once

Documentation

Overview

Package once contains utilities for managing actions that must be performed exactly once.

Index

• type Map
  • func (m *Map) Do(key interface{}, do func() error) error
  • func (m *Map) Forget(key interface{})
• type Task
  • func (o *Task) Do(do func() error) error
  • func (o *Task) Done() bool
  • func (o *Task) Reset()

Types

type Map

type Map sync.Map

Map coordinates actions that must happen exactly once, keyed by user-defined keys.

func (*Map) Do

func (m *Map) Do(key interface{}, do func() error) error

Perform the provided action named by a key. Do invokes the action exactly once for each key, and returns any errors produced by the provided action.

func (*Map) Forget

func (m *Map) Forget(key interface{})

Forget forgets past computations associated with the provided key.

type Task

type Task struct {
	// contains filtered or unexported fields
}

Task manages a computation that must be run at most once. It's similar to sync.Once, except it also handles and returns errors.

func (*Task) Do

func (o *Task) Do(do func() error) error

Do run the function do at most once. Successive invocations of Do guarantee exactly one invocation of the function do. Do returns the error of do's invocation.

func (*Task) Done

func (o *Task) Done() bool

Done returns whether the task is done.

func (*Task) Reset

func (o *Task) Reset()

Reset resets the task effectively making it possible for `Do` to invoke the underlying do func again. Reset will only reset the task if it was already completed.