[#9999] writecache: Make writecache as FSTree only

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

cmd/frostfs-lens/internal/writecache/inspect.go

@@ -1,11 +1,10 @@
 package writecache
 
 import (
-	"os"
-
 	common "git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-lens/internal"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/writecache"
-	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
+	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
 	"github.com/spf13/cobra"
 )
 
@@ -23,18 +22,20 @@ func init() {
 }
 
 func inspectFunc(cmd *cobra.Command, _ []string) {
-	var data []byte
+	wc := writecache.New(
+		writecache.WithPath(vPath),
+	)
+	common.ExitOnErr(cmd, common.Errf("could not open write-cache: %w", wc.Open(cmd.Context(), mode.ReadOnly)))
+	defer wc.Close()
 
-	db, err := writecache.OpenDB(vPath, true, os.OpenFile)
+	var addr oid.Address
-	common.ExitOnErr(cmd, common.Errf("could not open write-cache db: %w", err))
+	common.ExitOnErr(cmd, common.Errf("could not decode address: %w", addr.DecodeString(vAddress)))
-	defer db.Close()
 
-	data, err = writecache.Get(db, []byte(vAddress))
+	obj, err := wc.Get(cmd.Context(), addr)
 	common.ExitOnErr(cmd, common.Errf("could not fetch object: %w", err))
 
-	var o objectSDK.Object
+	common.PrintObjectHeader(cmd, *obj)
-	common.ExitOnErr(cmd, common.Errf("could not unmarshal object: %w", o.Unmarshal(data)))
+	data, err := obj.Marshal()
-
+	common.ExitOnErr(cmd, common.Errf("could not marshal object: %w", err))
-	common.PrintObjectHeader(cmd, o)
 	common.WriteObjectToFile(cmd, vOut, data)
 }

cmd/frostfs-lens/internal/writecache/list.go

@@ -3,11 +3,11 @@ package writecache
 import (
 	"fmt"
 	"io"
-	"os"
 
 	common "git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-lens/internal"
+	blobstor "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/writecache"
-	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
 	"github.com/spf13/cobra"
 )
 
@@ -26,15 +26,18 @@ func listFunc(cmd *cobra.Command, _ []string) {
 	// other targets can be supported
 	w := cmd.OutOrStderr()
 
-	wAddr := func(addr oid.Address) error {
+	wc := writecache.New(
-		_, err := io.WriteString(w, fmt.Sprintf("%s\n", addr))
+		writecache.WithPath(vPath),
+	)
+	common.ExitOnErr(cmd, common.Errf("could not open write-cache: %w", wc.Open(cmd.Context(), mode.ReadOnly)))
+	defer wc.Close()
+
+	var prm blobstor.IteratePrm
+	prm.IgnoreErrors = true
+	prm.Handler = func(ie blobstor.IterationElement) error {
+		_, err := io.WriteString(w, fmt.Sprintf("%s\n", ie.Address))
 		return err
 	}
-
+	_, err := wc.Iterate(cmd.Context(), prm)
-	db, err := writecache.OpenDB(vPath, true, os.OpenFile)
+	common.ExitOnErr(cmd, common.Errf("could not iterate write-cache: %w", err))
-	common.ExitOnErr(cmd, common.Errf("could not open write-cache db: %w", err))
-	defer db.Close()
-
-	err = writecache.IterateDB(db, wAddr)
-	common.ExitOnErr(cmd, common.Errf("write-cache iterator failure: %w", err))
 }

cmd/frostfs-node/config.go

@@ -146,9 +146,6 @@ type shardCfg struct {
 	writecacheCfg struct {
 		enabled          bool
 		path             string
-		maxBatchSize     int
-		maxBatchDelay    time.Duration
-		smallObjectSize  uint64
 		maxObjSize       uint64
 		flushWorkerCount int
 		sizeLimit        uint64
@@ -269,10 +266,7 @@ func (a *applicationConfiguration) setShardWriteCacheConfig(newConfig *shardCfg,
 
 		wc.enabled = true
 		wc.path = writeCacheCfg.Path()
-		wc.maxBatchSize = writeCacheCfg.BoltDB().MaxBatchSize()
-		wc.maxBatchDelay = writeCacheCfg.BoltDB().MaxBatchDelay()
 		wc.maxObjSize = writeCacheCfg.MaxObjectSize()
-		wc.smallObjectSize = writeCacheCfg.SmallObjectSize()
 		wc.flushWorkerCount = writeCacheCfg.WorkerCount()
 		wc.sizeLimit = writeCacheCfg.SizeLimit()
 		wc.noSync = writeCacheCfg.NoSync()
@@ -861,10 +855,7 @@ func (c *cfg) getWriteCacheOpts(shCfg shardCfg) []writecache.Option {
 	if wcRead := shCfg.writecacheCfg; wcRead.enabled {
 		writeCacheOpts = append(writeCacheOpts,
 			writecache.WithPath(wcRead.path),
-			writecache.WithMaxBatchSize(wcRead.maxBatchSize),
-			writecache.WithMaxBatchDelay(wcRead.maxBatchDelay),
 			writecache.WithMaxObjectSize(wcRead.maxObjSize),
-			writecache.WithSmallObjectSize(wcRead.smallObjectSize),
 			writecache.WithFlushWorkersCount(wcRead.flushWorkerCount),
 			writecache.WithMaxCacheSize(wcRead.sizeLimit),
 			writecache.WithNoSync(wcRead.noSync),

