network: allow to drop services and solve concurrency issues

Now that services can come and go we need to protect all of the associated
fields and allow to deregister them.

cli/server/server.go

@@ -549,9 +549,10 @@ Main:
 			configureAddresses(&cfgnew.ApplicationConfiguration)
 			switch sig {
 			case syscall.SIGHUP:
+				serv.DelService(&rpcServer)
 				rpcServer.Shutdown()
 				rpcServer = rpcsrv.New(chain, cfgnew.ApplicationConfiguration.RPC, serv, oracleSrv, log, errChan)
-				serv.AddService(&rpcServer) // Replaces old one by service name.
+				serv.AddService(&rpcServer)
 				if !cfgnew.ApplicationConfiguration.RPC.StartWhenSynchronized || serv.IsInSync() {
 					rpcServer.Start()
 				}
@@ -563,6 +564,7 @@ Main:
 				go prometheus.Start()
 			case syscall.SIGUSR1:
 				if oracleSrv != nil {
+					serv.DelService(oracleSrv)
 					chain.SetOracle(nil)
 					rpcServer.SetOracleHandler(nil)
 					oracleSrv.Shutdown()
@@ -579,6 +581,7 @@ Main:
 					}
 				}
 				if p2pNotary != nil {
+					serv.DelService(p2pNotary)
 					chain.SetNotary(nil)
 					p2pNotary.Shutdown()
 				}
@@ -590,6 +593,7 @@ Main:
 				if p2pNotary != nil && serv.IsInSync() {
 					p2pNotary.Start()
 				}
+				serv.DelExtensibleService(sr, stateroot.Category)
 				srMod.SetUpdateValidatorsCallback(nil)
 				sr.Shutdown()
 				sr, err = stateroot.New(cfgnew.ApplicationConfiguration.StateRoot, srMod, log, chain, serv.BroadcastExtensible)
@@ -603,6 +607,7 @@ Main:
 				}
 			case syscall.SIGUSR2:
 				if dbftSrv != nil {
+					serv.DelExtensibleHPService(dbftSrv, consensus.Category)
 					dbftSrv.Shutdown()
 				}
 				dbftSrv, err = mkConsensus(cfgnew.ApplicationConfiguration.UnlockWallet, serverConfig.TimePerBlock, chain, serv, log)

pkg/network/server.go

@@ -101,6 +101,8 @@ type (
 		notaryRequestPool *mempool.Pool
 		extensiblePool    *extpool.Pool
 		notaryFeer        NotaryFeer
+
+		serviceLock    sync.RWMutex
 		services       map[string]Service
 		extensHandlers map[string]func(*payload.Extensible) error
 		extensHighPrio string
@@ -263,9 +265,11 @@ func (s *Server) Shutdown() {
 	}
 	s.bQueue.discard()
 	s.bSyncQueue.discard()
+	s.serviceLock.RLock()
 	for _, svc := range s.services {
 		svc.Shutdown()
 	}
+	s.serviceLock.RUnlock()
 	if s.chain.P2PSigExtensionsEnabled() {
 		s.notaryRequestPool.StopSubscriptions()
 	}
@@ -274,20 +278,72 @@ func (s *Server) Shutdown() {
 
 // AddService allows to add a service to be started/stopped by Server.
 func (s *Server) AddService(svc Service) {
+	s.serviceLock.Lock()
+	defer s.serviceLock.Unlock()
+	s.addService(svc)
+}
+
+// addService is an unlocked version of AddService.
+func (s *Server) addService(svc Service) {
 	s.services[svc.Name()] = svc
 }
 
 // AddExtensibleService register a service that handles an extensible payload of some kind.
 func (s *Server) AddExtensibleService(svc Service, category string, handler func(*payload.Extensible) error) {
+	s.serviceLock.Lock()
+	defer s.serviceLock.Unlock()
+	s.addExtensibleService(svc, category, handler)
+}
+
+// addExtensibleService is an unlocked version of AddExtensibleService.
+func (s *Server) addExtensibleService(svc Service, category string, handler func(*payload.Extensible) error) {
 	s.extensHandlers[category] = handler
-	s.AddService(svc)
+	s.addService(svc)
 }
 
