rusted-ring

A high-performance, cache-optimized ring buffer library for Rust, designed for lock-free, multi-reader, single-writer scenarios with zero-allocation event processing.

Features

Cache-line aligned ring buffers for optimal CPU cache performance
Lock-free operations using atomic memory ordering
T-shirt sized pools for different event categories
Zero-copy operations with Pod/Zeroable support
Mobile optimized for ARM and x86 architectures
Single-writer, multi-reader design inspired by LMAX Disruptor

Quick Start

use rusted_ring::{RingBuffer, Reader, Writer, PooledEvent, EventPools};

// Create a ring buffer for 256-byte events with 1000 capacity
let ring = Arc::new(RingBuffer::<256, 1000>::new());

// Create writer and readers
let mut writer = Writer {
    ringbuffer: ring.clone(),
    last_ts: 0,
};

let mut reader = Reader {
    ringbuffer: ring.clone(),
    cursor: 0,
    last_ts: 0,
};

// Write events
let event = PooledEvent::<256>::zeroed();
writer.add(event);

// Read events
while let Some(event) = reader.next() {
    // Process event
    println!("Event type: {}", event.event_type);
}

Core Types

RingBuffer<const TSHIRT_SIZE: usize, const RING_CAPACITY: usize>

The main ring buffer structure. Cache-aligned and optimized for high-frequency access.

let ring = RingBuffer::<1024, 500>::new(); // 1KB events, 500 capacity

PooledEvent

Fixed-size event structure that implements Pod and Zeroable for zero-copy operations.

#[repr(C, align(64))]
pub struct PooledEvent<const TSHIRT_SIZE: usize> {
    data: [u8; TSHIRT_SIZE],
    len: u32,
    event_type: u32,
}

Writer<const TSHIRT_SIZE: usize, const RING_CAPACITY: usize>

Single-writer interface for adding events to the ring buffer.

let mut writer = Writer {
    ringbuffer: ring.clone(),
    last_ts: 0,
};

// Add events with proper memory ordering
writer.add(pooled_event);

Reader<const TSHIRT_SIZE: usize, const RING_CAPACITY: usize>

Multi-reader interface implementing Iterator for consuming events.

let mut reader = Reader {
    ringbuffer: ring.clone(),
    cursor: 0,
    last_ts: 0,
};

// Iterate over available events
for event in reader {
    // Process event
}

T-Shirt Sizing

Pre-defined event sizes for optimal memory usage:

pub enum EventSize {
    XS,  // 64 bytes   - Heartbeats, simple state changes
    S,   // 256 bytes  - Basic CRDT operations, chat messages  
    M,   // 1KB        - Document edits, small file attachments
    L,   // 4KB        - Whiteboard data, medium images
    XL,  // 16KB       - Large files, complex diagrams
    XXL, // 64KB+      - Heap fallback for rare huge events
}

EventPools

Manage multiple ring buffers by size category:

use rusted_ring::EventPools;

let pools = EventPools::new();

// Get appropriately sized writers
let xs_writer = pools.get_xs_writer(); // 64-byte events
let s_writer = pools.get_s_writer();   // 256-byte events
let m_writer = pools.get_m_writer();   // 1KB events
let l_writer = pools.get_l_writer();   // 4KB events
let xl_writer = pools.get_xl_writer(); // 16KB events

// Get readers for each size
let xs_reader = pools.get_xs_reader();
let s_reader = pools.get_s_reader();
// ... etc

Memory Ordering & Safety

The library uses careful memory ordering to ensure data visibility:

Writers: Use Release ordering when updating cursors
Readers: Use Acquire ordering when reading cursor positions
Data access: Protected by cursor coordination

This ensures readers never see stale data while maintaining lock-free performance.

Cache Optimization

All structures are cache-line aligned (64 bytes) to prevent false sharing:

#[repr(C, align(64))]
pub struct RingBuffer<...> { ... }

#[repr(C, align(64))]  
pub struct Reader<...> { ... }

#[repr(C, align(64))]
pub struct Writer<...> { ... }

Performance Characteristics

Allocation: Zero allocations after initialization
Write latency: ~10-50ns per event
Read latency: ~5-20ns per event
Memory usage: Predictable and bounded
Cache performance: Optimized for sequential access patterns

Use Cases

Perfect for:

Real-time systems requiring predictable latency
High-frequency event processing (trading, gaming, IoT)
Mobile applications with strict memory constraints
P2P systems needing efficient local buffering
CRDT operations and collaborative editing

Example: Event Processing Pipeline

use std::sync::Arc;
use rusted_ring::{EventPools, PooledEvent};

// Initialize pools
let pools = Arc::new(EventPools::new());

// Producer thread
let pools_producer = pools.clone();
std::thread::spawn(move || {
    let mut writer = pools_producer.get_s_writer();
    
    loop {
        let mut event = PooledEvent::<256>::zeroed();
        // Fill event with data...
        event.event_type = 42;
        
        writer.add(event);
        std::thread::sleep(std::time::Duration::from_millis(1));
    }
});

// Consumer thread  
let pools_consumer = pools.clone();
std::thread::spawn(move || {
    let mut reader = pools_consumer.get_s_reader();
    
    while let Some(event) = reader.next() {
        println!("Processed event type: {}", event.event_type);
    }
});

Memory Requirements

Approximate memory usage for default pool configurations:

XS Pool: 64 × 2000 = 128KB
S Pool: 256 × 1000 = 256KB
M Pool: 1024 × 500 = 512KB
L Pool: 4096 × 200 = 819KB
XL Pool: 16384 × 50 = 819KB

Total: ~2.5MB of pre-allocated ring buffer memory

License

MPL-2.0

rusted-ring 0.1.3