server/middlewares/cache.ts

   1 import * as express from 'express'
   2 import * as AsyncLock from 'async-lock'
   3 import { parseDuration } from '../helpers/utils'
   4 import { Redis } from '../lib/redis'
   5 import { logger } from '../helpers/logger'
   6
   7 const lock = new AsyncLock({ timeout: 5000 })
   8
   9 function cacheRoute (lifetime: number) {
  10   return async function (req: express.Request, res: express.Response, next: express.NextFunction) {
  11     const redisKey = Redis.Instance.buildCachedRouteKey(req)
  12
  13     await lock.acquire(redisKey, async (done) => {
  14       const cached = await Redis.Instance.getCachedRoute(req)
  15
  16       // Not cached
  17       if (!cached) {
  18         logger.debug('No cached results for route %s.', req.originalUrl)
  19
  20         const sendSave = res.send.bind(res)
  21
  22         res.send = (body) => {
  23           if (res.statusCode >= 200 && res.statusCode < 400) {
  24             const contentType = res.get('content-type')
  25             Redis.Instance.setCachedRoute(req, body, lifetime, contentType, res.statusCode)
  26                  .then(() => done())
  27                  .catch(err => {
  28                    logger.error('Cannot cache route.', { err })
  29                    return done(err)
  30                  })
  31           }
  32
  33           return sendSave(body)
  34         }
  35
  36         return next()
  37       }
  38
  39       if (cached.contentType) res.set('content-type', cached.contentType)
  40
  41       if (cached.statusCode) {
  42         const statusCode = parseInt(cached.statusCode, 10)
  43         if (!isNaN(statusCode)) res.status(statusCode)
  44       }
  45
  46       logger.debug('Use cached result for %s.', req.originalUrl)
  47       res.send(cached.body).end()
  48
  49       return done()
  50     })
  51   }
  52 }
  53
  54 const cache = (duration: number | string) => {
  55   const _lifetime = parseDuration(duration, 3600000)
  56   return cacheRoute(_lifetime)
  57 }
  58
  59 // ---------------------------------------------------------------------------
  60
  61 export {
  62   cacheRoute,
  63   cache
  64 }