[#188] shard: Implement SetMode method

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/local_object_storage/shard/mode.go

@@ -40,3 +40,15 @@ func (m Mode) String() string {
 		return "EVACUATE"
 	}
 }
+
+// SetMode sets mode of the shard.
+//
+// Returns any error encountered that did not allow
+// to set shard mode.
+func (s *Shard) SetMode(m Mode) error {
+	s.mode.Store(uint32(m))
+}
+
+func (s *Shard) getMode() Mode {
+	return Mode(s.mode.Load())
+}

pkg/local_object_storage/shard/shard.go

@@ -4,12 +4,15 @@ import (
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/blobstor"
 	meta "github.com/nspcc-dev/neofs-node/pkg/local_object_storage/metabase"
 	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
+	"go.uber.org/atomic"
 )
 
 // Shard represents single shard of NeoFS Local Storage Engine.
 type Shard struct {
 	*cfg
 
+	mode *atomic.Uint32
+
 	weight WeightValues
 
 	blobStor *blobstor.BlobStor
@@ -44,6 +47,7 @@ func New(opts ...Option) *Shard {
 
 	return &Shard{
 		cfg:      c,
+		mode:     atomic.NewUint32(0), // TODO: init with particular mode
 		blobStor: blobstor.New(c.blobOpts...),
 		metaBase: meta.NewDB(c.metaOpts...),
 	}