Module connection 

Lock-free connection & broadcasting registry.

Topology

The hot path for real-time servers is broadcast: one inbound event fans out to thousands of sockets. A naive Mutex<HashMap<Id, Sender>> serialises every send behind one lock — the classic C10K/C100K bottleneck.

arcly-http instead uses dashmap::DashMap, which shards the key space across N independent locks (N = 4 * num_cpus by default). Two broadcasts touching different shards never contend. Each connection owns a bounded mpsc::Sender; sending is a wait-free try_send that never blocks the frame-processing task. The per-socket writer drains its own receiver, and a client that can’t keep up is evicted when its queue fills — a slow consumer costs at most ws_outbound_buffer frames of memory, never an unbounded buffer.

Encapsulation

No axum/tower types appear here. The registry speaks WsMessage, an arcly-owned enum. The websocket boundary in super::ws is the single place that translates WsMessage ↔ axum::extract::ws::Message.

Structs

ConnectionRegistry

Sharded, lock-free-on-the-hot-path connection registry.

WsClient

A cheap, clonable handle to one connected client.

Enums

WsMessage

An arcly-owned outbound frame. The websocket boundary maps this onto the concrete transport frame type — keeping axum out of the public surface.

Type Aliases

ConnId

Monotonic, process-unique connection identifier.