Merge pull request #136 from cyprus-developer-community/feat-add-cach…

…e-to-github-events

feat: add in-memory cache to github events

app/features/providers/github/commands/getPastEvents.ts

@@ -8,22 +8,25 @@ import {
 } from '~/features/providers/misc/http'
 import { mapIssuesToEvents } from './misc/mapIssueToEvent'
 import type { Event } from './types'
+import { fetchCached } from './misc/cache'
 
 export const getPastEvents = async (
   nextToken?: String
 ): Promise<ApiResponse<Event[]>> => {
   try {
     const client = newGraphQLClientFactory()
 
-    const res = await client<GetPastEventsQuery>(getPastEventsQuery, {
-      owner: 'cyprus-developer-community',
-      repo: 'events',
-      size: 20,
-      after: nextToken
-    })
-
-    const events = await mapIssuesToEvents(res.repository.issues.nodes)
+    const cacheKey = 'pastEvents'
+    const events = await fetchCached(cacheKey, async () => {
+      const res = await client<GetPastEventsQuery>(getPastEventsQuery, {
+        owner: 'cyprus-developer-community',
+        repo: 'events',
+        size: 20,
+        after: nextToken
+      })
 
+      return mapIssuesToEvents(res.repository.issues.nodes)
+    })
     return newSuccessfulResponse(events)
   } catch (e) {
     return newErrorResponse(e)

app/features/providers/github/commands/getUpcomingEvents.ts

@@ -8,21 +8,25 @@ import {
 } from '~/features/providers/misc/http'
 import type { Event } from './types'
 import { mapIssuesToEvents } from './misc/mapIssueToEvent'
+import { fetchCached } from './misc/cache'
 
 export const getUpcomingEvents = async (
   nextToken?: String
 ): Promise<ApiResponse<Event[]>> => {
   try {
     const client = newGraphQLClientFactory()
 
-    const res = await client<GetUpcomingEventsQuery>(getUpcomingEventsQuery, {
-      owner: 'cyprus-developer-community',
-      repo: 'events',
-      size: 20,
-      after: nextToken
-    })
+    const cacheKey = 'upcomingEvents'
+    const events = await fetchCached(cacheKey, async () => {
+      const res = await client<GetUpcomingEventsQuery>(getUpcomingEventsQuery, {
+        owner: 'cyprus-developer-community',
+        repo: 'events',
+        size: 20,
+        after: nextToken
+      })
 
-    const events = await mapIssuesToEvents(res.repository.issues.nodes)
+      return mapIssuesToEvents(res.repository.issues.nodes)
+    })
     return newSuccessfulResponse(events)
   } catch (e) {
     return newErrorResponse(e)

app/features/providers/github/commands/misc/cache.ts

@@ -0,0 +1,49 @@
+import NodeCache from 'node-cache'
+
+let cache: NodeCache
+let expired = {}
+
+declare global {
+  var __cache: NodeCache | undefined
+  var __expired: { [key: string]: boolean }
+}
+
+if (process.env.NODE_ENV === 'production') {
+  cache = new NodeCache({ deleteOnExpire: false })
+} else {
+  if (!global.__cache) {
+    global.__cache = new NodeCache({ deleteOnExpire: false })
+  }
+  cache = global.__cache
+  if (!global.__expired) {
+    global.__expired = {}
+  }
+  expired = global.__expired
+}
+
+cache.on('expired', (key) => {
+  expired[key] = true
+})
+
+const fetchCached = async <T>(
+  cacheKey: string,
+  fetcher: () => Promise<T>,
+  ttl = 60 * 20
+) => {
+  let response: T
+  if (cache.has(cacheKey)) {
+    response = cache.get(cacheKey)
+    if (expired[cacheKey]) {
+      ;(async () => {
+        expired[cacheKey] = false
+        cache.set(cacheKey, await fetcher(), ttl)
+      })()
+    }
+    return response
+  }
+  response = await fetcher()
+  cache.set(cacheKey, response, ttl)
+  return response
+}
+
+export { cache, fetchCached }

package.json

@@ -63,6 +63,7 @@
     "date-fns-tz": "^2.0.0",
     "graphql": "^16.6.0",
     "marked": "^4.2.12",
+    "node-cache": "^5.1.2",
     "react": "^18.2.0",
     "react-dom": "^18.2.0",
     "react-error-boundary": "^4.0.11",