From 70f8bf155a08a55d112720b9b62bf31033ebcd3d Mon Sep 17 00:00:00 2001
From: Peter Hoddie <peter@moddable.tech>
Date: Thu, 1 Feb 2024 12:55:07 -0800
Subject: [PATCH] use elapsed-time-since-boot instead of UTC time-of-day for
 mqtt keepalive calculations

---
 examples/io/tcp/mqttclient/mqttclient.js | 13 +++++++------
 modules/network/mqtt/mqtt.js             | 11 ++++++-----
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/examples/io/tcp/mqttclient/mqttclient.js b/examples/io/tcp/mqttclient/mqttclient.js
index 73112ac23..e9b29045f 100644
--- a/examples/io/tcp/mqttclient/mqttclient.js
+++ b/examples/io/tcp/mqttclient/mqttclient.js
@@ -25,6 +25,7 @@
 */
 
 import Timer from "timer";
+import Time from "time";
 
 const Overhead = 8;
 const BufferFormat = "buffer";
@@ -249,7 +250,7 @@ class MQTTClient {
 
 			case MQTTClient.PINGREQ:
 				if (this.#options.keepalive)
-					this.#options.keepalive.write = Date.now();
+					this.#options.keepalive.write = Time.ticks;
 				// fall through
 			case MQTTClient.DISCONNECT:
 				if (2 > this.#writable)
@@ -664,7 +665,7 @@ class MQTTClient {
 			if (keepalive) {
 				options.keepalive = Timer.repeat(() => this.#keepalive(), keepalive * 250);
 				options.keepalive.interval = keepalive * 1000;
-				options.keepalive.read = options.keepalive.write = Date.now();
+				options.keepalive.read = options.keepalive.write = Time.ticks;
 			}
 
 			this.#state = "login";
@@ -694,7 +695,7 @@ class MQTTClient {
 // 		traceOperation(false, operation);
 
 		if ((operation == MQTTClient.PINGRESP) && this.#options.keepalive)
-			this.#options.keepalive.read = Date.now();
+			this.#options.keepalive.read = Time.ticks;
 
 		if (MQTTClient.CONNACK === operation) {
 			if (msg.returnCode)
@@ -730,12 +731,12 @@ class MQTTClient {
 	}
 	#keepalive() {
 		const options = this.#options, keepalive = options.keepalive, interval = keepalive.interval;
-		const now = Date.now();
+		const now = Time.ticks;
 
-		if ((now - keepalive.read) >= (keepalive.interval + (keepalive.interval >> 1)))
+		if (Time.delta(keepalive.read, now) >= (keepalive.interval + (keepalive.interval >> 1)))
 			return void this.#onError("time out");	// no control packet received in 1.5x keepalive interval (expected PINGRESP)
 
-		if ((now - keepalive.write) < (((keepalive.interval >> 2) * 3) - 500))
+		if (Time.delta(keepalive.write, now) < (((keepalive.interval >> 2) * 3) - 500))
 			return;
 
 		// haven't sent a ping in (just under) 3/4 the keep alive interval
diff --git a/modules/network/mqtt/mqtt.js b/modules/network/mqtt/mqtt.js
index 8b098b8e5..a9a9fdb4b 100644
--- a/modules/network/mqtt/mqtt.js
+++ b/modules/network/mqtt/mqtt.js
@@ -21,6 +21,7 @@
 import {Client as WSClient} from "websocket";
 import {Socket} from "socket";
 import Timer from "timer";
+import Time from "time";
 
 /*
  * Implements a basic MQTT client. Upon creation of a client instance, provides methods for
@@ -206,7 +207,7 @@ export default class Client {
 						}
 						else if (0xD0 === parse.state) {	// PINGRESP
 							if (this.#timer)
-								this.#timer.read = Date.now();
+								this.#timer.read = Time.ticks;
 						}
 						else if (0xE0 === parse.state) {	// DISCONNECT
 							return;
@@ -495,7 +496,7 @@ export default class Client {
 
 		if (timeout) {
 			this.#timer = Timer.repeat(this.keepalive.bind(this), this.timeout >> 2);
-			this.#timer.read = this.#timer.write = Date.now();
+			this.#timer.read = this.#timer.write = Time.ticks;
 		}
 
 		delete this.connect;
@@ -575,12 +576,12 @@ export default class Client {
 		this.state = -1;
 	}
 	keepalive() {
-		const now = Date.now();
-		if ((now - this.#timer.read) >= (this.timeout + (this.timeout >> 1)))
+		const now = Time.ticks;
+		if (Time.delta(this.#timer.read, now) >= (this.timeout + (this.timeout >> 1)))
 			return void this.fail("read time out");	// nothing received in 1.5x keep alive interval is fail for client and server (in write-only client, it means client didn't receive ping response)
 
 		if (!this.server) {	// client must send something within the keepalive interval. we always ping within that interval (ensures that write-only client occassionally receives something from server)
-			if ((now - this.#timer.write) >= (((this.timeout >> 2) * 3) - 500)) {		// haven't sent a ping in (just under) 3/4 the keep alive interval
+			if (Time.delta(this.#timer.write, now) >= (((this.timeout >> 2) * 3) - 500)) {		// haven't sent a ping in (just under) 3/4 the keep alive interval
 				try {
 					this.#timer.write = now;
 					this.ws.write(Uint8Array.of(0xC0, 0x00).buffer);		// ping