feat: make client features endpoint memoizable (#734)

src/lib/options.js

@@ -90,6 +90,12 @@ function defaultOptions() {
         version,
         secureHeaders: process.env.SECURE_HEADERS || false,
         enableOAS: process.env.ENABLE_OAS || false,
+        experimental: {
+            clientFeatureMemoize: {
+                enabled: process.env.CLIENT_FEATURE_MEMOIZE || false,
+                maxAge: process.env.CLIENT_FEATURE_MAXAGE || 1000,
+            },
+        },
     };
 }
 

src/lib/routes/client-api/feature.js

@@ -2,6 +2,8 @@
 
 import { handleErrors } from '../admin-api/util';
 
+const memoizee = require('memoizee');
+
 const Controller = require('../controller');
 
 const version = 1;
@@ -16,20 +18,43 @@ const FEATURE_COLUMNS_CLIENT = [
 ];
 
 class FeatureController extends Controller {
-    constructor({ featureToggleService }, getLogger) {
+    constructor({ featureToggleService }, { getLogger, experimental }) {
         super();
         this.toggleService = featureToggleService;
         this.logger = getLogger('client-api/feature.js');
         this.get('/', this.getAll);
         this.get('/:featureName', this.getFeatureToggle);
+        if (experimental && experimental.clientFeatureMemoize) {
+            this.cache = experimental.clientFeatureMemoize.enabled;
+            this.cachedFeatures = memoizee(
+                (query, fields) =>
+                    this.toggleService.getFeatures(query, fields),
+                {
+                    promise: true,
+                    maxAge: experimental.clientFeatureMemoize.maxAge,
+                    normalizer(args) {
+                        // args is arguments object as accessible in memoized function
+                        return JSON.stringify(args[0]);
+                    },
+                },
+            );
+        }
     }
 
     async getAll(req, res) {
         try {
-            const features = await this.toggleService.getFeatures(
-                req.query,
-                FEATURE_COLUMNS_CLIENT,
-            );
+            let features;
+            if (this.cache) {
+                features = await this.cachedFeatures(
+                    req.query,
+                    FEATURE_COLUMNS_CLIENT,
+                );
+            } else {
+                features = await this.toggleService.getFeatures(
+                    req.query,
+                    FEATURE_COLUMNS_CLIENT,
+                );
+            }
             res.json({ version, features });
         } catch (e) {
             handleErrors(res, this.logger, e);

src/lib/routes/client-api/feature.test.js

@@ -3,10 +3,12 @@
 const test = require('ava');
 const supertest = require('supertest');
 const { EventEmitter } = require('events');
+const sinon = require('sinon');
 const store = require('../../../test/fixtures/store');
 const getLogger = require('../../../test/fixtures/no-logger');
 const getApp = require('../../app');
 const { createServices } = require('../../services');
+const FeatureController = require('./feature');
 
 const eventBus = new EventEmitter();
 
@@ -40,6 +42,52 @@ test('should get empty getFeatures via client', t => {
         });
 });
 
+test('if caching is enabled should memoize', t => {
+    const getFeatures = sinon.fake.returns([]);
+
+    const featureToggleService = {
+        getFeatures,
+    };
+    const controller = new FeatureController(
+        { featureToggleService },
+        {
+            getLogger,
+            experimental: {
+                clientFeatureMemoize: {
+                    enabled: true,
+                    maxAge: 10000,
+                },
+            },
+        },
+    );
+    controller.getAll({ query: {} }, { json: () => {} });
+    controller.getAll({ query: {} }, { json: () => {} });
+    t.is(getFeatures.callCount, 1);
+});
+
+test('if caching is not enabled all calls goes to service', t => {
+    const getFeatures = sinon.fake.returns([]);
+
+    const featureToggleService = {
+        getFeatures,
+    };
+    const controller = new FeatureController(
+        { featureToggleService },
+        {
+            getLogger,
+            experimental: {
+                clientFeatureMemoize: {
+                    enabled: false,
+                    maxAge: 10000,
+                },
+            },
+        },
+    );
+    controller.getAll({ query: {} }, { json: () => {} });
+    controller.getAll({ query: {} }, { json: () => {} });
+    t.is(getFeatures.callCount, 2);
+});
+
 test('fetch single feature', t => {
     t.plan(1);
     const { request, featureToggleStore, base } = getSetup();

src/lib/routes/client-api/index.js

@@ -13,10 +13,7 @@ class ClientApi extends Controller {
         const { getLogger } = config;
 
         this.get('/', this.index);
-        this.use(
-            '/features',
-            new FeatureController(services, getLogger).router,
-        );
+        this.use('/features', new FeatureController(services, config).router);
         this.use('/metrics', new MetricsController(services, getLogger).router);
         this.use(
             '/register',

src/lib/routes/index.ts

@@ -22,10 +22,7 @@ class IndexRouter extends Controller {
 
         // legacy support (remove in 4.x)
         if (config.enableLegacyRoutes) {
-            const featureController = new FeatureController(
-                services,
-                config.getLogger,
-            );
+            const featureController = new FeatureController(services, config);
             this.use('/api/features', featureController.router);
         }
     }