README.md

multierrgroup

A simple combination of golang.org/x/sync/errgroup and go.uber.org/multierr.

multierrgroup have the exact same behaviour as errgroup, except that it captures all errors returned from the goroutines instead of just one.

Usage

multierrgroup is a drop-in replacement for errgroup and have the same methods and behaviour.

When any goroutine returns an error, it will colleceted using multierr.Append and Wait will return the multierr. Thus error can be split into their original errors, or worked on using errors.As/Is.

See the multierr documentation for more information.

Sample

package main

import (
	"errors"
	"fmt"
	"os"

	"go.ptx.dk/multierrgroup"
	"go.uber.org/multierr"
)

func main() {
	g := multierrgroup.Group{}

	for i := 0; i < 10; i++ {
		str := fmt.Sprintf("Error: %d", i)
		g.Go(func() error {
			return errors.New(str)
		})
		if i == 5 {
			g.Go(func() error {
				return os.ErrNotExist
			})
		}
	}
	err := g.Wait()
	fmt.Println("Got", len(multierr.Errors(err)), "errors")
	fmt.Println(err.Error())
	fmt.Println("Was one of the errors a ErrNotExists?", errors.Is(err, os.ErrNotExist))
}

Running the sample shows that errors from all goroutines are kept:

$ go run thesolution/main.go
Got 11 errors
Error: 9; Error: 5; file does not exist; Error: 6; Error: 7; Error: 8; Error: 1; Error: 0; Error: 2; Error: 3; Error: 4
Was one of the errors a ErrNotExists? true