feat(writer): support InsertIfAbsent functionality

Ensures documents are only inserted if their docIDs are not already present in the current index

Signed-off-by: Gao Hongtao <[email protected]>

index/batch.go

@@ -19,6 +19,7 @@ import segment "github.com/blugelabs/bluge_segment_api"
 type Batch struct {
 	documents         []segment.Document
 	ids               []segment.Term
+	insertIfAbsent    bool
 	persistedCallback func(error)
 }
 
@@ -30,6 +31,12 @@ func (b *Batch) Insert(doc segment.Document) {
 	b.documents = append(b.documents, doc)
 }
 
+func (b *Batch) InsertIfAbsent(id segment.Term, doc segment.Document) {
+	b.documents = append(b.documents, doc)
+	b.ids = append(b.ids, id)
+	b.insertIfAbsent = true
+}
+
 func (b *Batch) Update(id segment.Term, doc segment.Document) {
 	b.documents = append(b.documents, doc)
 	b.ids = append(b.ids, id)

index/writer.go

@@ -224,6 +224,15 @@ func (s *Writer) close() (err error) {
 
 // Batch applies a batch of changes to the index atomically
 func (s *Writer) Batch(batch *Batch) (err error) {
+	if batch.insertIfAbsent {
+		if err := s.removeExistingDocuments(batch); err != nil {
+			return err
+		}
+		if len(batch.documents) == 0 {
+			return nil
+		}
+	}
+
 	start := time.Now()
 
 	defer func() {
@@ -287,6 +296,31 @@ func (s *Writer) Batch(batch *Batch) (err error) {
 	return err
 }
 
+func (s *Writer) removeExistingDocuments(batch *Batch) error {
+	root := s.currentSnapshot()
+	defer func() { _ = root.Close() }()
+
+	for _, seg := range root.segment {
+		dict, err := seg.segment.Dictionary(batch.ids[0].Field())
+		if err != nil {
+			return err
+		}
+
+		for i := 0; i < len(batch.ids); i++ {
+			if ok, _ := dict.Contains(batch.ids[i].Term()); ok {
+				batch.documents = append(batch.documents[:i], batch.documents[i+1:]...)
+				batch.ids = append(batch.ids[:i], batch.ids[i+1:]...)
+				i--
+				if len(batch.documents) == 0 {
+					return nil
+				}
+			}
+		}
+	}
+	batch.ids = batch.ids[:0]
+	return nil
+}
+
 func (s *Writer) prepareSegment(newSegment *segmentWrapper, idTerms []segment.Term,
 	internalOps map[string][]byte, persistedCallback func(error)) error {
 	// new introduction
@@ -304,16 +338,18 @@ func (s *Writer) prepareSegment(newSegment *segmentWrapper, idTerms []segment.Te
 		introduction.persisted = make(chan error, 1)
 	}
 
-	// optimistically prepare obsoletes outside of rootLock
-	root := s.currentSnapshot()
-	defer func() { _ = root.Close() }()
+	if len(idTerms) > 0 {
+		// optimistically prepare obsoletes outside of rootLock
+		root := s.currentSnapshot()
+		defer func() { _ = root.Close() }()
 
-	for _, seg := range root.segment {
-		delta, err := seg.segment.DocsMatchingTerms(idTerms)
-		if err != nil {
-			return err
+		for _, seg := range root.segment {
+			delta, err := seg.segment.DocsMatchingTerms(idTerms)
+			if err != nil {
+				return err
+			}
+			introduction.obsoletes[seg.id] = delta
 		}
-		introduction.obsoletes[seg.id] = delta
 	}
 
 	introStartTime := time.Now()

index/writer_test.go

@@ -1631,3 +1631,139 @@ func TestIndexSeekBackwardsStats(t *testing.T) {
 			idx.stats.TotTermSearchersFinished)
 	}
 }
+
+func TestBatch_InsertIfAbsent(t *testing.T) {
+	cfg, cleanup := CreateConfig("TestBatch_InsertIfAbsent")
+	defer func() {
+		err := cleanup()
+		if err != nil {
+			t.Log(err)
+		}
+	}()
+
+	idx, err := OpenWriter(cfg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		err := idx.Close()
+		if err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	var expectedCount uint64
+
+	// Verify initial document count is zero
+	reader, err := idx.Reader()
+	if err != nil {
+		t.Fatal(err)
+	}
+	docCount, err := reader.Count()
+	if err != nil {
+		t.Error(err)
+	}
+	if docCount != expectedCount {
+		t.Errorf("Expected document count to be %d got %d", expectedCount, docCount)
+	}
+	err = reader.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Insert a document using InsertIfAbsent
+	docID := "doc-1"
+	doc := &FakeDocument{
+		NewFakeField("_id", docID, true, false, false),
+		NewFakeField("title", "mister", false, false, true),
+	}
+	batch := NewBatch()
+	batch.InsertIfAbsent(testIdentifier(docID), doc)
+
+	// Apply the batch
+	if err := idx.Batch(batch); err != nil {
+		t.Fatalf("failed to apply batch: %v", err)
+	}
+	expectedCount++
+
+	// Verify document count after insertion
+	reader, err = idx.Reader()
+	if err != nil {
+		t.Fatal(err)
+	}
+	docCount, err = reader.Count()
+	if err != nil {
+		t.Error(err)
+	}
+	if docCount != expectedCount {
+		t.Errorf("Expected document count to be %d got %d", expectedCount, docCount)
+	}
+	err = reader.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Attempt to InsertIfAbsent with the same ID
+	docDuplicate := &FakeDocument{
+		NewFakeField("_id", docID, true, false, false),
+		NewFakeField("title", "mister2", true, false, true),
+	}
+	batchDuplicate := NewBatch()
+	batchDuplicate.InsertIfAbsent(testIdentifier(docID), docDuplicate)
+
+	// Apply the duplicate batch
+	if err := idx.Batch(batchDuplicate); err != nil {
+		t.Fatalf("failed to apply duplicate batch: %v", err)
+	}
+
+	// Since it's InsertIfAbsent, the document should not be duplicated
+	// Verify document count remains the same
+	reader, err = idx.Reader()
+	if err != nil {
+		t.Fatal(err)
+	}
+	docCount, err = reader.Count()
+	if err != nil {
+		t.Error(err)
+	}
+	if docCount != expectedCount {
+		t.Errorf("Expected document count to be %d after duplicate insert, got %d", expectedCount, docCount)
+	}
+
+	docNum1, err := findNumberByID(reader, docID)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	dvr, err := reader.DocumentValueReader([]string{"title"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = dvr.VisitDocumentValues(docNum1, func(field string, term []byte) {
+		if field == "title" {
+			if string(term) != "mister" {
+				t.Errorf("expected title to be 'First Document', got '%s'", string(term))
+			}
+		}
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = reader.VisitStoredFields(docNum1, func(field string, value []byte) bool {
+		if field == "title" {
+			if string(value) != "mister" {
+				t.Errorf("expected title to be 'mister', got '%s'", string(value))
+			}
+		}
+		return true
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = reader.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+}