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

@@ -74,7 +74,6 @@ func TestEngineSection(t *testing.T) {
 				require.Equal(t, true, wc.NoSync())
 
 				require.Equal(t, "tmp/0/cache", wc.Path())
-				require.EqualValues(t, 16384, wc.SmallObjectSize())
 				require.EqualValues(t, 134217728, wc.MaxObjectSize())
 				require.EqualValues(t, 30, wc.WorkerCount())
 				require.EqualValues(t, 3221225472, wc.SizeLimit())
@@ -129,7 +128,6 @@ func TestEngineSection(t *testing.T) {
 				require.Equal(t, false, wc.NoSync())
 
 				require.Equal(t, "tmp/1/cache", wc.Path())
-				require.EqualValues(t, 16384, wc.SmallObjectSize())
 				require.EqualValues(t, 134217728, wc.MaxObjectSize())
 				require.EqualValues(t, 30, wc.WorkerCount())
 				require.EqualValues(t, 4294967296, wc.SizeLimit())

cmd/frostfs-node/config/engine/shard/writecache/config.go

@@ -10,9 +10,6 @@ import (
 type Config config.Config
 
 const (
-	// SmallSizeDefault is a default size of small objects.
-	SmallSizeDefault = 32 << 10
-
 	// MaxSizeDefault is a default value of the object payload size limit.
 	MaxSizeDefault = 64 << 20
 
@@ -51,22 +48,6 @@ func (x *Config) Path() string {
 	return p
 }
 
-// SmallObjectSize returns the value of "small_object_size" config parameter.
-//
-// Returns SmallSizeDefault if the value is not a positive number.
-func (x *Config) SmallObjectSize() uint64 {
-	s := config.SizeInBytesSafe(
-		(*config.Config)(x),
-		"small_object_size",
-	)
-
-	if s > 0 {
-		return s
-	}
-
-	return SmallSizeDefault
-}
-
 // MaxObjectSize returns the value of "max_object_size" config parameter.
 //
 // Returns MaxSizeDefault if the value is not a positive number.

config/example/node.env

@@ -101,7 +101,6 @@ FROSTFS_STORAGE_SHARD_0_MODE=read-only
 FROSTFS_STORAGE_SHARD_0_WRITECACHE_ENABLED=false
 FROSTFS_STORAGE_SHARD_0_WRITECACHE_NO_SYNC=true
 FROSTFS_STORAGE_SHARD_0_WRITECACHE_PATH=tmp/0/cache
-FROSTFS_STORAGE_SHARD_0_WRITECACHE_SMALL_OBJECT_SIZE=16384
 FROSTFS_STORAGE_SHARD_0_WRITECACHE_MAX_OBJECT_SIZE=134217728
 FROSTFS_STORAGE_SHARD_0_WRITECACHE_FLUSH_WORKER_COUNT=30
 FROSTFS_STORAGE_SHARD_0_WRITECACHE_CAPACITY=3221225472
@@ -155,7 +154,6 @@ FROSTFS_STORAGE_SHARD_1_MODE=read-write
 ### Write cache config
 FROSTFS_STORAGE_SHARD_1_WRITECACHE_ENABLED=true
 FROSTFS_STORAGE_SHARD_1_WRITECACHE_PATH=tmp/1/cache
-FROSTFS_STORAGE_SHARD_1_WRITECACHE_SMALL_OBJECT_SIZE=16384
 FROSTFS_STORAGE_SHARD_1_WRITECACHE_MAX_OBJECT_SIZE=134217728
 FROSTFS_STORAGE_SHARD_1_WRITECACHE_FLUSH_WORKER_COUNT=30
 FROSTFS_STORAGE_SHARD_1_WRITECACHE_CAPACITY=4294967296

config/example/node.json

@@ -145,7 +145,6 @@
           "enabled": false,
           "no_sync": true,
           "path": "tmp/0/cache",
-          "small_object_size": 16384,
           "max_object_size": 134217728,
           "flush_worker_count": 30,
           "capacity": 3221225472
@@ -203,7 +202,6 @@
           "enabled": true,
           "path": "tmp/1/cache",
           "memcache_capacity": 2147483648,
-          "small_object_size": 16384,
           "max_object_size": 134217728,
           "flush_worker_count": 30,
           "capacity": 4294967296

config/example/node.yaml

@@ -125,7 +125,6 @@ storage:
 
       writecache:
         enabled: true
-        small_object_size: 16k  # size threshold for "small" objects which are cached in key-value DB, not in FS, bytes
         max_object_size: 134217728  # size threshold for "big" objects which bypass write-cache and go to the storage directly, bytes
         flush_worker_count: 30  # number of write-cache flusher threads
 

