pkg/timeutils: lint and add comments

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)

pkg/timeutils/json.go

@@ -6,18 +6,21 @@ import (
 )
 
 const (
-	// Define our own version of RFC339Nano because we want one
+	// RFC3339NanoFixed is our own version of RFC339Nano because we want one
 	// that pads the nano seconds part with zeros to ensure
 	// the timestamps are aligned in the logs.
 	RFC3339NanoFixed = "2006-01-02T15:04:05.000000000Z07:00"
-	JSONFormat       = `"` + time.RFC3339Nano + `"`
+	// JSONFormat is the format used by FastMarshalJSON
+	JSONFormat = `"` + time.RFC3339Nano + `"`
 )
 
+// FastMarshalJSON avoids one of the extra allocations that
+// time.MarshalJSON is making.
 func FastMarshalJSON(t time.Time) (string, error) {
 	if y := t.Year(); y < 0 || y >= 10000 {
 		// RFC 3339 is clear that years are 4 digits exactly.
 		// See golang.org/issue/4556#c15 for more discussion.
-		return "", errors.New("Time.MarshalJSON: year outside of range [0,9999]")
+		return "", errors.New("time.MarshalJSON: year outside of range [0,9999]")
 	}
 	return t.Format(JSONFormat), nil
 }