[#1559] local_object_storage: Move shard.Mode to a separate package

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

cmd/neofs-node/config/engine/config_test.go

@@ -10,7 +10,7 @@ import (
 	shardconfig "github.com/nspcc-dev/neofs-node/cmd/neofs-node/config/engine/shard"
 	piloramaconfig "github.com/nspcc-dev/neofs-node/cmd/neofs-node/config/engine/shard/pilorama"
 	configtest "github.com/nspcc-dev/neofs-node/cmd/neofs-node/config/test"
-	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	"github.com/stretchr/testify/require"
 )
 
@@ -34,7 +34,7 @@ func TestEngineSection(t *testing.T) {
 
 		require.EqualValues(t, 0, engineconfig.ShardErrorThreshold(empty))
 		require.EqualValues(t, engineconfig.ShardPoolSizeDefault, engineconfig.ShardPoolSize(empty))
-		require.EqualValues(t, shard.ModeReadWrite, shardconfig.From(empty).Mode())
+		require.EqualValues(t, mode.ReadWrite, shardconfig.From(empty).Mode())
 	})
 
 	const path = "../../../../config/example/node"
@@ -95,7 +95,7 @@ func TestEngineSection(t *testing.T) {
 				require.Equal(t, 2*time.Minute, gc.RemoverSleepInterval())
 
 				require.Equal(t, false, sc.RefillMetabase())
-				require.Equal(t, shard.ModeReadOnly, sc.Mode())
+				require.Equal(t, mode.ReadOnly, sc.Mode())
 			case 1:
 				require.Equal(t, "tmp/1/blob/pilorama.db", pl.Path())
 				require.Equal(t, fs.FileMode(0644), pl.Perm())
@@ -133,7 +133,7 @@ func TestEngineSection(t *testing.T) {
 				require.Equal(t, 5*time.Minute, gc.RemoverSleepInterval())
 
 				require.Equal(t, true, sc.RefillMetabase())
-				require.Equal(t, shard.ModeReadWrite, sc.Mode())
+				require.Equal(t, mode.ReadWrite, sc.Mode())
 			}
 		})
 

cmd/neofs-node/config/engine/shard/config.go

@@ -9,7 +9,7 @@ import (
 	metabaseconfig "github.com/nspcc-dev/neofs-node/cmd/neofs-node/config/engine/shard/metabase"
 	piloramaconfig "github.com/nspcc-dev/neofs-node/cmd/neofs-node/config/engine/shard/pilorama"
 	writecacheconfig "github.com/nspcc-dev/neofs-node/cmd/neofs-node/config/engine/shard/writecache"
-	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 )
 
 // Config is a wrapper over the config section
@@ -75,7 +75,7 @@ func (x *Config) RefillMetabase() bool {
 //
 // Panics if read the value is not one of predefined
 // shard modes.
-func (x *Config) Mode() (m shard.Mode) {
+func (x *Config) Mode() (m mode.Mode) {
 	s := config.StringSafe(
 		(*config.Config)(x),
 		"mode",
@@ -83,11 +83,11 @@ func (x *Config) Mode() (m shard.Mode) {
 
 	switch s {
 	case "read-write", "":
-		m = shard.ModeReadWrite
+		m = mode.ReadWrite
 	case "read-only":
-		m = shard.ModeReadOnly
+		m = mode.ReadOnly
 	case "degraded":
-		m = shard.ModeDegraded
+		m = mode.Degraded
 	default:
 		panic(fmt.Sprintf("unknown shard mode: %s", s))
 	}

pkg/local_object_storage/engine/control_test.go

@@ -7,7 +7,7 @@ import (
 	"testing"
 
 	"github.com/nspcc-dev/neofs-node/pkg/core/object"
-	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	cidtest "github.com/nspcc-dev/neofs-sdk-go/container/id/test"
 	"github.com/stretchr/testify/require"
 )
@@ -58,7 +58,7 @@ func TestPersistentShardID(t *testing.T) {
 
 	e, _, id := newEngineWithErrorThreshold(t, dir, 1)
 
