add performance improvement

src/core/getPost.mts

@@ -4,13 +4,31 @@ import { postDirFilePath } from "../config.mts"
 import { readPostFile } from "./readPostFile.mts"
 import { Post } from "../types.mts"
 
+const cache: { [key: string]: { timestamp: number, post: Post }} = {};
+
 export const getPost = async (appId: string, postId: string): Promise<Post> => {
+
+  /*
+  const cacheKey = `${appId}_${postId}`;
+  const now = Date.now();
+  
+  // this is a tight cache (5 seconds)
+  if (cache[cacheKey] && (now - cache[cacheKey].timestamp) < (5 * 1000)) {
+    // return the cached data if it is less than 5 minutes old
+    return cache[cacheKey].post;
+  }
+  */
+
   const postFileName = `${appId}_${postId}.json`
 
   const postFilePath = path.join(postDirFilePath, postFileName)
 
   try {
     const post = await readPostFile(postFilePath)
+    
+    // if successful, cache the post and its fetch time
+    // cache[cacheKey] = { timestamp: now, post };
+
     return post
   } catch (err) {
     throw new Error(`couldn't find post ${postId} for app ${appId}`)

src/core/readPostFiles.mts

@@ -4,8 +4,17 @@ import { promises as fs } from "node:fs"
 import { Post } from "../types.mts"
 import { readPostFile } from "./readPostFile.mts"
 
+const cache = {} as { [directory: string]: { timestamp: number, files: Post[] } };
+
 export const readPostFiles = async (postDirFilePath: string, appId?: string): Promise<Post[]> => {
 
+  const now = Date.now()
+  
+  if (cache[postDirFilePath] && (now - cache[postDirFilePath].timestamp) < (5 * 60 * 1000)) { 
+    // return cached data if it's less than 5 minutes old
+    return cache[postDirFilePath].files
+  }
+
   let postFiles: string[] = []
   try {
     const filesInDir = await fs.readdir(postDirFilePath)
@@ -38,5 +47,8 @@ export const readPostFiles = async (postDirFilePath: string, appId?: string): Pr
     }
   }
 
+  // store results in cache with current timestamp
+  cache[postDirFilePath] = { timestamp: now, files: posts }
+  
   return posts
 }