61 lines
2 KiB
JavaScript
61 lines
2 KiB
JavaScript
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// @ts-check
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import crypto from 'node:crypto'
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import { mkdir, rename, unlink, writeFile } from 'node:fs/promises'
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import { dirname, join, resolve } from 'node:path'
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import fsDriver from 'unstorage/drivers/fs-lite'
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import lruCache from 'unstorage/drivers/lru-cache'
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/**
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* @param {string} item
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*/
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function normalizeFsKey (item) {
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const safe = item.replace(/[^\w.-]/g, '_')
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const prefix = safe.slice(0, 20)
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const hash = crypto.createHash('sha256').update(item).digest('hex')
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return `${prefix}-${hash}`
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}
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/**
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* Write `value` to `path` atomically so a concurrent reader never observes a
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* truncated file: the payload is written to a unique sibling and renamed over
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* the destination, which is a single filesystem operation.
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* @param {string} path
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* @param {string} value
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*/
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async function atomicWrite (path, value) {
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await mkdir(dirname(path), { recursive: true })
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const tmp = `${path}.${crypto.randomBytes(8).toString('hex')}.tmp`
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try {
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await writeFile(tmp, value, 'utf8')
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await rename(tmp, path)
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} catch (error) {
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await unlink(tmp).catch(() => {})
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throw error
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}
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}
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/**
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* @param {{ base?: string }} opts
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* @returns {import('unstorage').Driver} An unstorage driver that uses both LRU cache and file system, with LRU as the primary and file system as the fallback.
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*/
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export default function cacheDriver (opts) {
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const fs = fsDriver({ base: opts.base })
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const lru = lruCache({ max: 1000 })
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const base = resolve(opts.base || '.')
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return {
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...fs, // fall back to file system - only the bottom three methods are used in renderer
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async setItem (key, value, opts) {
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await atomicWrite(join(base, normalizeFsKey(key)), value)
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await lru.setItem?.(key, value, opts)
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},
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async hasItem (key, opts) {
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return await lru.hasItem(key, opts) || await fs.hasItem(normalizeFsKey(key), opts)
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},
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async getItem (key, opts) {
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return await lru.getItem(key, opts) || await fs.getItem(normalizeFsKey(key), opts)
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},
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}
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}
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