Crate nexus_slot 

High-performance conflation slots for latest-value-wins scenarios.

Two variants based on reader topology:

• spsc — Single producer, single consumer. Lowest overhead.
• spmc — Single producer, multiple consumers. SharedReader is Clone.

Both use a seqlock internally: the writer increments a sequence counter, copies data via word-at-a-time atomics, and increments again. Readers speculatively copy and retry if the sequence changed.

The Pod Trait

Types must implement Pod (Plain Old Data) — no heap allocations, no drop glue, byte-copyable. Any Copy type implements Pod automatically.

use nexus_slot::Pod;

#[repr(C)]
struct OrderBook {
    bids: [f64; 20],
    asks: [f64; 20],
    sequence: u64,
}

// SAFETY: OrderBook is just bytes — no heap allocations
unsafe impl Pod for OrderBook {}

Examples

#[derive(Copy, Clone, Default)]
struct Quote { bid: f64, ask: f64, seq: u64 }

// SPSC — single reader
let (mut writer, mut reader) = nexus_slot::spsc::slot::<Quote>();
writer.write(Quote { bid: 100.0, ask: 100.05, seq: 1 });
assert_eq!(reader.read().unwrap().seq, 1);

#[derive(Copy, Clone, Default)]
struct Quote { bid: f64, ask: f64, seq: u64 }

// SPMC — multiple readers
let (mut writer, mut reader1) = nexus_slot::spmc::shared_slot::<Quote>();
let mut reader2 = reader1.clone();

writer.write(Quote { bid: 100.0, ask: 100.05, seq: 1 });
assert!(reader1.read().is_some());
assert!(reader2.read().is_some()); // independent consumption

Modules

spmc

Single-producer, multiple-consumer conflation slot.

spsc

Single-producer, single-consumer conflation slot.

Traits

Pod

Marker trait for types safe to use in a conflated slot.