Task API

Last updated 2026-10-02

This page lists the core methods for registering, removing, and listing tasks, plus the task state constants.

Add

func (c *cron) Add(spec string, action interface{}, arg ...interface{}) (int64, error)

Parameter	Type	Description
`spec`	`string`	5-field cron, descriptor, or `@every <duration>`
`action`	`func()` or `func() error`	Task body
`arg`	`string`, `time.Duration`, `func()`, `[]Wait`, `[]int64`	Description, execution limit, timeout callback, prerequisites

Return	Condition
`id > 0, nil`	Registered
`0, failed to parse: ...`	Invalid field count, range, step, or duration in `spec`, or `@every` below 30 seconds
`0, action need to be func() or func()`	Unsupported `action` type
`0, need return value to get dependence support`	`func()` combined with `[]Wait` or `[]int64`

func (c *cron) Remove(id int64)

Disables the task with the given ID and removes it from the heap; no-op when the ID does not exist.

func (c *cron) RemoveAll()

Clears the heap while running; disables every task before Start.

func (c *cron) List() []*task

Returns pointers to enabled tasks in the heap; the exported field is ID int64.

for _, t := range c.List() {
    log.Println(t.ID)
}

const (
    TaskPending int = iota
    TaskRunning
    TaskCompleted
    TaskFailed
)

See Task Model for state transition rules.