Return error from iterator.Close() function.

badger/kv.go

@@ -356,7 +356,7 @@ func (s *KV) get(key []byte) (y.ValueStruct, error) {
 }
 
 // Get looks for key and returns a KVItem.
-// If key is not found, value returned is nil.
+// If key is not found, item.Value() is nil.
 func (s *KV) Get(key []byte, item *KVItem) error {
 	vs, err := s.get(key)
 	if err != nil {

skl/skl.go

@@ -393,8 +393,9 @@ type Iterator struct {
 	n    *node
 }
 
-func (s *Iterator) Close() {
+func (s *Iterator) Close() error {
 	s.list.DecrRef()
+	return nil
 }
 
 // Valid returns true iff the iterator is positioned at a valid node.
@@ -490,4 +491,4 @@ func (s *UniIterator) Key() []byte          { return s.iter.Key() }
 func (s *UniIterator) Value() y.ValueStruct { return s.iter.Value() }
 func (s *UniIterator) Valid() bool          { return s.iter.Valid() }
 func (s *UniIterator) Name() string         { return "UniMemtableIterator" }
-func (s *UniIterator) Close()               { s.iter.Close() }
+func (s *UniIterator) Close() error         { return s.iter.Close() }

table/iterator.go

@@ -209,8 +209,8 @@ func (t *Table) NewIterator(reversed bool) *TableIterator {
 	return ti
 }
 
-func (itr *TableIterator) Close() {
-	itr.t.DecrRef()
+func (itr *TableIterator) Close() error {
+	return itr.t.DecrRef()
 }
 
 func (itr *TableIterator) reset() {
@@ -529,8 +529,11 @@ func (s *ConcatIterator) Next() {
 	}
 }
 
-func (s *ConcatIterator) Close() {
+func (s *ConcatIterator) Close() error {
 	for _, it := range s.iters {
-		it.Close()
+		if err := it.Close(); err != nil {
+			return errors.Wrap(err, "ConcatIterator")
+		}
 	}
+	return nil
 }

y/iterator.go

@@ -19,6 +19,8 @@ package y
 import (
 	"bytes"
 	"container/heap"
+
+	"github.com/pkg/errors"
 	//	"fmt"
 )
 
@@ -39,7 +41,7 @@ type Iterator interface {
 	Name() string // Mainly for debug or testing.
 
 	// All iterators should be closed so that file garbage collection works.
-	Close()
+	Close() error
 }
 
 type elem struct {
@@ -196,8 +198,11 @@ func (s *MergeIterator) Seek(key []byte) {
 	s.initHeap()
 }
 
-func (s *MergeIterator) Close() {
+func (s *MergeIterator) Close() error {
 	for _, itr := range s.all {
-		itr.Close()
+		if err := itr.Close(); err != nil {
+			return errors.Wrap(err, "MergeIterator")
+		}
 	}
+	return nil
 }

y/iterator_test.go

@@ -36,7 +36,7 @@ var (
 	closeCount int
 )
 
-func (s *SimpleIterator) Close()       { closeCount++ }
+func (s *SimpleIterator) Close() error { closeCount++; return nil }
 func (s *SimpleIterator) Name() string { return "SimpleIterator" }
 
 func (s *SimpleIterator) Next() {