package subscriber import ( "context" "errors" "fmt" "sync" "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/morph/client" "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger" "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/neorpc/result" "github.com/nspcc-dev/neo-go/pkg/rpcclient" "github.com/nspcc-dev/neo-go/pkg/util" "go.uber.org/zap" ) type ( NotificationChannels struct { BlockCh <-chan *block.Block NotificationsCh <-chan *state.ContainedNotificationEvent NotaryRequestsCh <-chan *result.NotaryRequestEvent } // Subscriber is an interface of the NotificationEvent listener. Subscriber interface { SubscribeForNotification(...util.Uint160) error UnsubscribeForNotification() BlockNotifications() error SubscribeForNotaryRequests(mainTXSigner util.Uint160) error NotificationChannels() NotificationChannels Close() } subChannels struct { NotifyChan chan *state.ContainedNotificationEvent BlockChan chan *block.Block NotaryChan chan *result.NotaryRequestEvent } subscriber struct { *sync.RWMutex log *logger.Logger client *client.Client notifyChan chan *state.ContainedNotificationEvent blockChan chan *block.Block notaryChan chan *result.NotaryRequestEvent current subChannels // cached subscription information subscribedEvents map[util.Uint160]bool subscribedNotaryEvents map[util.Uint160]bool subscribedToNewBlocks bool } // Params is a group of Subscriber constructor parameters. Params struct { Log *logger.Logger StartFromBlock uint32 Client *client.Client } ) func (s *subscriber) NotificationChannels() NotificationChannels { return NotificationChannels{ BlockCh: s.blockChan, NotificationsCh: s.notifyChan, NotaryRequestsCh: s.notaryChan, } } 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") errNilClient = errors.New("chain/subscriber: client was not provided to the constructor") ) func (s *subscriber) SubscribeForNotification(contracts ...util.Uint160) error { s.Lock() defer s.Unlock() notifyIDs := make([]string, 0, len(contracts)) for i := range contracts { if s.subscribedEvents[contracts[i]] { continue } // subscribe to contract notifications id, err := s.client.ReceiveExecutionNotifications(contracts[i], s.current.NotifyChan) if err != nil { // if there is some error, undo all subscriptions and return error for _, id := range notifyIDs { _ = s.client.Unsubscribe(id) } return err } // save notification id notifyIDs = append(notifyIDs, id) } for i := range contracts { s.subscribedEvents[contracts[i]] = true } return nil } func (s *subscriber) UnsubscribeForNotification() { err := s.client.UnsubscribeAll() if err != nil { s.log.Error("unsubscribe for notification", zap.Error(err)) } } func (s *subscriber) Close() { s.client.Close() } func (s *subscriber) BlockNotifications() error { s.Lock() defer s.Unlock() if s.subscribedToNewBlocks { return nil } if _, err := s.client.ReceiveBlocks(s.current.BlockChan); err != nil { return fmt.Errorf("could not subscribe for new block events: %w", err) } s.subscribedToNewBlocks = true return nil } func (s *subscriber) SubscribeForNotaryRequests(mainTXSigner util.Uint160) error { s.Lock() defer s.Unlock() if s.subscribedNotaryEvents[mainTXSigner] { return nil } if _, err := s.client.ReceiveNotaryRequests(mainTXSigner, s.current.NotaryChan); err != nil { return fmt.Errorf("could not subscribe for notary request events: %w", err) } s.subscribedNotaryEvents[mainTXSigner] = true return nil } // 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 case p.Client == nil: return nil, errNilClient } err := awaitHeight(p.Client, p.StartFromBlock) if err != nil { return nil, err } sub := &subscriber{ RWMutex: new(sync.RWMutex), log: p.Log, client: p.Client, notifyChan: make(chan *state.ContainedNotificationEvent), blockChan: make(chan *block.Block), notaryChan: make(chan *result.NotaryRequestEvent), current: newSubChannels(), subscribedEvents: make(map[util.Uint160]bool), subscribedNotaryEvents: make(map[util.Uint160]bool), } // Worker listens all events from temporary NeoGo channel and puts them // into corresponding permanent channels. go sub.routeNotifications(ctx) return sub, nil } func (s *subscriber) routeNotifications(ctx context.Context) { var ( // TODO: not needed after nspcc-dev/neo-go#2980. cliCh = s.client.NotificationChannel() restoreCh = make(chan bool) restoreInProgress bool ) routeloop: for { var connLost bool s.RLock() curr := s.current s.RUnlock() select { case <-ctx.Done(): break routeloop case ev, ok := <-curr.NotifyChan: if ok { s.notifyChan <- ev } else { connLost = true } case ev, ok := <-curr.BlockChan: if ok { s.blockChan <- ev } else { connLost = true } case ev, ok := <-curr.NotaryChan: if ok { s.notaryChan <- ev } else { connLost = true } case _, ok := <-cliCh: connLost = !ok case ok := <-restoreCh: restoreInProgress = false if !ok { connLost = true } } if connLost { if !restoreInProgress { restoreInProgress, cliCh = s.switchEndpoint(ctx, restoreCh) if !restoreInProgress { break routeloop } curr.drain() } else { // Avoid getting additional !ok events. s.Lock() s.current.NotifyChan = nil s.current.BlockChan = nil s.current.NotaryChan = nil s.Unlock() } } } close(s.notifyChan) close(s.blockChan) close(s.notaryChan) } func (s *subscriber) switchEndpoint(ctx context.Context, finishCh chan<- bool) (bool, <-chan rpcclient.Notification) { s.log.Info("RPC connection lost, attempting reconnect") if !s.client.SwitchRPC(ctx) { s.log.Error("can't switch RPC node") return false, nil } cliCh := s.client.NotificationChannel() s.Lock() chs := newSubChannels() go func() { finishCh <- s.restoreSubscriptions(chs.NotifyChan, chs.BlockChan, chs.NotaryChan) }() s.current = chs s.Unlock() return true, cliCh } func newSubChannels() subChannels { return subChannels{ NotifyChan: make(chan *state.ContainedNotificationEvent), BlockChan: make(chan *block.Block), NotaryChan: make(chan *result.NotaryRequestEvent), } } func (s *subChannels) drain() { drainloop: for { select { case _, ok := <-s.NotifyChan: if !ok { s.NotifyChan = nil } case _, ok := <-s.BlockChan: if !ok { s.BlockChan = nil } case _, ok := <-s.NotaryChan: if !ok { s.NotaryChan = nil } default: break drainloop } } } // restoreSubscriptions restores subscriptions according to // cached information about them. func (s *subscriber) restoreSubscriptions(notifCh chan<- *state.ContainedNotificationEvent, blCh chan<- *block.Block, notaryCh chan<- *result.NotaryRequestEvent) bool { var err error // new block events restoration if s.subscribedToNewBlocks { _, err = s.client.ReceiveBlocks(blCh) if err != nil { s.log.Error("could not restore block subscription after RPC switch", zap.Error(err)) return false } } // notification events restoration for contract := range s.subscribedEvents { contract := contract // See https://github.com/nspcc-dev/neo-go/issues/2890 _, err = s.client.ReceiveExecutionNotifications(contract, notifCh) if err != nil { s.log.Error("could not restore notification subscription after RPC switch", zap.Error(err)) return false } } // notary notification events restoration for signer := range s.subscribedNotaryEvents { signer := signer // See https://github.com/nspcc-dev/neo-go/issues/2890 _, err = s.client.ReceiveNotaryRequests(signer, notaryCh) if err != nil { s.log.Error("could not restore notary notification subscription after RPC switch", zap.Error(err)) return false } } return true } // 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 // FrostFS nodes. func awaitHeight(cli *client.Client, startFrom uint32) error { if startFrom == 0 { return nil } height, err := cli.BlockCount() 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 }