[#148] linter: Add gocognit linter

Code with high cognitive complexity is hard intuitively to understand

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

.golangci.yml

@@ -27,8 +27,10 @@ linters-settings:
   staticcheck:
     checks: ["all", "-SA1019"] # TODO Enable SA1019 after deprecated warning are fixed.
   funlen:
-    lines: 80
-    statements: 60
+    lines: 80 # default 60
+    statements: 60 # default 40
+  gocognit:
+    min-complexity: 40 # default 30
 
 linters:
   enable:
@@ -58,5 +60,6 @@ linters:
     - whitespace
     - containedctx
     - funlen
+    - gocognit
   disable-all: true
   fast: false

cmd/frostfs-adm/internal/modules/morph/balance.go

@@ -44,7 +44,7 @@ const (
 	notaryEnabled = true
 )
 
-// nolint: funlen
+// nolint: funlen, gocognit
 func dumpBalances(cmd *cobra.Command, _ []string) error {
 	var (
 		dumpStorage, _  = cmd.Flags().GetBool(dumpBalancesStorageFlag)

pkg/innerring/innerring.go

@@ -322,7 +322,7 @@ func (s *Server) registerStarter(f func() error) {
 
 // New creates instance of inner ring sever structure.
 //
-// nolint: funlen
+// nolint: funlen, gocognit
 func New(ctx context.Context, log *logger.Logger, cfg *viper.Viper, errChan chan<- error) (*Server, error) {
 	var err error
 	server := &Server{log: log}

pkg/local_object_storage/engine/evacuate.go

@@ -58,7 +58,7 @@ var errMustHaveTwoShards = errors.New("must have at least 1 spare shard")
 // Evacuate moves data from one shard to the others.
 // The shard being moved must be in read-only mode.
 //
-// nolint: funlen
+// nolint: funlen, gocognit
 func (e *StorageEngine) Evacuate(prm EvacuateShardPrm) (EvacuateShardRes, error) {
 	sidList := make([]string, len(prm.shardID))
 	for i := range prm.shardID {

pkg/local_object_storage/metabase/inhume.go

@@ -119,7 +119,7 @@ var ErrLockObjectRemoval = logicerr.New("lock object removal")
 // NOTE: Marks any object with GC mark (despite any prohibitions on operations
 // with that object) if WithForceGCMark option has been provided.
 //
-// nolint: funlen
+// nolint: funlen, gocognit
 func (db *DB) Inhume(prm InhumePrm) (res InhumeRes, err error) {
 	db.modeMtx.RLock()
 	defer db.modeMtx.RUnlock()

pkg/local_object_storage/metabase/lock.go

@@ -138,6 +138,8 @@ func objectLocked(tx *bbolt.Tx, idCnr cid.ID, idObj oid.ID) bool {
 // Operation is very resource-intensive, which is caused by the admissibility
 // of multiple locks. Also, if we knew what objects are locked, it would be
 // possible to speed up the execution.
+//
+// nolint: gocognit
 func freePotentialLocks(tx *bbolt.Tx, idCnr cid.ID, locker oid.ID) error {
 	bucketLocked := tx.Bucket(bucketNameLocked)
 	if bucketLocked != nil {

pkg/morph/event/listener.go

@@ -191,7 +191,7 @@ func (l *listener) listen(ctx context.Context, intError chan<- error) error {
 	return nil
 }
 
-// nolint: funlen
+// nolint: funlen, gocognit
 func (l *listener) listenLoop(ctx context.Context, chEvent <-chan *state.ContainedNotificationEvent, intErr chan<- error) {
 	var (
 		blockChan <-chan *block.Block

pkg/services/object/get/v2/util.go

@@ -33,7 +33,7 @@ import (
 
 var errWrongMessageSeq = errors.New("incorrect message sequence")
 
-// nolint: funlen
+// nolint: funlen, gocognit
 func (s *Service) toPrm(req *objectV2.GetRequest, stream objectSvc.GetObjectStream) (*getsvc.Prm, error) {
 	body := req.GetBody()
 
@@ -200,7 +200,7 @@ func (s *Service) toPrm(req *objectV2.GetRequest, stream objectSvc.GetObjectStre
 	return p, nil
 }
 
-// nolint: funlen
+// nolint: funlen, gocognit
 func (s *Service) toRangePrm(req *objectV2.GetRangeRequest, stream objectSvc.GetObjectRangeStream) (*getsvc.RangePrm, error) {
 	body := req.GetBody()
 
@@ -426,7 +426,7 @@ func (w *headResponseWriter) WriteHeader(_ context.Context, hdr *object.Object)
 	return nil
 }
 
-// nolint: funlen
+// nolint: funlen, gocognit
 func (s *Service) toHeadPrm(ctx context.Context, req *objectV2.HeadRequest, resp *objectV2.HeadResponse) (*getsvc.HeadPrm, error) {
 	body := req.GetBody()
 

pkg/services/object/search/v2/util.go

@@ -22,7 +22,7 @@ import (
 	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
 )
 
-// nolint: funlen
+// nolint: funlen, gocognit
 func (s *Service) toPrm(req *objectV2.SearchRequest, stream objectSvc.SearchStream) (*searchsvc.Prm, error) {
 	body := req.GetBody()
 

pkg/services/object/util/chain.go

@@ -72,7 +72,7 @@ func TraverseSplitChain(r HeadReceiver, addr oid.Address, h SplitMemberHandler)
 	return err
 }
 
-// nolint: funlen
+// nolint: funlen, gocognit
 func traverseSplitChain(r HeadReceiver, addr oid.Address, h SplitMemberHandler) (bool, error) {
 	v, err := r.Head(addr)
 	if err != nil {

pkg/services/tree/sync.go

@@ -255,7 +255,7 @@ func (s *Service) SynchronizeAll() error {
 	}
 }
 
-// nolint: funlen
+// nolint: funlen, gocognit
 func (s *Service) syncLoop(ctx context.Context) {
 	for {
 		select {