Add exporter for FlatKV and CompositeSC

sei-db/state_db/sc/composite/exporter.go

@@ -0,0 +1,100 @@
+package composite
+
+import (
+	"errors"
+	"fmt"
+
+	errorutils "github.com/sei-protocol/sei-chain/sei-db/common/errors"
+	"github.com/sei-protocol/sei-chain/sei-db/state_db/sc/types"
+)
+
+var _ types.Exporter = (*SnapshotExporter)(nil)
+
+type exportPhase int
+
+const (
+	phaseCosmos exportPhase = iota
+	phaseFlatKV
+	phaseDone
+)
+
+// SnapshotExporter coordinates export from cosmos (memiavl) and flatKV backends.
+//
+// Next() returns items in stream order. Each item is either:
+//   - string: a module name header that starts a new module section
+//   - *types.SnapshotNode: a leaf key/value belonging to the current module
+//
+// FlatKV data is exported as a separate "evm_flatkv" module appended after all
+// cosmos modules complete. This keeps the two backends fully independent in the
+// snapshot stream.
+type SnapshotExporter struct {
+	cosmosExporter types.Exporter
+	evmExporter    types.Exporter
+	phase          exportPhase
+}
+
+// NewExporter creates a composite exporter. cosmosExporter must not be nil.
+// evmExporter may be nil when FlatKV is not active.
+func NewExporter(cosmosExporter types.Exporter, evmExporter types.Exporter) (*SnapshotExporter, error) {
+	if cosmosExporter == nil {
+		return nil, fmt.Errorf("cosmosExporter must not be nil")
+	}
+	return &SnapshotExporter{
+		cosmosExporter: cosmosExporter,
+		evmExporter:    evmExporter,
+		phase:          phaseCosmos,
+	}, nil
+}
+
+func (s *SnapshotExporter) Next() (interface{}, error) {
+	switch s.phase {
+	case phaseCosmos:
+		return s.nextFromCosmos()
+	case phaseFlatKV:
+		return s.nextFromFlatKV()
+	default:
+		return nil, errorutils.ErrorExportDone
+	}
+}
+
+func (s *SnapshotExporter) nextFromCosmos() (interface{}, error) {
+	item, err := s.cosmosExporter.Next()
+	if err != nil {
+		if !errors.Is(err, errorutils.ErrorExportDone) {
+			return nil, err
+		}
+
+		// Cosmos done. Append flatKV as a separate module.
+		if s.evmExporter != nil {
+			s.phase = phaseFlatKV
+			return EVMFlatKVStoreName, nil
+		}
+
+		s.phase = phaseDone
+		return nil, errorutils.ErrorExportDone
+	}
+	return item, nil
+}
+
+func (s *SnapshotExporter) nextFromFlatKV() (interface{}, error) {
+	item, err := s.evmExporter.Next()
+	if err != nil {
+		if !errors.Is(err, errorutils.ErrorExportDone) {
+			return nil, err
+		}
+		s.phase = phaseDone
+		return nil, errorutils.ErrorExportDone
+	}
+	return item, nil
+}
+
+func (s *SnapshotExporter) Close() error {
+	var errCosmos, errEVM error
+	if s.cosmosExporter != nil {
+		errCosmos = s.cosmosExporter.Close()
+	}
+	if s.evmExporter != nil {
+		errEVM = s.evmExporter.Close()
+	}
+	return errors.Join(errCosmos, errEVM)
+}

sei-db/state_db/sc/composite/importer.go

@@ -34,17 +34,26 @@ func (si *SnapshotImporter) Close() error {
 
 func (si *SnapshotImporter) AddModule(name string) error {
 	si.currentModule = name
+	if name == EVMFlatKVStoreName {
+		if si.evmImporter != nil {
+			return si.evmImporter.AddModule(name)
+		}
+		return nil
+	}
 	if si.cosmosImporter != nil {
 		return si.cosmosImporter.AddModule(name)
 	}
 	return nil
 }
 
 func (si *SnapshotImporter) AddNode(node *types.SnapshotNode) {
+	if si.currentModule == EVMFlatKVStoreName {
+		if si.evmImporter != nil {
+			si.evmImporter.AddNode(node)
+		}
+		return
+	}
 	if si.cosmosImporter != nil {
 		si.cosmosImporter.AddNode(node)
 	}
-	if si.evmImporter != nil && si.currentModule == "evm" && node.Height == 0 {
-		si.evmImporter.AddNode(node)
-	}
 }

sei-db/state_db/sc/composite/store.go

@@ -19,9 +19,14 @@ import (
 
 var logger = seilog.NewLogger("db", "state-db", "sc", "composite")
 
-// EVMStoreName is the module name for the EVM store
+// EVMStoreName is the module name for the EVM store in memiavl.
 const EVMStoreName = "evm"
 
+// EVMFlatKVStoreName is the module name used when exporting/importing
+// EVM data from the FlatKV backend. Treated as a separate module in
+// state-sync snapshots so that import routes data exclusively to FlatKV.
+const EVMFlatKVStoreName = "evm_flatkv"
+
 // For backward compatibility purpose reuse current interface
 var _ types.Committer = (*CompositeCommitStore)(nil)
 
@@ -270,8 +275,22 @@ func (cs *CompositeCommitStore) Exporter(version int64) (types.Exporter, error)
 	if version < 0 || version > math.MaxUint32 {
 		return nil, fmt.Errorf("version %d out of range", version)
 	}
-	// TODO: Add evm committer for exporter
-	return cs.cosmosCommitter.Exporter(version)
+
+	cosmosExporter, err := cs.cosmosCommitter.Exporter(version)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create cosmos exporter: %w", err)
+	}
+
+	var evmExporter types.Exporter
+	if cs.evmCommitter != nil && (cs.config.WriteMode == config.SplitWrite || cs.config.WriteMode == config.DualWrite) {
+		evmExporter, err = cs.evmCommitter.Exporter(version)
+		if err != nil {
+			_ = cosmosExporter.Close()
+			return nil, fmt.Errorf("failed to create evm exporter: %w", err)
+		}
+	}
+
+	return NewExporter(cosmosExporter, evmExporter)
 }
 
 // Importer returns an importer for state sync
@@ -284,7 +303,8 @@ func (cs *CompositeCommitStore) Importer(version int64) (types.Importer, error)
 	if cs.evmCommitter != nil {
 		evmImporter, err = cs.evmCommitter.Importer(version)
 		if err != nil {
-			return nil, err
+			_ = cosmosImporter.Close()
+			return nil, fmt.Errorf("failed to create evm importer: %w", err)
 		}
 	}
 	compositeImporter := NewImporter(cosmosImporter, evmImporter)