PeerTube/server/middlewares/cache/shared/api-cache.ts

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// Thanks: https://github.com/kwhitley/apicache
// We duplicated the library because it is unmaintened and prevent us to upgrade to recent NodeJS versions
2021-08-27 14:32:44 +02:00
import express from 'express'
import { OutgoingHttpHeaders } from 'http'
import { isTestInstance, parseDurationToMs } from '@server/helpers/core-utils'
import { logger } from '@server/helpers/logger'
import { Redis } from '@server/lib/redis'
import { HttpStatusCode } from '@shared/models'
export interface APICacheOptions {
headerBlacklist?: string[]
excludeStatus?: HttpStatusCode[]
}
interface CacheObject {
status: number
headers: OutgoingHttpHeaders
data: any
encoding: BufferEncoding
timestamp: number
}
export class ApiCache {
private readonly options: APICacheOptions
private readonly timers: { [ id: string ]: NodeJS.Timeout } = {}
private index: { all: string[] } = { all: [] }
constructor (options: APICacheOptions) {
this.options = {
headerBlacklist: [],
excludeStatus: [],
...options
}
}
buildMiddleware (strDuration: string) {
const duration = parseDurationToMs(strDuration)
return (req: express.Request, res: express.Response, next: express.NextFunction) => {
const key = Redis.Instance.getPrefix() + 'api-cache-' + req.originalUrl
const redis = Redis.Instance.getClient()
if (!redis.connected) return this.makeResponseCacheable(res, next, key, duration)
try {
redis.hgetall(key, (err, obj) => {
if (!err && obj && obj.response) {
return this.sendCachedResponse(req, res, JSON.parse(obj.response), duration)
}
return this.makeResponseCacheable(res, next, key, duration)
})
} catch (err) {
return this.makeResponseCacheable(res, next, key, duration)
}
}
}
private shouldCacheResponse (response: express.Response) {
if (!response) return false
if (this.options.excludeStatus.includes(response.statusCode)) return false
return true
}
private addIndexEntries (key: string) {
this.index.all.unshift(key)
}
private filterBlacklistedHeaders (headers: OutgoingHttpHeaders) {
return Object.keys(headers)
.filter(key => !this.options.headerBlacklist.includes(key))
.reduce((acc, header) => {
acc[header] = headers[header]
return acc
}, {})
}
private createCacheObject (status: number, headers: OutgoingHttpHeaders, data: any, encoding: BufferEncoding) {
return {
status,
headers: this.filterBlacklistedHeaders(headers),
data,
encoding,
// Seconds since epoch, used to properly decrement max-age headers in cached responses.
timestamp: new Date().getTime() / 1000
} as CacheObject
}
private cacheResponse (key: string, value: object, duration: number) {
const redis = Redis.Instance.getClient()
if (redis.connected) {
try {
redis.hset(key, 'response', JSON.stringify(value))
redis.hset(key, 'duration', duration + '')
redis.expire(key, duration / 1000)
} catch (err) {
logger.error('Cannot set cache in redis.', { err })
}
}
// add automatic cache clearing from duration, includes max limit on setTimeout
this.timers[key] = setTimeout(() => this.clear(key), Math.min(duration, 2147483647))
}
private accumulateContent (res: express.Response, content: any) {
if (!content) return
if (typeof content === 'string') {
res.locals.apicache.content = (res.locals.apicache.content || '') + content
return
}
if (Buffer.isBuffer(content)) {
let oldContent = res.locals.apicache.content
if (typeof oldContent === 'string') {
oldContent = Buffer.from(oldContent)
}
if (!oldContent) {
oldContent = Buffer.alloc(0)
}
res.locals.apicache.content = Buffer.concat(
[ oldContent, content ],
oldContent.length + content.length
)
return
}
res.locals.apicache.content = content
}
private makeResponseCacheable (res: express.Response, next: express.NextFunction, key: string, duration: number) {
const self = this
res.locals.apicache = {
write: res.write,
writeHead: res.writeHead,
end: res.end,
cacheable: true,
content: undefined,
headers: {}
}
// Patch express
res.writeHead = function () {
if (self.shouldCacheResponse(res)) {
res.setHeader('cache-control', 'max-age=' + (duration / 1000).toFixed(0))
} else {
res.setHeader('cache-control', 'no-cache, no-store, must-revalidate')
}
res.locals.apicache.headers = Object.assign({}, res.getHeaders())
return res.locals.apicache.writeHead.apply(this, arguments as any)
}
res.write = function (chunk: any) {
self.accumulateContent(res, chunk)
return res.locals.apicache.write.apply(this, arguments as any)
}
res.end = function (content: any, encoding: BufferEncoding) {
if (self.shouldCacheResponse(res)) {
self.accumulateContent(res, content)
if (res.locals.apicache.cacheable && res.locals.apicache.content) {
self.addIndexEntries(key)
const headers = res.locals.apicache.headers || res.getHeaders()
const cacheObject = self.createCacheObject(
res.statusCode,
headers,
res.locals.apicache.content,
encoding
)
self.cacheResponse(key, cacheObject, duration)
}
}
res.locals.apicache.end.apply(this, arguments as any)
} as any
next()
}
private sendCachedResponse (request: express.Request, response: express.Response, cacheObject: CacheObject, duration: number) {
const headers = response.getHeaders()
if (isTestInstance()) {
Object.assign(headers, {
'x-api-cache-cached': 'true'
})
}
Object.assign(headers, this.filterBlacklistedHeaders(cacheObject.headers || {}), {
// Set properly decremented max-age header
// This ensures that max-age is in sync with the cache expiration
'cache-control':
'max-age=' +
Math.max(
0,
(duration / 1000 - (new Date().getTime() / 1000 - cacheObject.timestamp))
).toFixed(0)
})
// unstringify buffers
let data = cacheObject.data
if (data && data.type === 'Buffer') {
data = typeof data.data === 'number'
? Buffer.alloc(data.data)
: Buffer.from(data.data)
}
// Test Etag against If-None-Match for 304
const cachedEtag = cacheObject.headers.etag
const requestEtag = request.headers['if-none-match']
if (requestEtag && cachedEtag === requestEtag) {
response.writeHead(304, headers)
return response.end()
}
response.writeHead(cacheObject.status || 200, headers)
return response.end(data, cacheObject.encoding)
}
private clear (target: string) {
const redis = Redis.Instance.getClient()
if (target) {
clearTimeout(this.timers[target])
delete this.timers[target]
try {
redis.del(target)
} catch (err) {
logger.error('Cannot delete %s in redis cache.', target, { err })
}
this.index.all = this.index.all.filter(key => key !== target)
} else {
for (const key of this.index.all) {
clearTimeout(this.timers[key])
delete this.timers[key]
try {
redis.del(key)
} catch (err) {
logger.error('Cannot delete %s in redis cache.', key, { err })
}
}
this.index.all = []
}
return this.index
}
}