[Bug] DDS reader leak: duplicate endpoints accumulate after publisher restart

[nypyp]

Describe the bug

zenoh-bridge-ros2dds v1.9.0 accumulates duplicate CycloneDDS reader endpoints when a ROS 2 publisher is killed and restarted while subscribers disconnect and reconnect.
Symptoms:

• Subscriber receives N× nominal frequency after N kill/restart cycles (10Hz → 20Hz → 30Hz...)
• ros2 topic info -v /topic shows multiple zenoh_bridge_ros2dds subscription endpoints with different GIDs
• Subscription count increases by 1 per cycle

To reproduce

Environment: Ubuntu 24.04 (Jazzy, hub) + Ubuntu 22.04 (Humble, client), TCP connection
Trigger sequence (no special config — reproduces with default zenoh-bridge-ros2dds):

# Hub side
ROS_DOMAIN_ID=10 zenoh-bridge-ros2dds
# Client side (other machine)
ROS_DOMAIN_ID=11 zenoh-bridge-ros2dds -e tcp/<hub-ip>:7447
# Publisher (hub side)
ROS_DOMAIN_ID=10 ros2 topic pub -r 10 /test std_msgs/msg/String "data: hello"
# Subscriber (client side)
ROS_DOMAIN_ID=11 ros2 topic hz /test  # → 10 Hz
Then reproduce the leak:
1. Kill publisher (Ctrl+C), kill subscriber (Ctrl+C) — both dead simultaneously
2. Restart publisher, restart subscriber
3. ros2 topic info -v /test → Subscription count: 2 (was 1)
4. Repeat → 3, 4...
After one cycle, ros2 topic info -v /test shows:
Subscription count: 2
  zenoh_bridge_ros2dds  GID: ...0f.04
  zenoh_bridge_ros2dds  GID: ...10.04
The subscriber also shows ~20Hz instead of 10Hz.

Root Cause

RoutePublisher::create() in zenoh-plugin-ros2dds/src/route_publisher.rs registers a matching listener via .background():

publisher
    .matching_listener()
    .callback(|status| {
        if status.matching() {
            activate_dds_reader(&dds_reader, ...) // creates DDS reader
        }
    })
    .background()  // ← callback outlives RoutePublisher
    .await?;

.background() detaches the callback from the RoutePublisher lifecycle. When the route is destroyed and re-created, the old background callback remains registered with its own clone of Arc<AtomicDDSEntity>.

On subscriber reconnect:

1. Old callback fires → activates reader on its dds_reader clone
2. New callback fires → activates reader on new dds_reader
   Result: two DDS readers, two distinct GIDs → 2× frequency.

Proposed Fix

Add cancelled: Arc<AtomicBool> to RoutePublisher, check in callback, set on Drop. Three changes in route_publisher.rs. Happy to submit a PR if accepted.

Related

• PR Fix route cleanup hashmap key mismatch #578 "Fix route cleanup hashmap key mismatch"

System info

	Hub	Client
Platform	x86_64	x86_64
OS	Ubuntu 24.04.4 LTS	Ubuntu 22.04 LTS
CPU	Intel Xeon W-2245 (16 cores)	-
ROS 2	Jazzy	Humble
zenoh-bridge-ros2dds	v1.9.0 (49c5764)	v1.9.0 (49c5764)
RMW	rmw_cyclonedds_cpp	rmw_cyclonedds_cpp