FEATURE: [bbgo] add maintenance sync check

pkg/bbgo/environment.go

@@ -296,7 +296,7 @@ func (environ *Environment) ConfigureExchangeSessions(userConfig *Config) error
 }
 
 func (environ *Environment) AddExchangesByViperKeys() error {
-	for n, _ := range types.SupportedExchanges {
+	for n := range types.SupportedExchanges {
 		if viper.IsSet(string(n) + "-api-key") {
 			exMinimal, err := exchange.NewWithEnvVarPrefix(n, "")
 			if err != nil {
@@ -520,6 +520,11 @@ func (environ *Environment) syncWithUserConfig(ctx context.Context, userConfig *
 		}
 	}
 	for _, session := range sessions {
+		if session.IsInMaintenance() {
+			log.Infof("session %s is in maintenance mode, skipping sync", session.Name)
+			continue
+		}
+
 		var syncSymbols []string
 		// if there are session specific symbols defined, we use those.
 		// Otherwise we use the rest symbols that are not categorized into any session.
@@ -583,6 +588,11 @@ func (environ *Environment) Sync(ctx context.Context, userConfig ...*Config) err
 	// the default sync logics
 	since := defaultSyncSinceTime()
 	for _, session := range environ.sessions {
+		if session.IsInMaintenance() {
+			log.Infof("session %s is in maintenance mode, skipping sync", session.Name)
+			continue
+		}
+
 		if err := environ.syncSession(ctx, session, since); err != nil {
 			return err
 		}
@@ -652,6 +662,11 @@ func (environ *Environment) RecordPosition(position *types.Position, trade types
 }
 
 func (environ *Environment) SyncSession(ctx context.Context, session *ExchangeSession, defaultSymbols ...string) error {
+	if session.IsInMaintenance() {
+		log.Infof("session %s is in maintenance mode, skipping SyncSession", session.Name)
+		return nil
+	}
+
 	if environ.SyncService == nil {
 		return nil
 	}

pkg/strategy/xalign/strategy.go

@@ -243,6 +243,11 @@ func (s *Strategy) selectSessionForCurrency(
 			continue
 		}
 
+		if session.IsInMaintenance() {
+			log.Infof("session %s is in maintenance, skipping", sessionName)
+			continue
+		}
+
 		account, err := session.UpdateAccount(ctx)
 		if err != nil {
 			log.WithError(err).Errorf("unable to update account for session %s", sessionName)
@@ -628,12 +633,33 @@ func (s *Strategy) align(ctx context.Context, sessions bbgo.ExchangeSessionMap)
 		}
 	}
 
+	anyMaintenance := false
+	for _, session := range sessions {
+		if session.IsInMaintenance() {
+			anyMaintenance = true
+			break
+		}
+	}
+
 	totalBalances, _, err := sessions.AggregateBalances(ctx, false)
 	if err != nil {
 		log.WithError(err).Errorf("unable to aggregate balances")
 		return activeTransferExists
 	}
 
+	balanceQueryAvailable := true
+	for _, session := range sessions {
+		if session.IsInMaintenance() && session.Maintenance != nil && !session.Maintenance.BalanceQueryAvailable {
+			balanceQueryAvailable = false
+			break
+		}
+	}
+
+	if anyMaintenance && !balanceQueryAvailable {
+		log.Warn("one of the sessions is in maintenance and balance query is not available, skipping align")
+		return activeTransferExists
+	}
+
 	s.recordBalances(totalBalances, time.Now())
 
 	log.Debugf("checking all fault balance records...")