Switch to singleton approach (#117)

auth.ts

@@ -3,10 +3,10 @@ import Discord from 'next-auth/providers/discord'
 import { addUser } from './lib/db/users'
 import { AccountType, type User } from './types/User'
 import { MongoDBAdapter } from '@auth/mongodb-adapter'
-import { dbClient } from './lib/db/db'
 import type { NextAuthConfig } from 'next-auth'
 import { findOneTyped } from './lib/db/dbTyped'
 import { Types } from './types/Components'
+import clientPromise from './lib/db/mongoDB'
 
 export const authOptions: NextAuthConfig = {
   providers: [Discord],
@@ -85,7 +85,7 @@ export const authOptions: NextAuthConfig = {
   },
 
   // A database is optional, but required to persist accounts in a database
-  adapter: MongoDBAdapter(dbClient(), {
+  adapter: MongoDBAdapter(clientPromise, {
     collections: {
       Users: 'nextauth_users',
       Sessions: 'nextauth_sessions',

lib/db/db.ts

@@ -1,7 +1,7 @@
 // docker run --name index-db -d -p 27017:27017 mongo
-import { MongoClient } from 'mongodb'
 import { hasOwnProperty } from '../utils'
 import { cleanId, polluteId } from './utils'
+import clientPromise from './mongoDB'
 
 const uri =
   'DATABASE_URL' in process.env
@@ -11,8 +11,6 @@ if (typeof uri !== 'string') {
   throw Error('Unable to connect to DB due to missing DATABASE_URL')
 }
 
-export const dbClient = () => new MongoClient(uri, { maxPoolSize: 5 })
-
 export async function exportData(isAdmin = false) {
   if (isAdmin) {
     return {
@@ -34,10 +32,8 @@ export async function exportData(isAdmin = false) {
 }
 
 export async function getAll(collection: string): Promise<object[]> {
-  const client = await dbClient().connect()
-  const db = client.db('index')
+  const db = (await clientPromise).db('index')
   let data = await db.collection(collection).find().toArray()
-  client.close()
   if (data.length > 0 && hasOwnProperty(data[0], 'name')) {
     data = data.sort((a, b) => (a.name < b.name ? -1 : 1))
   }
@@ -49,21 +45,18 @@ export async function find(
   collection: string,
   query: Record<string, any>
 ): Promise<object[]> {
-  const client = await dbClient().connect()
-  const db = client.db('index')
-  const data = await db.collection(collection).find(polluteId(query)).toArray()
-  client.close()
-  return cleanId(data)
+  const db = (await clientPromise).db('index')
+  return cleanId(
+    await db.collection(collection).find(polluteId(query)).toArray()
+  )
 }
 
 export async function findOne(
   collection: string,
   query: Record<string, any>
 ): Promise<object | null> {
-  const client = await dbClient().connect()
-  const db = client.db('index')
+  const db = (await clientPromise).db('index')
   const found = await db.collection(collection).findOne(polluteId(query))
-  client.close()
   if (found === null) {
     return null
   }
@@ -74,10 +67,8 @@ export async function count(
   collection: string,
   query: Record<string, any> = {}
 ): Promise<number> {
-  const client = await dbClient().connect()
-  const db = client.db('index')
+  const db = (await clientPromise).db('index')
   const data = await db.collection(collection).countDocuments(polluteId(query))
-  client.close()
   return data
 }
 
@@ -92,15 +83,13 @@ export async function insert(
   collection: string,
   data: Record<string, any>
 ): Promise<string> {
-  const client = await dbClient().connect()
   let tries = 1
   while (tries < 3) {
     try {
-      const db = client.db('index')
+      const db = (await clientPromise).db('index')
       data.createdAt = new Date()
       data.lastModified = new Date()
       const { insertedId } = await db.collection(collection).insertOne(data)
-      client.close()
       return insertedId.toString()
     } catch (error) {
       console.error(
@@ -112,7 +101,6 @@ export async function insert(
       tries++
     }
   }
-  client.close()
   throw Error('Unable to insert entry into ' + collection + ' after 3 retires')
 }
 
@@ -121,16 +109,14 @@ export async function updateOne(
   query: Record<string, any>,
   data: Record<string, any>
 ) {
-  const client = await dbClient().connect()
   let tries = 1
   while (tries < 3) {
     try {
-      const db = client.db('index')
+      const db = (await clientPromise).db('index')
       await db.collection(collection).updateOne(polluteId(query), {
         $set: data,
         $currentDate: { lastModified: true },
       })
-      client.close()
       return
     } catch (error) {
       console.error(
@@ -139,21 +125,18 @@ export async function updateOne(
       tries++
     }
   }
-  client.close()
   throw Error('Unable to update entry of ' + collection + ' after 3 retires')
 }
 
 export async function deleteOne(
   collection: string,
   query: Record<string, any>
 ) {
-  const client = await dbClient().connect()
   let tries = 1
   while (tries < 3) {
     try {
-      const db = client.db('index')
+      const db = (await clientPromise).db('index')
       await db.collection(collection).deleteOne(polluteId(query))
-      client.close()
       return
     } catch (error) {
       console.error(
@@ -165,6 +148,5 @@ export async function deleteOne(
       tries++
     }
   }
-  client.close()
   throw Error('Unable to delete entry from ' + collection + ' after 3 retires')
 }

lib/db/itemScreenshots.ts

@@ -1,6 +1,6 @@
-import { dbClient } from './db'
 import { GridFSBucket } from 'mongodb'
 import { Readable } from 'stream'
+import clientPromise from './mongoDB'
 
 export function bufferToStream(buffer: Buffer) {
   let stream = new Readable()
@@ -32,8 +32,7 @@ export async function addItemScreenshot(img: Uint8Array, itemId: string) {
   imgStream.push(img)
   imgStream.push(null)
 
