transports(daily): send transport messages in a task

We queue transport messages and send them in a task to avoid potential hangs by
sending urgent transport messages from a transport event handler.

CHANGELOG.md

@@ -13,6 +13,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   `filter_code` to filter code from text and `filter_tables` to filter tables
   from text.
 
+### Fixed
+
+- Fixed an issue in Daily transport that would cause tasks to be hanging if
+  urgent transport messages were being sent from a transport event handler.
+
 ## [0.0.43] - 2024-10-10
 
 ### Added

src/pipecat/transports/services/daily.py

@@ -720,15 +720,27 @@ class DailyOutputTransport(BaseOutputTransport):
 
         self._client = client
 
+        # Task to process outgoing messages.
+        self._messages_task = None
+        self._messages_queue = asyncio.Queue()
+
     async def start(self, frame: StartFrame):
         # Parent start.
         await super().start(frame)
         # Join the room.
         await self._client.join()
+        # Start messages task
+        self._messages_task = self.get_event_loop().create_task(self._messages_task_handler())
 
     async def stop(self, frame: EndFrame):
         # Parent stop.
         await super().stop(frame)
+        # Cancel messages task
+        if self._messages_task:
+            self._messages_task.cancel()
+            await self._messages_task
+            self._messages_task = None
+        self._messages_task = None
         # Leave the room.
         await self._client.leave()
 
@@ -743,7 +755,7 @@ class DailyOutputTransport(BaseOutputTransport):
         await self._client.cleanup()
 
     async def send_message(self, frame: TransportMessageFrame | TransportMessageUrgentFrame):
-        await self._client.send_message(frame)
+        await self._messages_queue.put(frame)
 
     async def send_metrics(self, frame: MetricsFrame):
         metrics = {}
@@ -768,7 +780,7 @@ class DailyOutputTransport(BaseOutputTransport):
         message = DailyTransportMessageFrame(
             message={"type": "pipecat-metrics", "metrics": metrics}
         )
-        await self._client.send_message(message)
+        await self._messages_queue.put(message)
 
     async def write_raw_audio_frames(self, frames: bytes):
         await self._client.write_raw_audio_frames(frames)
@@ -776,6 +788,17 @@ class DailyOutputTransport(BaseOutputTransport):
     async def write_frame_to_camera(self, frame: OutputImageRawFrame):
         await self._client.write_frame_to_camera(frame)
 
+    async def _messages_task_handler(self):
+        while True:
+            try:
+                message = await self._messages_queue.get()
+                await self._client.send_message(message)
+                self._messages_queue.task_done()
+            except asyncio.CancelledError:
+                break
+            except Exception as e:
+                logger.exception(f"{self} error processing message queue: {e}")
+
 
 class DailyTransport(BaseTransport):
     def __init__(