fix bug in curent goleveldb (must copy during iteration)

also changed over to mschoch fork of goleveldb (temporary)

the change to my fork is pending some read-only issues described
here:  https://github.com/syndtr/goleveldb/issues/111

hopefully we can find a path forward, and get that addressed upstream

index/store/goleveldb/batch.go

@@ -11,7 +11,7 @@ package goleveldb
 
 import (
 	"github.com/blevesearch/bleve/index/store"
-	"github.com/syndtr/goleveldb/leveldb"
+	"github.com/mschoch/goleveldb/leveldb"
 )
 
 type Batch struct {

index/store/goleveldb/iterator.go

@@ -10,13 +10,15 @@
 package goleveldb
 
 import (
-	"github.com/syndtr/goleveldb/leveldb"
-	"github.com/syndtr/goleveldb/leveldb/iterator"
+	"github.com/mschoch/goleveldb/leveldb"
+	"github.com/mschoch/goleveldb/leveldb/iterator"
 )
 
 type Iterator struct {
 	store    *Store
 	iterator iterator.Iterator
+	copyk    []byte
+	copyv    []byte
 }
 
 func newIterator(store *Store) *Iterator {
@@ -40,14 +42,20 @@ func newIteratorWithSnapshot(store *Store, snapshot *leveldb.Snapshot) *Iterator
 }
 
 func (ldi *Iterator) SeekFirst() {
+	ldi.copyk = nil
+	ldi.copyv = nil
 	ldi.iterator.First()
 }
 
 func (ldi *Iterator) Seek(key []byte) {
+	ldi.copyk = nil
+	ldi.copyv = nil
 	ldi.iterator.Seek(key)
 }
 
 func (ldi *Iterator) Next() {
+	ldi.copyk = nil
+	ldi.copyv = nil
 	ldi.iterator.Next()
 }
 
@@ -59,11 +67,21 @@ func (ldi *Iterator) Current() ([]byte, []byte, bool) {
 }
 
 func (ldi *Iterator) Key() []byte {
-	return ldi.iterator.Key()
+	k := ldi.iterator.Key()
+	if ldi.copyk == nil {
+		ldi.copyk = make([]byte, len(k))
+		copy(ldi.copyk, k)
+	}
+	return ldi.copyk
 }
 
 func (ldi *Iterator) Value() []byte {
-	return ldi.iterator.Value()
+	v := ldi.iterator.Value()
+	if ldi.copyv == nil {
+		ldi.copyv = make([]byte, len(v))
+		copy(ldi.copyv, v)
+	}
+	return ldi.copyv
 }
 
 func (ldi *Iterator) Valid() bool {
@@ -71,5 +89,7 @@ func (ldi *Iterator) Valid() bool {
 }
 
 func (ldi *Iterator) Close() error {
+	ldi.copyk = nil
+	ldi.copyv = nil
 	return nil
 }

index/store/goleveldb/reader.go

@@ -11,7 +11,7 @@ package goleveldb
 
 import (
 	"github.com/blevesearch/bleve/index/store"
-	"github.com/syndtr/goleveldb/leveldb"
+	"github.com/mschoch/goleveldb/leveldb"
 )
 
 type Reader struct {

index/store/goleveldb/store.go

@@ -15,9 +15,9 @@ import (
 
 	"github.com/blevesearch/bleve/index/store"
 	"github.com/blevesearch/bleve/registry"
-	"github.com/syndtr/goleveldb/leveldb"
-	"github.com/syndtr/goleveldb/leveldb/filter"
-	"github.com/syndtr/goleveldb/leveldb/opt"
+	"github.com/mschoch/goleveldb/leveldb"
+	"github.com/mschoch/goleveldb/leveldb/filter"
+	"github.com/mschoch/goleveldb/leveldb/opt"
 )
 
 const Name = "goleveldb"
@@ -132,6 +132,11 @@ func init() {
 func applyConfig(o *opt.Options, config map[string]interface{}) (
 	*opt.Options, error) {
 
+	ro, ok := config["read_only"].(bool)
+	if ok {
+		o.ReadOnly = ro
+	}
+
 	cim, ok := config["create_if_missing"].(bool)
 	if ok {
 		o.ErrorIfMissing = !cim

index/store/goleveldb/store_test.go

@@ -47,6 +47,32 @@ func TestLevelDBStore(t *testing.T) {
 	CommonTestKVStore(t, s)
 }
 
+func TestLevelDBStoreIterator(t *testing.T) {
+	defer func() {
+		err := os.RemoveAll("test")
+		if err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	s, err := New("test", leveldbTestOptions)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = s.Open()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		err := s.Close()
+		if err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	CommonTestKVStoreIterator(t, s)
+}
+
 func TestReaderIsolation(t *testing.T) {
 	defer func() {
 		err := os.RemoveAll("test")
@@ -294,3 +320,69 @@ func CommonTestReaderIsolation(t *testing.T, s store.KVStore) {
 	}
 
 }
+
+func CommonTestKVStoreIterator(t *testing.T, s store.KVStore) {
+
+	writer, err := s.Writer()
+	if err != nil {
+		t.Error(err)
+	}
+
+	data := []struct {
+		k []byte
+		v []byte
+	}{
+		{[]byte("t\x09\x00paint\xff/sponsor/gold/thumbtack/"), []byte("a")},
+		{[]byte("t\x09\x00party\xff/sponsor/gold/thumbtack/"), []byte("a")},
+		{[]byte("t\x09\x00personal\xff/sponsor/gold/thumbtack/"), []byte("a")},
+		{[]byte("t\x09\x00plan\xff/sponsor/gold/thumbtack/"), []byte("a")},
+	}
+
+	batch := writer.NewBatch()
+	for _, d := range data {
+		batch.Set(d.k, d.v)
+	}
+
+	err = batch.Execute()
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = writer.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	reader, err := s.Reader()
+	if err != nil {
+		t.Error(err)
+	}
+	defer func() {
+		err := reader.Close()
+		if err != nil {
+			t.Fatal(err)
+		}
+	}()
+	it := reader.Iterator([]byte("a"))
+	keys := make([][]byte, 0, len(data))
+	key, _, valid := it.Current()
+	for valid {
+		keys = append(keys, key)
+		it.Next()
+		key, _, valid = it.Current()
+	}
+
+	if len(keys) != len(data) {
+		t.Errorf("expected same number of keys, got %d != %d", len(keys), len(data))
+	}
+	for i, dk := range data {
+		if !reflect.DeepEqual(dk.k, keys[i]) {
+			t.Errorf("expected key %s got %s", dk.k, keys[i])
+		}
+
+	}
+
+	err = it.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+}

index/store/goleveldb/util.go

@@ -10,7 +10,7 @@
 package goleveldb
 
 import (
-	"github.com/syndtr/goleveldb/leveldb/opt"
+	"github.com/mschoch/goleveldb/leveldb/opt"
 )
 
 func defaultWriteOptions() *opt.WriteOptions {

index/store/goleveldb/writer.go

@@ -11,7 +11,7 @@ package goleveldb
 
 import (
 	"github.com/blevesearch/bleve/index/store"
-	"github.com/syndtr/goleveldb/leveldb"
+	"github.com/mschoch/goleveldb/leveldb"
 )
 
 type Writer struct {