guinea

amethystate-guinea lets a guinea timer’s period follow a value in the store. Change the setting, from the UI, from another thread or by editing the file, and the timer re-arms with the new period at once, without waiting out the old one.

Installation

[dependencies]
amethystate-guinea = "0.26"

The crate’s version is amethystate’s. It builds against guinea 0.18 and every later release, and like guinea it needs Rust 1.95.

A period that follows a field

use amethystate_guinea::IntoChanging;
use guinea::timers::Period;
use std::time::Duration;

cx.every(
    Period::follows(settings.ping_interval_ms().changing(), Duration::from_millis),
    &agent,
    || Ping,
);

changing() turns the field into what Period::follows asks for. guinea reads the value before every wait and watches the field for as long as the timer runs: a write cuts the wait under way short, and the next tick comes one new period after it. The watch ends with the timer, or when Timer::period gives it another period.

A write can come from any thread. guinea moves the re-arming to the UI thread itself.

A period that follows a map entry

A ReactiveCell takes changing() too, and that is how a map entry is followed:

let ping = intervals.entry_cell("ping".to_string());

cx.every(Period::follows(ping.changing(), Duration::from_millis), &agent, || Ping);

While the key is absent the cell has nothing to read, and the timer does not tick. It starts once the entry is inserted, and stops again if the entry is removed or the map is dropped.