Scheduler

Recurring background jobs — the desktop counterpart to Laravel's Schedule. Register async tasks and they run on background tasks for the life of the app.

Add the provider and register jobs in a provider's boot:

use elyra::{App, Ctx, Provider};
use elyra::scheduler::{Scheduler, SchedulerProvider};
use std::time::Duration;

struct Jobs;
impl Provider for Jobs {
    fn boot(&self, ctx: &Ctx) {
        let sched = ctx.get::<Scheduler>();

        sched.every(Duration::from_secs(30), "poll", || async {
            // … refresh something …
        });
        sched.hourly("digest", || async { /* … */ });
        sched.daily("cleanup", || async { /* … */ });
    }
}

App::new().provider(SchedulerProvider).provider(Jobs).run()?;

Intervals

Intervals are measured from app start: daily() means "every 24 hours", not "at midnight". For a time of day, use a clock job.

Clock times

use elyra::scheduler::Weekday;

sched.daily_at("09:00", "report", || async { /* … */ });
sched.weekdays_at("08:30", "standup", || async { /* … */ });
sched.weekly_on(Weekday::Monday, "07:00", "digest", || async { /* … */ });
sched.monthly_on(1, "00:00", "invoices", || async { /* … */ });
sched.hourly_at(15, "sync", || async { /* … */ });            // every hour at :15
sched.cron("*/15 9-17 * * mon-fri", "poll", || async { /* … */ });

cron takes a standard five-field expression — minute hour day month weekday — with *, values, ranges (9-17), steps (*/15, 5/20), lists (8,12,18) and three-letter names (mon-fri, jan,jul). Weekday 0 and 7 are both Sunday. When both day fields are restricted, a day matches if either does: 0 9 15 * mon runs on the 15th and every Monday. An invalid literal panics at registration, saying what is wrong; for expressions from user input, parse with Cron::parse (which returns a Result) and register with at.

Times are in the system time zone, re-read on every run, so a user who travels picks up the new zone.

Semantics

• Sleep and wake. A laptop that sleeps through a job's time runs it once, promptly after waking — clock jobs re-check the wall clock at least every 30 seconds instead of trusting one long timer, whose monotonic clock stops while the machine is suspended. Occurrences missed while asleep are not replayed.
• Daylight saving time. A time skipped by a spring-forward runs just after the gap (02:30 on that night runs at 03:30); a time repeated by a fall-back runs once.
• No overlap. A job's next run is computed only after the current one finishes, so a slow run is never doubled up — Laravel's withoutOverlapping() is the default. A run that overshoots the next occurrence skips it.
• Jobs run in their own background task; a slow job doesn't delay the others.
• Registration works before or after the scheduler starts, so provider order doesn't matter.
• In-process only: jobs stop when the app exits. For work that must survive a restart, have the scheduled task push a job onto a durable queue.

Related

• Queue — one-off background jobs. · Container & providers