-	checkShardState(t, e, id[0], 0, shard.ModeReadWrite)
+	checkShardState(t, e, id[0], 0, mode.ReadWrite)
 	require.NoError(t, e.Close())
 
 	e, _, newID := newEngineWithErrorThreshold(t, dir, 1)

pkg/local_object_storage/engine/engine.go

@@ -4,6 +4,7 @@ import (
 	"sync"
 
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	"github.com/nspcc-dev/neofs-node/pkg/util"
 	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
 	"go.uber.org/atomic"
@@ -50,7 +51,7 @@ func (e *StorageEngine) reportShardError(
 		return
 	}
 
-	err = sh.SetMode(shard.ModeDegraded)
+	err = sh.SetMode(mode.Degraded)
 	if err != nil {
 		e.log.Error("failed to move shard in degraded mode",
 			zap.Uint32("error count", errCount),

pkg/local_object_storage/engine/error_test.go

@@ -12,6 +12,7 @@ import (
 	meta "github.com/nspcc-dev/neofs-node/pkg/local_object_storage/metabase"
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/pilorama"
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	apistatus "github.com/nspcc-dev/neofs-sdk-go/client/status"
 	cidtest "github.com/nspcc-dev/neofs-sdk-go/container/id/test"
 	objectSDK "github.com/nspcc-dev/neofs-sdk-go/object"
@@ -79,16 +80,16 @@ func TestErrorReporting(t *testing.T) {
 		_, err = e.Get(GetPrm{addr: object.AddressOf(obj)})
 		require.NoError(t, err)
 
-		checkShardState(t, e, id[0], 0, shard.ModeReadWrite)
+		checkShardState(t, e, id[0], 0, mode.ReadWrite)
-		checkShardState(t, e, id[1], 0, shard.ModeReadWrite)
+		checkShardState(t, e, id[1], 0, mode.ReadWrite)
 
 		corruptSubDir(t, filepath.Join(dir, "0"))
 
 		for i := uint32(1); i < 3; i++ {
 			_, err = e.Get(GetPrm{addr: object.AddressOf(obj)})
 			require.Error(t, err)
-			checkShardState(t, e, id[0], i, shard.ModeReadWrite)
+			checkShardState(t, e, id[0], i, mode.ReadWrite)
-			checkShardState(t, e, id[1], 0, shard.ModeReadWrite)
+			checkShardState(t, e, id[1], 0, mode.ReadWrite)
 		}
 	})
 	t.Run("with error threshold", func(t *testing.T) {
@@ -109,30 +110,30 @@ func TestErrorReporting(t *testing.T) {
 		_, err = e.Get(GetPrm{addr: object.AddressOf(obj)})
 		require.NoError(t, err)
 
-		checkShardState(t, e, id[0], 0, shard.ModeReadWrite)
+		checkShardState(t, e, id[0], 0, mode.ReadWrite)
-		checkShardState(t, e, id[1], 0, shard.ModeReadWrite)
+		checkShardState(t, e, id[1], 0, mode.ReadWrite)
 
 		corruptSubDir(t, filepath.Join(dir, "0"))
 
 		for i := uint32(1); i < errThreshold; i++ {
 			_, err = e.Get(GetPrm{addr: object.AddressOf(obj)})
 			require.Error(t, err)
-			checkShardState(t, e, id[0], i, shard.ModeReadWrite)
+			checkShardState(t, e, id[0], i, mode.ReadWrite)
-			checkShardState(t, e, id[1], 0, shard.ModeReadWrite)
+			checkShardState(t, e, id[1], 0, mode.ReadWrite)
 		}
 
 		for i := uint32(0); i < 2; i++ {
 			_, err = e.Get(GetPrm{addr: object.AddressOf(obj)})
 			require.Error(t, err)
-			checkShardState(t, e, id[0], errThreshold+i, shard.ModeDegraded)
+			checkShardState(t, e, id[0], errThreshold+i, mode.Degraded)
-			checkShardState(t, e, id[1], 0, shard.ModeReadWrite)
+			checkShardState(t, e, id[1], 0, mode.ReadWrite)
 		}
 
-		require.NoError(t, e.SetShardMode(id[0], shard.ModeReadWrite, false))
+		require.NoError(t, e.SetShardMode(id[0], mode.ReadWrite, false))
-		checkShardState(t, e, id[0], errThreshold+1, shard.ModeReadWrite)
+		checkShardState(t, e, id[0], errThreshold+1, mode.ReadWrite)
 
