cron — scheduling

Imported from the facade: import { cron } from "@/core/facade.ts".

Named cron schedules backed by croner. Jobs are unique by name — re-scheduling the same name stops and replaces the old job. See Scheduler.

Signature

Function	Signature	Description
schedule	(name: string, expression: string, task: () => void | Promise<void>, options?: { timezone?: string }) => CronHandle	Register a named cron job (replacing any existing job with the same name) and return a handle.
stop	() => void	Stop all registered jobs (call on app shutdown).

Types

interface CronHandle { stop(): void; }

Use cases

Daily maintenance at a fixed hour

Standard 5-field cron expression; timezone makes the wall-clock time predictable across machines.

import { cron } from "@/core/facade.ts";

cron.schedule("cleanup", "0 4 * * *", async () => {
  await clearTempFiles();
  await vacuumDatabase();
}, { timezone: "UTC" });

Live heartbeat / UI ticker

Second-level expressions update a shared counter the UI polls or reads via bindings.

let tickCount = 0;
cron.schedule("demo.tick", "* * * * * *", () => {
  tickCount += 1;
});

To report a tick to the UI, register the counter on the backend and expose a read handler via a controller + binding (<module>.<controller>.<handler>).

Periodic background sync (every N minutes)

Register once at boot; the task runs as long as the app is alive.

cron.schedule("sync", "*/5 * * * *", async () => {
  await syncRemoteChanges();
});

Replace a job when settings change (named slots)

The same name replaces the old job — so re-applying user settings never double-schedules.

function applyReportHour(hour: number) {
  cron.schedule("report", `0 ${hour} * * *`, () => generateDailyReport());
}

// user changes the hour → just re-apply (old "report" job is stopped & replaced)
applyReportHour(9);

Stop everything on shutdown

Call cron.stop() during app teardown (also already done via db.close() shuts down paths).

// in app shutdown
cron.stop();

Notes

• Failing tasks are caught and logged (scheduler does not crash the app).
• Use name to make a job replaceable — the same name = the same job slot, so re-running setup never double-schedules.

Related

• queue · db