Clokwerk, a simple scheduler

Clokwerk is a simple scheduler, inspired by Python's Schedule and Ruby's clockwork. It uses a similar DSL for scheduling, rather than parsing cron strings.

By default, times and dates are relative to the local timezone, but the scheduler can be made to use a different timezone using the Scheduler::with_tz constructor.

Usage

// Scheduler, and trait for .seconds(), .minutes(), etc.
use clokwerk::{Scheduler, TimeUnits};
// Import week days and WeekDay
use clokwerk::Interval::*;
use std::thread;
use std::time::Duration;

// Create a new scheduler
let mut scheduler = Scheduler::new();
// or a scheduler with a given timezone
let mut scheduler = Scheduler::with_tz(chrono::Utc);
// Add some tasks to it
scheduler.every(10.minutes()).plus(30.seconds()).run(|| println!("Periodic task"));
scheduler.every(1.day()).at("3:20 pm").run(|| println!("Daily task"));
scheduler.every(Wednesday).at("14:20:17").run(|| println!("Weekly task"));
scheduler.every(Tuesday).at("14:20:17").and_every(Thursday).at("15:00").run(|| println!("Biweekly task"));
scheduler.every(Weekday).run(|| println!("Every weekday at midnight"));
scheduler.every(1.day()).at("3:20 pm").run(|| println!("I only run once")).once();
scheduler.every(Weekday).at("12:00").count(10).run(|| println!("Countdown"));
scheduler.every(1.day()).at("10:00 am").repeating_every(30.minutes()).times(6).run(|| println!("I run every half hour from 10 AM to 1 PM inclusive."));
scheduler.every(1.day()).at_time(chrono::NaiveTime::from_hms(13, 12, 14)).run(|| println!("You can also pass chrono::NaiveTimes to `at_time`."));

// Manually run the scheduler in an event loop
for _ in 1..10 {
    scheduler.run_pending();
    thread::sleep(Duration::from_millis(10));
}
// Or run it in a background thread
let thread_handle = scheduler.watch_thread(Duration::from_millis(100));
// The scheduler stops when `thread_handle` is dropped, or `stop` is called
thread_handle.stop();

Caveats

Some combinations of times or intervals are permissible, but make little sense, e.g. every(10.seconds()).at("16:00"), which would next run at the next 4 PM after the next multiple of 10 seconds.

Similar libraries

• schedule-rs and job_scheduler are two other Rust scheduler libraries. Both use cron syntax for scheduling.