use route-cache middleware for microCache (#246)

* use route-cache middleware for microCache

* add back comment block

Author: bradoyler

package.json

@@ -22,6 +22,7 @@
     "extract-text-webpack-plugin": "^2.1.0",
     "firebase": "^3.7.2",
     "lru-cache": "^4.0.2",
+    "route-cache": "0.4.2",
     "serve-favicon": "^2.4.1",
     "vue": "^2.4.1",
     "vue-router": "^2.7.0",

server.js

@@ -4,6 +4,7 @@ const LRU = require('lru-cache')
 const express = require('express')
 const favicon = require('serve-favicon')
 const compression = require('compression')
+const microcache = require('route-cache')
 const resolve = file => path.resolve(__dirname, file)
 const { createBundleRenderer } = require('vue-server-renderer')
 
@@ -65,18 +66,13 @@ app.use('/public', serve('./public', true))
 app.use('/manifest.json', serve('./manifest.json', true))
 app.use('/service-worker.js', serve('./dist/service-worker.js'))
 
-// 1-second microcache.
-// https://www.nginx.com/blog/benefits-of-microcaching-nginx/
-const microCache = LRU({
-  max: 100,
-  maxAge: 1000
-})
-
 // since this app has no user-specific content, every page is micro-cacheable.
 // if your app involves user-specific content, you need to implement custom
 // logic to determine whether a request is cacheable based on its url and
 // headers.
-const isCacheable = req => useMicroCache
+// 1-second microcache.
+// https://www.nginx.com/blog/benefits-of-microcaching-nginx/
+app.use(microcache.cacheSeconds(1, () => useMicroCache))
 
 function render (req, res) {
   const s = Date.now()
@@ -88,26 +84,15 @@ function render (req, res) {
     if (err.url) {
       res.redirect(err.url)
     } else if(err.code === 404) {
-      res.status(404).end('404 | Page Not Found')
+      res.status(404).send('404 | Page Not Found')
     } else {
       // Render Error Page or Redirect
-      res.status(500).end('500 | Internal Server Error')
+      res.status(500).send('500 | Internal Server Error')
       console.error(`error during render : ${req.url}`)
       console.error(err.stack)
     }
   }
 
-  const cacheable = isCacheable(req)
-  if (cacheable) {
-    const hit = microCache.get(req.url)
-    if (hit) {
-      if (!isProd) {
-        console.log(`cache hit!`)
-      }
-      return res.end(hit)
-    }
-  }
-
   const context = {
     title: 'Vue HN 2.0', // default title
     url: req.url
@@ -116,10 +101,7 @@ function render (req, res) {
     if (err) {
       return handleError(err)
     }
-    res.end(html)
-    if (cacheable) {
-      microCache.set(req.url, html)
-    }
+    res.send(html)
     if (!isProd) {
       console.log(`whole request: ${Date.now() - s}ms`)
     }