add caching to apollo queries

backend/package.json

@@ -50,6 +50,7 @@
   },
   "dependencies": {
     "@apollo/server": "^4.1.0",
+    "@apollo/server-plugin-response-cache": "^4.1.3",
     "@graphql-tools/schema": "^10.0.0",
     "@graphql-tools/utils": "^10.0.7",
     "axios": "^1.5.1",
@@ -66,6 +67,7 @@
     "mongoose": "^7.6.3",
     "passport": "^0.6.0",
     "passport-google-oauth20": "^2.0.0",
+    "redis": "^4.6.13",
     "reflect-metadata": "^0.1.13"
   },
   "overrides": {

backend/src/bootstrap/loaders/apollo.ts

@@ -1,14 +1,46 @@
 import { ApolloServer } from "@apollo/server";
 import { buildSchema } from "../graphql/buildSchema";
 import { ApolloServerPluginLandingPageLocalDefault } from '@apollo/server/plugin/landingPage/default';
+import { ApolloServerPluginCacheControl } from '@apollo/server/plugin/cacheControl';
+import { KeyValueCache, KeyValueCacheSetOptions } from '@apollo/utils.keyvaluecache';
+import responseCachePlugin from '@apollo/server-plugin-response-cache';
+import { RedisClientType, createClient } from 'redis';
 
-export default async () => {
+class RedisCache implements KeyValueCache {
+  client: RedisClientType;
+  prefix: string = 'apollo-cache:';
+
+  constructor(client: RedisClientType) {
+    this.client = client;
+  }
+
+  async get(key: string) {
+    return await this.client.get(this.prefix + key) ?? undefined;
+  }
+
+  async set(key: string, value: string, _?: KeyValueCacheSetOptions | undefined) {
+    // ttl options are intentionally ignored because we will invalidate cache in update script
+    await this.client.set(this.prefix + key, value) 
+  }
+
+  async delete(key: string) {
+    return await this.client.del(this.prefix + key) === 1;
+  }
+
+}
+
+export default async (redis: RedisClientType) => {
   const schema = buildSchema();
 
   const server = new ApolloServer({
     schema,
-    plugins: [ApolloServerPluginLandingPageLocalDefault({ includeCookies: true })],
+    plugins: [
+      ApolloServerPluginLandingPageLocalDefault({ includeCookies: true }),
+      ApolloServerPluginCacheControl({ calculateHttpHeaders: false }),
+      responseCachePlugin(),
+    ],
     introspection: true, // TODO(production): disable introspection upon final deployment
+    cache: new RedisCache(redis),
   });
   await server.start();
 

backend/src/bootstrap/loaders/index.ts

@@ -5,6 +5,7 @@ import { config } from "../../config";
 import apolloLoader from "./apollo";
 import expressLoader from "./express";
 import mongooseLoader from "./mongoose";
+import redisLoader from "./redis";
 
 export default async (root: Application): Promise<void> => {
   const app = Router() as Application;
@@ -13,9 +14,13 @@ export default async (root: Application): Promise<void> => {
   console.log("Booting up mongo...");
   await mongooseLoader();
 
+  // connect to redis
+  console.log("Booting up redis...");
+  const redis = await redisLoader();
+
   // load apollo server config. must be loaded before express
   console.log("Loading apollo...");
-  const server = await apolloLoader();
+  const server = await apolloLoader(redis);
 
   // load everything related to express. depends on apollo
   console.log("Loading express...");

backend/src/bootstrap/loaders/redis.ts

@@ -0,0 +1,6 @@
+import { RedisClientType, createClient } from "redis"
+import { config } from "../../config";
+
+export default async (): Promise<RedisClientType> => {
+    return await createClient({ url: config.redisUri }).connect() as RedisClientType;
+}

backend/src/config.ts

@@ -30,6 +30,7 @@ export interface Config {
   SESSION_SECRET: string;
   GOOGLE_CLIENT_ID: string;
   GOOGLE_CLIENT_SECRET: string;
+  redisUri: string;
 }
 
 // All your secrets, keys go here
@@ -51,4 +52,5 @@ export const config: Config = {
   SESSION_SECRET: env("SESSION_SECRET"),
   GOOGLE_CLIENT_ID: env("GOOGLE_CLIENT_ID"),
   GOOGLE_CLIENT_SECRET: env("GOOGLE_CLIENT_SECRET"),
+  redisUri: env("REDIS_URI"),
 };

backend/src/generated-types/graphql.ts

@@ -17,6 +17,10 @@ export type Scalars = {
   JSONObject: any;
 };
 
