From b2ecfa83ffc48993232bdef72fac38bf01765f9a Mon Sep 17 00:00:00 2001
From: Rodrigo Nascimento <rodrigoknascimento@gmail.com>
Date: Thu, 4 Feb 2021 14:01:15 -0300
Subject: [PATCH] =?UTF-8?q?Chore:=20Improve=20performance=20of=20messages?=
 =?UTF-8?q?=E2=80=99=20watcher=20(#20519)?=
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---
 server/modules/watchers/watchers.module.ts | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/server/modules/watchers/watchers.module.ts b/server/modules/watchers/watchers.module.ts
index ca202fc85ee..a6f856a4413 100644
--- a/server/modules/watchers/watchers.module.ts
+++ b/server/modules/watchers/watchers.module.ts
@@ -1,3 +1,5 @@
+import mem from 'mem';
+
 import { SubscriptionsRaw } from '../../../app/models/server/raw/Subscriptions';
 import { UsersRaw } from '../../../app/models/server/raw/Users';
 import { SettingsRaw } from '../../../app/models/server/raw/Settings';
@@ -13,7 +15,7 @@ import { IBaseRaw } from '../../../app/models/server/raw/BaseRaw';
 import { LivechatInquiryRaw } from '../../../app/models/server/raw/LivechatInquiry';
 import { IBaseData } from '../../../definition/IBaseData';
 import { IPermission } from '../../../definition/IPermission';
-import { ISetting } from '../../../definition/ISetting';
+import { ISetting, SettingValue } from '../../../definition/ISetting';
 import { IInquiry } from '../../../definition/IInquiry';
 import { UsersSessionsRaw } from '../../../app/models/server/raw/UsersSessions';
 import { IUserSession } from '../../../definition/IUserSession';
@@ -83,6 +85,13 @@ export function initWatchers(models: IModelsParam, broadcast: BroadcastCallback,
 		EmailInbox,
 	} = models;
 
+	const getSettingCached = mem(async (setting: string): Promise<SettingValue> => Settings.getValueById(setting), { maxAge: 10000 });
+
+	const getUserNameCached = mem(async (userId: string): Promise<string | undefined> => {
+		const user = await Users.findOneById(userId, { projection: { name: 1 } });
+		return user?.name;
+	}, { maxAge: 10000 });
+
 	watch<IMessage>(Messages, async ({ clientAction, id, data }) => {
 		switch (clientAction) {
 			case 'inserted':
@@ -93,18 +102,16 @@ export function initWatchers(models: IModelsParam, broadcast: BroadcastCallback,
 				}
 
 				if (message._hidden !== true && message.imported == null) {
-					const UseRealName = await Settings.getValueById('UI_Use_Real_Name') === true;
+					const UseRealName = await getSettingCached('UI_Use_Real_Name') === true;
 
 					if (UseRealName) {
 						if (message.u?._id) {
-							const user = await Users.findOneById(message.u._id);
-							message.u.name = user?.name;
+							message.u.name = await getUserNameCached(message.u._id);
 						}
 
 						if (message.mentions?.length) {
 							for await (const mention of message.mentions) {
-								const user = await Users.findOneById(mention._id);
-								mention.name = user?.name;
+								mention.name = await getUserNameCached(mention._id);
 							}
 						}
 					}