From 3beb5dd78fc4184f47e57a5b2ccb008f59406686 Mon Sep 17 00:00:00 2001
From: Matthew McGowan <mat.mcgowan+git@gmail.com>
Date: Sat, 31 Jan 2026 17:10:50 -0800
Subject: [PATCH] fix: clean shutdown without hanging on Ctrl+C

When pressing Ctrl+C to exit, the application would sometimes hang
because BLE notifications continued to queue data during shutdown,
preventing the run loop from reaching its exit sentinel.

Changes:
- linux_pty.py: Add _stopping flag to reject writes during shutdown
- linux_pty.py: Clear pending queue items before adding exit sentinel
- main.py: Reorder shutdown to stop loops before cleanup
- main.py: Add timeouts to prevent hanging on disconnect

This ensures a clean, prompt shutdown even when BLE data is still
being received.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
---
 ble_serial/main.py            | 29 +++++++++++++++++++++++++++--
 ble_serial/ports/linux_pty.py | 10 ++++++++++
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/ble_serial/main.py b/ble_serial/main.py
index 2fa8596..a4da0f4 100644
--- a/ble_serial/main.py
+++ b/ble_serial/main.py
@@ -75,10 +75,35 @@ async def _run(self):
             logging.exception(e)
         finally:
             logging.warning('Shutdown initiated')
+
+            # Stop the run loops first (signals tasks to exit gracefully)
             if hasattr(self, 'uart'):
-                self.uart.remove()
+                self.uart.stop_loop()
             if hasattr(self, 'bt'):
-                await self.bt.disconnect()
+                self.bt.stop_loop()
+
+            # Cancel and await pending tasks before cleanup
+            try:
+                if pending:
+                    for t in pending:
+                        t.cancel()
+                    await asyncio.wait_for(
+                        asyncio.gather(*pending, return_exceptions=True),
+                        timeout=2.0
+                    )
+            except NameError:
+                pass  # pending not defined if we failed before asyncio.wait
+            except asyncio.TimeoutError:
+                logging.warning('Timeout waiting for tasks to cancel')
+
+            # Now safe to disconnect BLE and remove uart
+            if hasattr(self, 'bt'):
+                try:
+                    await asyncio.wait_for(self.bt.disconnect(), timeout=3.0)
+                except asyncio.TimeoutError:
+                    logging.warning('Timeout disconnecting BLE')
+            if hasattr(self, 'uart'):
+                self.uart.remove()
             if hasattr(self, 'log'):
                 self.log.finish()
             logging.info('Shutdown complete.')
diff --git a/ble_serial/ports/linux_pty.py b/ble_serial/ports/linux_pty.py
index 2709609..e09ed55 100644
--- a/ble_serial/ports/linux_pty.py
+++ b/ble_serial/ports/linux_pty.py
@@ -11,6 +11,7 @@ def __init__(self, symlink: str, ev_loop: asyncio.AbstractEventLoop, mtu: int):
         self.loop = ev_loop
         self.mtu = mtu
         self._send_queue = asyncio.Queue()
+        self._stopping = False
 
         self._controller_fd, endpoint_fd = pty.openpty()
         self.endpoint_path = os.ttyname(endpoint_fd)
@@ -39,6 +40,13 @@ def start(self):
 
     def stop_loop(self):
         logging.info('Stopping serial event loop')
+        self._stopping = True
+        # Clear any pending items so we exit quickly
+        while not self._send_queue.empty():
+            try:
+                self._send_queue.get_nowait()
+            except asyncio.QueueEmpty:
+                break
         self._send_queue.put_nowait(None)
 
     def remove(self):
@@ -58,6 +66,8 @@ def read_sync(self):
         return value
 
     def queue_write(self, value: bytes):
+        if self._stopping:
+            return  # Ignore writes during shutdown
         self._send_queue.put_nowait(value)
 
     async def run_loop(self):