Crate sacs

SACS - Simple Asynchronous Cron Scheduler

SACS is easy to use, lightweight scheduler and executor of repeatable async tasks for Tokio runtime.

Features

• Runs tasks with different types of schedule: once, with delay, by interval, with a cron schedule.
• Uses current Tokio runtime or creates new one with the specified type, number of threads and limited parallelism.
• Allows task cancellation, getting current state and runtime statistics of the task.
• Task execution time may be limited.
• Lightweight, small, easy to use.

Quick start

Just create Scheduler and add Task to it. Refer to scheduler and task modules documentation for more examples and details of possible usage.

use sacs::{
    scheduler::{Scheduler, ShutdownOpts, TaskScheduler},
    task::{CronOpts, Task, TaskSchedule},
    Result,
};
use std::time::Duration;
use tracing::info;

#[tokio::main]
async fn main() -> Result<()> {
    tracing_subscriber::fmt::init();

    // Create scheduler with default config
    let scheduler = Scheduler::default();

    // Create a task with cron schedule: repeat it every 3 seconds
    let cron = TaskSchedule::Cron("*/3 * * * * *".try_into()?, CronOpts::default());
    let task = Task::new(cron, |id| {
        Box::pin(async move {
            info!("Job {id} started.");
            // Actual async workload here
            tokio::time::sleep(Duration::from_secs(2)).await;
            // ...
            info!("Job {id} finished.");
        })
    });

    // Post task to the scheduler and forget it :)
    let _task_id = scheduler.add(task).await?;

    // ... and do any other async work in parallel
    tokio::time::sleep(Duration::from_secs(10)).await;

    // It's not mandatory, but good to shut down scheduler
    // Wait for completion of all running jobs
    scheduler.shutdown(ShutdownOpts::WaitForFinish).await
}

Feature flags

• tz - enables cron schedules with timezone, see cron-lite documentation for details.

Modules

job

Contains primitive JobId which uniquely identifies executing Task instance.

scheduler

Scheduler is the most essential structure of SACS, its heart. This is an entry point to schedule tasks and control on tasks and on whole jobs runtime.

task

Task object represents a single job with schedule. Use it to create workload of different types and post it to Scheduler.

Enums

Error

Represents SACS specific errors.

Type Aliases

Result

Convenient alias for Result.