Task Dependencies

Last updated 2026-10-21

This page explains how a task waits on prerequisites and what happens when a prerequisite fails.

Declaring Prerequisites

prepareID, err := c.Add("@every 1m", prepare, "prepare")
if err != nil {
	log.Fatal(err)
}
_, err = c.Add("@every 1m", process, "process", []core.Wait{
	{ID: prepareID, State: core.Skip},
})
if err != nil {
	log.Fatal(err)
}

The dependent task's action must be func() error; Add rejects func() combined with prerequisites.

Evaluation Rules

When a dependent task fires, it enters the wait queue and a worker checks prerequisite states every 1ms:

• The wait limit is fixed at 1 minute; Wait.Delay is currently not applied
• Evaluation uses each prerequisite's current state, not a run in the same trigger cycle
• Prerequisites registered with func() are TaskCompleted from the moment they are added
• A dependent task whose state is TaskRunning or TaskCompleted skips the trigger without checking prerequisites, so after one successful run it is not executed again; a TaskFailed dependent task is evaluated again on its next trigger

See Dependency API for the Wait and WaitState types.