server: prevent server from auto-terminating

- IMPORTANT: We need the setInterval for detached to work, so that the server
  does not auto-terminate when the parent does. See the code comment.

- Additional: As a safety measure we allow a detached LS without a client/parent to live
  for at most a week. This is an arbitrary amount.
Signed-off-by: nkomonen-amazon <nkomonen@amazon.com>

Author: nkomonen-amazon

server/src/node/main.ts

@@ -46,23 +46,33 @@ function isDetached() {
 	}
 
 	if(process.argv.includes('--detached')) {
-		setDetached();
-	} else {
-		_isDetached = false;
-	}
-	return _isDetached;
-
-	function setDetached() {
 		_isDetached = true;
 
 		// Ignores the default behavior when then parent/child communication
 		// channel (e.g. IPC) disconnects, the child terminates.
 		process.on('disconnect', () => {});
+
+		// Keeps the server alive since node may terminate this process if
+		// the parent terminates + this process has nothing in the event loop.
+		const oneWeekMilliseconds = 7 * 24 * 60 * 60 * 1000;
+		const oneHourMilliseconds = 60 * 60 * 1000;
+		setInterval(() => {
+			// Allow detached servers to live at most 1 week after disconnecting from the client
+			if (_protocolConnectionEndTime && Date.now() - _protocolConnectionEndTime >= oneWeekMilliseconds) {
+				process.exit(7);
+			}
+		}, oneHourMilliseconds);
+	} else {
+		_isDetached = false;
 	}
+	return _isDetached;
 }
 
 let _protocolConnection: ProtocolConnection | undefined;
+let _protocolConnectionEndTime: number | undefined = undefined;
 function endProtocolConnection(): void {
+	_protocolConnectionEndTime = Date.now();
+
 	if (_protocolConnection === undefined) {
 		return;
 	}