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