package subscriber import ( "context" "errors" "fmt" "sync" "time" "github.com/nspcc-dev/neo-go/pkg/core/block" "github.com/nspcc-dev/neo-go/pkg/core/state" "github.com/nspcc-dev/neo-go/pkg/rpc/client" "github.com/nspcc-dev/neo-go/pkg/rpc/response" "github.com/nspcc-dev/neo-go/pkg/rpc/response/result/subscriptions" "github.com/nspcc-dev/neo-go/pkg/util" "go.uber.org/zap" ) type ( // Subscriber is an interface of the NotificationEvent listener. Subscriber interface { SubscribeForNotification(...util.Uint160) (<-chan *state.NotificationEvent, error) UnsubscribeForNotification() BlockNotifications() (<-chan *block.Block, error) SubscribeForNotaryRequests(mainTXSigner util.Uint160) (<-chan *subscriptions.NotaryRequestEvent, error) Close() } subscriber struct { *sync.RWMutex log *zap.Logger client *client.WSClient notifyChan chan *state.NotificationEvent notifyIDs map[util.Uint160]string blockChan chan *block.Block notaryChan chan *subscriptions.NotaryRequestEvent } // Params is a group of Subscriber constructor parameters. Params struct { Log *zap.Logger Endpoint string DialTimeout time.Duration StartFromBlock uint32 } ) var ( errNilParams = errors.New("chain/subscriber: config was not provided to the constructor") errNilLogger = errors.New("chain/subscriber: logger was not provided to the constructor") ) func (s *subscriber) SubscribeForNotification(contracts ...util.Uint160) (<-chan *state.NotificationEvent, error) { s.Lock() defer s.Unlock() notifyIDs := make(map[util.Uint160]string, len(contracts)) for i := range contracts { // do not subscribe to already subscribed contracts if _, ok := s.notifyIDs[contracts[i]]; ok { continue } // subscribe to contract notifications id, err := s.client.SubscribeForExecutionNotifications(&contracts[i], nil) if err != nil { // if there is some error, undo all subscriptions and return error for _, id := range notifyIDs { _ = s.client.Unsubscribe(id) } return nil, err } // save notification id notifyIDs[contracts[i]] = id } // update global map of subscribed contracts for contract, id := range notifyIDs { s.notifyIDs[contract] = id } return s.notifyChan, nil } func (s *subscriber) UnsubscribeForNotification() { s.Lock() defer s.Unlock() for i := range s.notifyIDs { err := s.client.Unsubscribe(s.notifyIDs[i]) if err != nil { s.log.Error("unsubscribe for notification", zap.String("event", s.notifyIDs[i]), zap.Error(err)) } delete(s.notifyIDs, i) } } func (s *subscriber) Close() { s.client.Close() } func (s *subscriber) BlockNotifications() (<-chan *block.Block, error) { if _, err := s.client.SubscribeForNewBlocks(nil); err != nil { return nil, fmt.Errorf("could not subscribe for new block events: %w", err) } return s.blockChan, nil } func (s *subscriber) SubscribeForNotaryRequests(mainTXSigner util.Uint160) (<-chan *subscriptions.NotaryRequestEvent, error) { if _, err := s.client.SubscribeForNotaryRequests(nil, &mainTXSigner); err != nil { return nil, fmt.Errorf("could not subscribe for notary request events: %w", err) } return s.notaryChan, nil } func (s *subscriber) routeNotifications(ctx context.Context) { for { select { case <-ctx.Done(): return case notification, ok := <-s.client.Notifications: if !ok { s.log.Warn("remote notification channel has been closed") close(s.notifyChan) close(s.blockChan) close(s.notaryChan) return } switch notification.Type { case response.NotificationEventID: notification, ok := notification.Value.(*state.NotificationEvent) if !ok { s.log.Error("can't cast notify event value to the notify struct") continue } s.notifyChan <- notification case response.BlockEventID: b, ok := notification.Value.(*block.Block) if !ok { s.log.Error("can't cast block event value to block") continue } s.blockChan <- b case response.NotaryRequestEventID: notaryRequest, ok := notification.Value.(*subscriptions.NotaryRequestEvent) if !ok { s.log.Error("can't cast notify event value to the notary request struct") continue } s.notaryChan <- notaryRequest default: s.log.Debug("unsupported notification from the chain", zap.Uint8("type", uint8(notification.Type)), ) } } } } // New is a constructs Neo:Morph event listener and returns Subscriber interface. func New(ctx context.Context, p *Params) (Subscriber, error) { switch { case p == nil: return nil, errNilParams case p.Log == nil: return nil, errNilLogger } wsClient, err := client.NewWS(ctx, p.Endpoint, client.Options{ DialTimeout: p.DialTimeout, }) if err != nil { return nil, err } if err := wsClient.Init(); err != nil { return nil, fmt.Errorf("could not init ws client: %w", err) } p.Log.Debug("event subscriber awaits RPC node", zap.String("endpoint", p.Endpoint), zap.Uint32("min_block_height", p.StartFromBlock)) err = awaitHeight(wsClient, p.StartFromBlock) if err != nil { return nil, err } sub := &subscriber{ RWMutex: new(sync.RWMutex), log: p.Log, client: wsClient, notifyChan: make(chan *state.NotificationEvent), notifyIDs: make(map[util.Uint160]string), blockChan: make(chan *block.Block), notaryChan: make(chan *subscriptions.NotaryRequestEvent), } // Worker listens all events from neo-go websocket and puts them // into corresponding channel. It may be notifications, transactions, // new blocks. For now only notifications. go sub.routeNotifications(ctx) return sub, nil } // awaitHeight checks if remote client has least expected block height and // returns error if it is not reached that height after timeout duration. // This function is required to avoid connections to unsynced RPC nodes, because // they can produce events from the past that should not be processed by // NeoFS nodes. func awaitHeight(wsClient *client.WSClient, startFrom uint32) error { if startFrom == 0 { return nil } height, err := wsClient.GetBlockCount() if err != nil { return fmt.Errorf("could not get block height: %w", err) } if height < startFrom { return fmt.Errorf("RPC block counter %d didn't reach expected height %d", height, startFrom) } return nil }