Add caching of user-data (#568)

* Add caching of user-data for 600 seconds

* Make cache-entry interface commonly usable

* Extract revision types

* Remove revision-cache rule

* Use seconds as cache-time interval (Date.now uses milliseconds)

* Fix import error

* Extract cache logic into common cache-class

* Add cache class that was forgotten to commit in last commit

* Start adding unit tests

* Fix bug detected during unit-testing

* Add unit tests for cache

* Made entry-limit test more explicit

* Renamed files to lower-case starting letter

src/api/revisions/index.ts

@@ -1,23 +1,21 @@
+import { Cache } from '../../components/common/cache/cache'
 import { defaultFetchConfig, expectResponseCode, getApiUrl } from '../utils'
+import { Revision, RevisionListEntry } from './types'
 
-export interface Revision {
-  content: string
-  timestamp: number
-  authors: string[]
-}
-
-export interface RevisionListEntry {
-  timestamp: number
-  length: number
-  authors: string[]
-}
+const revisionCache = new Cache<string, Revision>(3600)
 
 export const getRevision = async (noteId: string, timestamp: number): Promise<Revision> => {
+  const cacheKey = `${noteId}:${timestamp}`
+  if (revisionCache.has(cacheKey)) {
+    return revisionCache.get(cacheKey)
+  }
   const response = await fetch(getApiUrl() + `/notes/${noteId}/revisions/${timestamp}`, {
     ...defaultFetchConfig
   })
   expectResponseCode(response)
-  return await response.json() as Promise<Revision>
+  const revisionData = await response.json() as Revision
+  revisionCache.put(cacheKey, revisionData)
+  return revisionData
 }
 
 export const getAllRevisions = async (noteId: string): Promise<RevisionListEntry[]> => {

src/api/revisions/types.d.ts

@@ -0,0 +1,11 @@
+export interface Revision {
+  content: string
+  timestamp: number
+  authors: string[]
+}
+
+export interface RevisionListEntry {
+  timestamp: number
+  length: number
+  authors: string[]
+}

src/api/users/index.ts

@@ -1,10 +1,18 @@
+import { Cache } from '../../components/common/cache/cache'
 import { defaultFetchConfig, expectResponseCode, getApiUrl } from '../utils'
 import { UserResponse } from './types'
 
+const cache = new Cache<string, UserResponse>(600)
+
 export const getUserById = async (userid: string): Promise<UserResponse> => {
+  if (cache.has(userid)) {
+    return cache.get(userid)
+  }
   const response = await fetch(`${getApiUrl()}/users/${userid}`, {
     ...defaultFetchConfig
   })
   expectResponseCode(response)
-  return (await response.json()) as UserResponse
+  const userData = (await response.json()) as UserResponse
+  cache.put(userid, userData)
+  return userData
 }