initial add hashicorp raft

weed/topology/cluster_commands.go

@@ -1,9 +1,12 @@
 package topology
 
 import (
+	"encoding/json"
+	"fmt"
 	"github.com/chrislusf/raft"
 	"github.com/chrislusf/seaweedfs/weed/glog"
 	"github.com/chrislusf/seaweedfs/weed/storage/needle"
+	hashicorpRaft "github.com/hashicorp/raft"
 )
 
 type MaxVolumeIdCommand struct {
@@ -29,3 +32,19 @@ func (c *MaxVolumeIdCommand) Apply(server raft.Server) (interface{}, error) {
 
 	return nil, nil
 }
+
+func (s *MaxVolumeIdCommand) Persist(sink hashicorpRaft.SnapshotSink) error {
+	b, err := json.Marshal(s)
+	if err != nil {
+		return fmt.Errorf("marshal: %v", err)
+	}
+	_, err = sink.Write(b)
+	if err != nil {
+		sink.Cancel()
+		return fmt.Errorf("sink.Write(): %v", err)
+	}
+	return sink.Close()
+}
+
+func (s *MaxVolumeIdCommand) Release() {
+}