Module io 

Available on crate feature tokio only.

Async real-socket UDP adapter over the sans-IO SRT engine.

The sans-IO crate::caller::CallerHandshake / crate::listener::ListenerHandshake engines never touch a socket — they turn state transitions into typed events and byte buffers. The ARQ sender/receiver, TSBPD scheduler, and LiveCC pacing controller follow the same contract: all take caller-supplied now: core::time::Duration and never read a wall clock.

This module is the thin tokio layer that actually moves bytes over a tokio::net::UdpSocket, drives the handshake to completion, and then runs a background driver task per connection that pumps socket RX → engines → socket TX and, crucially, ticks the timers (retransmit, ACK, NAK, TSBPD release) on a fixed tokio::time::interval — so loss recovery keeps making progress even when the application is neither sending nor receiving at that instant. The sans-IO core stays no_std; the adapter is pure plumbing.

Why a background task

SRT reliability is bidirectional and continuous: a receiver that detects a gap emits a NAK, and the sender must react to that NAK by retransmitting — long after the application handed it the original payload. A purely pull-based send/recv (one that only advances the protocol while the app is blocked inside a call) deadlocks the moment a fire-and-forget sender stops calling send: the inbound NAK is never drained and the lost packet is never resent. The driver task decouples protocol progress from application call timing: SrtSocket::send enqueues a payload and returns immediately, SrtSocket::recv awaits a delivered payload, and the task in between runs the select loop (RX / app-send / periodic tick) forever until the peer shuts down or the SrtSocket is dropped.

Structure

• SrtListener — binds a UDP port and accepts incoming SRT connections, returning a SrtSocket per connected peer.
• SrtSocket — a handle to an established SRT connection (caller or listener role) with async send and recv for application payloads; the actual protocol runs on the background driver task the handle owns.

Feature gate

Only available with features = ["tokio"] (implies std). Without the tokio feature, the crate stays no_std+alloc and nothing in this module is compiled.

Structs

SrtListener

An SRT listener that accepts incoming Caller connections.

SrtSocket

A handle to an established SRT connection over UDP.