-		require.NoError(t, e.SetShardMode(id[0], shard.ModeReadWrite, true))
+		require.NoError(t, e.SetShardMode(id[0], mode.ReadWrite, true))
-		checkShardState(t, e, id[0], 0, shard.ModeReadWrite)
+		checkShardState(t, e, id[0], 0, mode.ReadWrite)
 	})
 }
 
@@ -166,7 +167,7 @@ func TestBlobstorFailback(t *testing.T) {
 		require.NoError(t, err)
 	}
 
-	checkShardState(t, e, id[0], 0, shard.ModeReadWrite)
+	checkShardState(t, e, id[0], 0, mode.ReadWrite)
 	require.NoError(t, e.Close())
 
 	p1 := e.shards[id[0].String()].Shard.DumpInfo().BlobStorInfo.RootPath
@@ -192,11 +193,11 @@ func TestBlobstorFailback(t *testing.T) {
 		require.ErrorAs(t, err, &apistatus.ObjectOutOfRange{})
 	}
 
-	checkShardState(t, e, id[0], 4, shard.ModeDegraded)
+	checkShardState(t, e, id[0], 4, mode.Degraded)
-	checkShardState(t, e, id[1], 0, shard.ModeReadWrite)
+	checkShardState(t, e, id[1], 0, mode.ReadWrite)
 }
 
-func checkShardState(t *testing.T, e *StorageEngine, id *shard.ID, errCount uint32, mode shard.Mode) {
+func checkShardState(t *testing.T, e *StorageEngine, id *shard.ID, errCount uint32, mode mode.Mode) {
 	e.mtx.RLock()
 	sh := e.shards[id.String()]
 	e.mtx.RUnlock()

pkg/local_object_storage/engine/shards.go

@@ -7,6 +7,7 @@ import (
 	"github.com/google/uuid"
 	"github.com/nspcc-dev/hrw"
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	oid "github.com/nspcc-dev/neofs-sdk-go/object/id"
 	"github.com/panjf2000/ants/v2"
 	"go.uber.org/atomic"
@@ -129,7 +130,7 @@ func (e *StorageEngine) iterateOverUnsortedShards(handler func(hashedShard) (sto
 // SetShardMode sets mode of the shard with provided identifier.
 //
 // Returns an error if shard mode was not set, or shard was not found in storage engine.
-func (e *StorageEngine) SetShardMode(id *shard.ID, m shard.Mode, resetErrorCounter bool) error {
+func (e *StorageEngine) SetShardMode(id *shard.ID, m mode.Mode, resetErrorCounter bool) error {
 	e.mtx.RLock()
 	defer e.mtx.RUnlock()
 

pkg/local_object_storage/shard/delete.go

@@ -4,6 +4,7 @@ import (
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/blobovnicza"
 	"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/local_object_storage/shard/mode"
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/writecache"
 	oid "github.com/nspcc-dev/neofs-sdk-go/object/id"
 	"go.uber.org/zap"
@@ -27,7 +28,7 @@ func (p *DeletePrm) SetAddresses(addr ...oid.Address) {
 // Delete removes data from the shard's writeCache, metaBase and
 // blobStor.
 func (s *Shard) Delete(prm DeletePrm) (DeleteRes, error) {
-	if s.GetMode() != ModeReadWrite {
+	if s.GetMode() != mode.ReadWrite {
 		return DeleteRes{}, ErrReadOnlyMode
 	}
 

pkg/local_object_storage/shard/dump.go

@@ -7,6 +7,7 @@ import (
 	"os"
 
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/blobstor"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/writecache"
 )
 
@@ -55,7 +56,7 @@ func (s *Shard) Dump(prm DumpPrm) (DumpRes, error) {
 	s.m.RLock()
 	defer s.m.RUnlock()
 
-	if s.info.Mode != ModeReadOnly {
+	if s.info.Mode != mode.ReadOnly {
 		return DumpRes{}, ErrMustBeReadOnly
 	}
 

pkg/local_object_storage/shard/dump_test.go

@@ -14,6 +14,7 @@ import (
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/blobovnicza"
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/blobstor"
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/writecache"
 	cidtest "github.com/nspcc-dev/neofs-sdk-go/container/id/test"
 	objectSDK "github.com/nspcc-dev/neofs-sdk-go/object"
@@ -62,7 +63,7 @@ func testDump(t *testing.T, objCount int, hasWriteCache bool) {
 		require.ErrorIs(t, err, shard.ErrMustBeReadOnly)
 	})
 
