Struct Metrics 

pub struct Metrics { /* private fields */ }

Lock-free counters for BEAM actor sends, drops, and hot-path throughput.

Cheap to share via Arc<Metrics>. Designed to be passed via ActorContext (Composition-Root IoC) so any actor can record metrics without coupling to a global registry.

All counters are cumulative for the lifetime of the Metrics instance. They never reset — start a new Metrics if you need per-window observation.

Counter semantics

Drop & quorum counters (original)

• dropped_sends: incremented when Addr::send returns Err(()) in a fire-and-forget context. The primary “silent drop is no longer invisible” counter.
• reaped_quorums: incremented when the quorum reaper evicts an expired entry. Indicates that quorum timeouts are happening.
• put_acks_seen: incremented when a Node receives any Put ack.
• put_acks_quorum: incremented when a Put ack completes a quorum (the __quorum_met__ sentinel fired).

Hot-path counters (v0.11.0)

These trace the relay hot path: WebSocket → parse → router → serialize → WebSocket. Under load, the ratio between these counters reveals the bottleneck:

• If messages_parsed >> messages_relayed → dedup is dropping most messages
• If messages_relayed >> ws_messages_sent → serialization or I/O is the bottleneck
• If ws_messages_received ≈ messages_parsed → parse is keeping up
• subscriber_fanout_total / messages_relayed → average fanout ratio

Implementations

impl Metrics

pub fn new() -> Self

Create a new Metrics with all counters at zero.

pub fn record_dropped_send(&self)

Record that a fire-and-forget send was dropped.

Call this when Addr::send(msg) returns Err(()) in a context where you accept the loss but want to know it happened.

pub fn record_reaped_quorum(&self)

Record that the quorum reaper evicted an expired entry.

pub fn record_put_ack(&self)

Record that a Put ack was received.

pub fn record_quorum_ack(&self)

Record that a Put ack completed a quorum.

pub fn record_parsed(&self)

Record that a wire message was parsed from JSON into a Message struct.

Called at the entry point of every inbound message — Message::try_from. This is the first counter in the hot path.

pub fn record_relayed(&self)

Record that a Put was successfully relayed to peers/subscribers.

Called in Router::handle_put_relay after fan-out completes.

pub fn record_dropped_dup(&self)

Record that a message was dropped by the dedup gate.

Called in Router::handle_put when Dup::check returns true.

pub fn record_serialization(&self)

Record a wire-format serialization call.

Called in Message::to_string / Put::to_string.

pub fn record_subscriber_fanout(&self, count: u64)

Record subscriber deliveries from a relay fan-out.

Called in Router::handle_put_relay with the number of subscribers that received this message. Pass 0 if no subscribers were present (the relay still happened, just nobody was listening).

pub fn record_ws_received(&self)

Record an inbound WebSocket message frame.

Called in WsConn::handle on each incoming Text or Binary frame.

pub fn record_ws_sent(&self)

Record an outbound WebSocket message frame.

Called on each successful WsConn send.

pub fn record_dropped_ham(&self)

Record that a Put was dropped by the HAM stale-data pre-filter.

Called in Router::handle_put when ham_filter returns false. Each increment represents a Put that was not forwarded to storage or relayed — work avoided, not just work made cheaper.

pub fn snapshot(&self) -> MetricsSnapshot

Read all counters as a plain struct.

Non-atomic across counters — values may be slightly inconsistent. Acceptable for telemetry; do not use for control flow.

Trait Implementations

impl Debug for Metrics

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

Formats the value using the given formatter.

impl Default for Metrics

fn default() -> Metrics

Returns the “default value” for a type.