docs/storage-node-configuration.md

@@ -287,7 +287,6 @@ writecache:
   enabled: true
   path: /path/to/writecache
   capacity: 4294967296
-  small_object_size: 16384
   max_object_size: 134217728
   flush_worker_count: 30
 ```
@@ -296,11 +295,8 @@ writecache:
 |----------------------|------------|---------------|----------------------------------------------------------------------------------------------------------------------|
 | `path`               | `string`   |               | Path to the metabase file.                                                                                           |
 | `capacity`           | `size`     | unrestricted  | Approximate maximum size of the writecache. If the writecache is full, objects are written to the blobstor directly. |
-| `small_object_size`  | `size`     | `32K`         | Maximum object size for "small" objects. This objects are stored in a key-value database instead of a file-system.   |
 | `max_object_size`    | `size`     | `64M`         | Maximum object size allowed to be stored in the writecache.                                                          |
 | `flush_worker_count` | `int`      | `20`          | Amount of background workers that move data from the writecache to the blobstor.                                     |
-| `max_batch_size`     | `int`      | `1000`        | Maximum amount of small object `PUT` operations to perform in a single transaction.                                  |
-| `max_batch_delay`    | `duration` | `10ms`        | Maximum delay before a batch starts.                                                                                 |
 
 
 # `node` section

internal/logs/logs.go

@@ -278,7 +278,6 @@ const (
 	ShardCouldNotMarkObjectToDeleteInMetabase                            = "could not mark object to delete in metabase"
 	WritecacheTriedToFlushItemsFromWritecache                            = "tried to flush items from write-cache"
 	WritecacheWaitingForChannelsToFlush                                  = "waiting for channels to flush"
-	WritecacheCantRemoveObjectsFromTheDatabase                           = "can't remove objects from the database"
 	WritecacheCantRemoveObjectFromWritecache                             = "can't remove object from write-cache"
 	BlobovniczatreeCouldNotGetObjectFromLevel                            = "could not get object from level"
 	BlobovniczatreeCouldNotCloseBlobovnicza                              = "could not close Blobovnicza"

pkg/local_object_storage/engine/writecache.go

@@ -166,8 +166,7 @@ func (m *writeCacheMetrics) Put(d time.Duration, success bool, st writecache.Sto
 	m.metrics.AddMethodDuration(m.shardID, m.path, st.String(), "Put", success, d)
 }
 
-func (m *writeCacheMetrics) SetEstimateSize(db, fstree uint64) {
+func (m *writeCacheMetrics) SetEstimateSize(fstree uint64) {
-	m.metrics.SetEstimateSize(m.shardID, m.path, writecache.StorageTypeDB.String(), db)
 	m.metrics.SetEstimateSize(m.shardID, m.path, writecache.StorageTypeFSTree.String(), fstree)
 }
 
@@ -175,8 +174,7 @@ func (m *writeCacheMetrics) SetMode(mod mode.ComponentMode) {
 	m.metrics.SetMode(m.shardID, mod.String())
 }
 
-func (m *writeCacheMetrics) SetActualCounters(db, fstree uint64) {
+func (m *writeCacheMetrics) SetActualCounters(fstree uint64) {
-	m.metrics.SetActualCount(m.shardID, m.path, writecache.StorageTypeDB.String(), db)
 	m.metrics.SetActualCount(m.shardID, m.path, writecache.StorageTypeFSTree.String(), fstree)
 }
 

pkg/local_object_storage/writecache/benchmark/writecache_test.go

@@ -95,6 +95,5 @@ func newCache(b *testing.B) writecache.Cache {
 		writecache.WithBlobstor(bs),
 		writecache.WithMetabase(testMetabase{}),
 		writecache.WithMaxCacheSize(256<<30),
-		writecache.WithSmallObjectSize(128<<10),
 	)
 }

pkg/local_object_storage/writecache/cache.go

@@ -10,8 +10,6 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/metaerr"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger"
-	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
-	"go.etcd.io/bbolt"
 	"go.uber.org/zap"
 )
 
@@ -28,14 +26,10 @@ type cache struct {
 	// whether object should be compressed.
 	compressFlags map[string]struct{}
 
-	// flushCh is a channel with objects to flush.
-	flushCh chan objectInfo
 	// cancel is cancel function, protected by modeMtx in Close.
 	cancel atomic.Value
 	// wg is a wait group for flush workers.
 	wg sync.WaitGroup
-	// store contains underlying database.
-	store
 	// fsTree contains big files stored directly on file-system.
 	fsTree *fstree.FSTree
 }
@@ -43,40 +37,26 @@ type cache struct {
 // wcStorageType is used for write-cache operations logging.
 const wcStorageType = "write-cache"
 
-type objectInfo struct {
-	addr string
-	data []byte
-	obj  *objectSDK.Object
-}
-
 const (
-	defaultMaxObjectSize   = 64 * 1024 * 1024 // 64 MiB
+	defaultMaxObjectSize = 64 * 1024 * 1024 // 64 MiB
-	defaultSmallObjectSize = 32 * 1024        // 32 KiB
+	defaultMaxCacheSize  = 1 << 30          // 1 GiB
-	defaultMaxCacheSize    = 1 << 30          // 1 GiB
 )
 
-var (
+var dummyCanceler context.CancelFunc = func() {}
-	defaultBucket                    = []byte{0}
-	dummyCanceler context.CancelFunc = func() {}
-)
 
 // New creates new writecache instance.
 func New(opts ...Option) Cache {
 	c := &cache{
-		flushCh: make(chan objectInfo),
