sync

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sync

Fork of https://github.com/golang/go/blob/release-branch.go1.15/src/sync/once.go

Documentation

Index

• type Once
  • func (o *Once) Do(f func() error)

Types

type Once

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

Once is an object that will perform exactly one action.

A Once must not be copied after first use.

func (*Once) Do

func (o *Once) Do(f func() error)

Do calls the function f if and only if Do is being called for the first time successfully for this instance of Once. In other words, given

var once Once

if once.Do(f) is called multiple times, f will be invoked until first successful execution. A new instance of Once is required for each function to execute.

Do is intended for initialization that must be run exactly once successfully.

Because no call to Do returns until the one call to f returns, if f causes Do to be called, it will deadlock.

If f panics, Do considers it to have returned successfully; future calls of Do return without calling f.

This is an adaptation from https://golang.org/pkg/sync/#Once