Handle empty subscription queue and OOP-ify

api/subscriptions.js

@@ -3,6 +3,7 @@ const db = require("../utils/db")
 const {fetchChannelLatest} = require("../utils/youtube")
 const {getUser} = require("../utils/getuser")
 const {timeToPastText} = require("../utils/converters")
+const {refresher} = require("../background/feed-update")
 
 module.exports = [
 	{
@@ -13,6 +14,8 @@ module.exports = [
 			let channels = []
 			let refreshed = null
 			if (user.token) {
+				// 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(", ")

background/feed-update.js

@@ -61,9 +61,16 @@ class RefreshQueue {
 	}
 }
 
-const refreshQueue = new RefreshQueue()
+class Refresher {
+	constructor() {
+		this.sym = constants.symbols.refresher
+		this.refreshQueue = new RefreshQueue()
+		this.state = this.sym.ACTIVE
+		this.waitingTimeout = null
+		this.next()
+	}
 
-function refreshChannel(ucid) {
+	refreshChannel(ucid) {
 		return fetch(`http://localhost:3000/api/v1/channels/${ucid}/latest`).then(res => res.json()).then(root => {
 			if (Array.isArray(root)) {
 				root.forEach(video => {
@@ -84,20 +91,38 @@ function refreshChannel(ucid) {
 		})
 	}
 
-function refreshNext() {
+	next() {
-	if (refreshQueue.isEmpty()) {
+		if (this.refreshQueue.isEmpty()) {
-		const timeSinceLastLoop = Date.now() - refreshQueue.lastLoadTime
+			const timeSinceLastLoop = Date.now() - this.refreshQueue.lastLoadTime
 			if (timeSinceLastLoop < constants.caching.subscriptions_refresh_loop_min) {
 				const timeToWait = constants.caching.subscriptions_refresh_loop_min - timeSinceLastLoop
 				console.log(`waiting ${timeToWait} before next loop`)
-			return setTimeout(refreshNext, timeToWait)
+				this.state = this.sym.WAITING
+				this.waitingTimeout = setTimeout(() => this.next(), timeToWait)
+				return
 			} else {
-			refreshQueue.load()
+				this.refreshQueue.load()
 			}
 		}
 
-	const ucid = refreshQueue.next()
+		if (!this.refreshQueue.isEmpty()) {
-	refreshChannel(ucid).then(refreshNext)
+			this.state = this.sym.ACTIVE
+			const ucid = this.refreshQueue.next()
+			this.refreshChannel(ucid).then(() => this.next())
+		} else {
+			this.state = this.sym.EMPTY
+		}
 	}
 
-refreshNext()
+	skipWaiting() {
+		if (this.state !== this.sym.ACTIVE) {
+			clearTimeout(this.waitingTimeout)
+			this.refreshQueue.lastLoadTime = 0
+			this.next()
+		}
+	}
+}
+
+const refresher = new Refresher()
+
+module.exports.refresher = refresher

utils/constants.js

@@ -19,6 +19,14 @@ const constants = {
 	regex: {
 		ucid: "[A-Za-z0-9-_]+",
 		video_id: "[A-Za-z0-9-_]+"
+	},
+
+	symbols: {
+		refresher: {
+			ACTIVE: Symbol("ACTIVE"),
+			WAITING: Symbol("WAITING"),
+			EMPTY: Symbol("EMPTY")
+		}
 	}
 }