+		mode: mode.Disabled,
-		mode:    mode.Disabled,
 
 		compressFlags: make(map[string]struct{}),
 		options: options{
-			log:             &logger.Logger{Logger: zap.NewNop()},
+			log:           &logger.Logger{Logger: zap.NewNop()},
-			maxObjectSize:   defaultMaxObjectSize,
+			maxObjectSize: defaultMaxObjectSize,
-			smallObjectSize: defaultSmallObjectSize,
+			workersCount:  defaultFlushWorkersCount,
-			workersCount:    defaultFlushWorkersCount,
+			maxCacheSize:  defaultMaxCacheSize,
-			maxCacheSize:    defaultMaxCacheSize,
+			openFile:      os.OpenFile,
-			maxBatchSize:    bbolt.DefaultMaxBatchSize,
+			metrics:       DefaultMetrics(),
-			maxBatchDelay:   bbolt.DefaultMaxBatchDelay,
-			openFile:        os.OpenFile,
-			metrics:         DefaultMetrics(),
 		},
 	}
 
@@ -111,7 +91,8 @@ func (c *cache) Open(_ context.Context, mod mode.Mode) error {
 		return metaerr.Wrap(err)
 	}
 
-	return metaerr.Wrap(c.initCounters())
+	_ = c.estimateCacheSize()
+	return nil
 }
 
 // Init runs necessary services.
@@ -138,14 +119,6 @@ func (c *cache) Close() error {
 
 	c.modeMtx.Lock()
 	defer c.modeMtx.Unlock()
-
-	var err error
-	if c.db != nil {
-		err = c.db.Close()
-		if err != nil {
-			c.db = nil
-		}
-	}
 	c.metrics.Close()
 	return nil
 }

pkg/local_object_storage/writecache/delete.go

@@ -2,7 +2,6 @@ package writecache
 
 import (
 	"context"
-	"math"
 	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
@@ -10,7 +9,6 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/metaerr"
 	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
 	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
-	"go.etcd.io/bbolt"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
 )
@@ -47,39 +45,6 @@ func (c *cache) Delete(ctx context.Context, addr oid.Address) error {
 
 	saddr := addr.EncodeToString()
 
-	var dataSize int
-	_ = c.db.View(func(tx *bbolt.Tx) error {
-		b := tx.Bucket(defaultBucket)
-		dataSize = len(b.Get([]byte(saddr)))
-		return nil
-	})
-
-	if dataSize > 0 {
-		storageType = StorageTypeDB
-		var recordDeleted bool
-		err := c.db.Update(func(tx *bbolt.Tx) error {
-			b := tx.Bucket(defaultBucket)
-			key := []byte(saddr)
-			recordDeleted = b.Get(key) != nil
-			err := b.Delete(key)
-			return err
-		})
-		if err != nil {
-			return err
-		}
-		storagelog.Write(c.log,
-			storagelog.AddressField(saddr),
-			storagelog.StorageTypeField(wcStorageType),
-			storagelog.OpField("db DELETE"),
-		)
-		if recordDeleted {
-			c.objCounters.cDB.Add(math.MaxUint64)
-			c.estimateCacheSize()
-		}
-		deleted = true
-		return nil
-	}
-
 	storageType = StorageTypeFSTree
 	_, err := c.fsTree.Delete(ctx, common.DeletePrm{Address: addr})
 	if err == nil {

pkg/local_object_storage/writecache/flush.go

@@ -1,7 +1,6 @@
 package writecache
 
 import (
-	"bytes"
 	"context"
 	"errors"
 	"time"
@@ -15,142 +14,33 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
 	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
-	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
-	"github.com/mr-tron/base58"
-	"go.etcd.io/bbolt"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
 	"go.uber.org/zap"
 )
 
 const (
-	// flushBatchSize is amount of keys which will be read from cache to be flushed
-	// to the main storage. It is used to reduce contention between cache put
-	// and cache persist.
-	flushBatchSize = 512
 	// defaultFlushWorkersCount is number of workers for putting objects in main storage.
 	defaultFlushWorkersCount = 20
 	// defaultFlushInterval is default time interval between successive flushes.
-	defaultFlushInterval = time.Second
+	defaultFlushInterval = 10 * time.Second
 )
 
-var errIterationCompleted = errors.New("iteration completed")
-
 // runFlushLoop starts background workers which periodically flush objects to the blobstor.
 func (c *cache) runFlushLoop(ctx context.Context) {
 	if c.disableBackgroundFlush {
 		return
 	}
-	for i := 0; i < c.workersCount; i++ {
-		c.wg.Add(1)
-		go c.workerFlushSmall(ctx)
-	}
 
 	c.wg.Add(1)
 	go func() {
 		c.workerFlushBig(ctx)
 		c.wg.Done()
 	}()
-
-	c.wg.Add(1)
-	go func() {
-		defer c.wg.Done()
-
-		tt := time.NewTimer(defaultFlushInterval)
-		defer tt.Stop()
-
-		for {
-			select {
-			case <-tt.C:
-				c.flushSmallObjects(ctx)
-				tt.Reset(defaultFlushInterval)
-				c.estimateCacheSize()
-			case <-ctx.Done():
-				return
-			}
-		}
-	}()
-}
-
-func (c *cache) flushSmallObjects(ctx context.Context) {
-	var lastKey []byte
-	for {
-		select {
-		case <-ctx.Done():
-			return
-		default:
-		}
-
-		var m []objectInfo
-
-		c.modeMtx.RLock()
-		if c.readOnly() {
-			c.modeMtx.RUnlock()
-			time.Sleep(time.Second)
-			continue
-		}
-
-		// We put objects in batches of fixed size to not interfere with main put cycle a lot.
-		_ = c.db.View(func(tx *bbolt.Tx) error {
-			b := tx.Bucket(defaultBucket)
-			cs := b.Cursor()
-
-			var k, v []byte
-
-			if len(lastKey) == 0 {
-				k, v = cs.First()
-			} else {
-				k, v = cs.Seek(lastKey)
-				if bytes.Equal(k, lastKey) {
-					k, v = cs.Next()
-				}
-			}
-
-			for ; k != nil && len(m) < flushBatchSize; k, v = cs.Next() {
-				if len(lastKey) == len(k) {
-					copy(lastKey, k)
-				} else {
-					lastKey = bytes.Clone(k)
-				}
-
-				m = append(m, objectInfo{
-					addr: string(k),
-					data: bytes.Clone(v),
-				})
-			}
-			return nil
-		})
-
-		var count int
-		for i := range m {
-			obj := objectSDK.New()
-			if err := obj.Unmarshal(m[i].data); err != nil {
-				continue
-			}
-			m[i].obj = obj
-
-			count++
-			select {
-			case c.flushCh <- m[i]:
-			case <-ctx.Done():
-				c.modeMtx.RUnlock()
-				return
-			}
-		}
-
-		c.modeMtx.RUnlock()
-		if count == 0 {
-			break
-		}
-
-		c.log.Debug(logs.WritecacheTriedToFlushItemsFromWritecache,
-			zap.Int("count", count),
-			zap.String("start", base58.Encode(lastKey)))
-	}
 }
 
 func (c *cache) workerFlushBig(ctx context.Context) {
-	tick := time.NewTicker(defaultFlushInterval * 10)
+	tick := time.NewTicker(defaultFlushInterval)
 	for {
 		select {
 		case <-tick.C:
@@ -211,29 +101,6 @@ func (c *cache) flushFSTree(ctx context.Context, ignoreErrors bool) error {
 	return err
 }
 
-// workerFlushSmall writes small objects to the main storage.
-func (c *cache) workerFlushSmall(ctx context.Context) {
-	defer c.wg.Done()
-
-	var objInfo objectInfo
-	for {
-		// Give priority to direct put.
-		select {
-		case objInfo = <-c.flushCh:
-		case <-ctx.Done():
-			return
-		}
-
-		err := c.flushObject(ctx, objInfo.obj, objInfo.data, StorageTypeDB)
-		if err != nil {
-			// Error is handled in flushObject.
-			continue
-		}
-
-		c.deleteFromDB(objInfo.addr, true)
-	}
-}
-
 // flushObject is used to write object directly to the main storage.
 func (c *cache) flushObject(ctx context.Context, obj *objectSDK.Object, data []byte, st StorageType) error {
 	var err error
@@ -300,74 +167,5 @@ func (c *cache) Flush(ctx context.Context, ignoreErrors, seal bool) error {
 }
 
 func (c *cache) flush(ctx context.Context, ignoreErrors bool) error {
-	if err := c.flushFSTree(ctx, ignoreErrors); err != nil {
+	return c.flushFSTree(ctx, ignoreErrors)
-		return err
-	}
-
-	var last string
-	for {
-		batch, err := c.readNextDBBatch(ignoreErrors, last)
-		if err != nil {
-			return err
-		}
-		if len(batch) == 0 {
-			break
-		}
-		for _, item := range batch {
-			var obj objectSDK.Object
-			if err := obj.Unmarshal(item.data); err != nil {
-				c.reportFlushError(logs.FSTreeCantDecodeDBObjectAddress, item.address, metaerr.Wrap(err))
-				if ignoreErrors {
-					continue
-				}
-				return err
-			}
-
-			if err := c.flushObject(ctx, &obj, item.data, StorageTypeDB); err != nil {
-				return err
-			}
-			c.deleteFromDB(item.address, false)
-		}
-		last = batch[len(batch)-1].address
-	}
-	return nil
-}
-
-type batchItem struct {
-	data    []byte
-	address string
-}
-
-func (c *cache) readNextDBBatch(ignoreErrors bool, last string) ([]batchItem, error) {
-	const batchSize = 100
-	var batch []batchItem
-	err := c.db.View(func(tx *bbolt.Tx) error {
-		var addr oid.Address
-
-		b := tx.Bucket(defaultBucket)
-		cs := b.Cursor()
-		for k, data := cs.Seek([]byte(last)); k != nil; k, data = cs.Next() {
-			sa := string(k)
-			if sa == last {
-				continue
-			}
-			if err := addr.DecodeString(sa); err != nil {
-				c.reportFlushError(logs.FSTreeCantDecodeDBObjectAddress, sa, metaerr.Wrap(err))
-				if ignoreErrors {
-					continue
-				}
-				return err
-			}
-
-			batch = append(batch, batchItem{data: bytes.Clone(data), address: sa})
-			if len(batch) == batchSize {
-				return errIterationCompleted
-			}
-		}
-		return nil
-	})
-	if err == nil || errors.Is(err, errIterationCompleted) {
-		return batch, nil
-	}
-	return nil, err
 }

pkg/local_object_storage/writecache/flush_test.go

@@ -19,7 +19,6 @@ import (
 	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
 	oidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id/test"
 	"github.com/stretchr/testify/require"
-	"go.etcd.io/bbolt"
 	"go.uber.org/zap"
 )
 
@@ -31,7 +30,6 @@ func TestFlush(t *testing.T) {
 			append([]Option{
 				WithLogger(testlogger),
 				WithPath(filepath.Join(t.TempDir(), "writecache")),
-				WithSmallObjectSize(smallSize),
 				WithMetabase(mb),
 				WithBlobstor(bs),
 				WithDisableBackgroundFlush(),
@@ -47,31 +45,6 @@ func TestFlush(t *testing.T) {
 	}
 
 	failures := []TestFailureInjector[Option]{
-		{
-			Desc: "db, invalid address",
-			InjectFn: func(t *testing.T, wc Cache) {
-				c := wc.(*cache)
-				obj := testutil.GenerateObject()
-				data, err := obj.Marshal()
-				require.NoError(t, err)
-				require.NoError(t, c.db.Batch(func(tx *bbolt.Tx) error {
-					b := tx.Bucket(defaultBucket)
-					return b.Put([]byte{1, 2, 3}, data)
-				}))
-			},
-		},
-		{
-			Desc: "db, invalid object",
-			InjectFn: func(t *testing.T, wc Cache) {
-				c := wc.(*cache)
-				require.NoError(t, c.db.Batch(func(tx *bbolt.Tx) error {
-					b := tx.Bucket(defaultBucket)
-					k := []byte(oidtest.Address().EncodeToString())
-					v := []byte{1, 2, 3}
-					return b.Put(k, v)
-				}))
-			},
-		},
 		{
 			Desc: "fs, read error",
 			InjectFn: func(t *testing.T, wc Cache) {

pkg/local_object_storage/writecache/get.go

@@ -1,7 +1,6 @@
 package writecache
 
 import (
-	"bytes"
 	"context"
 	"time"
 
@@ -12,7 +11,6 @@ import (
 	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
 	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
 	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
-	"go.etcd.io/bbolt"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
 )
@@ -37,11 +35,11 @@ func (c *cache) Get(ctx context.Context, addr oid.Address) (*objectSDK.Object, e
 		return nil, ErrDegraded
 	}
 
