Improve asyncio usage in telnet server

telnetserver/telnetserver.py

@@ -21,21 +21,16 @@ class TelnetServer:
         self._running = False
         self._clients = set()
         self._loop = None
+        self._shutdown_event = asyncio.Event()
 
     def start(self, port=7373):
         """Starts the telnet server"""
 
         self._port = port
 
-        # Start telnet server on the async loop
+        # Start the telnet server. asyncio.run() needs a coroutine, and threading.Thread needs a plain callable, so
-        def run_loop():
+        # hand Thread the bridge between the two directly rather than writing a one-line wrapper method for it.
-            self._loop = asyncio.new_event_loop()
+        t = threading.Thread(target=asyncio.run, args=(self._start_internal(),), name="TelnetServer", daemon=True)
-            asyncio.set_event_loop(self._loop)
-            self._loop.run_until_complete(self._start_internal())
-            self._loop.run_forever()
-
-        # Start the network thread as a daemon so it exits cleanly when the main script stops
-        t = threading.Thread(target=run_loop, daemon=True)
         t.start()
         logger.debug("Telnet server background thread spawned")
 
@@ -44,8 +39,16 @@ class TelnetServer:
         self._running = True
 
     async def _start_internal(self):
+        """Start method (async). Sets up the telnet server and waits for shutdown."""
+
+        self._loop = asyncio.get_running_loop()
+
+        server = await asyncio.start_server(self._handle_client, "0.0.0.0", self._port)
         logger.info(f"Telnet server listening on port {self._port}")
-        await asyncio.start_server(self._handle_client, "0.0.0.0", self._port)
+        async with server:
+            await self._shutdown_event.wait()
+
+        await self._stop_internal()
 
     async def _handle_client(self, reader, writer):
         """Handles a new client connection"""
@@ -73,26 +76,13 @@ class TelnetServer:
                 if not data:
                     break
 
-                text = data.decode("ascii", errors="ignore")
+                input_buffer, command = self._consume_input(input_buffer, data)
-
-                for char in text:
-                    if char in ("\r", "\n"):
-                        # User pressed Enter, evaluate the command
-                        command = input_buffer.strip().lower()
-                        input_buffer = ""
-
                 if command == "exit":
                     writer.write(b"Goodbye!\r\n")
                     await writer.drain()
                     # Exit the while read loop, this will disconnect the client.
                     return
 
-                    elif char in ("\b", "\x7f"):
-                        # Handle backspaces
-                        input_buffer = input_buffer[:-1]
-                    else:
-                        input_buffer += char
-
         except asyncio.CancelledError:
             pass
         except Exception:
@@ -106,9 +96,10 @@ class TelnetServer:
     def stop(self):
         """Stops the telnet server"""
 
+        self._running = False
         if self._loop and self._loop.is_running():
             logger.debug("Stopping telnet server...")
-            self._loop.call_soon_threadsafe(self._loop.stop)
+            self._loop.call_soon_threadsafe(self._shutdown_event.set)
 
     async def _stop_internal(self):
         """Stops the telnet server"""
@@ -146,6 +137,25 @@ class TelnetServer:
         for writer in disconnected_clients:
             self._clients.discard(writer)
 
+    @staticmethod
+    def _consume_input(input_buffer: str, data: bytes) -> tuple[str, str | None]:
+        """Handle any input the user gives us, keeping a rolling buffer that we keep passing back through and
+        adding to. Once we get a command, return that as well, so the caller can deal with it."""
+
+        command = None
+        for char in data.decode("ascii", errors="ignore"):
+            if char in ("\r", "\n"):
+                stripped = input_buffer.strip().lower()
+                if stripped:
+                    command = stripped
+                input_buffer = ""
+            elif char in ("\b", "\x7f"):
+                # Handle backspaces
+                input_buffer = input_buffer[:-1]
+            else:
+                input_buffer += char
+        return input_buffer, command
+
     @staticmethod
     def _format_dxspider_spot(spot: Spot) -> str:
         """Formats a spot into the format DXspider uses:

templates/add_spot.html

@@ -77,7 +77,7 @@
 
 </div>
 
-<script src="/static/js/add-spot.js?v=1789140190"></script>
+<script src="/static/js/add-spot.js?v=1789159102"></script>
 <script>$(document).ready(function () {
     $("#nav-link-add-spot").addClass("active");
 }); <!-- highlight active page in nav --></script>