-	require.NoError(t, sh.SetMode(shard.ModeReadOnly))
+	require.NoError(t, sh.SetMode(mode.ReadOnly))
 	outEmpty := out + ".empty"
 	var dumpPrm shard.DumpPrm
 	dumpPrm.WithPath(outEmpty)
@@ -70,7 +71,7 @@ func testDump(t *testing.T, objCount int, hasWriteCache bool) {
 	res, err := sh.Dump(dumpPrm)
 	require.NoError(t, err)
 	require.Equal(t, 0, res.Count())
-	require.NoError(t, sh.SetMode(shard.ModeReadWrite))
+	require.NoError(t, sh.SetMode(mode.ReadWrite))
 
 	// Approximate object header size.
 	const headerSize = 400
@@ -100,7 +101,7 @@ func testDump(t *testing.T, objCount int, hasWriteCache bool) {
 		require.NoError(t, err)
 	}
 
-	require.NoError(t, sh.SetMode(shard.ModeReadOnly))
+	require.NoError(t, sh.SetMode(mode.ReadOnly))
 
 	t.Run("invalid path", func(t *testing.T) {
 		var dumpPrm shard.DumpPrm
@@ -198,13 +199,13 @@ func testDump(t *testing.T, objCount int, hasWriteCache bool) {
 		var prm shard.RestorePrm
 		prm.WithPath(out)
 		t.Run("must allow write", func(t *testing.T) {
-			require.NoError(t, sh.SetMode(shard.ModeReadOnly))
+			require.NoError(t, sh.SetMode(mode.ReadOnly))
 
 			_, err := sh.Restore(prm)
 			require.ErrorIs(t, err, shard.ErrReadOnlyMode)
 		})
 
-		require.NoError(t, sh.SetMode(shard.ModeReadWrite))
+		require.NoError(t, sh.SetMode(mode.ReadWrite))
 
 		checkRestore(t, sh, prm, objects)
 	})
@@ -230,7 +231,7 @@ func TestStream(t *testing.T) {
 		require.NoError(t, err)
 	}
 
-	require.NoError(t, sh1.SetMode(shard.ModeReadOnly))
+	require.NoError(t, sh1.SetMode(mode.ReadOnly))
 
 	r, w := io.Pipe()
 	finish := make(chan struct{})
@@ -352,7 +353,7 @@ func TestDumpIgnoreErrors(t *testing.T) {
 
 	bsOpts = append(bsOpts, blobstor.WithBlobovniczaShallowWidth(3))
 	sh = newCustomShard(t, dir, true, wcOpts, bsOpts)
-	require.NoError(t, sh.SetMode(shard.ModeReadOnly))
+	require.NoError(t, sh.SetMode(mode.ReadOnly))
 
 	{
 		// 2. Invalid object in blobovnicza.

pkg/local_object_storage/shard/exists.go

@@ -3,6 +3,7 @@ package shard
 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/local_object_storage/shard/mode"
 	oid "github.com/nspcc-dev/neofs-sdk-go/object/id"
 	"go.uber.org/zap"
 )
@@ -42,7 +43,7 @@ func (s *Shard) Exists(prm ExistsPrm) (ExistsRes, error) {
 	if err != nil {
 		// If the shard is in degraded mode, try to consult blobstor directly.
 		// Otherwise, just return an error.
-		if s.GetMode() == ModeDegraded {
+		if s.GetMode() == mode.Degraded {
 			var p blobstor.ExistsPrm
 			p.SetAddress(prm.addr)
 

pkg/local_object_storage/shard/gc.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	meta "github.com/nspcc-dev/neofs-node/pkg/local_object_storage/metabase"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	"github.com/nspcc-dev/neofs-node/pkg/util"
 	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
 	"github.com/nspcc-dev/neofs-sdk-go/object"
@@ -179,7 +180,7 @@ func (gc *gc) stop() {
 // with GC-marked graves.
 // Does nothing if shard is in "read-only" mode.
 func (s *Shard) removeGarbage() {
-	if s.GetMode() != ModeReadWrite {
+	if s.GetMode() != mode.ReadWrite {
 		return
 	}
 