-	obj, err := c.getInternal(ctx, saddr, addr)
+	obj, err := c.getInternal(ctx, addr)
 	return obj, metaerr.Wrap(err)
 }
 
-func (c *cache) getInternal(ctx context.Context, saddr string, addr oid.Address) (*objectSDK.Object, error) {
+func (c *cache) getInternal(ctx context.Context, addr oid.Address) (*objectSDK.Object, error) {
 	found := false
 	storageType := StorageTypeUndefined
 	startedAt := time.Now()
@@ -49,14 +47,6 @@ func (c *cache) getInternal(ctx context.Context, saddr string, addr oid.Address)
 		c.metrics.Get(time.Since(startedAt), found, storageType)
 	}()
 
-	value, err := Get(c.db, []byte(saddr))
-	if err == nil {
-		obj := objectSDK.New()
-		found = true
-		storageType = StorageTypeDB
-		return obj, obj.Unmarshal(value)
-	}
-
 	res, err := c.fsTree.Get(ctx, common.GetPrm{Address: addr})
 	if err != nil {
 		return nil, logicerr.Wrap(new(apistatus.ObjectNotFound))
@@ -87,34 +77,10 @@ func (c *cache) Head(ctx context.Context, addr oid.Address) (*objectSDK.Object,
 		return nil, ErrDegraded
 	}
 
-	obj, err := c.getInternal(ctx, saddr, addr)
+	obj, err := c.getInternal(ctx, addr)
 	if err != nil {
 		return nil, metaerr.Wrap(err)
 	}
 
 	return obj.CutPayload(), nil
 }
-
-// Get fetches object from the underlying database.
-// Key should be a stringified address.
-//
-// Returns an error of type apistatus.ObjectNotFound if the requested object is missing in db.
-func Get(db *bbolt.DB, key []byte) ([]byte, error) {
-	if db == nil {
-		return nil, ErrNotInitialized
-	}
-	var value []byte
-	err := db.View(func(tx *bbolt.Tx) error {
-		b := tx.Bucket(defaultBucket)
-		if b == nil {
-			return ErrNoDefaultBucket
-		}
-		value = b.Get(key)
-		if value == nil {
-			return logicerr.Wrap(new(apistatus.ObjectNotFound))
-		}
-		value = bytes.Clone(value)
-		return nil
-	})
-	return value, metaerr.Wrap(err)
-}

pkg/local_object_storage/writecache/iterate.go

@@ -1,39 +1,28 @@
 package writecache
 
 import (
-	"errors"
+	"context"
-	"fmt"
 
-	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/metaerr"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
-	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
+	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
-	"go.etcd.io/bbolt"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
 )
 
-// ErrNoDefaultBucket is returned by IterateDB when default bucket for objects is missing.
+func (c *cache) Iterate(ctx context.Context, prm common.IteratePrm) (common.IterateRes, error) {
-var ErrNoDefaultBucket = errors.New("no default bucket")
+	ctx, span := tracing.StartSpanFromContext(ctx, "writecache.Iterate",
+		trace.WithAttributes(
+			attribute.Bool("ignore_errors", prm.IgnoreErrors),
+		))
+	defer span.End()
 
-// IterateDB iterates over all objects stored in bbolt.DB instance and passes them to f until error return.
+	if !c.modeMtx.TryRLock() {
-// It is assumed that db is an underlying database of some WriteCache instance.
+		return common.IterateRes{}, ErrNotInitialized
-//
+	}
-// Returns ErrNoDefaultBucket if there is no default bucket in db.
+	defer c.modeMtx.RUnlock()
-//
+	if c.mode.NoMetabase() {
-// DB must not be nil and should be opened.
+		return common.IterateRes{}, ErrDegraded
-func IterateDB(db *bbolt.DB, f func(oid.Address) error) error {
+	}
-	return metaerr.Wrap(db.View(func(tx *bbolt.Tx) error {
-		b := tx.Bucket(defaultBucket)
-		if b == nil {
-			return ErrNoDefaultBucket
-		}
 
-		var addr oid.Address
+	return c.fsTree.Iterate(ctx, prm)
-
-		return b.ForEach(func(k, _ []byte) error {
-			err := addr.DecodeString(string(k))
-			if err != nil {
-				return fmt.Errorf("could not parse object address: %w", err)
-			}
-
-			return f(addr)
-		})
-	}))
 }

pkg/local_object_storage/writecache/metrics.go

@@ -14,7 +14,6 @@ func (t StorageType) String() string {
 
 const (
 	StorageTypeUndefined StorageType = "null"
-	StorageTypeDB        StorageType = "db"
 	StorageTypeFSTree    StorageType = "fstree"
 )
 
@@ -26,9 +25,9 @@ type Metrics interface {
 	Flush(success bool, st StorageType)
 	Evict(st StorageType)
 
-	SetEstimateSize(db, fstree uint64)
+	SetEstimateSize(uint64)
 	SetMode(m mode.ComponentMode)
-	SetActualCounters(db, fstree uint64)
+	SetActualCounters(uint64)
 	SetPath(path string)
 	Close()
 }
@@ -47,11 +46,11 @@ func (metricsStub) Delete(time.Duration, bool, StorageType) {}
 
 func (metricsStub) Put(time.Duration, bool, StorageType) {}
 
-func (metricsStub) SetEstimateSize(uint64, uint64) {}
+func (metricsStub) SetEstimateSize(uint64) {}
 
 func (metricsStub) SetMode(mode.ComponentMode) {}
 
-func (metricsStub) SetActualCounters(uint64, uint64) {}
+func (metricsStub) SetActualCounters(uint64) {}
 
 func (metricsStub) Flush(bool, StorageType) {}
 

pkg/local_object_storage/writecache/mode.go

@@ -2,10 +2,7 @@ package writecache
 
 import (
 	"context"
-	"fmt"
-	"time"
 
-	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
 	"go.opentelemetry.io/otel/attribute"
@@ -25,7 +22,7 @@ func (c *cache) SetMode(m mode.Mode) error {
 	c.modeMtx.Lock()
 	defer c.modeMtx.Unlock()
 
-	err := c.setMode(ctx, m, true)
+	err := c.setMode(ctx, m, !m.NoMetabase())
 	if err == nil {
 		c.metrics.SetMode(mode.ConvertToComponentModeDegraded(m))
 	}
@@ -44,20 +41,6 @@ func (c *cache) setMode(ctx context.Context, m mode.Mode, ignoreErrors bool) err
 		}
 	}
 
-	if c.db != nil {
-		if err = c.db.Close(); err != nil {
