feat: keepalive manager

DEVELOPMENT.md

@@ -19,10 +19,9 @@ npm test
 
 This will run both `browser` and `node` tests.
 
-
 ### Running specific tests
 
-For example, you can run `node -r esbuild-register --test test/pingTimer.ts`
+For example, you can run `node -r esbuild-register --test test/keepaliveManager.ts`
 
 ### Browser
 

example.ts

@@ -1,7 +1,7 @@
 import mqtt from './src/index'
 
 const client = mqtt.connect('mqtts://test.mosquitto.org', {
-	keepalive: 10,
+	// keepalive: 10,
 	port: 8883,
 	reconnectPeriod: 15000,
 	rejectUnauthorized: false,

src/lib/KeepaliveManager.ts

@@ -0,0 +1,89 @@
+import type MqttClient from './client'
+import getTimer, { type Timer } from './get-timer'
+import type { TimerVariant } from './shared'
+
+export default class KeepaliveManager {
+	private _keepalive: number
+
+	private timerId: number
+
+	private timer: Timer
+
+	private destroyed = false
+
+	private counter: number
+
+	private client: MqttClient
+
+	private _keepaliveTimeoutTimestamp: number
+
+	/** Timestamp of next keepalive timeout */
+	get keepaliveTimeoutTimestamp() {
+		return this._keepaliveTimeoutTimestamp
+	}
+
+	set keepalive(value: number) {
+		if (
+			// eslint-disable-next-line no-restricted-globals
+			isNaN(value) ||
+			value < 0 ||
+			value * 1000 > 2147483647
+		) {
+			throw new Error(
+				`Keepalive value must be a number between 0 and 2147483647. Provided value is ${this._keepalive}`,
+			)
+		}
+
+		this._keepalive = value * 1000
+	}
+
+	get keepalive() {
+		return this._keepalive
+	}
+
+	constructor(client: MqttClient, variant: TimerVariant) {
+		this.keepalive = client.options.keepalive
+		this.client = client
+		this.timer = getTimer(variant)
+		this.reschedule()
+	}
+
+	private clear() {
+		if (this.timerId) {
+			this.timer.clear(this.timerId)
+			this.timerId = null
+		}
+	}
+
+	destroy() {
+		this.clear()
+		this.destroyed = true
+	}
+
+	reschedule() {
+		if (this.destroyed) {
+			return
+		}
+
+		this.clear()
+		this.counter = 0
+		// https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Figure_3.5_Keep
+		this._keepaliveTimeoutTimestamp = Date.now() + this._keepalive * 1.5
+
+		this.timerId = this.timer.set(() => {
+			// this should never happen, but just in case
+			if (this.destroyed) {
+				return
+			}
+
+			this.counter += 1
+
+			// after keepalive seconds, send a pingreq
+			if (this.counter === 2) {
+				this.client.sendPing()
+			} else if (this.counter > 2) {
+				this.client.onKeepaliveTimeout()
+			}
+		}, this._keepalive / 2)
+	}
+}

src/lib/client.ts

@@ -39,7 +39,7 @@ import {
 } from './shared'
 import TopicAliasSend from './topic-alias-send'
 import { TypedEventEmitter } from './TypedEmitter'
-import PingTimer from './PingTimer'
+import KeepaliveManager from './KeepaliveManager'
 import isBrowser, { isWebWorker } from './is-browser'
 
 const setImmediate =
@@ -433,10 +433,7 @@ export default class MqttClient extends TypedEventEmitter<MqttClientEventCallbac
 
 	public noop: (error?: any) => void
 
-	/** Timestamp of last received control packet */
-	public pingResp: number
-
-	public pingTimer: PingTimer
+	public keepaliveManager: KeepaliveManager
 
 	/**
 	 * The connection to the Broker. In browsers env this also have `socket` property
@@ -572,8 +569,8 @@ export default class MqttClient extends TypedEventEmitter<MqttClientEventCallbac
 		// map of a subscribe messageId and a topic
 		this.messageIdToTopic = {}
 
-		// Ping timer, setup in _setupPingTimer
-		this.pingTimer = null
+		// Keepalive manager, setup in _setupKeepaliveManager
+		this.keepaliveManager = null
 		// Is the client connected?
 		this.connected = false
 		// Are we disconnecting?
@@ -660,7 +657,7 @@ export default class MqttClient extends TypedEventEmitter<MqttClientEventCallbac
 			this.log('close :: clearing connackTimer')
 			clearTimeout(this.connackTimer)
 
-			this._destroyPingTimer()
+			this._destroyKeepaliveManager()
 
 			if (this.topicAliasRecv) {
 				this.topicAliasRecv.clear()
@@ -1780,7 +1777,7 @@ export default class MqttClient extends TypedEventEmitter<MqttClientEventCallbac
 			this._setupReconnect()
 		}
 
-		this._destroyPingTimer()
+		this._destroyKeepaliveManager()
 
 		if (done && !this.connected) {
 			this.log(
@@ -2064,45 +2061,36 @@ export default class MqttClient extends TypedEventEmitter<MqttClientEventCallbac
 	}
 
