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:

1. Sender marks next reserved slot dirty
2. Sender writes payload into current reserved slot
3. Sender clears dirty flag of current slot (= commit)
4. 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

Copyright © 2005–2025 IKH Software, Inc.

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.