Add logging to broadcast subscription task

apps/blockchain-node/src/aitbc_chain/gossip/broker.py

@@ -150,16 +150,27 @@ class BroadcastGossipBackend(GossipBackend):
         stop_event = asyncio.Event()
 
         async def _run_subscription() -> None:
-            async with self._broadcast.subscribe(topic) as subscriber:  # type: ignore[attr-defined,union-attr]
-                async for event in subscriber:  # type: ignore[union-attr]
-                    if stop_event.is_set():
-                        break
-                    data = _decode_message(getattr(event, "message", event))
-                    try:
-                        await queue.put(data)
-                        _set_queue_gauge(topic, queue.qsize())
-                    except asyncio.CancelledError:
-                        break
+            import logging
+            logger = logging.getLogger(__name__)
+            logger.info(f"Starting broadcast subscription for topic: {topic}")
+            try:
+                async with self._broadcast.subscribe(topic) as subscriber:  # type: ignore[attr-defined,union-attr]
+                    logger.info(f"Successfully subscribed to broadcast topic: {topic}")
+                    async for event in subscriber:  # type: ignore[union-attr]
+                        if stop_event.is_set():
+                            logger.info(f"Stop event set for topic: {topic}")
+                            break
+                        data = _decode_message(getattr(event, "message", event))
+                        logger.info(f"Received message from broadcast for topic {topic}")
+                        try:
+                            await queue.put(data)
+                            _set_queue_gauge(topic, queue.qsize())
+                        except asyncio.CancelledError:
+                            logger.warning(f"Subscription cancelled for topic: {topic}")
+                            break
+            except Exception as e:
+                logger.error(f"Broadcast subscription error for topic {topic}: {e}")
+            logger.info(f"Broadcast subscription ended for topic: {topic}")
 
         task = asyncio.create_task(_run_subscription(), name=f"broadcast-sub:{topic}")
         async with self._lock: