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

   1 import * as asyncLRU from 'async-lru'
   2 import { join } from 'path'
   3 import { createWriteStream } from 'fs'
   4
   5 import { database as db, CONFIG, CACHE } from '../../initializers'
   6 import { logger, unlinkPromise, fetchRemoteVideoPreview } from '../../helpers'
   7 import { VideoInstance } from '../../models'
   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   getPreviewPath (key: string) {
  37     return new Promise<string>((res, rej) => {
  38       this.lru.get(key, (err, value) => {
  39         err ? rej(err) : res(value)
  40       })
  41     })
  42   }
  43
  44   private async loadPreviews (key: string) {
  45     const video = await db.Video.loadByUUIDAndPopulateAccountAndServerAndTags(key)
  46     if (!video) return undefined
  47
  48     if (video.isOwned()) return join(CONFIG.STORAGE.PREVIEWS_DIR, video.getPreviewName())
  49
  50     const res = await this.saveRemotePreviewAndReturnPath(video)
  51
  52     return res
  53   }
  54
  55   private saveRemotePreviewAndReturnPath (video: VideoInstance) {
  56     const req = fetchRemoteVideoPreview(video)
  57
  58     return new Promise<string>((res, rej) => {
  59       const path = join(CACHE.DIRECTORIES.PREVIEWS, video.getPreviewName())
  60       const stream = createWriteStream(path)
  61
  62       req.pipe(stream)
  63          .on('finish', () => res(path))
  64          .on('error', (err) => rej(err))
  65     })
  66   }
  67 }
  68
  69 export {
  70   VideosPreviewCache
  71 }