templates/alerts.html

@@ -83,7 +83,7 @@
 
 </div>
 
-<script src="/static/js/alerts.js?v=1789140190"></script>
+<script src="/static/js/alerts.js?v=1789159102"></script>
 <script>$(document).ready(function () {
     $("#nav-link-alerts").addClass("active");
 }); <!-- highlight active page in nav --></script>

templates/bands.html

@@ -76,8 +76,8 @@
 
 </div>
 
-<script src="/static/js/spotsbandsandmap.js?v=1789140190"></script>
+<script src="/static/js/spotsbandsandmap.js?v=1789159102"></script>
-<script src="/static/js/bands.js?v=1789140190"></script>
+<script src="/static/js/bands.js?v=1789159102"></script>
 <script>$(document).ready(function () {
     $("#nav-link-bands").addClass("active");
 }); <!-- highlight active page in nav --></script>

templates/base.html

@@ -1,6 +1,6 @@
 {% extends "skeleton.html" %}
 {% block head_extra %}
-<link rel="stylesheet" href="/static/css/style.css?v=1789140190" type="text/css">
+<link rel="stylesheet" href="/static/css/style.css?v=1789159102" type="text/css">
 <link href="/static/vendor/css/bootstrap-5.3.8.min.css" rel="stylesheet">
 <link href="/static/vendor/css/fontawesome-6.7.2.min.css" rel="stylesheet">
 <link href="/static/vendor/css/solid-6.7.2.min.css" rel="stylesheet">
@@ -16,10 +16,10 @@
     window.fetchEventSource = fetchEventSource;
 </script>
 
-<script src="/static/js/utils.js?v=1789140190"></script>
+<script src="/static/js/utils.js?v=1789159102"></script>
-<script src="/static/js/ui-ham.js?v=1789140190"></script>
+<script src="/static/js/ui-ham.js?v=1789159102"></script>
-<script src="/static/js/geo.js?v=1789140190"></script>
+<script src="/static/js/geo.js?v=1789159102"></script>
-<script src="/static/js/common.js?v=1789140190"></script>
+<script src="/static/js/common.js?v=1789159102"></script>
 {% end %}
 {% block body %}
 <div class="container">

templates/conditions.html

@@ -284,7 +284,7 @@
 </div>
 
 <script src="/static/vendor/js/chart-4.4.9.umd.min.js"></script>
-<script src="/static/js/conditions.js?v=1789140190"></script>
+<script src="/static/js/conditions.js?v=1789159102"></script>
 <script>$(document).ready(function () {
     $("#nav-link-conditions").addClass("active");
 }); <!-- highlight active page in nav --></script>

templates/map.html

@@ -113,8 +113,8 @@
     const CARTODB_API_KEY = "{{ web_ui_options.get('cartodb_api_key', '') }}";
 </script>
 
-<script src="/static/js/spotsbandsandmap.js?v=1789140190"></script>
+<script src="/static/js/spotsbandsandmap.js?v=1789159102"></script>
-<script src="/static/js/map.js?v=1789140190"></script>
+<script src="/static/js/map.js?v=1789159102"></script>
 <script>$(document).ready(function () {
     $("#nav-link-map").addClass("active");
 }); <!-- highlight active page in nav --></script>

templates/spots.html

@@ -125,8 +125,8 @@
 
 </div>
 
-<script src="/static/js/spotsbandsandmap.js?v=1789140190"></script>
+<script src="/static/js/spotsbandsandmap.js?v=1789159102"></script>
-<script src="/static/js/spots.js?v=1789140190"></script>
+<script src="/static/js/spots.js?v=1789159102"></script>
 <script>$(document).ready(function () {
     $("#nav-link-spots").addClass("active");
 }); <!-- highlight active page in nav --></script>

templates/status.html

@@ -86,7 +86,7 @@
     </div>
 </div>
 
-<script src="/static/js/status.js?v=1789140190"></script>
+<script src="/static/js/status.js?v=1789159102"></script>
 <script>
     $(document).ready(function () {
         $("#nav-link-status").addClass("active");