SPMC broadcast channel for HFT and real-time systems

A lightweight, ultra-low-latency single-producer / multi-consumer broadcast channel designed for use in high-frequency trading (HFT) and other real-time systems.

Provides predictable performance, minimal contention, and carefully controlled memory access patterns. Works for thread-to-thread broadcasting via local memory, or inter-process communication using shared memory.

Features

Lock-free single-producer / multi-consumer broadcast channel
Seq_no protocol ensures overwrite detection
Spin-wait receivers for ultra-low latency
Cache-friendly layout (CachePadded)
Works between threads, or between processes via shared memory
Zero allocations after initialization
no_std-friendly design

Spin-Wait Behavior

Receivers use busy-waiting (spin loops) to wait for the producer to complete publishing the next message.

Implications:

Lowest possible latency (no OS scheduling)
A receiver consumes one logical CPU core while waiting
Best when producer and receivers are on the same NUMA node
Not ideal for scenarios where power efficiency matters
No OS blocking (by design)

This design is intended for HFT, trading engines, matching engines, real-time telemetry, and other performance-critical workloads.

Installation

[dependencies]
hft-channel = "0.1"

Quick Example

use hft-channel::spmc_broadcast::channel;

let (tx, rx) = channel::<u64>("/test", 512);

let (_, payload) = tx.reserve();
*payload = 42;
tx.commit();

let (_, payload) = rx.recv();

Design Overview

The channel tracks state as:

[ dirty (1 bit, MSB) | seq_no (63 bits) ]

Guarantees:

At least one slot is always dirty
Dirty slot = being written, reserved for writing
Clean slot = readable and stable
If receiver sees seq_no changed, the slot was overwritten

Pattern:

Sender marks next reserved slot dirty
Sender writes payload into current reserved slot
Sender clears dirty flag of current slot (= commit)
Receiver waits for dirty == false, then copies or peeks

Benchmarks

RUSTFLAGS="-C target-cpu=native" cargo build --release --example bench
./target/release/examples/bench --help
./target/release/examples/bench broadcast -p 1000 -m 2

Testing

cargo test

License

Licensed under LGPL-3.0-or-later. See LICENSE or https://www.gnu.org/licenses/lgpl-3.0.html.

Contributing

Contributions are welcome! Please open issues or pull requests on GitHub.

By submitting a contribution, you agree that it will be licensed under the project’s LGPL-3.0-or-later license.

hft-channel 0.2.1