Add simple lru cache of URLs into authenticate action

web-server/actions/authenticate-action.js

@@ -1,21 +1,31 @@
 import fs from 'fs';
 import axios from 'axios';
 import path from 'path';
-import  os from 'os';
+import os from 'os';
+import LRU from 'lru-cache';
 import { getTempFilename as tempFilename } from 'express-fileupload/lib/utilities';
 import { authenticatePhoto } from '../imagehash/authenticate-photo'
 
+const cache = new LRU(500);
+
 async function authenticate(req, res) {
   const imageUrl = req.query.url;
+
   if (!imageUrl)
     return res.status(400).send('No file uploaded');
 
+  const imageInfo = cache.get(imageUrl);
+  if (imageInfo)
+    return res.json(imageInfo);
+
   let imagePath = null;
   try {
     imagePath = await downloadImage(imageUrl);
 
     const authInfo = await authenticatePhoto(imagePath);
 
+    cache.set(imageUrl, authInfo);
+
     res.json(authInfo);
   } catch (e) {
     res.status(500).send(`Authenticating failed: ${e.message}`);

web-server/package.json

@@ -8,6 +8,7 @@
     "debug": "~2.6.9",
     "express": "~4.16.1",
     "express-fileupload": "^1.1.5",
+    "lru-cache": "^5.1.1",
     "lz-string": "^1.4.4",
     "morgan": "~1.9.1",
     "web3": "0.20.6"
@@ -24,7 +25,9 @@
     "start": "babel-node ./bin/www"
   },
   "nodemonConfig": {
-    "ignore": ["ethereum/fingerprints/*"],
+    "ignore": [
+      "ethereum/fingerprints/*"
+    ],
     "delay": "2500"
   }
 }