How can i handle multiple errors from Parallel execution

[Kirhchoff]

I can't seem to figure out how to handle multiple errors occurring in parallel.

func fail(msg string) floc.Job {
	return func(ctx floc.Context, ctrl floc.Control) error {
		return errors.New("error " + msg)
	}
}

flow := run.Parallel(fail("asd"), fail("qwe"))
result, data, err := floc.Run(flow)

The err only contains one of the errors as far as I can tell. Seems like there is an ErrMultiple type, but I don't know how to use it.

Thank you for your help!

[workanator]

run.Parallel returns floc.ErrMultiple in case of any error occurs. Try "casting" the returned error to that type and access the list of errors here.

flow := run.Parallel(fail("asd"), fail("qwe"))
result, data, err := floc.Run(flow)
if err != nil {
  var multi floc.ErrMultiple
  if errors.As(err, &multi) {
    for _, errItem := range multi.List() {
      fmt.Println(errItem)
    }
  }
}

I cannot check the code I provided at the moment, but it shows the main idea.

[Kirhchoff]

Thank you for the answer. It doesn't work though, because the err type i get is *errors.errorString for some reason, and the As function returns false.

[workanator]

Probably ErrMultiple lacks some implementations of interfaces required by errors package so errors.As cannot cast the error.

Try casting explicitly e, ok := err.(floc.ErrMultiple).

Anyway I would recommend using idiomatic Go instead of floc. There is a great support in Go and lots of great tools for making multiprocessing apps easily.