164 lines
3.7 KiB
Go
164 lines
3.7 KiB
Go
package subscriber
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import (
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"context"
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"errors"
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"sync"
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"time"
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"github.com/nspcc-dev/neo-go/pkg/rpc/client"
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"github.com/nspcc-dev/neo-go/pkg/rpc/response"
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"github.com/nspcc-dev/neo-go/pkg/rpc/response/result"
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"github.com/nspcc-dev/neo-go/pkg/util"
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"go.uber.org/zap"
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)
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type (
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// Subscriber is an interface of the NotificationEvent listener.
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Subscriber interface {
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SubscribeForNotification(...util.Uint160) (<-chan *result.NotificationEvent, error)
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UnsubscribeForNotification()
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Close()
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}
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subscriber struct {
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*sync.RWMutex
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log *zap.Logger
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client *client.WSClient
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notify chan *result.NotificationEvent
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notifyIDs map[util.Uint160]string
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}
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// Params is a group of Subscriber constructor parameters.
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Params struct {
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Log *zap.Logger
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Endpoint string
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DialTimeout time.Duration
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}
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)
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var (
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errNilParams = errors.New("chain/subscriber: config was not provided to the constructor")
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errNilLogger = errors.New("chain/subscriber: logger was not provided to the constructor")
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)
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func (s *subscriber) SubscribeForNotification(contracts ...util.Uint160) (<-chan *result.NotificationEvent, error) {
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s.Lock()
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defer s.Unlock()
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notifyIDs := make(map[util.Uint160]string, len(contracts))
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for i := range contracts {
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// do not subscribe to already subscribed contracts
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if _, ok := s.notifyIDs[contracts[i]]; ok {
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continue
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}
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// subscribe to contract notifications
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id, err := s.client.SubscribeForExecutionNotifications(&contracts[i], nil)
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if err != nil {
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// if there is some error, undo all subscriptions and return error
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for _, id := range notifyIDs {
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_ = s.client.Unsubscribe(id)
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}
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return nil, err
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}
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// save notification id
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notifyIDs[contracts[i]] = id
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}
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// update global map of subscribed contracts
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for contract, id := range notifyIDs {
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s.notifyIDs[contract] = id
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}
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return s.notify, nil
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}
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func (s *subscriber) UnsubscribeForNotification() {
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s.Lock()
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defer s.Unlock()
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for i := range s.notifyIDs {
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err := s.client.Unsubscribe(s.notifyIDs[i])
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if err != nil {
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s.log.Error("unsubscribe for notification",
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zap.String("event", s.notifyIDs[i]),
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zap.Error(err))
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}
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delete(s.notifyIDs, i)
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}
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}
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func (s *subscriber) Close() {
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s.client.Close()
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}
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func (s *subscriber) routeNotifications(ctx context.Context) {
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for {
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select {
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case <-ctx.Done():
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return
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case notification, ok := <-s.client.Notifications:
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if !ok {
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s.log.Warn("remote channel has been closed")
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close(s.notify)
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return
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}
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switch notification.Type {
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case response.NotificationEventID:
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notification, ok := notification.Value.(*result.NotificationEvent)
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if !ok {
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s.log.Error("can't cast notify event to the notify struct")
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continue
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}
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s.notify <- notification
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default:
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s.log.Debug("unsupported notification from the chain",
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zap.Uint8("type", uint8(notification.Type)),
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)
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}
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}
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}
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}
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// New is a constructs Neo:Morph event listener and returns Subscriber interface.
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func New(ctx context.Context, p *Params) (Subscriber, error) {
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switch {
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case p == nil:
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return nil, errNilParams
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case p.Log == nil:
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return nil, errNilLogger
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}
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wsClient, err := client.NewWS(ctx, p.Endpoint, client.Options{
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DialTimeout: p.DialTimeout,
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})
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if err != nil {
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return nil, err
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}
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sub := &subscriber{
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RWMutex: new(sync.RWMutex),
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log: p.Log,
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client: wsClient,
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notify: make(chan *result.NotificationEvent),
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notifyIDs: make(map[util.Uint160]string),
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}
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// Worker listens all events from neo-go websocket and puts them
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// into corresponding channel. It may be notifications, transactions,
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// new blocks. For now only notifications.
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go sub.routeNotifications(ctx)
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return sub, nil
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}
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