Extract some common code into telnet_spot_provier as a base class for DX cluster and RBN

providers/spot/telnet_spot_provider.py

@@ -0,0 +1,117 @@
+import logging
+import socket
+from datetime import datetime
+from threading import Event, Lock, Thread
+
+import pytz
+import telnetlib3
+
+from core.utils import decode_telnet_bytes
+from providers.spot.spot_provider import SpotProvider
+
+logger = logging.getLogger(__name__)
+
+
+class TelnetSpotProvider(SpotProvider):
+    """Base class for spot providers that connect to a telnet server to receive spots."""
+
+    def __init__(self, name, provider_config, host, port, login_prompt, login_response):
+        """Constructor. host/port are the telnet server to connect to. login_prompt is the text to wait for before
+        logging in, and login_response is the callsign to send in response."""
+
+        super().__init__(name, provider_config)
+        self._host = host
+        self._port = port
+        self._login_prompt = login_prompt
+        self._login_response = login_response
+        self._telnet = None
+        self._telnet_lock = Lock()
+        self._thread = None
+        self._stop_event = Event()
+
+    def _parse_line(self, line):
+        """Parse a line of telnet output and return a Spot, or None if the line did not contain a spot. Subclasses
+        must implement this method."""
+
+        raise NotImplementedError("Subclasses must implement this method")
+
+    def start(self):
+        self._thread = Thread(target=self._handle, name=f"{self.name}SpotProvider", daemon=True)
+        self._thread.start()
+
+    def stop(self):
+        self._stop_event.set()
+        with self._telnet_lock:
+            if self._telnet:
+                try:
+                    self._telnet.sock.shutdown(socket.SHUT_RDWR)
+                except (AttributeError, OSError):
+                    pass
+                self._telnet.close()
+        if self._thread:
+            self._thread.join(timeout=5)
+            if self._thread.is_alive():
+                logger.warning(f"{self.name} worker thread did not exit on time and will be killed.")
+
+    def _handle(self):
+        while not self._stop_event.is_set():
+            connected = False
+            while not connected and not self._stop_event.is_set():
+                try:
+                    self.status = "Connecting"
+                    logger.info(f"{self.name} connecting to {self._host}:{self._port!s}...")
+                    new_telnet = telnetlib3.Telnet(self._host, self._port)
+                    with self._telnet_lock:
+                        self._telnet = new_telnet
+                        if self._stop_event.is_set():
+                            # stop() was called while we were connecting, close the connection rather than trying to
+                            # read when we know it won't work
+                            new_telnet.close()
+                            break
+                    self._telnet.read_until(self._login_prompt.encode("latin-1"))
+                    self._telnet.write(f"{self._login_response}\n".encode("latin-1"))
+                    connected = True
+                    logger.info(f"{self.name} connected.")
+                except ConnectionRefusedError:
+                    self.status = "Error"
+                    logger.warning(f"Connection refused to {self.name} ({self._host}:{self._port!s}).")
+                    self._stop_event.wait(timeout=300)
+                except Exception:
+                    self.status = "Error"
+                    logger.exception(f"Exception while connecting to {self.name} ({self._host}:{self._port!s}).")
+                    self._stop_event.wait(timeout=5)
+
+            self.status = "Waiting for Data"
+            while connected and not self._stop_event.is_set():
+                try:
+                    # Check new telnet info against regular expression
+                    telnet_output = self._telnet.read_until("\n".encode("latin-1"))
+                    spot = self._parse_line(decode_telnet_bytes(telnet_output))
+                    if spot:
+                        # Add to our list
+                        self._submit(spot)
+
+                        self.status = "OK"
+                        self.last_update_time = datetime.now(pytz.UTC)
+                        logger.debug(f"Data received from {self.name}.")
+
+                except EOFError:
+                    connected = False
+                    if not self._stop_event.is_set():
+                        self.status = "Restarting"
+                        logger.warning(f"Disconnected from {self.name}. Reconnecting...")
+                        self._stop_event.wait(timeout=5)
+                    else:
+                        logger.info(f"{self.name} shutting down...")
+                        self.status = "Shutting down"
+                except Exception:
+                    connected = False
+                    if not self._stop_event.is_set():
+                        self.status = "Error"
+                        logger.exception(f"Exception in {self.name}")
+                        self._stop_event.wait(timeout=5)
+                    else:
+                        logger.info(f"{self.name} shutting down...")
+                        self.status = "Shutting down"
+
+            self.status = "Disconnected"