better

pkg/actor/disk_storage.go

@@ -0,0 +1,62 @@
+package actor
+
+import (
+	"errors"
+	"fmt"
+	"log"
+	"os"
+	"path/filepath"
+
+	"github.com/gogo/protobuf/proto"
+)
+
+type DiskStorage[V any] struct {
+	*StateStorage
+	path string
+}
+
+type LogStorage[V any] interface {
+	LoadEvents(id uint64, grain Grain[V]) error
+	AppendEvent(id uint64, msg proto.Message) error
+}
+
+func NewDiskStorage[V any](path string, registry MutationRegistry) LogStorage[V] {
+	return &DiskStorage[V]{
+		StateStorage: NewState(registry),
+		path:         path,
+	}
+}
+
+func (s *DiskStorage[V]) logPath(id uint64) string {
+	return filepath.Join(s.path, fmt.Sprintf("%d.events.log", id))
+}
+
+func (s *DiskStorage[V]) LoadEvents(id uint64, grain Grain[V]) error {
+	path := s.logPath(id)
+	if _, err := os.Stat(path); errors.Is(err, os.ErrNotExist) {
+		// No log -> nothing to replay
+		return nil
+	}
+
+	fh, err := os.Open(path)
+	if err != nil {
+		return fmt.Errorf("open replay file: %w", err)
+	}
+	defer fh.Close()
+	return s.Load(fh, func(msg proto.Message) {
+		s.registry.Apply(grain, msg)
+	})
+}
+
+func (s *DiskStorage[V]) AppendEvent(id uint64, msg proto.Message) error {
+	path := s.logPath(id)
+	fh, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		log.Printf("failed to open event log file: %v", err)
+		return err
+	}
+	defer fh.Close()
+
+	return s.Append(fh, msg)
+
+}