added signal (SIGINT) handler for gracefully exit

network_backend.py

@@ -1,6 +1,7 @@
 import socket
 import selectors
 import time
+import signal, os
 
 from msg_container import MsgContainer
 from receiver.nmea_packetizer import NmeaPacketizer
@@ -34,8 +35,9 @@ class NetworkBackend(ABackend):
 		self.thread.start()
 
 	def stop(self):
-		self.loop_enable = False
-		self.thread.join()
+		if self.loop_enable:
+			self.loop_enable = False
+			self.thread.join()
 
 	def create_xcvr(self, name: str) -> Transceiver:
 		obj = Transceiver(self, name)
@@ -113,6 +115,12 @@ class NetworkBackend(ABackend):
 		finally:
 			self.sel.close()
 
+def handler(signum, frame, be: NetworkBackend):
+	sig_name = signal.Signals(signum).name
+	print(f'Signal handler called with signal {sig_name} ({signum})')
+	be.stop()
+	be.disconnect()
+
 if __name__ == "__main__":
 	server_list = [
 		{'name': " neo-f9p", 'host': "192.168.22.93", 'port': 8721},
@@ -120,8 +128,13 @@ if __name__ == "__main__":
 	]
 
 	transceiver = {}
+
 	# TCPIP multi source receiver
 	mc = NetworkBackend(server_list)
+
+	# Set the signal handler
+	signal.signal(signal.SIGINT, lambda signum, frame: handler(signum, frame, mc))
+
 	for grm in [" neo-f9p", "zed-x20p"]:
 		nmea_rx_list = [
 			Gll(grm, 'GN'),
@@ -170,9 +183,13 @@ if __name__ == "__main__":
 	# Start thread
 	mc.start()
 
-	for n in range(10):
-		for grm in [" neo-f9p", "zed-x20p"]:
-			transceiver[grm].send(b'Hallo')
+	while True:
+		try:
+			for grm in [" neo-f9p", "zed-x20p"]:
+				transceiver[grm].send(b'Hallo')
+		except ValueError:
+			break
+
 		time.sleep(1)
 
 	# Stop thread
@@ -180,3 +197,5 @@ if __name__ == "__main__":
 
 	# code never reached
 	mc.disconnect()
+
+