 // AddExtensibleHPService registers a high-priority service that handles an extensible payload of some kind.
 func (s *Server) AddExtensibleHPService(svc Service, category string, handler func(*payload.Extensible) error, txCallback func(*transaction.Transaction)) {
+	s.serviceLock.Lock()
+	defer s.serviceLock.Unlock()
 	s.txCallback = txCallback
 	s.extensHighPrio = category
-	s.AddExtensibleService(svc, category, handler)
+	s.addExtensibleService(svc, category, handler)
+}
+
+// DelService drops a service from the list, use it when the service is stopped
+// outside of the Server.
+func (s *Server) DelService(svc Service) {
+	s.serviceLock.Lock()
+	defer s.serviceLock.Unlock()
+	s.delService(svc)
+}
+
+// delService is an unlocked version of DelService.
+func (s *Server) delService(svc Service) {
+	delete(s.services, svc.Name())
+}
+
+// DelExtensibleService drops a service that handler extensible payloads from the
+// list, use it when the service is stopped outside of the Server.
+func (s *Server) DelExtensibleService(svc Service, category string) {
+	s.serviceLock.Lock()
+	defer s.serviceLock.Unlock()
+	s.delExtensibleService(svc, category)
+}
+
+// delExtensibleService is an unlocked version of DelExtensibleService.
+func (s *Server) delExtensibleService(svc Service, category string) {
+	delete(s.extensHandlers, category)
+	s.delService(svc)
+}
+
+// DelExtensibleHPService unregisters a high-priority service that handles an extensible payload of some kind.
+func (s *Server) DelExtensibleHPService(svc Service, category string) {
+	s.serviceLock.Lock()
+	defer s.serviceLock.Unlock()
+	s.txCallback = nil
+	s.extensHighPrio = ""
+	s.delExtensibleService(svc, category)
 }
 
 // GetNotaryPool allows to retrieve notary pool, if it's configured.
@@ -428,9 +484,11 @@ func (s *Server) tryStartServices() {
 		if s.chain.P2PSigExtensionsEnabled() {
 			s.notaryRequestPool.RunSubscriptions() // WSClient is also a subscriber.
 		}
+		s.serviceLock.RLock()
 		for _, svc := range s.services {
 			svc.Start()
 		}
+		s.serviceLock.RUnlock()
 	}
 }
 
@@ -931,7 +989,9 @@ func (s *Server) handleExtensibleCmd(e *payload.Extensible) error {
 	if !ok { // payload is already in cache
 		return nil
 	}
+	s.serviceLock.RLock()
 	handler := s.extensHandlers[e.Category]
+	s.serviceLock.RUnlock()
 	if handler != nil {
 		err = handler(e)
 		if err != nil {
@@ -944,7 +1004,10 @@ func (s *Server) handleExtensibleCmd(e *payload.Extensible) error {
 
 func (s *Server) advertiseExtensible(e *payload.Extensible) {
 	msg := NewMessage(CMDInv, payload.NewInventory(payload.ExtensibleType, []util.Uint256{e.Hash()}))
-	if e.Category == s.extensHighPrio {
+	s.serviceLock.RLock()
+	hp := s.extensHighPrio
+	s.serviceLock.RUnlock()
+	if e.Category == hp {
 		// It's high priority because it directly affects consensus process,
 		// even though it's just an inv.
 		s.broadcastHPMessage(msg)
@@ -966,8 +1029,11 @@ func (s *Server) handleTxCmd(tx *transaction.Transaction) error {
 	}
 	s.txInMap[tx.Hash()] = struct{}{}
 	s.txInLock.Unlock()
-	if s.txCallback != nil {
+	s.serviceLock.RLock()
-		s.txCallback(tx)
+	txCallback := s.txCallback
+	s.serviceLock.RUnlock()
+	if txCallback != nil {
+		txCallback(tx)
 	}
 	if s.verifyAndPoolTX(tx) == nil {
 		s.broadcastTX(tx, nil)