singleflight

Documentation

Overview

Package singleflight provides a duplicate function call suppression mechanism.

Index

• type Group
  • func (g *Group) Do(key string, fn func() (interface{}, error)) (v interface{}, shared bool, err error)
  • func (g *Group) DoChan(key string, fn func() (interface{}, error)) (<-chan Result, bool)
  • func (g *Group) Forget(key string)
• type Result

Types

type Group

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

Group represents a class of work and forms a namespace in which units of work can be executed with duplicate suppression.

func (*Group) Do

func (g *Group) Do(
	key string, fn func() (interface{}, error),
) (v interface{}, shared bool, err error)

Do executes and returns the results of the given function, making sure that only one execution is in-flight for a given key at a time. If a duplicate comes in, the duplicate caller waits for the original to complete and receives the same results. The return value shared indicates whether v was given to multiple callers.

func (*Group) DoChan

func (g *Group) DoChan(key string, fn func() (interface{}, error)) (<-chan Result, bool)

DoChan is like Do but returns a channel that will receive the results when they are ready. The method also returns a boolean specifying whether the caller's fn function will be called or not.

func (*Group) Forget

func (g *Group) Forget(key string)

Forget tells the singleflight to forget about a key. Future calls to Do for this key will call the function rather than waiting for an earlier call to complete.

type Result

type Result struct {
	Val    interface{}
	Err    error
	Shared bool
}

Result holds the results of Do, so they can be passed on a channel.