Add code from express-unpkg repo

server/middleware/RegistryCache.js

@@ -0,0 +1,49 @@
+const redis = require('redis')
+const createLRUCache = require('lru-cache')
+
+const createRedisCache = (redisURL) => {
+  const client = redis.createClient(redisURL)
+
+  const createKey = (key) => 'registry:' + key
+
+  const set = (key, value, expiry) => {
+    client.set(createKey(key), JSON.stringify(value))
+    client.pexpire(createKey(key), expiry)
+  }
+
+  const get = (key, callback) => {
+    client.get(createKey(key), (error, value) => {
+      callback(error, value && JSON.parse(value))
+    })
+  }
+
+  const del = (key) => {
+    client.del(createKey(key))
+  }
+
+  return { set, get, del }
+}
+
+const createMemoryCache = (options) => {
+  const cache = createLRUCache(options)
+
+  const set = (key, value, expiry) => {
+    cache.set(key, value, expiry)
+  }
+
+  const get = (key, callback) => {
+    callback(null, cache.get(key))
+  }
+
+  const del = (key) => {
+    cache.del(key)
+  }
+
+  return { set, get, del }
+}
+
+const RegistryCache = process.env.REDIS_URL
+  ? createRedisCache(process.env.REDIS_URL)
+  : createMemoryCache({ max: 1000 })
+
+module.exports = RegistryCache