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 import * as Promise from 'bluebird'
   5
   6 import { database as db, CONFIG, CACHE } from '../../initializers'
   7 import { logger, unlinkPromise } from '../../helpers'
   8 import { VideoInstance } from '../../models'
   9 import { fetchRemotePreview } from '../../lib'
  10
  11 class VideosPreviewCache {
  12
  13   private static instance: VideosPreviewCache
  14
  15   private lru
  16
  17   private constructor () { }
  18
  19   static get Instance () {
  20     return this.instance || (this.instance = new this())
  21   }
  22
  23   init (max: number) {
  24     this.lru = new asyncLRU({
  25       max,
  26       load: (key, cb) => {
  27         this.loadPreviews(key)
  28           .then(res => cb(null, res))
  29           .catch(err => cb(err))
  30       }
  31     })
  32
  33     this.lru.on('evict', (obj: { key: string, value: string }) => {
  34       unlinkPromise(obj.value).then(() => logger.debug('%s evicted from VideosPreviewCache', obj.value))
  35     })
  36   }
  37
  38   getPreviewPath (key: string) {
  39     return new Promise<string>((res, rej) => {
  40       this.lru.get(key, (err, value) => {
  41         err ? rej(err) : res(value)
  42       })
  43     })
  44   }
  45
  46   private loadPreviews (key: string) {
  47     return db.Video.loadByUUIDAndPopulateAuthorAndPodAndTags(key)
  48       .then(video => {
  49         if (!video) return undefined
  50
  51         if (video.isOwned()) return join(CONFIG.STORAGE.PREVIEWS_DIR, video.getPreviewName())
  52
  53         return this.saveRemotePreviewAndReturnPath(video)
  54       })
  55   }
  56
  57   private saveRemotePreviewAndReturnPath (video: VideoInstance) {
  58     const req = fetchRemotePreview(video.Author.Pod, video)
  59
  60     return new Promise<string>((res, rej) => {
  61       const path = join(CACHE.DIRECTORIES.PREVIEWS, video.getPreviewName())
  62       const stream = createWriteStream(path)
  63
  64       req.pipe(stream)
  65          .on('finish', () => res(path))
  66          .on('error', (err) => rej(err))
  67     })
  68   }
  69 }
  70
  71 export {
  72   VideosPreviewCache
  73 }