+export type CacheControlScope =
+  | 'PRIVATE'
+  | 'PUBLIC';
+
 export type CatalogClass = {
   __typename?: 'CatalogClass';
   description?: Maybe<Scalars['String']>;
@@ -208,6 +212,7 @@ export type Query = {
    */
   courseList?: Maybe<Array<Maybe<CourseListItem>>>;
   grade?: Maybe<Grade>;
+  /** @deprecated test */
   ping: Scalars['String'];
   /** Takes in a schedule's ObjectID and returns a specific schedule. */
   scheduleByID?: Maybe<Schedule>;
@@ -453,6 +458,7 @@ export type DirectiveResolverFn<TResult = {}, TParent = {}, TContext = {}, TArgs
 /** Mapping between all available schema types and the resolvers types */
 export type ResolversTypes = {
   Boolean: ResolverTypeWrapper<Scalars['Boolean']>;
+  CacheControlScope: CacheControlScope;
   CatalogClass: ResolverTypeWrapper<CatalogClass>;
   CatalogItem: ResolverTypeWrapper<CatalogItem>;
   Class: ResolverTypeWrapper<Class>;
@@ -523,6 +529,14 @@ export type AuthDirectiveArgs = { };
 
 export type AuthDirectiveResolver<Result, Parent, ContextType = any, Args = AuthDirectiveArgs> = DirectiveResolverFn<Result, Parent, ContextType, Args>;
 
+export type CacheControlDirectiveArgs = {
+  inheritMaxAge?: Maybe<Scalars['Boolean']>;
+  maxAge?: Maybe<Scalars['Int']>;
+  scope?: Maybe<CacheControlScope>;
+};
+
+export type CacheControlDirectiveResolver<Result, Parent, ContextType = any, Args = CacheControlDirectiveArgs> = DirectiveResolverFn<Result, Parent, ContextType, Args>;
+
 export type CatalogClassResolvers<ContextType = any, ParentType extends ResolversParentTypes['CatalogClass'] = ResolversParentTypes['CatalogClass']> = {
   description?: Resolver<Maybe<ResolversTypes['String']>, ParentType, ContextType>;
   enrollCount?: Resolver<ResolversTypes['Int'], ParentType, ContextType>;
@@ -757,6 +771,7 @@ export type Resolvers<ContextType = any> = {
 
 export type DirectiveResolvers<ContextType = any> = {
   auth?: AuthDirectiveResolver<any, any, ContextType>;
+  cacheControl?: CacheControlDirectiveResolver<any, any, ContextType>;
 };
 
 export type IsoDate = Scalars["ISODate"];

backend/src/modules/catalog/typedefs/catalog.ts

@@ -24,7 +24,7 @@ type Query {
 """
 Info shared between Classes within and across semesters.
 """
-type Course {
+type Course @cacheControl(maxAge: 1) {
     classes(term: TermInput): [Class]!
     crossListing: [Course]
     sections(term: TermInput, primary: Boolean): [Section]!
@@ -48,7 +48,7 @@ type Course {
 """
 Data for a specific class in a specific semester. There may be more than one Class for a given Course in a given semester.
 """
-type Class {
+type Class @cacheControl(maxAge: 1) {
     course: Course!
     primarySection: Section!
     sections: [Section]!
@@ -74,7 +74,7 @@ type Class {
 """
 Sections are each associated with one Class. 
 """
-type Section {
+type Section @cacheControl(maxAge: 1) {
     class: Class!
     course: Course!
     enrollmentHistory: [EnrollmentDay]
@@ -100,30 +100,30 @@ type Section {
     lastUpdated: ISODate!
 }
 
-type Instructor {
+type Instructor @cacheControl(maxAge: 1) {
     familyName: String!
     givenName: String!
 }
 
-type EnrollmentDay {
+type EnrollmentDay @cacheControl(maxAge: 1) {
     enrollCount: Int!
     enrollMax: Int!
     waitlistCount: Int!
     waitlistMax: Int!
 }
 
-type CatalogItem {
+type CatalogItem @cacheControl(maxAge: 1) {
     subject: String!
     number: String!
-    title: String!
+    title: String! @cacheControl(maxAge: 30)
     description: String!
     classes: [CatalogClass]!
     gradeAverage: Float
 
     lastUpdated: ISODate!
 }
 
-type CatalogClass {
+type CatalogClass @cacheControl(maxAge: 1) {
     number: String!
     title: String
     description: String
@@ -135,7 +135,7 @@ type CatalogClass {
     lastUpdated: ISODate!
 }
 
-type CourseListItem {
+type CourseListItem @cacheControl(maxAge: 1) {
     subject: String!
     number: String!
 }