server/lib/cache/videos-preview-cache.ts

   1 import * as asyncLRU from 'async-lru'
   2 import { createWriteStream } from 'fs'
   3 import { join } from 'path'
   4 import { logger, unlinkPromise } from '../../helpers'
   5 import { CACHE, CONFIG } from '../../initializers'
   6 import { VideoModel } from '../../models/video/video'
   7 import { fetchRemoteVideoPreview } from '../activitypub'
   8
   9 class VideosPreviewCache {
  10
  11   private static instance: VideosPreviewCache
  12
  13   private lru
  14
  15   private constructor () { }
  16
  17   static get Instance () {
  18     return this.instance || (this.instance = new this())
  19   }
  20
  21   init (max: number) {
  22     this.lru = new asyncLRU({
  23       max,
  24       load: (key, cb) => {
  25         this.loadPreviews(key)
  26           .then(res => cb(null, res))
  27           .catch(err => cb(err))
  28       }
  29     })
  30
  31     this.lru.on('evict', (obj: { key: string, value: string }) => {
  32       unlinkPromise(obj.value).then(() => logger.debug('%s evicted from VideosPreviewCache', obj.value))
  33     })
  34   }
  35
  36   async getPreviewPath (key: string) {
  37     const video = await VideoModel.loadByUUID(key)
  38     if (!video) return undefined
  39
  40     if (video.isOwned()) return join(CONFIG.STORAGE.PREVIEWS_DIR, video.getPreviewName())
  41
  42     return new Promise<string>((res, rej) => {
  43       this.lru.get(key, (err, value) => {
  44         err ? rej(err) : res(value)
  45       })
  46     })
  47   }
  48
  49   private async loadPreviews (key: string) {
  50     const video = await VideoModel.loadByUUIDAndPopulateAccountAndServerAndTags(key)
  51     if (!video) return undefined
  52
  53     if (video.isOwned()) throw new Error('Cannot load preview of owned video.')
  54
  55     const res = await this.saveRemotePreviewAndReturnPath(video)
  56
  57     return res
  58   }
  59
  60   private saveRemotePreviewAndReturnPath (video: VideoModel) {
  61     const req = fetchRemoteVideoPreview(video)
  62
  63     return new Promise<string>((res, rej) => {
  64       const path = join(CACHE.DIRECTORIES.PREVIEWS, video.getPreviewName())
  65       const stream = createWriteStream(path)
  66
  67       req.pipe(stream)
  68          .on('finish', () => res(path))
  69          .on('error', (err) => rej(err))
  70     })
  71   }
  72 }
  73
  74 export {
  75   VideosPreviewCache
  76 }