From 735fd3770755863dd6ab359365ec9bf3ec8c251e Mon Sep 17 00:00:00 2001
From: Laura Hausmann <laura@hausmann.dev>
Date: Wed, 22 Nov 2023 19:52:04 +0100
Subject: [PATCH] [backend] Only pack each user once per request

---
 .../backend/src/models/repositories/note.ts   | 11 +++--
 .../backend/src/models/repositories/user.ts   | 41 ++++++++++++++++++-
 2 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/packages/backend/src/models/repositories/note.ts b/packages/backend/src/models/repositories/note.ts
index 7c976d8d8..ad4ef0c0d 100644
--- a/packages/backend/src/models/repositories/note.ts
+++ b/packages/backend/src/models/repositories/note.ts
@@ -28,6 +28,7 @@ import {
 } from "@/misc/populate-emojis.js";
 import { db } from "@/db/postgre.js";
 import { IdentifiableError } from "@/misc/identifiable-error.js";
+import { PackedUserCache } from "@/models/repositories/user.js";
 
 export async function populatePoll(note: Note, meId: User["id"] | null) {
 	const poll = await Polls.findOneByOrFail({ noteId: note.id });
@@ -173,6 +174,7 @@ export const NoteRepository = db.getRepository(Note).extend({
 				myRenotes: Map<Note["id"], boolean>;
 			};
 		},
+		userCache: PackedUserCache = Users.getFreshPackedUserCache(),
 	): Promise<Packed<"Note">> {
 		const opts = Object.assign(
 			{
@@ -221,7 +223,7 @@ export const NoteRepository = db.getRepository(Note).extend({
 			id: note.id,
 			createdAt: note.createdAt.toISOString(),
 			userId: note.userId,
-			user: Users.pack(note.user ?? note.userId, me, {
+			user: Users.packCached(note.user ?? note.userId, userCache, me, {
 				detail: false,
 			}),
 			text: text,
@@ -265,14 +267,14 @@ export const NoteRepository = db.getRepository(Note).extend({
 							? this.tryPack(note.reply || note.replyId, me, {
 									detail: false,
 									_hint_: options?._hint_,
-							  })
+							  }, userCache)
 							: undefined,
 
 						renote: note.renoteId
 							? this.pack(note.renote || note.renoteId, me, {
 									detail: true,
 									_hint_: options?._hint_,
-							  })
+							  }, userCache)
 							: undefined,
 				  }
 				: {}),
@@ -309,9 +311,10 @@ export const NoteRepository = db.getRepository(Note).extend({
 				myRenotes: Map<Note["id"], boolean>;
 			};
 		},
+		userCache: PackedUserCache = Users.getFreshPackedUserCache(),
 	): Promise<Packed<"Note"> | undefined> {
 		try {
-			return await this.pack(src, me, options);
+			return await this.pack(src, me, options, userCache);
 		} catch {
 			return undefined;
 		}
diff --git a/packages/backend/src/models/repositories/user.ts b/packages/backend/src/models/repositories/user.ts
index 3a8b7874a..37a84779a 100644
--- a/packages/backend/src/models/repositories/user.ts
+++ b/packages/backend/src/models/repositories/user.ts
@@ -7,7 +7,6 @@ import type { Packed } from "@/misc/schema.js";
 import type { Promiseable } from "@/prelude/await-all.js";
 import { awaitAll } from "@/prelude/await-all.js";
 import { populateEmojis } from "@/misc/populate-emojis.js";
-import { getAntennas } from "@/misc/antenna-cache.js";
 import { USER_ACTIVE_THRESHOLD, USER_ONLINE_THRESHOLD } from "@/const.js";
 import { Cache } from "@/misc/cache.js";
 import { db } from "@/db/postgre.js";
@@ -37,6 +36,7 @@ import {
 	UserSecurityKeys,
 } from "../index.js";
 import type { Instance } from "../entities/instance.js";
+import AsyncLock from "async-lock";
 
 const userInstanceCache = new Cache<Instance | null>(
 	"userInstance",
@@ -59,6 +59,11 @@ type IsMeAndIsUserDetailed<
 
 const ajv = new Ajv();
 
+export type PackedUserCache = {
+	locks: AsyncLock;
+	results: IsMeAndIsUserDetailed<any, any>[];
+}
+
 const localUsernameSchema = {
 	type: "string",
 	pattern: /^\w{1,20}$/.toString().slice(1, -1),
@@ -366,6 +371,37 @@ export const UserRepository = db.getRepository(User).extend({
 		return `${config.url}/identicon/${userId}`;
 	},
 
+	getFreshPackedUserCache(): PackedUserCache {
+		return {
+			locks: new AsyncLock(),
+			results: [],
+		};
+	},
+
+	async packCached<
+		ExpectsMe extends boolean | null = null,
+		D extends boolean = false,
+	>(
+		src: User["id"] | User,
+		cache: PackedUserCache,
+		me?: { id: User["id"] } | null | undefined,
+		options?: {
+			detail?: D;
+			includeSecrets?: boolean;
+			isPrivateMode?: boolean;
+		},
+	): Promise<IsMeAndIsUserDetailed<ExpectsMe, D>> {
+		const id = typeof src === "object" ? src.id : src;
+		return cache.locks.acquire(id, async () => {
+			const result = cache.results.find(p => p.id === id);
+			if (result) return result as IsMeAndIsUserDetailed<ExpectsMe, D>
+			return this.pack<ExpectsMe, D>(src, me, options).then(result => {
+				cache.results.push(result);
+				return result;
+			});
+		});
+	},
+
 	async pack<
 		ExpectsMe extends boolean | null = null,
 		D extends boolean = false,
@@ -638,8 +674,9 @@ export const UserRepository = db.getRepository(User).extend({
 			detail?: D;
 			includeSecrets?: boolean;
 		},
+		cache?: PackedUserCache,
 	): Promise<IsUserDetailed<D>[]> {
-		return Promise.all(users.map((u) => this.pack(u, me, options)));
+		return Promise.all(users.map((u) => this.packCached(u, cache ?? this.getFreshPackedUserCache(), me, options)));
 	},
 
 	isLocalUser,