pkg/local_object_storage/shard/get.go

@@ -6,6 +6,7 @@ import (
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/blobovnicza"
 	"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/local_object_storage/shard/mode"
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/writecache"
 	apistatus "github.com/nspcc-dev/neofs-sdk-go/client/status"
 	objectSDK "github.com/nspcc-dev/neofs-sdk-go/object"
@@ -121,7 +122,7 @@ func (s *Shard) fetchObjectData(addr oid.Address, skipMeta bool, big, small stor
 		mPrm.SetAddress(addr)
 
 		mRes, err := s.metaBase.Exists(mPrm)
-		if err != nil && s.GetMode() != ModeDegraded {
+		if err != nil && s.GetMode() != mode.Degraded {
 			return res, false, err
 		}
 		exists = mRes.Exists()

pkg/local_object_storage/shard/info.go

@@ -4,6 +4,7 @@ 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/local_object_storage/pilorama"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/writecache"
 )
 
@@ -13,7 +14,7 @@ type Info struct {
 	ID *ID
 
 	// Shard mode.
-	Mode Mode
+	Mode mode.Mode
 
 	// Information about the metabase.
 	MetaBaseInfo meta.Info

pkg/local_object_storage/shard/inhume.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 
 	meta "github.com/nspcc-dev/neofs-node/pkg/local_object_storage/metabase"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	oid "github.com/nspcc-dev/neofs-sdk-go/object/id"
 	"go.uber.org/zap"
 )
@@ -61,7 +62,7 @@ var ErrLockObjectRemoval = meta.ErrLockObjectRemoval
 //
 // Returns ErrReadOnlyMode error if shard is in "read-only" mode.
 func (s *Shard) Inhume(prm InhumePrm) (InhumeRes, error) {
-	if s.GetMode() != ModeReadWrite {
+	if s.GetMode() != mode.ReadWrite {
 		return InhumeRes{}, ErrReadOnlyMode
 	}
 

pkg/local_object_storage/shard/lock.go

@@ -3,6 +3,7 @@ package shard
 import (
 	"fmt"
 
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	cid "github.com/nspcc-dev/neofs-sdk-go/container/id"
 	oid "github.com/nspcc-dev/neofs-sdk-go/object/id"
 )
@@ -14,7 +15,7 @@ import (
 //
 // Locked list should be unique. Panics if it is empty.
 func (s *Shard) Lock(idCnr cid.ID, locker oid.ID, locked []oid.ID) error {
-	if s.GetMode() != ModeReadWrite {
+	if s.GetMode() != mode.ReadWrite {
 		return ErrReadOnlyMode
 	}
 

pkg/local_object_storage/shard/mode.go

@@ -3,62 +3,23 @@ package shard
 import (
 	"errors"
 
-	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/writecache"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 )
 
-// Mode represents enumeration of Shard work modes.
-type Mode uint32
-
 // ErrReadOnlyMode is returned when it is impossible to apply operation
 // that changes shard's memory due to the "read-only" shard's mode.
 var ErrReadOnlyMode = errors.New("shard is in read-only mode")
 
-const (
-	// ModeReadWrite is a Mode value for shard that is available
-	// for read and write operations. Default shard mode.
-	ModeReadWrite Mode = iota
-
-	// ModeReadOnly is a Mode value for shard that does not
-	// accept write operation but is readable.
-	ModeReadOnly
-
-	// ModeDegraded is a Mode value for shard that is set automatically
-	// after a certain number of errors is encountered. It is the same as
-	// `ModeReadOnly` but also enables fallback algorithms for getting object
-	// in case metabase is corrupted.
-	ModeDegraded
-)
-
-func (m Mode) String() string {
-	switch m {
-	default:
-		return "UNDEFINED"
-	case ModeReadWrite:
-		return "READ_WRITE"
-	case ModeReadOnly:
-		return "READ_ONLY"
-	case ModeDegraded:
-		return "DEGRADED"
-	}
-}
-
 // SetMode sets mode of the shard.
 //
 // Returns any error encountered that did not allow
 // setting shard mode.
-func (s *Shard) SetMode(m Mode) error {
+func (s *Shard) SetMode(m mode.Mode) error {
 	s.m.Lock()
 	defer s.m.Unlock()
 
