Crate nexus_timer 

High-performance timer wheel with O(1) insert and cancel.

nexus-timer provides a hierarchical timer wheel inspired by the Linux kernel’s timer infrastructure (Gleixner 2016). Timers are placed into coarser slots at higher levels — no cascading, no entry movement after insertion.

Design

• No cascade: Once placed, an entry never moves. Poll checks each entry’s exact deadline. This eliminates the latency spikes that cascading timer wheels exhibit.
• Intrusive active-slot lists: Only non-empty slots are visited during poll and next-deadline queries. No bitmap, no full scan.
• Embedded refcounting: Lightweight Cell<u8> refcount per entry enables fire-and-forget timers alongside cancellable timers without external reference-counting machinery.
• Generic storage: Parameterized over slab backend — bounded (fixed-capacity) or unbounded (growable).

Quick Start

use std::time::{Duration, Instant};
use nexus_timer::Wheel;

let now = Instant::now();
let mut wheel: Wheel<u64> = Wheel::unbounded(4096, now);

// Schedule a timer 100ms from now
let handle = wheel.schedule(now + Duration::from_millis(100), 42u64);

// Cancel before it fires — get the value back
let value = wheel.cancel(handle);
assert_eq!(value, Some(42));

Modules

store

Slab storage traits for instance-based (non-ZST) slabs.

Structs

BoundedWheelBuilder

Terminal builder for a bounded timer wheel.

Full

Error returned when a bounded allocator is full.

TimerHandle

Handle to a scheduled timer.

TimerWheel

A multi-level, no-cascade timer wheel.

UnboundedWheelBuilder

Terminal builder for an unbounded timer wheel.

WheelBuilder

Builder for configuring a timer wheel.

WheelEntry

Timer wheel entry stored inside a slab slot.

Type Aliases

BoundedWheel

A timer wheel backed by a fixed-capacity slab.

Wheel

A timer wheel backed by a growable slab.