Crate subms_timer_wheel 

Single-level hashed timer wheel. O(1) schedule and cancel.

The wheel has N buckets. A scheduled timer at delay ticks goes into bucket (now + delay) % N with a rounds counter of how many full revolutions it must sit out first. On tick(), the hand walks one bucket forward: timers with rounds == 0 fire (their values are returned); the rest have rounds decremented. Cancel drops the id from the index and flags the entry; the flagged entry is reclaimed on the next visit to its bucket.

Tradeoff vs the hierarchical wheel: with a single level, a long delay causes many no-op revolutions. For workloads with delays bounded by N ticks, the single level is optimal.

Thread safety: TimerWheel is single-threaded. Every method takes &mut self, so one caller owns the wheel and there is no interior synchronisation to pay for. It is Send when V: Send and can be moved to a ticker thread; to arm timers from several threads at once, enable the concurrent feature or hand work to the ticker thread through a queue.

use subms_timer_wheel::TimerWheel;
let mut w: TimerWheel<&'static str> = TimerWheel::new(256);
let id = w.schedule(5, "hello");
for _ in 0..4 { assert!(w.tick().is_empty()); }
assert_eq!(w.tick(), vec!["hello"]);
let _ = id; // returned id can be used to cancel before firing

Full writeup, design notes and measured benchmarks: https://www.submillisecond.com/cookbook/recipes/subms-timer-wheel

Re-exports

pub use error::TimerError;

pub use features::concurrent::ConcurrentTimerWheel;

pub use features::cron::CronError;

pub use features::cron::CronSchedule;

pub use features::cron::CronScheduler;

pub use features::deadline_scheduler::Clock;

pub use features::deadline_scheduler::DeadlineScheduler;

pub use features::deadline_scheduler::MonotonicClock;

pub use features::deadline_scheduler::TestClock;

pub use features::hierarchical::HierarchicalTimerWheel;

pub use features::metrics::MeteredTimerWheel;

pub use features::metrics::TimerMetrics;

Modules

error

Typed error surface for the wheel family.

features

Opt-in feature catalog. Each submodule is gated by its own Cargo feature flag and adds a specific capability to the base timer wheel without bloating the core build.

recipe

SubMsRecipe impl.

Structs

TimerWheel