Struct SubscriptionRouter 

pub struct SubscriptionRouter {
    pub total_routed: u64,
    pub total_delivered: u64,
    pub total_dropped: u64,
    /* private fields */
}

Topic/type-based message routing engine.

Manages subscriber registrations, evaluates SubscriptionFilter predicates, logs delivery attempts to a bounded ring-buffer, and exposes rich query and eviction helpers.

Design

• Messages with ttl == 0 on arrival are immediately dropped (counted in total_dropped); their TTL is not decremented because the router does not modify the caller-owned message.
• The delivery log is a VecDeque capped at max_log_size. Oldest entries are evicted when the cap is reached.
• All statistics counters are plain u64 fields (not atomic) because the router is designed for single-threaded or externally-synchronized use. Wrap in Arc<Mutex<_>> if concurrent access is required.

Fields

total_routed: u64

Total messages passed to route.

total_delivered: u64

Total successful deliveries.

total_dropped: u64

Total dropped messages.

Implementations

impl SubscriptionRouter

pub fn new(max_log_size: usize) -> Self

Create a new SubscriptionRouter with a delivery log bounded at max_log_size entries.

pub fn subscribe( &mut self, peer_id: String, topic: MessageTopic, filter: SubscriptionFilter, now: u64, ) -> u64

Register a subscription and return its stable ID.

If a subscription with the same derived ID already exists it is silently replaced.

pub fn unsubscribe(&mut self, subscription_id: u64) -> bool

Remove the subscription with the given subscription_id.

Returns true if a subscription was found and removed, false if none existed with that ID.

pub fn route(&mut self, message: &RoutingMessage, now: u64) -> Vec<u64>

Route message to all matching subscriptions.

Rules applied in order:

1. If message.ttl == 0 the message is immediately dropped (counted in total_dropped); an empty Vec is returned.
2. For every subscription, Self::matches is called. Matching subscriptions have their message_count incremented and receive a successful DeliveryRecord.
3. If no subscriptions match, total_dropped is incremented and a failing DeliveryRecord with subscription_id = 0 is appended.

Returns the list of subscription IDs that were delivered to.

pub fn matches(sub: &Subscription, msg: &RoutingMessage) -> bool

Return true when sub’s topic matches msg’s topic and the subscription’s filter accepts the message.

This is a pub method as required by the specification.

pub fn filter_matches(filter: &SubscriptionFilter, msg: &RoutingMessage) -> bool

Recursively evaluate filter against msg.

This is a pub method as required by the specification.

pub fn subscriptions_for_topic( &self, topic: &MessageTopic, ) -> Vec<&Subscription>

Return references to all active subscriptions for topic.

pub fn subscriptions_for_peer(&self, peer_id: &str) -> Vec<&Subscription>

Return references to all subscriptions owned by peer_id.

pub fn delivery_rate(&self, since: u64) -> f64

Compute the delivery rate over records whose delivered_at >= since.

Returns 1.0 when there are no matching records.

pub fn recent_deliveries(&self, n: usize) -> Vec<&DeliveryRecord>

Return references to the n most-recent delivery records.

If fewer than n records exist, all are returned.

pub fn evict_stale_subscriptions(&mut self, max_age_ms: u64, now: u64) -> usize

Remove subscriptions that have never delivered a message and were created more than max_age_ms milliseconds before now.

Returns the number of subscriptions evicted.

pub fn stats(&self, now: u64) -> SubRouterStats

Return a SubRouterStats snapshot computed at the given logical now timestamp (used only for the delivery_rate calculation).