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 (lifetimeArg: string | number) {
  10   return async function (req: express.Request, res: express.Response, next: express.NextFunction) {
  11     const redisKey = Redis.Instance.buildCachedRouteKey(req)
  12
  13     try {
  14       await lock.acquire(redisKey, async (done) => {
  15         const cached = await Redis.Instance.getCachedRoute(req)
  16
  17         // Not cached
  18         if (!cached) {
  19           logger.debug('No cached results for route %s.', req.originalUrl)
  20
  21           const sendSave = res.send.bind(res)
  22
  23           res.send = (body) => {
  24             if (res.statusCode >= 200 && res.statusCode < 400) {
  25               const contentType = res.get('content-type')
  26               const lifetime = parseDuration(lifetimeArg)
  27
  28               Redis.Instance.setCachedRoute(req, body, lifetime, contentType, res.statusCode)
  29                    .then(() => done())
  30                    .catch(err => {
  31                      logger.error('Cannot cache route.', { err })
  32                      return done(err)
  33                    })
  34             }
  35
  36             return sendSave(body)
  37           }
  38
  39           return next()
  40         }
  41
  42         if (cached.contentType) res.set('content-type', cached.contentType)
  43
  44         if (cached.statusCode) {
  45           const statusCode = parseInt(cached.statusCode, 10)
  46           if (!isNaN(statusCode)) res.status(statusCode)
  47         }
  48
  49         logger.debug('Use cached result for %s.', req.originalUrl)
  50         res.send(cached.body).end()
  51
  52         return done()
  53       })
  54     } catch (err) {
  55       logger.error('Cannot serve cached route.', err)
  56       return next()
  57     }
  58   }
  59 }
  60
  61 // ---------------------------------------------------------------------------
  62
  63 export {
  64   cacheRoute
  65 }