 	if s.hasWriteCache() {
-		switch m {
+		s.writeCache.SetMode(m)
-		case ModeReadOnly:
-			s.writeCache.SetMode(writecache.ModeReadOnly)
-		case ModeDegraded:
-			s.writeCache.SetMode(writecache.ModeDegraded)
-		case ModeReadWrite:
-			s.writeCache.SetMode(writecache.ModeReadWrite)
-		}
 	}
 
 	s.info.Mode = m
@@ -67,7 +28,7 @@ func (s *Shard) SetMode(m Mode) error {
 }
 
 // GetMode returns mode of the shard.
-func (s *Shard) GetMode() Mode {
+func (s *Shard) GetMode() mode.Mode {
 	s.m.RLock()
 	defer s.m.RUnlock()
 

pkg/local_object_storage/shard/mode/mode.go

@@ -0,0 +1,33 @@
+package mode
+
+// Mode represents enumeration of Shard work modes.
+type Mode uint32
+
+const (
+	// ReadWrite is a Mode value for shard that is available
+	// for read and write operations. Default shard mode.
+	ReadWrite Mode = iota
+
+	// ReadOnly is a Mode value for shard that does not
+	// accept write operation but is readable.
+	ReadOnly
+
+	// Degraded is a Mode value for shard that is set automatically
+	// after a certain number of errors is encountered. It is the same as
+	// `mode.ReadOnly` but also enables fallback algorithms for getting object
+	// in case metabase is corrupted.
+	Degraded
+)
+
+func (m Mode) String() string {
+	switch m {
+	default:
+		return "UNDEFINED"
+	case ReadWrite:
+		return "READ_WRITE"
+	case ReadOnly:
+		return "READ_ONLY"
+	case Degraded:
+		return "DEGRADED"
+	}
+}

pkg/local_object_storage/shard/move.go

@@ -2,6 +2,7 @@ package shard
 
 import (
 	meta "github.com/nspcc-dev/neofs-node/pkg/local_object_storage/metabase"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	oid "github.com/nspcc-dev/neofs-sdk-go/object/id"
 	"go.uber.org/zap"
 )
@@ -23,7 +24,7 @@ func (p *ToMoveItPrm) SetAddress(addr oid.Address) {
 // ToMoveIt calls metabase.ToMoveIt method to mark object as relocatable to
 // another shard.
 func (s *Shard) ToMoveIt(prm ToMoveItPrm) (ToMoveItRes, error) {
-	if s.GetMode() != ModeReadWrite {
+	if s.GetMode() != mode.ReadWrite {
 		return ToMoveItRes{}, ErrReadOnlyMode
 	}
 

pkg/local_object_storage/shard/put.go

@@ -5,6 +5,7 @@ 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/local_object_storage/shard/mode"
 	"github.com/nspcc-dev/neofs-sdk-go/object"
 	"go.uber.org/zap"
 )
@@ -29,7 +30,7 @@ func (p *PutPrm) SetObject(obj *object.Object) {
 //
 // Returns ErrReadOnlyMode error if shard is in "read-only" mode.
 func (s *Shard) Put(prm PutPrm) (PutRes, error) {
-	if s.GetMode() != ModeReadWrite {
+	if s.GetMode() != mode.ReadWrite {
 		return PutRes{}, ErrReadOnlyMode
 	}
 

pkg/local_object_storage/shard/restore.go

@@ -7,6 +7,7 @@ import (
 	"io"
 	"os"
 
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	"github.com/nspcc-dev/neofs-sdk-go/object"
 )
 
@@ -61,7 +62,7 @@ func (s *Shard) Restore(prm RestorePrm) (RestoreRes, error) {
 	s.m.RLock()
 	defer s.m.RUnlock()
 
-	if s.info.Mode != ModeReadWrite {
+	if s.info.Mode != mode.ReadWrite {
 		return RestoreRes{}, ErrReadOnlyMode
 	}
 

pkg/local_object_storage/shard/shard.go

@@ -8,6 +8,7 @@ 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/local_object_storage/pilorama"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/writecache"
 	"github.com/nspcc-dev/neofs-node/pkg/util"
 	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
@@ -235,9 +236,9 @@ func WithRefillMetabase(v bool) Option {
 }
 
