JavaScript
/**
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* Simple LRU cache handler with max entries eviction policy.
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* When the cache exceeds maxEntries, the least recently used entries are evicted.
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*/
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const MAX_IMAGE_ENTRIES = parseInt(
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process.env.MAX_IMAGE_CACHE_ENTRIES || '2',
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10
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)
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class LRUCache {
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constructor(maxEntries) {
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this.maxEntries = maxEntries
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this.cache = new Map()
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}
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get(key) {
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if (!this.cache.has(key)) {
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return undefined
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}
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// Move to end (most recently used)
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const value = this.cache.get(key)
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this.cache.delete(key)
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this.cache.set(key, value)
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return value
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}
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set(key, value) {
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// If key exists, delete it first (will be re-added at end)
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if (this.cache.has(key)) {
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this.cache.delete(key)
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}
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// Evict oldest entries if at capacity
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while (this.cache.size >= this.maxEntries) {
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const oldestKey = this.cache.keys().next().value
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console.log('cache-handler evicting', oldestKey)
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this.cache.delete(oldestKey)
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}
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this.cache.set(key, value)
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}
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has(key) {
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return this.cache.has(key)
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}
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get size() {
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return this.cache.size
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}
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keys() {
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return Array.from(this.cache.keys())
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}
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}
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// Separate caches for different kinds
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const imageCache = new LRUCache(MAX_IMAGE_ENTRIES)
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const pageCache = new LRUCache(100) // Higher limit for pages
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class CacheHandler {
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constructor(options) {
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this.options = options
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console.log('initialized custom cache-handler')
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console.log('max image cache entries:', MAX_IMAGE_ENTRIES)
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}
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async get(key, ctx) {
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const kind = ctx?.kind
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console.log('cache-handler get', key, 'kind:', kind)
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const cache = kind === 'IMAGE' ? imageCache : pageCache
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const entry = cache.get(key)
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if (entry) {
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console.log('cache-handler hit', key)
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return entry
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}
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console.log('cache-handler miss', key)
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return null
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}
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async set(key, data, ctx) {
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const kind = data?.kind
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console.log('cache-handler set', key, 'kind:', kind)
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const cache = kind === 'IMAGE' ? imageCache : pageCache
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cache.set(key, {
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value: data,
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lastModified: Date.now(),
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})
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if (kind === 'IMAGE') {
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console.log('cache-handler image cache size:', imageCache.size)
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console.log(
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'cache-handler image cache keys:',
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imageCache.keys().join(', ')
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)
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}
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}
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async revalidateTag(tags) {
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console.log('cache-handler revalidateTag', tags)
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}
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}
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module.exports = CacheHandler
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