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Scheduler

The scheduler manages recurring tasks that need to happen automatically without user intervention. This is essential for maintenance operations, data processing, and system health checks.

Basic Scheduling

The scheduler works by associating functions with periodicity rules. Each function can only have one scheduled task at a time, which keeps the system simple and predictable:

fn backup_database() {
    // perform database backup...
}

fn schedule_backups() {
    // Schedule backup every day at 2 AM
    Scheduler::add(
        backup_database,
        DailyPeriodicity { hour: 2 },
        null
    );
}

Advanced Scheduling Options

For more complex scenarios, you can control exactly when a task starts, how long they’re allowed to run, and whether they’re initially active:

fn health_check() {
    // check system health and log results...
}

fn schedule_health_checks() {
    // Schedule health checks every 5 minutes
    // Start in 1 hour, limit each check to 30 seconds
    Scheduler::add(
        health_check,
        FixedPeriodicity { every: 5min },
        PeriodicOptions { 
            start: time::now() + 1hour,
            max_duration: 30s,
        }
    );
}

Managing Scheduled Tasks

You can dynamically control scheduled periodic tasks during runtime without needing to restart your application:

fn manage_scheduled_tasks() {
    // Find a specific task
    var ptask = Scheduler::find(health_check);
    if (ptask != null) {
        print("Health check runs every ${ptask.periodicity.every}");
    }
    
    // Temporarily disable a task
    Scheduler::deactivate(backup_database);
    
    // Re-enable it later
    Scheduler::activate(backup_database);
    
    // List all scheduled tasks
    var all_tasks = Scheduler::list();
    for (_, ptask in all_tasks) {
        print("${ptask.function}: active=${ptask.is_active}");
    }
}