perf: only load thumbs for topics that actually have thumbs

src/topics/index.js

@@ -82,7 +82,7 @@ Topics.getTopicsByTids = async function (tids, options) {
 			user.getMultipleUserSettings(uids),
 			categories.getCategoriesFields(cids, ['cid', 'name', 'slug', 'icon', 'backgroundImage', 'imageClass', 'bgColor', 'color', 'disabled']),
 			loadGuestHandles(),
-			Topics.thumbs.get(tids),
+			Topics.thumbs.load(topics),
 		]);
 
 		users.forEach((userObj, idx) => {
@@ -167,11 +167,11 @@ Topics.getTopicWithPosts = async function (topicData, set, uid, start, stop, rev
 		getDeleter(topicData),
 		getMerger(topicData),
 		getRelated(topicData, uid),
-		Topics.thumbs.get(topicData.tid),
+		Topics.thumbs.load([topicData]),
 		Topics.events.get(topicData.tid),
 	]);
 
-	topicData.thumbs = thumbs;
+	topicData.thumbs = thumbs[0];
 	topicData.posts = posts;
 	topicData.events = events;
 	topicData.category = category;

src/topics/thumbs.js

@@ -1,6 +1,7 @@
 
 'use strict';
 
+const _ = require('lodash');
 const nconf = require('nconf');
 const path = require('path');
 const validator = require('validator');
@@ -19,6 +20,14 @@ Thumbs.exists = async function (tid, path) {
 	return db.isSortedSetMember(`topic:${tid}:thumbs`, path);
 };
 
+Thumbs.load = async function (topicData) {
+	const topicsWithThumbs = topicData.filter(t => parseInt(t.numThumbs, 10) > 0);
+	const tidsWithThumbs = topicsWithThumbs.map(t => t.tid);
+	const thumbs = await Thumbs.get(tidsWithThumbs);
+	const tidToThumbs = _.zipObject(tidsWithThumbs, thumbs);
+	return topicData.map(t => tidToThumbs[t.tid] || []);
+};
+
 Thumbs.get = async function (tids) {
 	// Allow singular or plural usage
 	let singular = false;
@@ -27,14 +36,14 @@ Thumbs.get = async function (tids) {
 		singular = true;
 	}
 
-	if (!meta.config.allowTopicsThumbnail) {
+	if (!meta.config.allowTopicsThumbnail || !tids.length) {
 		return singular ? [] : tids.map(() => []);
 	}
 
 	const hasTimestampPrefix = /^\d+-/;
 	const upload_url = nconf.get('relative_path') + nconf.get('upload_url');
 	const sets = tids.map(tid => `${validator.isUUID(String(tid)) ? 'draft' : 'topic'}:${tid}:thumbs`);
-	const thumbs = await Promise.all(sets.map(set => getThumbs(set)));
+	const thumbs = await Promise.all(sets.map(getThumbs));
 	let response = thumbs.map((thumbSet, idx) => thumbSet.map(thumb => ({
 		id: tids[idx],
 		name: (() => {
@@ -69,13 +78,15 @@ Thumbs.associate = async function ({ id, path: relativePath, url }) {
 	if (relativePath) {
 		value = value.replace(nconf.get('upload_path'), '');
 	}
-
+	const topics = require('.');
 	await db.sortedSetAdd(set, numThumbs, value);
+	if (!isDraft) {
+		await topics.setTopicField(id, 'numThumbs', numThumbs);
+	}
 	cache.del(set);
 
 	// Associate thumbnails with the main pid (only on local upload)
 	if (!isDraft && relativePath) {
-		const topics = require('.');
 		const mainPid = (await topics.getMainPids([id]))[0];
 		posts.uploads.associate(mainPid, relativePath.replace('/files/', ''));
 	}
@@ -110,6 +121,10 @@ Thumbs.delete = async function (id, relativePath) {
 		// Dissociate thumbnails with the main pid
 		if (!isDraft) {
 			const topics = require('.');
+			const numThumbs = await db.sortedSetCard(set);
+			if (!numThumbs) {
+				await db.deleteObjectField('topic:' + id, 'numThumbs');
+			}
 			const mainPid = (await topics.getMainPids([id]))[0];
 			posts.uploads.dissociate(mainPid, relativePath.replace('/files/', ''));
 		}

src/upgrades/1.17.0/topic_thumb_count.js

@@ -0,0 +1,29 @@
+'use strict';
+
+const _ = require('lodash');
+const db = require('../../database');
+const batch = require('../../batch');
+
+module.exports = {
+	name: 'Store number of thumbs a topic has in the topic object',
+	timestamp: Date.UTC(2021, 1, 7),
+	method: async function () {
+		const progress = this.progress;
+
+		await batch.processSortedSet('topics:tid', async function (tids) {
+			const keys = tids.map(tid => 'topic:' + tid + ':thumbs');
+			const counts = await db.sortedSetsCard(keys);
+			const tidToCount = _.zip(tids, counts);
+			const tidsWithThumbs = tids.filter((t, i) => counts[i] > 0);
+			await db.setObjectBulk(
+				tidsWithThumbs.map(tid => 'topic:' + tid),
+				tidsWithThumbs.map(tid => ({ numThumbs: tidToCount[tid] }))
+			);
+
+			progress.incr(tids.length);
+		}, {
+			batch: 500,
+			progress: progress,
+		});
+	},
+};