fix handling of snapshots with 0 segments

index/snapshot.go

@@ -575,7 +575,7 @@ func (i *Snapshot) ReadFrom(r io.Reader) (int64, error) {
 
 	// read bluge snapshot format version
 	peek, err := br.Peek(binary.MaxVarintLen64)
-	if err != nil {
+	if err != nil && err != io.EOF {
 		return bytesRead, fmt.Errorf("error peeking snapshot format version %d: %w", i.epoch, err)
 	}
 	snapshotFormatVersion, n := binary.Uvarint(peek)
@@ -598,7 +598,7 @@ func (i *Snapshot) readFromVersion1(br *bufio.Reader) (int64, error) {
 
 	// read number of segments
 	peek, err := br.Peek(binary.MaxVarintLen64)
-	if err != nil {
+	if err != nil && err != io.EOF {
 		return bytesRead, fmt.Errorf("error peeking snapshot number of segments %d: %w", i.epoch, err)
 	}
 	numSegments, n := binary.Uvarint(peek)

index/writer.go

@@ -508,7 +508,7 @@ func (s *Writer) loadSnapshot(epoch uint64) (*Snapshot, error) {
 	for _, segSnapshot := range snapshot.segment {
 		segPlugin, err := loadSegmentPlugin(s.config.supportedSegmentPlugins, segSnapshot.segmentType, segSnapshot.segmentVersion)
 		if err != nil {
-			return nil, fmt.Errorf("error loading required segmetn plugin: %v", err)
+			return nil, fmt.Errorf("error loading required segment plugin: %v", err)
 		}
 		segSnapshot.segment, err = s.loadSegment(segSnapshot.id, segPlugin)
 		if err != nil {

index_test.go

@@ -1412,3 +1412,61 @@ func randStrn(n int) string {
 func randStr() string {
 	return randStrn(maxRandStrLen)
 }
+
+func TestBug54(t *testing.T) {
+	tmpIndexPath := createTmpIndexPath(t)
+	defer cleanupTmpIndexPath(t, tmpIndexPath)
+
+	// first index 2 documents
+	config := DefaultConfig(tmpIndexPath)
+	indexWriter, err := OpenWriter(config)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	doc := NewDocument("a1")
+	doc.AddField(NewTextField("TestKey1", "TestKey Data1"))
+	if err = indexWriter.Update(doc.ID(), doc); err != nil {
+		t.Fatal(err)
+	}
+
+	doc = NewDocument("a2")
+	doc.AddField(NewTextField("TestKey2", "TestKey Data2"))
+	if err = indexWriter.Update(doc.ID(), doc); err != nil {
+		t.Fatal(err)
+	}
+
+	err = indexWriter.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// now delete both documents
+	indexWriter, err = OpenWriter(config)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err = indexWriter.Delete(Identifier("a1")); err != nil {
+		t.Fatal(err)
+	}
+
+	if err = indexWriter.Delete(Identifier("a2")); err != nil {
+		t.Fatal(err)
+	}
+
+	err = indexWriter.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// now open index again
+	indexWriter, err = OpenWriter(config)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = indexWriter.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+}