 	/**
-	 * _setupPingTimer - setup the ping timer
-	 *
-	 * @api private
+	 * _setupKeepaliveManager - setup the keepalive manager
 	 */
-	private _setupPingTimer() {
+	private _setupKeepaliveManager() {
 		this.log(
-			'_setupPingTimer :: keepalive %d (seconds)',
+			'_setupKeepaliveManager :: keepalive %d (seconds)',
 			this.options.keepalive,
 		)
 
-		if (!this.pingTimer && this.options.keepalive) {
-			this.pingTimer = new PingTimer(
-				this.options.keepalive,
-				() => {
-					this._checkPing()
-				},
+		if (!this.keepaliveManager && this.options.keepalive) {
+			this.keepaliveManager = new KeepaliveManager(
+				this,
 				this.options.timerVariant,
 			)
-			this.pingResp = Date.now()
 		}
 	}
 
-	private _destroyPingTimer() {
-		if (this.pingTimer) {
-			this.log('_destroyPingTimer :: destroying ping timer')
-			this.pingTimer.destroy()
-			this.pingTimer = null
+	private _destroyKeepaliveManager() {
+		if (this.keepaliveManager) {
+			this.log('_destroyKeepaliveManager :: destroying keepalive manager')
+			this.keepaliveManager.destroy()
+			this.keepaliveManager = null
 		}
 	}
 
 	/**
-
-	 * _shiftPingInterval - reschedule the ping interval
-	 *
-	 * @api private
+	 * reschedule the ping interval
 	 */
-	private _shiftPingInterval() {
+	public shiftPing() {
 		if (
-			this.pingTimer &&
+			this.keepaliveManager &&
 			this.options.keepalive &&
 			this.options.reschedulePings
 		) {
@@ -2115,34 +2103,20 @@ export default class MqttClient extends TypedEventEmitter<MqttClientEventCallbac
 	 */
 	private _reschedulePing() {
 		this.log('_reschedulePing :: rescheduling ping')
-		this.pingTimer.reschedule()
+		this.keepaliveManager.reschedule()
 	}
 
-	/**
-	 * _checkPing - check if a pingresp has come back, and ping the server again
-	 *
-	 * @api private
-	 */
-	private _checkPing() {
-		this.log('_checkPing :: checking ping...')
-		// give 100ms offset to avoid ping timeout when receiving fast responses
-		const timeSincePing = Date.now() - this.pingResp - 100
-		if (timeSincePing <= this.options.keepalive * 1000) {
-			this.log('_checkPing :: ping response received in time')
-			this._sendPing()
-		} else {
-			// do a forced cleanup since socket will be in bad shape
-			this.emit('error', new Error('Keepalive timeout'))
-			this.log('_checkPing :: calling _cleanUp with force true')
-			this._cleanUp(true)
-		}
-	}
-
-	private _sendPing() {
+	public sendPing() {
 		this.log('_sendPing :: sending pingreq')
 		this._sendPacket({ cmd: 'pingreq' })
 	}
 
+	public onKeepaliveTimeout() {
+		this.emit('error', new Error('Keepalive timeout'))
+		this.log('onKeepaliveTimeout :: calling _cleanUp with force true')
+		this._cleanUp(true)
+	}
+
 	/**
 	 * _resubscribe
 	 * @api private
@@ -2205,7 +2179,7 @@ export default class MqttClient extends TypedEventEmitter<MqttClientEventCallbac
 
 		this.connackPacket = packet
 		this.messageIdProvider.clear()
-		this._setupPingTimer()
+		this._setupKeepaliveManager()
 
 		this.connected = true
 

src/lib/get-timer.ts

@@ -1,23 +1,23 @@
 import isBrowser, { isWebWorker, isReactNativeBrowser } from './is-browser'
-import { clearTimeout as clearT, setTimeout as setT } from 'worker-timers'
+import { clearInterval as clearI, setInterval as setI } from 'worker-timers'
 import type { TimerVariant } from './shared'
 
 // dont directly assign globals to class props otherwise this throws in web workers: Uncaught TypeError: Illegal invocation
 // See: https://stackoverflow.com/questions/9677985/uncaught-typeerror-illegal-invocation-in-chrome
 
 export interface Timer {
-	set: typeof setT
-	clear: typeof clearT
+	set: typeof setI
+	clear: typeof clearI
 }
 
 const workerTimer: Timer = {
-	set: setT,
-	clear: clearT,
+	set: setI,
+	clear: clearI,
 }
 
 const nativeTimer: Timer = {
-	set: (func, time) => setTimeout(func, time),
-	clear: (timerId) => clearTimeout(timerId),
+	set: (func, time) => setInterval(func, time),
+	clear: (timerId) => clearInterval(timerId),
 }
 
 const getTimer = (variant: TimerVariant): Timer => {

src/lib/handlers/connack.ts

@@ -29,8 +29,10 @@ const handleConnack: PacketHandler = (client, packet: IConnackPacket) => {
 		}
 		if (packet.properties.serverKeepAlive && options.keepalive) {
 			options.keepalive = packet.properties.serverKeepAlive
-			client['_shiftPingInterval']()
+			client.keepaliveManager.keepalive = options.keepalive
+			client.shiftPing()
 		}
+
 		if (packet.properties.maximumPacketSize) {
 			if (!options.properties) {
 				options.properties = {}