Struct TopicRouter 

pub struct TopicRouter { /* private fields */ }

Pub/sub topic router for kernel IPC.

Manages subscriptions as a mapping from topic name to the list of subscribers. A subscriber can be an in-kernel PID inbox or an external streaming client (SubscriberSink). Uses DashMap for lock-free concurrent access.

Dead subscriber cleanup

When a message is published, the router checks each PID subscriber’s state in the process table. PID subscribers whose processes have exited are automatically removed from the subscription list (lazy cleanup). External streams that have closed their receiver are removed on the next publish attempt.

Implementations

impl TopicRouter

pub fn new(process_table: Arc<ProcessTable>) -> Self

Create a new topic router.

pub fn subscribe_sink(&self, topic: &str, sink: SubscriberSink) -> SubscriberId

Subscribe a sink to a topic.

Returns the assigned SubscriberId. For PID inbox sinks, if the same PID is already subscribed to the topic the existing subscription is kept and its id is returned (idempotent).

pub fn subscribe(&self, pid: Pid, topic: &str)

Subscribe a process to a topic (convenience for PID inboxes).

If the process is already subscribed, this is a no-op — the existing subscription is preserved.

pub fn unsubscribe(&self, pid: Pid, topic: &str)

Unsubscribe a process from a topic.

If the process is not subscribed, this is a no-op. Empty subscription lists are removed.

pub fn unsubscribe_id(&self, topic: &str, id: SubscriberId)

Unsubscribe a specific subscriber (by id) from a topic.

Use this to tear down external streaming subscriptions on disconnect without affecting other subscribers on the same topic.

pub fn live_sinks(&self, topic: &str) -> Vec<(SubscriberId, SubscriberSink)>

Get the list of live sinks for a topic.

Performs lazy cleanup: removes PID sinks whose processes have exited and SubscriberSink::ExternalStream sinks whose receiver has been dropped. Returns a cloned list safe to use outside the lock.

pub fn live_subscribers(&self, topic: &str) -> Vec<Pid>

Get the list of running PID subscribers for a topic.

Convenience wrapper around Self::live_sinks that returns only in-kernel agent PIDs. External streaming subscribers are handled separately by the caller via Self::live_sinks.

pub fn subscribers(&self, topic: &str) -> Vec<Pid>

Get all PID subscribers for a topic (including potentially dead ones).

Use TopicRouter::live_subscribers for a filtered list.

pub fn list_topics(&self) -> Vec<(String, usize)>

List all topics with their subscriber counts.

pub fn topics_for_pid(&self, pid: Pid) -> Vec<String>

List all topics a specific PID is subscribed to.

pub fn topic_count(&self) -> usize

Get the total number of active topics.

pub fn has_subscribers(&self, topic: &str) -> bool

Check whether a topic has any subscribers.

pub fn unsubscribe_all(&self, pid: Pid)

Remove all subscriptions for a PID (used during process cleanup).