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 { unlinkPromise } from '../../helpers/core-utils'
   5 import { logger } from '../../helpers/logger'
   6 import { CACHE, CONFIG } from '../../initializers'
   7 import { VideoModel } from '../../models/video/video'
   8 import { fetchRemoteVideoPreview } from '../activitypub'
   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   async getPreviewPath (key: string) {
  38     const video = await VideoModel.loadByUUID(key)
  39     if (!video) return undefined
  40
  41     if (video.isOwned()) return join(CONFIG.STORAGE.PREVIEWS_DIR, video.getPreviewName())
  42
  43     return new Promise<string>((res, rej) => {
  44       this.lru.get(key, (err, value) => {
  45         err ? rej(err) : res(value)
  46       })
  47     })
  48   }
  49
  50   private async loadPreviews (key: string) {
  51     const video = await VideoModel.loadByUUIDAndPopulateAccountAndServerAndTags(key)
  52     if (!video) return undefined
  53
  54     if (video.isOwned()) throw new Error('Cannot load preview of owned video.')
  55
  56     return this.saveRemotePreviewAndReturnPath(video)
  57   }
  58
  59   private saveRemotePreviewAndReturnPath (video: VideoModel) {
  60     return new Promise<string>((res, rej) => {
  61       const req = fetchRemoteVideoPreview(video, rej)
  62       const path = join(CACHE.DIRECTORIES.PREVIEWS, video.getPreviewName())
  63       const stream = createWriteStream(path)
  64
  65       req.pipe(stream)
  66         .on('error', (err) => rej(err))
  67         .on('finish', () => res(path))
  68     })
  69   }
  70 }
  71
  72 export {
  73   VideosPreviewCache
  74 }