store: handle EOF via url.Error check

[stolowski]

Handle EOF errors such as "Post http://127.0.0.1:36904/updates/: EOF" by introspection via url.Error. Added test cases for EOF.

[mvo5]

Looks good, thanks for tracking this done! Some small suggestions inside but no blockers.

[mvo5]

You could write this slightly shorter by using a json.Decoder, something like:

var resp struct {
			Snaps  []map[string]interface{} `json:"snaps"`
			Fields []string                 `json:"fields"`
		}
		err := json.NewDecoder(r.Body).Decode(&resp)
		c.Assert(err, IsNil)

[stolowski]

Right, good idea, done.

[mvo5]

This looks unneeded.

[stolowski]

I've simplified it a bit, there is no need to examine all that in detail indeed (we have other tests that do that), but I think a sanity test that ensure the client sends seinsible data on retry is useful (this gives us confidence that subsequent requests have proper body after initial failure). Let me know if that is what you meant here?

[zyga]

I think what mvo meant is that you don't need to define it as the subsequent line does it for you.

[stolowski]

Ah, right, thanks for pointing out. Fixed.

[niemeyer]

LGTM, but let's please tweak the logic just slightly:

[niemeyer]

Instead of repeating the check here, it'd be better to just unwrap and let the follow up code run

if urlErr, ok := err.(*url.Error); ok {
        err = urlErr
}

[stolowski]

Good idea, done, althouth it needs to be urlErr.Err, and also the follow up condition on netErr needs "else if", otherwise the re-assigned err falls into it and into Timeout() check.

[mvo5]

@stolowski Thanks for addressing gustavos point!