cordis-timer

cordis-timer adds complete, generation-owned time operations to a Cordis v3 Context without making time policy part of cordis-core.

It provides three operations through TimerExt:

sleep(delay) — one pinned one-shot delay;
interval(period) — a fixed-phase stream of ticks;
timeout(delay, work) — owns and races one caller Future against a pinned deadline.

Installation

For an application using the cordis facade:

[dependencies]
cordis-rs = "0.8"
cordis-timer = "0.3"
tokio = { version = "1", features = ["macros", "rt-multi-thread", "time"] }

Framework and Plugin crates may depend on cordis-core = "0.3" instead of cordis-rs; TimerExt is implemented for the same underlying Context type.

Quick example

use std::time::Duration;

use cordis::{BoxError, Context};
use cordis_timer::{TimeoutOutcome, TimerExt};

#[tokio::main]
async fn main() -> Result<(), BoxError> {
    let ctx = Context::new();

    ctx.sleep(Duration::from_millis(10))?.await?;

    let outcome = ctx
        .timeout(Duration::from_secs(1), async { 42 })?
        .await?;

    match outcome {
        TimeoutOutcome::Completed(value) => assert_eq!(value, 42),
        TimeoutOutcome::Elapsed => println!("deadline elapsed"),
    }

    Ok(())
}

A usable Tokio time environment must be current when an operation is constructed.

Lifecycle semantics

Timer operations are not detached scheduler handles. Successful construction registers exactly one cleanup obligation with the selected Context generation. That gives timer completion three intentionally different classes of outcome:

registration refusal — construction returns TimerRegistrationError and no operation is delivered;
normal timer outcome — sleep completes, interval yields a tick, or timeout returns TimeoutOutcome::{Completed, Elapsed};
generation cancellation — a live operation returns TimerCancelled when the generation that registered it closes.

Timeout expiry is therefore not the same thing as lifecycle cancellation. TimeoutOutcome::Elapsed is a normal timer result; TimerCancelled says the owning Cordis generation ended first.

Operation details

Sleep

Context::sleep pins its monotonic deadline during successful construction. A zero delay is valid. Natural completion disarms the generation cleanup occurrence.

Interval

Context::interval rejects a zero period. Its phase is anchored at successful construction; missed ticks coalesce without shifting that phase. Generation cancellation appears once as Err(TimerCancelled) and then the stream ends.

Use futures::StreamExt (or another Stream consumer) to await interval ticks.

Timeout

Context::timeout owns the supplied Future. Construction does not poll the Future. The deadline is pinned before the operation is delivered, and completion returns either the Future output in Completed(T) or Elapsed.

Dropping a live timer operation abandons it. Drop does not synthesize a cancellation result, and later generation cleanup does not perform a second user-visible timer action.

Boundary with `cordis-core`

cordis-core knows only that a generation has a cleanup obligation. It does not know about Tokio deadlines, interval schedulers, timeout arbitration, or timer outcome types. Those semantics belong entirely to this crate.

Compatibility and MSRV

cordis-timer v3 began at 0.1.x; the current 0.3.x line depends on cordis-core 0.3.x, requires Rust 1.88 or newer, and uses Rust edition 2024.

Documentation

Licensed under MIT.

cordis-timer 0.3.3