 // WithMode returns option to set shard's mode. Mode must be one of the predefined:
-//	- ModeReadWrite;
+//	- mode.ReadWrite;
-//	- ModeReadOnly.
+//	- mode.ReadOnly.
-func WithMode(v Mode) Option {
+func WithMode(v mode.Mode) Option {
 	return func(c *cfg) {
 		c.info.Mode = v
 	}

pkg/local_object_storage/shard/tree.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/pilorama"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	cidSDK "github.com/nspcc-dev/neofs-sdk-go/container/id"
 )
 
@@ -17,7 +18,7 @@ func (s *Shard) TreeMove(d pilorama.CIDDescriptor, treeID string, m *pilorama.Mo
 	if s.pilorama == nil {
 		return nil, ErrPiloramaDisabled
 	}
-	if s.GetMode() != ModeReadWrite {
+	if s.GetMode() != mode.ReadWrite {
 		return nil, ErrReadOnlyMode
 	}
 	return s.pilorama.TreeMove(d, treeID, m)
@@ -28,7 +29,7 @@ func (s *Shard) TreeAddByPath(d pilorama.CIDDescriptor, treeID string, attr stri
 	if s.pilorama == nil {
 		return nil, ErrPiloramaDisabled
 	}
-	if s.GetMode() != ModeReadWrite {
+	if s.GetMode() != mode.ReadWrite {
 		return nil, ErrReadOnlyMode
 	}
 	return s.pilorama.TreeAddByPath(d, treeID, attr, path, meta)
@@ -39,7 +40,7 @@ func (s *Shard) TreeApply(d pilorama.CIDDescriptor, treeID string, m *pilorama.M
 	if s.pilorama == nil {
 		return ErrPiloramaDisabled
 	}
-	if s.GetMode() != ModeReadWrite {
+	if s.GetMode() != mode.ReadWrite {
 		return ErrReadOnlyMode
 	}
 	return s.pilorama.TreeApply(d, treeID, m)

pkg/local_object_storage/writecache/mode.go

@@ -3,20 +3,8 @@ package writecache
 import (
 	"errors"
 	"time"
-)
 
-// Mode represents write-cache mode of operation.
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
-type Mode uint32
-
-const (
-	// ModeReadWrite is a default mode allowing objects to be flushed.
-	ModeReadWrite Mode = iota
-
-	// ModeReadOnly is a mode in which write-cache doesn't flush anything to a metabase.
-	ModeReadOnly
-
-	// ModeDegraded is similar to a shard's degraded mode.
-	ModeDegraded
 )
 
 // ErrReadOnly is returned when Put/Write is performed in a read-only mode.
@@ -25,7 +13,7 @@ var ErrReadOnly = errors.New("write-cache is in read-only mode")
 // SetMode sets write-cache mode of operation.
 // When shard is put in read-only mode all objects in memory are flushed to disk
 // and all background jobs are suspended.
-func (c *cache) SetMode(m Mode) {
+func (c *cache) SetMode(m mode.Mode) {
 	c.modeMtx.Lock()
 	defer c.modeMtx.Unlock()
 	if c.mode == m {
@@ -33,7 +21,7 @@ func (c *cache) SetMode(m Mode) {
 	}
 
 	c.mode = m
-	if m == ModeReadWrite {
+	if m == mode.ReadWrite {
 		return
 	}
 
@@ -57,5 +45,5 @@ func (c *cache) SetMode(m Mode) {
 // readOnly returns true if current mode is read-only.
 // `c.modeMtx` must be taken.
 func (c *cache) readOnly() bool {
-	return c.mode != ModeReadWrite
+	return c.mode != mode.ReadWrite
 }

pkg/local_object_storage/writecache/writecache.go

@@ -4,6 +4,7 @@ import (
 	"sync"
 