-			return fmt.Errorf("can't close write-cache database: %w", err)
-		}
-	}
-
-	// Suspend producers to ensure there are channel send operations in fly.
-	// flushCh is populated by `flush` with `modeMtx` taken, thus waiting until it is empty
-	// guarantees that there are no in-fly operations.
-	for len(c.flushCh) != 0 {
-		c.log.Info(logs.WritecacheWaitingForChannelsToFlush)
-		time.Sleep(time.Second)
-	}
-
 	if turnOffMeta {
 		c.mode = m
 		return nil

pkg/local_object_storage/writecache/mode_test.go

@@ -1,30 +0,0 @@
-package writecache
-
-import (
-	"context"
-	"testing"
-
-	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
-	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger/test"
-	"github.com/stretchr/testify/require"
-)
-
-func TestMode(t *testing.T) {
-	t.Parallel()
-	wc := New(
-		WithLogger(test.NewLogger(t)),
-		WithFlushWorkersCount(2),
-		WithPath(t.TempDir()))
-
-	require.NoError(t, wc.Open(context.Background(), mode.DegradedReadOnly))
-	require.Nil(t, wc.(*cache).db)
-	require.NoError(t, wc.Init())
-	require.Nil(t, wc.(*cache).db)
-	require.NoError(t, wc.Close())
-
-	require.NoError(t, wc.Open(context.Background(), mode.Degraded))
-	require.Nil(t, wc.(*cache).db)
-	require.NoError(t, wc.Init())
-	require.Nil(t, wc.(*cache).db)
-	require.NoError(t, wc.Close())
-}

pkg/local_object_storage/writecache/options.go

@@ -3,7 +3,6 @@ package writecache
 import (
 	"io/fs"
 	"os"
-	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger"
 	"go.uber.org/zap"
@@ -22,19 +21,13 @@ type options struct {
 	metabase Metabase
 	// maxObjectSize is the maximum size of the object stored in the write-cache.
 	maxObjectSize uint64
-	// smallObjectSize is the maximum size of the object stored in the database.
-	smallObjectSize uint64
 	// workersCount is the number of workers flushing objects in parallel.
 	workersCount int
-	// maxCacheSize is the maximum total size of all objects saved in cache (DB + FS).
+	// maxCacheSize is the maximum total size of all objects saved in cache.
 	// 1 GiB by default.
 	maxCacheSize uint64
 	// objCounters contains atomic counters for the number of objects stored in cache.
 	objCounters counters
-	// maxBatchSize is the maximum batch size for the small object database.
-	maxBatchSize int
-	// maxBatchDelay is the maximum batch wait time for the small object database.
-	maxBatchDelay time.Duration
 	// noSync is true iff FSTree allows unsynchronized writes.
 	noSync bool
 	// reportError is the function called when encountering disk errors in background workers.
@@ -84,15 +77,6 @@ func WithMaxObjectSize(sz uint64) Option {
 	}
 }
 
-// WithSmallObjectSize sets maximum object size to be stored in write-cache.
-func WithSmallObjectSize(sz uint64) Option {
-	return func(o *options) {
-		if sz > 0 {
-			o.smallObjectSize = sz
-		}
-	}
-}
-
 func WithFlushWorkersCount(c int) Option {
 	return func(o *options) {
 		if c > 0 {
@@ -108,24 +92,6 @@ func WithMaxCacheSize(sz uint64) Option {
 	}
 }
 
-// WithMaxBatchSize sets max batch size for the small object database.
-func WithMaxBatchSize(sz int) Option {
-	return func(o *options) {
-		if sz > 0 {
-			o.maxBatchSize = sz
-		}
-	}
-}
-
-// WithMaxBatchDelay sets max batch delay for the small object database.
-func WithMaxBatchDelay(d time.Duration) Option {
-	return func(o *options) {
-		if d > 0 {
-			o.maxBatchDelay = d
-		}
-	}
-}
-
 // WithNoSync sets an option to allow returning to caller on PUT before write is persisted.
 // Note, that we use this flag for FSTree only and DO NOT use it for a bolt DB because
 // we cannot yet properly handle the corrupted database during the startup. This SHOULD NOT

pkg/local_object_storage/writecache/put.go

@@ -8,7 +8,6 @@ import (
 	storagelog "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/log"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/metaerr"
 	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
-	"go.etcd.io/bbolt"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
 )
@@ -50,63 +49,17 @@ func (c *cache) Put(ctx context.Context, prm common.PutPrm) (common.PutRes, erro
 		return common.PutRes{}, ErrBigObject
 	}
 
-	oi := objectInfo{
-		addr: prm.Address.EncodeToString(),
-		obj:  prm.Object,
-		data: prm.RawData,
-	}
-
-	if sz <= c.smallObjectSize {
-		storageType = StorageTypeDB
-		err := c.putSmall(oi)
-		if err == nil {
-			added = true
-		}
-		return common.PutRes{}, err
-	}
-
 	storageType = StorageTypeFSTree
-	err := c.putBig(ctx, oi.addr, prm)
+	err := c.putBig(ctx, prm)
 	if err == nil {
 		added = true
 	}
 	return common.PutRes{}, metaerr.Wrap(err)
 }
 
-// putSmall persists small objects to the write-cache database and
-// pushes the to the flush workers queue.
-func (c *cache) putSmall(obj objectInfo) error {
-	cacheSize := c.estimateCacheSize()
-	if c.maxCacheSize < c.incSizeDB(cacheSize) {
-		return ErrOutOfSpace
-	}
-
-	var newRecord bool
-	err := c.db.Batch(func(tx *bbolt.Tx) error {
-		b := tx.Bucket(defaultBucket)
-		key := []byte(obj.addr)
-		newRecord = b.Get(key) == nil
-		if newRecord {
-			return b.Put(key, obj.data)
-		}
-		return nil
-	})
-	if err == nil {
-		storagelog.Write(c.log,
-			storagelog.AddressField(obj.addr),
-			storagelog.StorageTypeField(wcStorageType),
-			storagelog.OpField("db PUT"),
-		)
-		if newRecord {
-			c.objCounters.cDB.Add(1)
