Task Dependencies

Last updated 2026-10-02

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:

Prerequisite state	`State: core.Stop`	`State: core.Skip`
`TaskCompleted`	Satisfied	Satisfied
`TaskFailed`	Dependent task marked `TaskFailed`	Prerequisite ignored
`TaskPending` / `TaskRunning`	Keep waiting	Keep waiting
ID missing	Dependent task marked `TaskFailed`	Dependent task marked `TaskFailed`

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

See Dependency API for the Wait and WaitState types.