NmeaClient/network_backend.py

import socket
import selectors
import time
import signal
from threading import Thread
from queue import Queue

from msg.container import MsgContainer
from transceiver import Transceiver
from a_backend import ABackend

from nmea import NmeaPacketizer
from nmea.messages import Gll, Gsa, Gsv, Gga, Rmc

from ubx.ubx import frame_create
from ubx.packetizer import UbxPacketizer
from ubx.messages import Sig, Sat, RawX, UbxMsg
from ubx.listener import UbxListener


class NetworkBackend(ABackend):
	def __init__(self, servers: list[dict]):
		self.sel = None
		self.sock_list = [{'name': s['name'], 'addr': (s['host'], s['port']), 'xcvr': None, 'queue': Queue()} for s in servers]
		self.thread = Thread(target=self.event_loop)
		self.loop_enable = True

	def send(self, name: str, data: bytes):
		sock = self.find_by_name(name)
		sock['queue'].put(data)
		if sock is not None:
			self.sel.modify(sock['sock'], selectors.EVENT_READ + selectors.EVENT_WRITE, None)

	def start(self):
		self.thread.start()

	def stop(self):
		if self.loop_enable:
			self.loop_enable = False
			self.thread.join()

	def create_xcvr(self, name: str) -> Transceiver:
		obj = Transceiver(self, name)
		if not self.register_xcvr(obj):
			raise Exception(f"No socket found for \"{name}\"")
		return obj

		self.sel.register(name, selectors.EVENT_READ, data=None)
	def register_xcvr(self, xcvr: Transceiver):
		found = False
		for sock in self.sock_list:
			if xcvr.name in sock['name']:
				found = True
				sock['xcvr'] = xcvr
				break

		return found
	def find_by_addr(self, addr):
		for sock in self.sock_list:
			if sock['addr'] == addr:
				return sock
		return None

	def find_by_name(self, name: str):
		for sock in self.sock_list:
			if sock['name'] == name:
				return sock
		return None

	def _prepare(self):
		for server in self.sock_list:
			sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
			sock.setblocking(False)
			server['sock'] = sock

	def connect(self):
		self._prepare()
		self.sel = selectors.DefaultSelector()
		events = selectors.EVENT_READ
		for sock in self.sock_list:
			print(f"Starting connection {sock['name']} to {sock['addr']}")
			self.sel.register(sock['sock'], events, data=None)
			sock['sock'].connect_ex(sock['addr'])

	def disconnect(self):
		for sock in self.sock_list:
			sock['sock'].close()

	def on_send(self, name: str, data: bytes):
		sock = self.find_by_name(name)
		if sock is not None:
			self.sel.modify(sock['sock'], selectors.EVENT_READ + selectors.EVENT_WRITE, data)

	def event_loop(self):
		try:
			while self.loop_enable:
				events = self.sel.select(timeout=100)
				for key, mask in events:
					descr = self.find_by_addr(key.fileobj.getpeername())
					name = descr['name']
					sock = self.find_by_name(name)
					if mask & selectors.EVENT_READ:
						timestamp = time.time()
						data = key.fileobj.recv(64)
						sock['xcvr'].on_recv(MsgContainer(name, timestamp, data))
					if mask & selectors.EVENT_WRITE:
						data = sock['queue'].get()
						key.fileobj.send(data)
						print(f"Send: {sock['name']}: {data}")
						if sock['queue'].empty():
							self.sel.modify(sock['sock'], selectors.EVENT_READ, None)

		except KeyboardInterrupt:
			print("Caught keyboard interrupt, exiting")
		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},
		{'name': "zed-x20p", 'host': "192.168.22.93", 'port': 8731}
	]

	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'),
			Gsa(grm, 'GN'),
			Gsv(grm, 'GP'),
			Gga(grm, 'GP'),
			Rmc(grm, 'GN'),
			Gga(grm, 'GN'),
		]
		ubx_rx_list = [
			UbxListener(Sig(), 0x01, 0x43),
			UbxListener(Sat(), 0x01, 0x35),
			UbxListener(RawX(), 0x02, 0x15),

			UbxListener(UbxMsg(), 0x05, 0x01),
			UbxListener(UbxMsg(), 0x05, 0x00),
		]

		# Topology
		# Receiver-0.0 \
		# Receiver-0.1 <- Packetizer-0 <- Transceiver-0 \
		#                               /                \
		#                      Send-0->/                  \
		#                                                  + Backend
		#                      Send-1->\                  /
		#                               \                /
		# Receiver-1.0 <- Packetizer-1 <- Transceiver-1 /
		# Receiver-1.1 /

		# Create transceiver
		transceiver[grm] = mc.create_xcvr(grm)

		# Create NMEA-Packetizer
		nmea_packetizer = NmeaPacketizer()
		ubx_packetizer = UbxPacketizer()

		# Register NMEA-Packetizer to transceiver
		transceiver[grm].register_listener(nmea_packetizer)
		transceiver[grm].register_listener(ubx_packetizer)

		# Register Receiver to NMEA-Packetizer
		for rx in nmea_rx_list:
			nmea_packetizer.register_listener(rx)

		# Register Receiver to UBX-Packetizer
		for rx in ubx_rx_list:
			ubx_packetizer.register_listener(rx)


	# Connect all sources
	mc.connect()

	# Start thread
	mc.start()

	while True:
		try:
			for grm in [" neo-f9p", "zed-x20p"]:
				# Poll UBX-NAV-CLOCK (0x01 0x22)
				frame = frame_create(0x01, 0x22, b'')
				transceiver[grm].send(frame)
				# Poll UBX-NAV-SIG (0x01 0x43)
				frame = frame_create(0x01, 0x43, b'')
				transceiver[grm].send(frame)
				# Poll UBX-NAV-SAT (0x01 0x35)
				frame = frame_create(0x01, 0x35, b'')
				transceiver[grm].send(frame)
				# Poll UBX-RXM-RAWX (0x02 0x15)
				frame = frame_create(0x02, 0x15, b'')
				transceiver[grm].send(frame)
		except ValueError:
			break

		time.sleep(1)

	# Stop thread
	mc.stop()

	# code never reached
	mc.disconnect()