Add temporary cache in lib/acl-checker.js (#1467)

* Add temporary cache in lib/acl-checker.js

* Set timeout to 10 seconds

* Use Node 12 on Travis

* reset acl cache in afterEach

Author: michielbdejong

.travis.yml

@@ -1,7 +1,7 @@
 sudo: false
 language: node_js
 node_js:
-  - "10"
+  - "12"
   - "lts/*"
   - "node"
 

lib/acl-checker.js

@@ -14,6 +14,11 @@ const httpFetch = require('node-fetch')
 const DEFAULT_ACL_SUFFIX = '.acl'
 const ACL = rdf.Namespace('http://www.w3.org/ns/auth/acl#')
 
+// TODO: expunge-on-write so that we can increase the caching time
+// For now this cache is a big performance gain but very simple
+const EXPIRY_MS = 10000 // 10 seconds
+let temporaryCache = {}
+
 // An ACLChecker exposes the permissions on a specific resource
 class ACLChecker {
   constructor (resource, options = {}) {
@@ -189,7 +194,7 @@ class ACLChecker {
  * @return {Function} Returns a `fetch(uri, callback)` handler
  */
 function fetchLocalOrRemote (mapper, serverUri) {
-  return async function fetch (url, graph = rdf.graph()) {
+  async function doFetch (url) {
     // Convert the URL into a filename
     let body, path, contentType
 
@@ -208,7 +213,17 @@ function fetchLocalOrRemote (mapper, serverUri) {
       body = await response.text()
       contentType = response.headers.get('content-type')
     }
-
+    return { body, contentType }
+  }
+  return async function fetch (url, graph = rdf.graph()) {
+    if (!temporaryCache[url] || temporaryCache[url].timestamp < new Date().getTime() - EXPIRY_MS) {
+      debug(temporaryCache[url] ? `Repopulating cache, content is ${new Date().getTime() - temporaryCache[url].timestamp} ms old` : 'Populating cache', url)
+      temporaryCache[url] = {
+        timestamp: new Date().getTime(),
+        promise: doFetch(url)
+      }
+    }
+    const { body, contentType } = await temporaryCache[url].promise
     // Parse the file as Turtle
     rdf.parse(body, graph, url, contentType)
     return graph
@@ -222,3 +237,8 @@ function lastSlash (string, pos = string.length) {
 
 module.exports = ACLChecker
 module.exports.DEFAULT_ACL_SUFFIX = DEFAULT_ACL_SUFFIX
+
+// Used in the unit tests:
+module.exports.clearAclCache = function () {
+  temporaryCache = {}
+}

test/integration/acl-oidc-test.js

@@ -4,7 +4,7 @@ const request = require('request')
 const path = require('path')
 const { loadProvider, rm, checkDnsSettings, cleanDir } = require('../utils')
 const IDToken = require('@solid/oidc-op/src/IDToken')
-
+const { clearAclCache } = require('../../lib/acl-checker')
 const ldnode = require('../../index')
 
 const port = 7777
@@ -79,6 +79,10 @@ describe('ACL with WebID+OIDC over HTTP', function () {
     }).catch(console.error)
   })
 
+  afterEach(() => {
+    clearAclCache()
+  })
+
   after(() => {
     if (ldpHttpsServer) ldpHttpsServer.close()
     cleanDir(rootPath)