fix accessing store via Advanced() method which was broken

index/firestorm/firestorm.go

@@ -546,6 +546,10 @@ func (f *Firestorm) Wait(timeout time.Duration) error {
 	return f.dictUpdater.waitTasksDone(timeout)
 }
 
+func (f *Firestorm) Advanced() (store.KVStore, error) {
+	return f.store, nil
+}
+
 func init() {
 	registry.RegisterIndexType(Name, NewFirestorm)
 }

index/index.go

@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"github.com/blevesearch/bleve/document"
+	"github.com/blevesearch/bleve/index/store"
 )
 
 var ErrorUnknownStorageType = fmt.Errorf("unknown storage type")
@@ -43,6 +44,8 @@ type Index interface {
 	Stats() json.Marshaler
 
 	Analyze(d *document.Document) *AnalysisResult
+
+	Advanced() (store.KVStore, error)
 }
 
 // AsyncIndex is an interface for indexes which perform

index/upside_down/upside_down.go

@@ -1024,6 +1024,10 @@ func (udc *UpsideDownCouch) Stats() json.Marshaler {
 	return udc.stats
 }
 
+func (udc *UpsideDownCouch) Advanced() (store.KVStore, error) {
+	return udc.store, nil
+}
+
 func (udc *UpsideDownCouch) fieldIndexOrNewRow(name string) (uint16, *FieldRow) {
 	index, existed := udc.fieldCache.FieldNamed(name, true)
 	if !existed {

index_impl.go

@@ -32,7 +32,6 @@ type indexImpl struct {
 	path  string
 	name  string
 	meta  *indexMeta
-	s     store.KVStore
 	i     index.Index
 	m     *IndexMapping
 	mutex sync.RWMutex
@@ -251,7 +250,11 @@ func openIndexUsing(path string, runtimeConfig map[string]interface{}) (rv *inde
 // Advanced returns implementation internals
 // necessary ONLY for advanced usage.
 func (i *indexImpl) Advanced() (index.Index, store.KVStore, error) {
-	return i.i, i.s, nil
+	s, err := i.i.Advanced()
+	if err != nil {
+		return nil, nil, err
+	}
+	return i.i, s, nil
 }
 
 // Mapping returns the IndexMapping in use by this