stateroot: handle double start/shutdown

pkg/services/stateroot/service.go

@@ -14,6 +14,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/network/payload"
 	"github.com/nspcc-dev/neo-go/pkg/wallet"
+	"go.uber.org/atomic"
 	"go.uber.org/zap"
 )
 
@@ -44,6 +45,7 @@ type (
 		Network netmode.Magic
 
 		log       *zap.Logger
+		started   *atomic.Bool
 		accMtx    sync.RWMutex
 		accHeight uint32
 		myIndex   byte
@@ -72,6 +74,7 @@ func New(cfg config.StateRoot, sm *stateroot.Module, log *zap.Logger, bc Ledger,
 	s := &service{
 		Module:          sm,
 		Network:         bcConf.Magic,
+		started:         atomic.NewBool(false),
 		chain:           bc,
 		log:             log,
 		incompleteRoots: make(map[uint32]*incompleteRoot),

pkg/services/stateroot/validators.go

@@ -24,6 +24,9 @@ func (s *service) Name() string {
 
 // Start runs service instance in a separate goroutine.
 func (s *service) Start() {
+	if !s.started.CAS(false, true) {
+		return
+	}
 	s.log.Info("starting state validation service")
 	s.chain.SubscribeForBlocks(s.blockCh)
 	go s.run()
@@ -60,6 +63,9 @@ drainloop:
 
 // Shutdown stops the service.
 func (s *service) Shutdown() {
+	if !s.started.CAS(true, false) {
+		return
+	}
 	s.chain.UnsubscribeFromBlocks(s.blockCh)
 	close(s.done)
 }