-			c.estimateCacheSize()
-		}
-	}
-	return err
-}
-
 // putBig writes object to FSTree and pushes it to the flush workers queue.
-func (c *cache) putBig(ctx context.Context, addr string, prm common.PutPrm) error {
+func (c *cache) putBig(ctx context.Context, prm common.PutPrm) error {
+	addr := prm.Address.EncodeToString()
 	cacheSz := c.estimateCacheSize()
 	if c.maxCacheSize < c.incSizeFS(cacheSz) {
 		return ErrOutOfSpace

pkg/local_object_storage/writecache/state.go

@@ -1,29 +1,21 @@
 package writecache
 
 import (
-	"fmt"
 	"math"
 	"sync/atomic"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/fstree"
-	"go.etcd.io/bbolt"
 )
 
 func (c *cache) estimateCacheSize() uint64 {
-	dbCount := c.objCounters.DB()
 	fsCount := c.objCounters.FS()
 	if fsCount > 0 {
 		fsCount-- // db file
 	}
-	dbSize := dbCount * c.smallObjectSize
 	fsSize := fsCount * c.maxObjectSize
-	c.metrics.SetEstimateSize(dbSize, fsSize)
+	c.metrics.SetEstimateSize(fsSize)
-	c.metrics.SetActualCounters(dbCount, fsCount)
+	c.metrics.SetActualCounters(fsCount)
-	return dbSize + fsSize
+	return fsSize
-}
-
-func (c *cache) incSizeDB(sz uint64) uint64 {
-	return sz + c.smallObjectSize
 }
 
 func (c *cache) incSizeFS(sz uint64) uint64 {
@@ -33,11 +25,7 @@ func (c *cache) incSizeFS(sz uint64) uint64 {
 var _ fstree.FileCounter = &counters{}
 
 type counters struct {
-	cDB, cFS atomic.Uint64
+	cFS atomic.Uint64
-}
-
-func (x *counters) DB() uint64 {
-	return x.cDB.Load()
 }
 
 func (x *counters) FS() uint64 {
@@ -58,20 +46,3 @@ func (x *counters) Inc() {
 func (x *counters) Dec() {
 	x.cFS.Add(math.MaxUint64)
 }
-
-func (c *cache) initCounters() error {
-	var inDB uint64
-	err := c.db.View(func(tx *bbolt.Tx) error {
-		b := tx.Bucket(defaultBucket)
-		if b != nil {
-			inDB = uint64(b.Stats().KeyN)
-		}
-		return nil
-	})
-	if err != nil {
-		return fmt.Errorf("could not read write-cache DB counter: %w", err)
-	}
-	c.objCounters.cDB.Store(inDB)
-	c.estimateCacheSize()
-	return nil
-}

pkg/local_object_storage/writecache/storage.go

@@ -3,7 +3,6 @@ package writecache
 import (
 	"context"
 	"fmt"
-	"math"
 	"os"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
@@ -14,42 +13,15 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util"
 	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client"
 	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
-	"go.etcd.io/bbolt"
 	"go.uber.org/zap"
 )
 
-// store represents persistent storage with in-memory LRU cache
-// for flushed items on top of it.
-type store struct {
-	db *bbolt.DB
-}
-
-const dbName = "small.bolt"
-
 func (c *cache) openStore(mod mode.ComponentMode) error {
 	err := util.MkdirAllX(c.path, os.ModePerm)
 	if err != nil {
 		return err
 	}
 
-	c.db, err = OpenDB(c.path, mod.ReadOnly(), c.openFile)
-	if err != nil {
-		return fmt.Errorf("could not open database: %w", err)
-	}
-
-	c.db.MaxBatchSize = c.maxBatchSize
-	c.db.MaxBatchDelay = c.maxBatchDelay
-
-	if !mod.ReadOnly() {
-		err = c.db.Update(func(tx *bbolt.Tx) error {
-			_, err := tx.CreateBucketIfNotExists(defaultBucket)
-			return err
-		})
-		if err != nil {
-			return fmt.Errorf("could not create default bucket: %w", err)
-		}
-	}
-
 	c.fsTree = fstree.New(
 		fstree.WithPath(c.path),
 		fstree.WithPerm(os.ModePerm),
@@ -68,41 +40,6 @@ func (c *cache) openStore(mod mode.ComponentMode) error {
 	return nil
 }
 
-func (c *cache) deleteFromDB(key string, batched bool) {
-	var recordDeleted bool
-	var err error
-	if batched {
-		err = c.db.Batch(func(tx *bbolt.Tx) error {
-			b := tx.Bucket(defaultBucket)
-			key := []byte(key)
-			recordDeleted = b.Get(key) != nil
-			return b.Delete(key)
-		})
-	} else {
-		err = c.db.Update(func(tx *bbolt.Tx) error {
-			b := tx.Bucket(defaultBucket)
-			key := []byte(key)
-			recordDeleted = b.Get(key) != nil
-			return b.Delete(key)
-		})
-	}
-
-	if err == nil {
-		c.metrics.Evict(StorageTypeDB)
-		storagelog.Write(c.log,
-			storagelog.AddressField(key),
-			storagelog.StorageTypeField(wcStorageType),
-			storagelog.OpField("db DELETE"),
-		)
-		if recordDeleted {
-			c.objCounters.cDB.Add(math.MaxUint64)
-			c.estimateCacheSize()
-		}
-	} else {
-		c.log.Error(logs.WritecacheCantRemoveObjectsFromTheDatabase, zap.Error(err))
-	}
-}
-
 func (c *cache) deleteFromDisk(ctx context.Context, addr oid.Address) {
 	_, err := c.fsTree.Delete(ctx, common.DeletePrm{Address: addr})
 	if err != nil && !client.IsErrObjectNotFound(err) {

pkg/local_object_storage/writecache/util.go

@@ -1,20 +0,0 @@
-package writecache
-
-import (
-	"io/fs"
-	"os"
-	"path/filepath"
-	"time"
-
-	"go.etcd.io/bbolt"
-)
-
-// OpenDB opens BoltDB instance for write-cache. Opens in read-only mode if ro is true.
-func OpenDB(p string, ro bool, openFile func(string, int, fs.FileMode) (*os.File, error)) (*bbolt.DB, error) {
-	return bbolt.Open(filepath.Join(p, dbName), os.ModePerm, &bbolt.Options{
-		NoFreelistSync: true,
-		ReadOnly:       ro,
-		Timeout:        100 * time.Millisecond,
-		OpenFile:       openFile,
-	})
-}

pkg/local_object_storage/writecache/writecache.go

@@ -37,6 +37,7 @@ type Cache interface {
 	DumpInfo() Info
 	Flush(context.Context, bool, bool) error
 	Seal(context.Context, bool) error
+	Iterate(context.Context, common.IteratePrm) (common.IterateRes, error)
 
 	Init() error
 	Open(ctx context.Context, mode mode.Mode) error