11x speed up of subscription page generation

My 30 subscriptions now take 25 ms to generate, instead of around 280.

Around 120 ms were saved by creating a database index.
Around 120 ms were saved by pre-compiling the pug template for video
description timestamps.
The other changes in this commit produced slight improvements.

api/subscriptions.js

@@ -16,18 +16,15 @@ module.exports = [
 				// trigger a background refresh, needed if they came back from being inactive
 				refresher.skipWaiting()
 				// get channels
-				const subscriptions = user.getSubscriptions()
-				const template = Array(subscriptions.length).fill("?").join(", ")
-				channels = db.prepare(`SELECT * FROM Channels WHERE ucid IN (${template}) ORDER BY name`).all(subscriptions)
+				channels = db.prepare(`SELECT Channels.* FROM Channels INNER JOIN Subscriptions ON Channels.ucid = Subscriptions.ucid WHERE token = ? ORDER BY name`).all(user.token)
 				// get refreshed status
-				refreshed = db.prepare(`SELECT min(refreshed) as min, max(refreshed) as max, count(refreshed) as count FROM Channels WHERE ucid IN (${template})`).get(subscriptions)
+				refreshed = db.prepare(`SELECT min(refreshed) as min, max(refreshed) as max, count(refreshed) as count FROM Channels INNER JOIN Subscriptions ON Channels.ucid = Subscriptions.ucid WHERE token = ?`).get(user.token)
 				// get watched videos
 				const watchedVideos = user.getWatchedVideos()
 				// get videos
-				if (subscriptions.length) {
+				if (channels.length) {
 					hasSubscriptions = true
-					const template = Array(subscriptions.length).fill("?").join(", ")
-					videos = db.prepare(`SELECT * FROM Videos WHERE authorId IN (${template}) ORDER BY published DESC LIMIT 60`).all(subscriptions)
+					videos = db.prepare(`SELECT Videos.* FROM Videos INNER JOIN Subscriptions ON Videos.authorID = Subscriptions.ucid WHERE token = ? ORDER BY published DESC LIMIT 60`).all(user.token)
 						.map(video => {
 							video.publishedText = timeToPastText(video.published * 1000)
 							video.watched = watchedVideos.includes(video.videoId)

utils/converters.js

@@ -58,6 +58,7 @@ function normaliseVideoInfo(video) {
 	}
 }
 
+const timeDisplayCompiled = pug.compile(`a(href=url data-clickable-timestamp=timeSeconds)= timeDisplay`)
 function rewriteVideoDescription(descriptionHtml, id) {
 	// replace timestamps to clickable links and rewrite youtube links to stay on the instance instead of pointing to YouTube
 	// test cases
@@ -93,7 +94,7 @@ function rewriteVideoDescription(descriptionHtml, id) {
 		params.set("t", timeURL)
 		const url = "/watch?" + params
 
-		return pug.render(`a(href=url data-clickable-timestamp=timeSeconds)= timeDisplay`, {url, timeURL, timeDisplay, timeSeconds})
+		return timeDisplayCompiled({url, timeURL, timeDisplay, timeSeconds})
 	})
 
 	return descriptionHtml

utils/getuser.js

@@ -14,7 +14,10 @@ function getToken(req, responseHeaders) {
 			return null
 		}
 	}
-	db.prepare("REPLACE INTO SeenTokens (token, seen) VALUES (?, ?)").run([token, Date.now()])
+	db.prepare(
+		"INSERT INTO SeenTokens (token, seen) VALUES (?, ?)"
+			+ " ON CONFLICT (token) DO UPDATE SET seen = excluded.seen"
+	).run([token, Date.now()])
 	return token
 }
 

utils/upgradedb.js

@@ -58,6 +58,11 @@ const deltas = [
 	function() {
 		db.prepare("ALTER TABLE Subscriptions ADD COLUMN channel_missing INTEGER DEFAULT 0")
 			.run()
+	},
+	// 9: add index Videos (authorID)
+	function() {
+		db.prepare("CREATE INDEX Videos_authorID ON Videos (authorID)")
+			.run()
 	}
 ]