server/middlewares/cache.ts

   1 import * as express from 'express'
   2 import * as AsyncLock from 'async-lock'
   3 import { Redis } from '../lib/redis'
   4 import { logger } from '../helpers/logger'
   5
   6 const lock = new AsyncLock({ timeout: 5000 })
   7
   8 function cacheRoute (lifetime: number) {
   9   return async function (req: express.Request, res: express.Response, next: express.NextFunction) {
  10     const redisKey = Redis.Instance.buildCachedRouteKey(req)
  11
  12     await lock.acquire(redisKey, async (done) => {
  13       const cached = await Redis.Instance.getCachedRoute(req)
  14
  15       // Not cached
  16       if (!cached) {
  17         logger.debug('Not cached result for route %s.', req.originalUrl)
  18
  19         const sendSave = res.send.bind(res)
  20
  21         res.send = (body) => {
  22           if (res.statusCode >= 200 && res.statusCode < 400) {
  23             const contentType = res.getHeader('content-type').toString()
  24             Redis.Instance.setCachedRoute(req, body, lifetime, contentType, res.statusCode)
  25                  .then(() => done())
  26                  .catch(err => {
  27                    logger.error('Cannot cache route.', { err })
  28                    return done(err)
  29                  })
  30           }
  31
  32           return sendSave(body)
  33         }
  34
  35         return next()
  36       }
  37
  38       if (cached.contentType) res.contentType(cached.contentType)
  39
  40       if (cached.statusCode) {
  41         const statusCode = parseInt(cached.statusCode, 10)
  42         if (!isNaN(statusCode)) res.status(statusCode)
  43       }
  44
  45       logger.debug('Use cached result for %s.', req.originalUrl)
  46       res.send(cached.body).end()
  47
  48       return done()
  49     })
  50   }
  51 }
  52
  53 // ---------------------------------------------------------------------------
  54
  55 export {
  56   cacheRoute
  57 }