Struct FloodSubRouter 

pub struct FloodSubRouter { /* private fields */ }

Topic-based message flooding router.

Responsibilities

1. Maintain per-peer topic subscriptions.
2. Deduplicate messages using a bounded, TTL-based ID cache.
3. Track which peers have already received a given message to prevent loops.
4. Compute forward sets excluding the origin peer and previously-forwarded peers.

Thread safety

FloodSubRouter is not Send + Sync by default; callers should wrap it in a Mutex or RwLock when sharing across threads.

Implementations

impl FloodSubRouter

pub fn new(config: RouterConfig) -> Self

Create a new router with the supplied configuration.

pub fn subscribe(&mut self, peer_id: &str, topic: &FloodTopic, now: u64) -> bool

Subscribe peer_id to topic.

Returns true if this was a new subscription, false if the peer was already subscribed to this topic.

The subscription is rejected (returns false) when either:

• the per-topic peer limit (max_peers_per_topic) would be exceeded, or
• the global topic limit (max_topics) would be exceeded by a new topic.

pub fn unsubscribe(&mut self, peer_id: &str, topic: &FloodTopic) -> bool

Unsubscribe peer_id from topic.

Returns true if the subscription existed and was removed.

pub fn peers_for_topic(&self, topic: &FloodTopic) -> Vec<String>

Return all peer IDs subscribed to topic.

pub fn topics_for_peer(&self, peer_id: &str) -> Vec<FloodTopic>

Return all topics to which peer_id is subscribed.

pub fn route(&mut self, msg: &FloodMessage, now: u64) -> ForwardDecision

Decide how to forward msg and update all internal state accordingly.

Decision logic (in order)

1. If msg.id is already in the dedup cache → Drop (duplicate).
2. If msg.ttl <= config.min_ttl → Drop (TTL exhausted).
3. If no peer is subscribed to msg.topic → Drop (no subscribers).
4. Insert msg.id into the dedup cache with now as the timestamp.
5. Build the candidate forward set: all subscribers except the origin peer and peers already recorded in forwarded_to[msg.id].
6. Record the candidate set in forwarded_to.
7. If the candidate set is empty and the origin is the only subscriber → Loopback.
8. If the candidate set is empty (all already forwarded) → Drop.
9. Otherwise → Forward { to_peers }.

pub fn mark_forwarded(&mut self, id: &FloodMessageId, peer_id: &str)

Record that msg_id was manually forwarded to peer_id.

Useful when the caller forwards a message outside of route and wants to keep the loop-prevention state consistent.

pub fn expire_cache(&mut self, now: u64)

Evict all dedup-cache entries older than config.dedup_window_secs.

Should be called periodically (e.g. every 10–30 seconds) to bound memory consumption.

pub fn stats(&self) -> &FsrRouterStats

Return a reference to the current operational statistics.

pub fn compute_message_id( payload: &[u8], topic: &FloodTopic, peer_id: &str, now: u64, ) -> FloodMessageId

Compute a FloodMessageId from payload, topic, peer_id, and a Unix-epoch timestamp.

The ID is produced by running FNV-1a over all inputs concatenated in a deterministic order, then taking two sequential hashes to fill 16 bytes.

pub fn cache_full(&self) -> bool

Return true when the dedup cache is at capacity.

pub fn forwarded_count(&self, id: &FloodMessageId) -> usize

Return the number of peers that have already been sent id.

pub fn is_subscribed(&self, peer_id: &str, topic: &FloodTopic) -> bool

Return true if peer_id is subscribed to topic.

pub fn subscription( &self, peer_id: &str, topic: &FloodTopic, ) -> Option<&SubscriptionRecord>

Return the SubscriptionRecord for peer_id on topic, if any.

pub fn subscription_count(&self) -> usize

Return the total number of active subscriptions.

pub fn all_subscriptions(&self) -> impl Iterator<Item = &SubscriptionRecord>

Return an iterator over all active SubscriptionRecords.