package core import ( "context" "fmt" "time" tmpubsub "github.com/tendermint/tendermint/libs/pubsub" tmquery "github.com/tendermint/tendermint/libs/pubsub/query" ctypes "github.com/tendermint/tendermint/rpc/core/types" rpctypes "github.com/tendermint/tendermint/rpc/jsonrpc/types" ) const ( // Buffer on the Tendermint (server) side to allow some slowness in clients. subBufferSize = 100 ) // Subscribe for events via WebSocket. // More: https://docs.tendermint.com/master/rpc/#/Websocket/subscribe func Subscribe(ctx *rpctypes.Context, query string) (*ctypes.ResultSubscribe, error) { addr := ctx.RemoteAddr() if env.EventBus.NumClients() >= env.Config.MaxSubscriptionClients { return nil, fmt.Errorf("max_subscription_clients %d reached", env.Config.MaxSubscriptionClients) } else if env.EventBus.NumClientSubscriptions(addr) >= env.Config.MaxSubscriptionsPerClient { return nil, fmt.Errorf("max_subscriptions_per_client %d reached", env.Config.MaxSubscriptionsPerClient) } env.Logger.Info("Subscribe to query", "remote", addr, "query", query) q, err := tmquery.New(query) if err != nil { return nil, fmt.Errorf("failed to parse query: %w", err) } subCtx, cancel := context.WithTimeout(ctx.Context(), SubscribeTimeout) defer cancel() sub, err := env.EventBus.Subscribe(subCtx, addr, q, subBufferSize) if err != nil { return nil, err } // Capture the current ID, since it can change in the future. subscriptionID := ctx.JSONReq.ID go func() { for { select { case msg := <-sub.Out(): var ( resultEvent = &ctypes.ResultEvent{Query: query, Data: msg.Data(), Events: msg.Events()} resp = rpctypes.NewRPCSuccessResponse(subscriptionID, resultEvent) ) writeCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second) defer cancel() if err := ctx.WSConn.WriteRPCResponse(writeCtx, resp); err != nil { env.Logger.Info("Can't write response (slow client)", "to", addr, "subscriptionID", subscriptionID, "err", err) } case <-sub.Cancelled(): if sub.Err() != tmpubsub.ErrUnsubscribed { var reason string if sub.Err() == nil { reason = "Tendermint exited" } else { reason = sub.Err().Error() } var ( err = fmt.Errorf("subscription was cancelled (reason: %s)", reason) resp = rpctypes.RPCServerError(subscriptionID, err) ) if ok := ctx.WSConn.TryWriteRPCResponse(resp); !ok { env.Logger.Info("Can't write response (slow client)", "to", addr, "subscriptionID", subscriptionID, "err", err) } } return } } }() return &ctypes.ResultSubscribe{}, nil } // Unsubscribe from events via WebSocket. // More: https://docs.tendermint.com/master/rpc/#/Websocket/unsubscribe func Unsubscribe(ctx *rpctypes.Context, query string) (*ctypes.ResultUnsubscribe, error) { addr := ctx.RemoteAddr() env.Logger.Info("Unsubscribe from query", "remote", addr, "query", query) q, err := tmquery.New(query) if err != nil { return nil, fmt.Errorf("failed to parse query: %w", err) } err = env.EventBus.Unsubscribe(context.Background(), addr, q) if err != nil { return nil, err } return &ctypes.ResultUnsubscribe{}, nil } // UnsubscribeAll from all events via WebSocket. // More: https://docs.tendermint.com/master/rpc/#/Websocket/unsubscribe_all func UnsubscribeAll(ctx *rpctypes.Context) (*ctypes.ResultUnsubscribe, error) { addr := ctx.RemoteAddr() env.Logger.Info("Unsubscribe from all", "remote", addr) err := env.EventBus.UnsubscribeAll(context.Background(), addr) if err != nil { return nil, err } return &ctypes.ResultUnsubscribe{}, nil }