Merge pull request #163 from wbstack/fr/async-request

Handle HTTP calls asynchronously, add response caching
wbstack · Jun 21, 2023 · c28d975 · c28d975
2 parents 324e084 + 1b7d653
commit c28d975
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Showing 5 changed files with 85 additions and 35 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # queryservice-gateway
 
+## June 2023
+
+- 2.2 - Use asynchronous requests when fetching data from Platform API
+
 ## November 2020
 
 - 2.1 - From Github actions build

diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -10,6 +10,7 @@
   "author": "",
   "license": "ISC",
   "dependencies": {
+    "@isaacs/ttlcache": "^1.4.0",
     "redbird": "^0.9.1",
     "url-parse": "^1.5.1",
     "xmlhttprequest": "^1.8.0"

diff --git a/resolver.js b/resolver.js
@@ -1,5 +1,6 @@
 var parse = require('url-parse'),
     XMLHttpRequest = require("xmlhttprequest").XMLHttpRequest
+    TTLCache = require('@isaacs/ttlcache')
 
 var domainForResolver = function domainForResolver(req) {
 
@@ -33,45 +34,72 @@ var domainForResolver = function domainForResolver(req) {
 }
 
 var defaultResolver = function resolver(host, url, req) {
+    var wikiDomain = domainForResolver(req)
+    if (wikiDomain === null) {
+        return Promise.resolve(null)
+    }
+
+    return fetchWikiForDomain(wikiDomain)
+        .then(function (response) {
+            if (!response || !response.data) {
+                return null
+            }
+
+            let backend = response.data.wiki_queryservice_namespace.backend
+            let namespace = response.data.wiki_queryservice_namespace.namespace
+            var parsed = parse('http://' + host + url, true)
+            parsed.set('pathname', '/bigdata/namespace/' + namespace)
+            parsed.set('hostname', backend)
+            // unset the port as it is set in the backend host...
+            parsed.set('port', '')
+
+            return parsed.toString()
+        })
+        .catch(function (err) {
+            console.error(err)
+            throw err
+        })
+
+}
 
-    // Try and log on failures (so this process keeps running...)
-    try {
+var responseCache = new TTLCache({
+    ttl: parseInt(process.env.RESPONSE_CACHE_TTL || 60 * 60, 10) * 1000
+})
 
-        var wikiDomain = domainForResolver(req)
-        if(wikiDomain === null) {
-            return null
-        }
+function fetchWikiForDomain (wikiDomain) {
+    var cachedResponse = responseCache.get(wikiDomain)
+    if (cachedResponse) {
+        return Promise.resolve(cachedResponse)
+    }
 
-        // TODO should this be async?! What promise should i be returning...
-        var xmlHttp = new XMLHttpRequest();
+    return new Promise(function (resolve, reject) {
+        var xmlHttp = new XMLHttpRequest()
         xmlHttp.open(
             "GET",
-            "http://"+process.env["PLATFORM_API_BACKEND_HOST"]+"/backend/wiki/getWikiForDomain?domain=" + encodeURI(wikiDomain),
-            false // false for synchronous request
+            "http://"+process.env["PLATFORM_API_BACKEND_HOST"]+"/backend/wiki/getWikiForDomain?domain=" + encodeURI(wikiDomain)
         );
         xmlHttp.setRequestHeader("User-Agent", "WBStack - Query Service - Gateway");
         xmlHttp.send(null);
-        var response = JSON.parse(xmlHttp.responseText);
-
-        if(!response.data) {
-            return null
-        }
-
-        let backend = response.data.wiki_queryservice_namespace.backend;
-        let namespace = response.data.wiki_queryservice_namespace.namespace;
-        var parsed = parse('http://' + host + url, true);
-        parsed.set('pathname', '/bigdata/namespace/' + namespace)
-        parsed.set('hostname', backend)
-        // unset the port as it is set in the backend host...
-        parsed.set('port', '')
-
-        return parsed.toString()
-
-    }
-    catch (error) {
-        console.error(error);
-    }
-
+        xmlHttp.onreadystatechange = function() {
+            if (this.readyState === 4) {
+                if (this.status === 200) {
+                    try {
+                        resolve(JSON.parse(xmlHttp.responseText))
+                    } catch (err) {
+                        reject(err)
+                    }
+                    return
+                }
+                reject(
+                    new Error(`Unexpected status code ${this.status} with error: ${xmlHttp.responseText}`)
+                )
+            }
+        };
+    })
+        .then(function (response) {
+            responseCache.set(wikiDomain, response)
+            return response
+        })
 }
 
 module.exports = {

diff --git a/test/defaultResolver.js b/test/defaultResolver.js
@@ -3,10 +3,13 @@ var r = require("./../resolver.js")
 
 describe('resolver.defaultResolver', function() {
     it('nothing', function() {
-        assert.strictEqual(
-            r.defaultResolver('', '', {headers:{}}),
-            null
-        );
+        return Promise.resolve(r.defaultResolver('', '', {headers:{}}))
+            .then(function (result) {
+                assert.strictEqual(
+                    result,
+                    null
+                );
+            })
     });
     // TODO make that target backend testable or mockable somehow :)
     // it('domain ', function() {