JobScheduler

The job scheduler uses cron expressions to define when jobs run. The Cronos library parses the cron expressions.

5-field (minute granularity):

* * * * *
| | | | |
| | | | +-- Day of week (0-6, Sunday=0)
| | | +---- Month (1-12)
| | +------ Day of month (1-31)
| +-------- Hour (0-23)
+---------- Minute (0-59)

6-field (second granularity):

* * * * * *
| | | | | |
| | | | | +-- Day of week (0-6, Sunday=0)
| | | | +---- Month (1-12)
| | | +------ Day of month (1-31)
| | +-------- Hour (0-23)
| +---------- Minute (0-59)
+------------ Second (0-59)

The library auto-detects the format based on the number of fields.

All times are UTC.

Each scheduled job exposes its schedule through the IJobSchedule interface:

public interface IJobSchedule
{
    string OriginalText { get; }           // the cron expression as provided
    string Description { get; }            // human-readable (via CronExpressionDescriptor)
    DateTimeOffset Next();                 // next occurrence from now
    DateTimeOffset Next(DateTimeOffset after);
    DateTimeOffset? Previous();            // last occurrence (null if none in lookback window)
    DateTimeOffset? Previous(DateTimeOffset atOrBefore);
}

The Description property returns a human-readable string (e.g., "Every 5 seconds"). The CronExpressionDescriptor library generates this string.

Previous() scans backward over a 48-hour lookback window. It returns null if no matching time exists within that window.

After you call AddUpdateJob, you get an IScheduledJob with these properties:

Methods: StartSchedule(), StopSchedule(), UpdateSchedule(string cronExpression), UpdateSchedule(IJobSchedule schedule).

// List all registered jobs
var jobs = scheduler.GetAllJobs();

// Remove a job by name
bool removed = scheduler.RemoveJob("test job1");

// Check shutdown state
if (scheduler.IsShuttingDown) { /* ... */ }

• Scheduler: setup and usage
• Queue Creation: custom queue options for scheduled jobs
• Time Settings: clock sync and time providers
• Redundancy: running multiple schedulers