[#585] writecache: Fix DB counter

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

pkg/local_object_storage/writecache/writecachebbolt/storage.go

@@ -3,6 +3,7 @@ package writecachebbolt
 import (
 	"context"
 	"fmt"
+	"math"
 	"os"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
@@ -68,9 +69,12 @@ func (c *cache) openStore(readOnly bool) error {
 }
 
 func (c *cache) deleteFromDB(key string) {
+	var recordDeleted bool
 	err := c.db.Batch(func(tx *bbolt.Tx) error {
 		b := tx.Bucket(defaultBucket)
-		return b.Delete([]byte(key))
+		key := []byte(key)
+		recordDeleted = !recordDeleted && b.Get(key) != nil
+		return b.Delete(key)
 	})
 
 	if err == nil {
@@ -80,7 +84,10 @@ func (c *cache) deleteFromDB(key string) {
 			storagelog.StorageTypeField(wcStorageType),
 			storagelog.OpField("db DELETE"),
 		)
-		c.estimateCacheSize()
+		if recordDeleted {
+			c.objCounters.cDB.Add(math.MaxUint64)
+			c.estimateCacheSize()
+		}
 	} else {
 		c.log.Error(logs.WritecacheCantRemoveObjectsFromTheDatabase, zap.Error(err))
 	}