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/blobstor/fstree"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	"github.com/nspcc-dev/neofs-sdk-go/object"
 	oid "github.com/nspcc-dev/neofs-sdk-go/object/id"
 	"go.etcd.io/bbolt"
@@ -23,7 +24,7 @@ type Cache interface {
 	Delete(oid.Address) error
 	Iterate(IterationPrm) error
 	Put(*object.Object) error
-	SetMode(Mode)
+	SetMode(mode.Mode)
 	SetLogger(*zap.Logger)
 	DumpInfo() Info
 
@@ -39,7 +40,7 @@ type cache struct {
 	mtx sync.RWMutex
 	mem []objectInfo
 
-	mode    Mode
+	mode    mode.Mode
 	modeMtx sync.RWMutex
 
 	// compressFlags maps address of a big object to boolean value indicating
@@ -90,7 +91,7 @@ func New(opts ...Option) Cache {
 		metaCh:   make(chan *object.Object),
 		closeCh:  make(chan struct{}),
 		evictCh:  make(chan []byte),
-		mode:     ModeReadWrite,
+		mode:     mode.ReadWrite,
 
 		compressFlags: make(map[string]struct{}),
 		options: options{
@@ -152,7 +153,7 @@ func (c *cache) Init() error {
 // Close closes db connection and stops services. Executes ObjectCounters.FlushAndClose op.
 func (c *cache) Close() error {
 	// Finish all in-progress operations.
-	c.SetMode(ModeReadOnly)
+	c.SetMode(mode.ReadOnly)
 
 	close(c.closeCh)
 	c.objCounters.FlushAndClose()

pkg/services/control/server/list_shards.go

@@ -3,7 +3,7 @@ package control
 import (
 	"context"
 
-	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	"github.com/nspcc-dev/neofs-node/pkg/services/control"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
@@ -34,20 +34,20 @@ func (s *Server) ListShards(_ context.Context, req *control.ListShardsRequest) (
 		si.SetWriteCachePath(sh.WriteCacheInfo.Path)
 		si.SetPiloramaPath(sh.PiloramaInfo.Path)
 
-		var mode control.ShardMode
+		var m control.ShardMode
 
 		switch sh.Mode {
-		case shard.ModeReadWrite:
+		case mode.ReadWrite:
-			mode = control.ShardMode_READ_WRITE
+			m = control.ShardMode_READ_WRITE
-		case shard.ModeReadOnly:
+		case mode.ReadOnly:
-			mode = control.ShardMode_READ_ONLY
+			m = control.ShardMode_READ_ONLY
-		case shard.ModeDegraded:
+		case mode.Degraded:
-			mode = control.ShardMode_DEGRADED
+			m = control.ShardMode_DEGRADED
 		default:
-			mode = control.ShardMode_SHARD_MODE_UNDEFINED
+			m = control.ShardMode_SHARD_MODE_UNDEFINED
 		}
 
-		si.SetMode(mode)
+		si.SetMode(m)
 		si.SetErrorCount(sh.ErrorCount)
 
 		shardInfos = append(shardInfos, si)

pkg/services/control/server/set_shard_mode.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
 	"github.com/nspcc-dev/neofs-node/pkg/services/control"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
@@ -18,7 +19,7 @@ func (s *Server) SetShardMode(_ context.Context, req *control.SetShardModeReques
 	}
 
 	var (
-		mode shard.Mode
+		m mode.Mode
 
 		requestedMode  = req.GetBody().GetMode()
 		requestedShard = shard.NewIDFromBytes(req.Body.GetShard_ID())
@@ -26,16 +27,16 @@ func (s *Server) SetShardMode(_ context.Context, req *control.SetShardModeReques
 
 	switch requestedMode {
 	case control.ShardMode_READ_WRITE:
-		mode = shard.ModeReadWrite
+		m = mode.ReadWrite
 	case control.ShardMode_READ_ONLY:
-		mode = shard.ModeReadOnly
+		m = mode.ReadOnly
 	case control.ShardMode_DEGRADED:
-		mode = shard.ModeDegraded
+		m = mode.Degraded
 	default:
 		return nil, status.Error(codes.Internal, fmt.Sprintf("unknown shard mode: %s", requestedMode))
 	}
 
-	err = s.s.SetShardMode(requestedShard, mode, false)
+	err = s.s.SetShardMode(requestedShard, m, false)
 	if err != nil {
 		return nil, status.Error(codes.Internal, err.Error())
 	}