Add a watchdog for the heartbeat #601
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Pull Request Overview
This PR adds a watchdog timer mechanism to detect lost WebSocket connections that aren't properly detected by the socket client. The watchdog is reset by heartbeat messages (which occur every 25 seconds) and triggers a connection close if no heartbeat is received within 30 seconds.
- Adds a 30-second timeout constant for the watchdog mechanism
- Implements a watchdog callback function that closes the connection with code 1006
- Sets up and resets the watchdog timer on heartbeat messages and connection open
| SockJS.prototype._websocketWatchdogCb = function(websocket) { | ||
| debug("watchdog websocket timeout"); | ||
| websocket._close(1006, 'Server lost session'); |
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The parameter name 'websocket' is misleading as it refers to the SockJS instance, not a WebSocket. This should be 'sockjs' or 'self' to accurately reflect what it represents.
| SockJS.prototype._websocketWatchdogCb = function(websocket) { | |
| debug("watchdog websocket timeout"); | |
| websocket._close(1006, 'Server lost session'); | |
| SockJS.prototype._websocketWatchdogCb = function(sockjs) { | |
| debug("watchdog websocket timeout"); | |
| sockjs._close(1006, 'Server lost session'); |
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| @@ -257,6 +263,8 @@ SockJS.prototype._transportMessage = function(msg) { | |||
| case 'h': | |||
| this.dispatchEvent(new Event('heartbeat')); | |||
| debug('heartbeat', this.transport); | |||
| clearTimeout(this.heartbeatWatchdog); | |||
| this.heartbeatWatchdog = setTimeout(this._websocketWatchdogCb, SockJS.WATCHDOG_WEBSOCKET_TIMEOUT, this); | |||
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The watchdog timer should be cleared when the connection is closed to prevent potential memory leaks and unexpected behavior. Consider adding clearTimeout(this.heartbeatWatchdog) in the _close method.
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Co-authored-by: Copilot <[email protected]>
If your client device loose the network connection to the device running the websocket server this will not be detected by the socket client.
This watchdog will be reseted by the heartbeat message (appears every 25 seconds) if the watchdog will not be resetted in a 30 second window the connection can be marked as lost => 1006
Found with OctoPrint, if you connect to the OctoPrint instance with a laptop and this goes to sleep mode for some time (network will be disabled)
After you wake the device again you still see the UI but the websocket connection is not connected anymore.
You can reproduce this by disabling your network on the laptop, wait some time and connect again.