[#176] shard: Get rid of using the global RW lock

In previous implementation each shard operation locked
RW shard mutex. With this approach RW operations were executed
one-by-one and blocked the execution of RO operations.

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

pkg/local_object_storage/shard/delete.go

@@ -31,9 +31,6 @@ func (p *DeletePrm) WithAddress(addr *objectSDK.Address) *DeletePrm {
 // Returns any error encountered that did not allow to completely
 // mark the object to delete.
 func (s *Shard) Delete(prm *DeletePrm) (*DeleteRes, error) {
-	s.mtx.Lock()
-	defer s.mtx.Unlock()
-
 	// mark object to delete in metabase
 	if err := s.metaBase.Delete(prm.addr); err != nil {
 		s.log.Warn("could not mark object to delete in metabase",

pkg/local_object_storage/shard/exists.go

@@ -33,9 +33,6 @@ func (p *ExistsRes) Exists() bool {
 // Returns any error encountered that does not allow to
 // unambiguously determine the presence of an object.
 func (s *Shard) Exists(prm *ExistsPrm) (*ExistsRes, error) {
-	s.mtx.RLock()
-	defer s.mtx.RUnlock()
-
 	// FIXME: implement me
 	return &ExistsRes{
 		ex: false,

pkg/local_object_storage/shard/get.go

@@ -71,9 +71,6 @@ func (r *GetRes) Object() *object.Object {
 //
 // Returns ErrObjectNotFound if requested object is missing in shard.
 func (s *Shard) Get(prm *GetPrm) (*GetRes, error) {
-	s.mtx.RLock()
-	defer s.mtx.RUnlock()
-
 	if prm.ln < 0 {
 		// try to read from WriteCache
 		// TODO: implement

pkg/local_object_storage/shard/put.go

@@ -28,9 +28,6 @@ func (p *PutPrm) WithObject(obj *object.Object) *PutPrm {
 // Returns any error encountered that
 // did not allow to completely save the object.
 func (s *Shard) Put(prm *PutPrm) (*PutRes, error) {
-	s.mtx.Lock()
-	defer s.mtx.Unlock()
-
 	// check object existence
 	ex, err := s.metaBase.Exists(prm.obj.Address())
 	if err != nil {

pkg/local_object_storage/shard/select.go

@@ -34,9 +34,6 @@ func (r *SelectRes) AddressList() []*objectSDK.Address {
 // Returns any error encountered that
 // did not allow to completely select the objects.
 func (s *Shard) Select(prm *SelectPrm) (*SelectRes, error) {
-	s.mtx.RLock()
-	defer s.mtx.RUnlock()
-
 	addrList, err := s.metaBase.Select(prm.filters)
 	if err != nil {
 		return nil, errors.Wrap(err, "could not select objects from metabase")

pkg/local_object_storage/shard/shard.go

@@ -1,8 +1,6 @@
 package shard
 
 import (
-	"sync"
-
 	"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"
@@ -12,8 +10,6 @@ import (
 type Shard struct {
 	*cfg
 
-	mtx *sync.RWMutex
-
 	weight WeightValues
 
 	blobStor *blobstor.BlobStor
@@ -48,7 +44,6 @@ func New(opts ...Option) *Shard {
 
 	return &Shard{
 		cfg:      c,
-		mtx:      new(sync.RWMutex),
 		blobStor: blobstor.New(c.blobOpts...),
 		metaBase: meta.NewDB(c.metaOpts...),
 	}