-  const client = await dbClient().connect()
-  const db = client.db('index')
+  const db = (await clientPromise).db('index')
   const bucket = new GridFSBucket(db, {
     bucketName: 'itemScreenshots',
   })
@@ -57,51 +56,38 @@ export async function addItemScreenshot(img: Uint8Array, itemId: string) {
     stream.on('finish', resolve)
     imgStream.on('error', reject)
   })
-  client.close()
 }
 
 export async function getItemScreenshotBuffer(itemId: string) {
-  const client = await dbClient().connect()
-  const db = client.db('index')
+  const db = (await clientPromise).db('index')
   const bucket = new GridFSBucket(db, {
     bucketName: 'itemScreenshots',
   })
 
-  const data = await streamToBuffer(bucket.openDownloadStreamByName(itemId))
-  client.close()
-  return data
+  return await streamToBuffer(bucket.openDownloadStreamByName(itemId))
 }
 
 export async function screenshotExists(itemId: string) {
-  const client = await dbClient().connect()
-  const db = client.db('index')
+  const db = (await clientPromise).db('index')
   const bucket = new GridFSBucket(db, {
     bucketName: 'itemScreenshots',
   })
   const cursor = await bucket.find({ filename: itemId })
-  const data = await cursor.hasNext()
-  client.close()
-  return data
+  return await cursor.hasNext()
 }
 
 export async function clearAllScreenshots() {
-  const client = await dbClient().connect()
-  const db = client.db('index')
+  const db = (await clientPromise).db('index')
   const bucket = new GridFSBucket(db, {
     bucketName: 'itemScreenshots',
   })
-  const data = await bucket.drop()
-  client.close()
-  return data
+  return await bucket.drop()
 }
 
 export async function listScreenshotsOfItem(itemId: string) {
-  const client = await dbClient().connect()
-  const db = client.db('index')
+  const db = (await clientPromise).db('index')
   const bucket = new GridFSBucket(db, {
     bucketName: 'itemScreenshots',
   })
-  const data = bucket.find({ filename: itemId })
-  client.close()
-  return data
+  return bucket.find({ filename: itemId })
 }

lib/db/mongoDB.ts

@@ -0,0 +1,44 @@
+import { MongoClient } from 'mongodb'
+
+const uri = (
+  'DATABASE_URL' in process.env
+    ? process.env.DATABASE_URL
+    : 'mongodb://localhost'
+) as string
+if (typeof uri !== 'string') {
+  throw Error('Unable to connect to DB due to missing DATABASE_URL')
+}
+
+declare global {
+  var _mongoClientPromise: Promise<MongoClient>
+}
+
+class Singleton {
+  private static _instance: Singleton
+  private client: MongoClient
+  private clientPromise: Promise<MongoClient>
+  private constructor() {
+    this.client = new MongoClient(uri, {
+      maxPoolSize: 5,
+      directConnection: true,
+    })
+    this.clientPromise = this.client.connect()
+    if (process.env.NODE_ENV === 'development') {
+      // In development mode, use a global variable so that the value
+      // is preserved across module reloads caused by HMR (Hot Module Replacement).
+      global._mongoClientPromise = this.clientPromise
+    }
+  }
+
+  public static get instance() {
+    if (!this._instance) {
+      this._instance = new Singleton()
+    }
+    return this._instance.clientPromise
+  }
+}
+const clientPromise = Singleton.instance
+
+// Export a module-scoped MongoClient promise. By doing this in a
+// separate module, the client can be shared across functions.
+export default clientPromise

lib/db/views.ts

@@ -1,15 +1,15 @@
-import { count, dbClient, deleteOne, find, findOne, getAll, insert } from './db'
+import { count, deleteOne, find, findOne, getAll, insert } from './db'
 import { cleanId } from './utils'
 import { Types } from '../../types/Components'
 import { findOneTyped } from './dbTyped'
+import clientPromise from './mongoDB'
 
 export async function getViews() {
   return await getAll('views')
 }
 
 export async function getLastViews(type: Types, n: number) {
-  const client = await dbClient().connect()
-  const db = client.db('index')
+  const db = (await clientPromise).db('index')
   const data = cleanId(
     await db
       .collection('views')
@@ -18,7 +18,6 @@ export async function getLastViews(type: Types, n: number) {
       .limit(n)
       .toArray()
   )
-  client.close()
   console.log('Found', data.length, 'entries in views table for', type)
 
   // count what has been popular recently