add TTLs object and update initialization

src/repositories/ApiBasedRepository.ts

@@ -11,18 +11,26 @@ export interface ApiBasedRepositoryCache {
   // To speed things up, implement caches for other data later
 }
 
-export class ApiBasedRepository implements GetterRepository {
+export interface ApiBasedRepositoryMillisecondTTLs {
-  private cache: ApiBasedRepositoryCache;
+  etasForShuttleId: number,
+  etasForStopId: number,
+}
 
-  constructor(initialCache: ApiBasedRepositoryCache | undefined = undefined) {
+const emptyCache: ApiBasedRepositoryCache = {
-    if (initialCache) {
-      this.cache = initialCache;
-    } else {
-      this.cache = {
   etasForShuttleId: {},
   etasForStopId: {},
 }
+
+const defaultTtls: ApiBasedRepositoryMillisecondTTLs = {
+  etasForShuttleId: 10000,
+  etasForStopId: 10000,
 }
+
+export class ApiBasedRepository implements GetterRepository {
+  constructor(
+    private initialCache: ApiBasedRepositoryCache | undefined = emptyCache,
+    private ttls: ApiBasedRepositoryMillisecondTTLs = defaultTtls,
+  ) {
   }
 
   public async getEtaForShuttleAndStopId(shuttleId: string, stopId: string): Promise<IEta | null> {