Struct SubscriberSet 

pub struct SubscriberSet { /* private fields */ }

The set of sessions currently listening.

Reads are lock-free: the subscriber list is behind an ArcSwap for the same reason the primitive set is, and a publish walks a Vec of Arcs that no writer can mutate.

Implementations

impl SubscriberSet

pub fn new() -> Self

An empty set.

pub fn all(&self) -> Vec<Arc<Subscriber>>

The current subscribers, as one owned snapshot.

pub fn len(&self) -> usize

How many sessions are listening.

pub fn is_empty(&self) -> bool

Whether anyone is listening.

pub fn add(&self, subscriber: Subscriber)

Adds a session’s standing interest.

pub fn remove_by_sink(&self, sink: &Arc<dyn DynFrameSink>) -> usize

Drops every subscriber whose sink is sink, by identity.

By pointer identity rather than by session id because a session id is the thing this module is not allowed to log, and comparing two of them to decide who to remove would be a use of one anyway. The sink is the connection, and a connection is what a disconnect closes.

Returns how many were dropped, so a caller can assert that a disconnect actually unsubscribed rather than assuming it.

pub async fn announce( &self, snapshot: &Snapshot, kinds: &[PrimitiveKind], ) -> Fanout

Tells the eligible subscribers that kinds changed in snapshot.

A subscriber is told when both hold: it registered for a kind this publish touched, and its own negotiated profile permits the notification. The kind test comes from the publish; the profile test comes from the subscriber. Neither can be derived from the other, which is why both are here.

The subscriber list is loaded once, so a subscriber that disconnects mid-fan-out is either told or not told but never told twice, and a subscriber that joins mid-fan-out is not told about a change it could not have observed.

Trait Implementations

impl Debug for SubscriberSet

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for SubscriberSet

fn default() -> Self

Returns the “default value” for a type.