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package singleflight

import "golang.org/x/sync/singleflight"

Package singleflight provides a duplicate function call suppression mechanism.

singleflight.go

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

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

DoChan is like Do but returns a channel that will receive the results when they are ready.

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 struct { Val interface{} Err error Shared bool }

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