From 78fa734017fa7804c83f57320d2026391f679212 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bar=C4=B1=C5=9F=20Soner=20U=C5=9Fakl=C4=B1?=
 <barisusakli@gmail.com>
Date: Sun, 9 Dec 2018 16:03:41 -0500
Subject: [PATCH] feat: cache category tag whitelist

---
 src/categories/delete.js |  1 +
 src/categories/index.js  | 28 ++++++++++++++++++++++++++--
 src/categories/update.js |  4 ++++
 src/topics/tags.js       | 13 +++++++------
 4 files changed, 38 insertions(+), 8 deletions(-)

diff --git a/src/categories/delete.js b/src/categories/delete.js
index 9b5f208049..69f5a24045 100644
--- a/src/categories/delete.js
+++ b/src/categories/delete.js
@@ -104,6 +104,7 @@ module.exports = function (Categories) {
 						'cid:0:children',
 						'cid:' + results.parentCid + ':children',
 						'cid:' + cid + ':children',
+						'cid:' + cid + ':tag:whitelist',
 					]);
 					next();
 				});
diff --git a/src/categories/index.js b/src/categories/index.js
index 37c7c97d3d..3a325b33f1 100644
--- a/src/categories/index.js
+++ b/src/categories/index.js
@@ -178,8 +178,32 @@ Categories.getCategories = function (cids, uid, callback) {
 };
 
 Categories.getTagWhitelist = function (cids, callback) {
-	const keys = cids.map(cid => 'cid:' + cid + ':tag:whitelist');
-	db.getSortedSetsMembers(keys, callback);
+	const cachedData = {};
+
+	const nonCachedCids = cids.filter((cid) => {
+		const data = cache.get('cid:' + cid + ':tag:whitelist');
+		const isInCache = data !== undefined;
+		if (isInCache) {
+			cachedData[cid] = data;
+		}
+		return !isInCache;
+	});
+
+	if (!nonCachedCids.length) {
+		return setImmediate(callback, null, _.clone(cids.map(cid => cachedData[cid])));
+	}
+
+	const keys = nonCachedCids.map(cid => 'cid:' + cid + ':tag:whitelist');
+	db.getSortedSetsMembers(keys, function (err, data) {
+		if (err) {
+			return callback(err);
+		}
+		nonCachedCids.forEach((cid, index) => {
+			cachedData[cid] = data[index];
+			cache.set('cid:' + cid + ':tag:whitelist', data[index]);
+		});
+		callback(null, _.clone(cids.map(cid => cachedData[cid])));
+	});
 };
 
 function calculateTopicPostCount(category) {
diff --git a/src/categories/update.js b/src/categories/update.js
index b876cd22d6..a1ca3cc01f 100644
--- a/src/categories/update.js
+++ b/src/categories/update.js
@@ -137,6 +137,10 @@ module.exports = function (Categories) {
 				var scores = tags.map((tag, index) => index);
 				db.sortedSetAdd('cid:' + cid + ':tag:whitelist', scores, tags, next);
 			},
+			function (next) {
+				cache.del('cid:' + cid + ':tag:whitelist');
+				next();
+			},
 		], callback);
 	}
 
diff --git a/src/topics/tags.js b/src/topics/tags.js
index 5f78c39b97..4acc8810b5 100644
--- a/src/topics/tags.js
+++ b/src/topics/tags.js
@@ -7,6 +7,7 @@ var validator = require('validator');
 var _ = require('lodash');
 var db = require('../database');
 var meta = require('../meta');
+var categories = require('../categories');
 var plugins = require('../plugins');
 var utils = require('../utils');
 var batch = require('../batch');
@@ -59,13 +60,13 @@ module.exports = function (Topics) {
 				Topics.getTopicField(tid, 'cid', next);
 			},
 			function (cid, next) {
-				db.getSortedSetRange('cid:' + cid + ':tag:whitelist', 0, -1, next);
+				categories.getTagWhitelist([cid], next);
 			},
 			function (tagWhitelist, next) {
-				if (!tagWhitelist.length) {
+				if (!Array.isArray(tagWhitelist[0]) || !tagWhitelist[0].length) {
 					return next(null, tags);
 				}
-				var whitelistSet = new Set(tagWhitelist);
+				const whitelistSet = new Set(tagWhitelist[0]);
 				tags = tags.filter(tag => whitelistSet.has(tag));
 				next(null, tags);
 			},
@@ -398,14 +399,14 @@ module.exports = function (Topics) {
 		async.waterfall([
 			function (next) {
 				if (parseInt(cid, 10)) {
-					db.getSortedSetRange('cid:' + cid + ':tag:whitelist', 0, -1, next);
+					categories.getTagWhitelist([cid], next);
 				} else {
 					setImmediate(next, null, []);
 				}
 			},
 			function (tagWhitelist, next) {
-				if (tagWhitelist.length) {
-					setImmediate(next, null, tagWhitelist);
+				if (Array.isArray(tagWhitelist[0]) && tagWhitelist[0].length) {
+					setImmediate(next, null, tagWhitelist[0]);
 				} else {
 					db.getSortedSetRevRange('tags:topic:count', 0, -1, next);
 				}