Data race in Template.Parse

[bep]

I get a data race reported in some of Hugo's tests:

https://travis-ci.org/gohugoio/hugo/jobs/540393974

https://github.com/nicksnyder/go-i18n/blob/master/internal/template.go#L16

[bep]

I tried to have a go at fixing this, and my first instinct would be to:

t.parseInit.Do(func() {
		if strings.Contains(t.Src, leftDelim) {
			gt, err := gotemplate.New("").Funcs(funcs).Delims(leftDelim, rightDelim).Parse(t.Src)
			t.Template = gt
			t.ParseErr = err
		}
	})

But that doesn't work since you take leftDelim etc. as argument to Parse and hence needs to be reparsed. Locking with a mutex would work, but sounds unneededly ineffecient; why not parse the template once when you create the Template? Do you support multiple delimiters? Possibly related to #182

[nicksnyder]

Thanks for reporting, I will take a look!

why not parse the template once when you create the Template?

This might be the right path forward.

[nicksnyder]

Do you support multiple delimiters?

Technically, each translation could define its own set of delimiters, but that actually isn't the problem here I think since those delimiters would be stored in the translation file and I could lift those parameter out of the parse function.

why not parse the template once when you create the Template?

The limiting factor here is actually Funcs from the LocalizeConfig. Since we don't know this when the templates are loaded it needs to be lazily parsed. Might need to lock; still thinking about it.

[nicksnyder]

This should be fixed in v2.0.1