Crate nexus_channel 

High-performance bounded SPSC channel for low-latency systems.

This crate provides a blocking single-producer single-consumer channel optimized for trading systems and other latency-critical workloads.

For MPSC (multi-producer), use crossbeam-channel which is well-optimized for that use case. For raw MPSC queue performance without blocking semantics, see nexus-queue::mpsc.

Design

The channel uses a three-phase backoff strategy that minimizes syscall overhead:

1. Fast path: Try the operation immediately
2. Backoff: Spin with exponential backoff using crossbeam::Backoff
3. Park: Sleep until woken by the other end

The key optimization is conditional parking: we only issue expensive unpark syscalls when the other end has actually gone to sleep. This dramatically reduces tail latency compared to channels that unpark unconditionally.

Quick Start

use nexus_channel::channel;

let (tx, rx) = channel::<u64>(1024);

tx.send(42).unwrap();
assert_eq!(rx.recv().unwrap(), 42);

Timeout Support

use nexus_channel::{channel, RecvTimeoutError};
use std::time::Duration;

let (tx, rx) = channel::<u64>(4);

match rx.recv_timeout(Duration::from_millis(100)) {
    Ok(value) => println!("got {}", value),
    Err(RecvTimeoutError::Timeout) => println!("timed out"),
    Err(RecvTimeoutError::Disconnected) => println!("sender dropped"),
}

Performance

Benchmarked against crossbeam-channel on Intel Core Ultra 7 @ 2.7GHz, pinned to physical cores with turbo disabled:

Metric	nexus-channel	crossbeam-channel	Improvement
p50 latency	665 cycles	1344 cycles	2.0x
p999 latency	2501 cycles	37023 cycles	14.8x
Throughput	64 M msgs/sec	34 M msgs/sec	1.9x

The large p999 improvement comes from avoiding unnecessary syscalls.

Modules

spsc

Single-producer single-consumer bounded channel (re-export).

Structs

Receiver

The receiving half of an SPSC channel.

RecvError

Error returned when receiving fails due to disconnection.

SendError

Error returned when sending fails due to disconnection.

Sender

The sending half of an SPSC channel.

Enums

RecvTimeoutError

Error returned by recv_timeout.

TryRecvError

Error returned by try_recv.

TrySendError

Error returned by try_send.

Functions

channel

Creates a bounded SPSC channel with the given capacity.

channel_with_config

Creates a bounded SPSC channel with custom backoff configuration.