Move middleware utils into server/utils

server/utils/incrementCounter.js

@@ -0,0 +1,15 @@
+const db = require("./redis");
+
+function incrementCounter(counter, key, by) {
+  return new Promise((resolve, reject) => {
+    db.hincrby(counter, key, by, (error, value) => {
+      if (error) {
+        reject(error);
+      } else {
+        resolve(value);
+      }
+    });
+  });
+}
+
+module.exports = incrementCounter;