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127 lines
4.0 KiB
127 lines
4.0 KiB
package core
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import (
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"context"
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"errors"
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"fmt"
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"time"
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tmpubsub "github.com/tendermint/tendermint/libs/pubsub"
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tmquery "github.com/tendermint/tendermint/libs/pubsub/query"
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"github.com/tendermint/tendermint/rpc/coretypes"
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rpctypes "github.com/tendermint/tendermint/rpc/jsonrpc/types"
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)
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const (
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// Buffer on the Tendermint (server) side to allow some slowness in clients.
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subBufferSize = 100
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// maxQueryLength is the maximum length of a query string that will be
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// accepted. This is just a safety check to avoid outlandish queries.
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maxQueryLength = 512
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)
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// Subscribe for events via WebSocket.
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// More: https://docs.tendermint.com/master/rpc/#/Websocket/subscribe
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func (env *Environment) Subscribe(ctx *rpctypes.Context, query string) (*coretypes.ResultSubscribe, error) {
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addr := ctx.RemoteAddr()
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if env.EventBus.NumClients() >= env.Config.MaxSubscriptionClients {
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return nil, fmt.Errorf("max_subscription_clients %d reached", env.Config.MaxSubscriptionClients)
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} else if env.EventBus.NumClientSubscriptions(addr) >= env.Config.MaxSubscriptionsPerClient {
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return nil, fmt.Errorf("max_subscriptions_per_client %d reached", env.Config.MaxSubscriptionsPerClient)
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} else if len(query) > maxQueryLength {
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return nil, errors.New("maximum query length exceeded")
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}
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env.Logger.Info("Subscribe to query", "remote", addr, "query", query)
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q, err := tmquery.New(query)
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if err != nil {
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return nil, fmt.Errorf("failed to parse query: %w", err)
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}
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subCtx, cancel := context.WithTimeout(ctx.Context(), SubscribeTimeout)
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defer cancel()
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sub, err := env.EventBus.SubscribeWithArgs(subCtx, tmpubsub.SubscribeArgs{
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ClientID: addr,
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Query: q,
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Limit: subBufferSize,
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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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// Capture the current ID, since it can change in the future.
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subscriptionID := ctx.JSONReq.ID
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go func() {
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opctx, opcancel := context.WithCancel(context.Background())
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defer opcancel()
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for {
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msg, err := sub.Next(opctx)
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if errors.Is(err, tmpubsub.ErrUnsubscribed) {
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// The subscription was removed by the client.
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return
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} else if errors.Is(err, tmpubsub.ErrTerminated) {
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// The subscription was terminated by the publisher.
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resp := rpctypes.RPCServerError(subscriptionID, err)
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ok := ctx.WSConn.TryWriteRPCResponse(opctx, resp)
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if !ok {
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env.Logger.Info("Unable to write response (slow client)",
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"to", addr, "subscriptionID", subscriptionID, "err", err)
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}
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return
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}
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// We have a message to deliver to the client.
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resp := rpctypes.NewRPCSuccessResponse(subscriptionID, &coretypes.ResultEvent{
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Query: query,
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Data: msg.Data(),
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Events: msg.Events(),
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})
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wctx, cancel := context.WithTimeout(opctx, 10*time.Second)
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err = ctx.WSConn.WriteRPCResponse(wctx, resp)
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cancel()
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if err != nil {
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env.Logger.Info("Unable to write response (slow client)",
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"to", addr, "subscriptionID", subscriptionID, "err", err)
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}
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}
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}()
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return &coretypes.ResultSubscribe{}, nil
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}
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// Unsubscribe from events via WebSocket.
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// More: https://docs.tendermint.com/master/rpc/#/Websocket/unsubscribe
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func (env *Environment) Unsubscribe(ctx *rpctypes.Context, query string) (*coretypes.ResultUnsubscribe, error) {
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args := tmpubsub.UnsubscribeArgs{Subscriber: ctx.RemoteAddr()}
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env.Logger.Info("Unsubscribe from query", "remote", args.Subscriber, "subscription", query)
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var err error
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args.Query, err = tmquery.New(query)
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if err != nil {
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args.ID = query
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}
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err = env.EventBus.Unsubscribe(ctx.Context(), args)
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if err != nil {
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return nil, err
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}
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return &coretypes.ResultUnsubscribe{}, nil
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}
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// UnsubscribeAll from all events via WebSocket.
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// More: https://docs.tendermint.com/master/rpc/#/Websocket/unsubscribe_all
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func (env *Environment) UnsubscribeAll(ctx *rpctypes.Context) (*coretypes.ResultUnsubscribe, error) {
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addr := ctx.RemoteAddr()
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env.Logger.Info("Unsubscribe from all", "remote", addr)
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err := env.EventBus.UnsubscribeAll(ctx.Context(), addr)
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if err != nil {
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return nil, err
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}
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return &coretypes.ResultUnsubscribe{}, nil
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}
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