github.com/Oyster-zx/tendermint@v0.34.24-fork/rpc/core/events.go (about)

     1  package core
     2  
     3  import (
     4  	"context"
     5  	"errors"
     6  	"fmt"
     7  	"time"
     8  
     9  	tmpubsub "github.com/tendermint/tendermint/libs/pubsub"
    10  	tmquery "github.com/tendermint/tendermint/libs/pubsub/query"
    11  	ctypes "github.com/tendermint/tendermint/rpc/core/types"
    12  	rpctypes "github.com/tendermint/tendermint/rpc/jsonrpc/types"
    13  )
    14  
    15  const (
    16  	// maxQueryLength is the maximum length of a query string that will be
    17  	// accepted. This is just a safety check to avoid outlandish queries.
    18  	maxQueryLength = 512
    19  )
    20  
    21  // Subscribe for events via WebSocket.
    22  // More: https://docs.tendermint.com/v0.34/rpc/#/Websocket/subscribe
    23  func Subscribe(ctx *rpctypes.Context, query string) (*ctypes.ResultSubscribe, error) {
    24  	addr := ctx.RemoteAddr()
    25  
    26  	if env.EventBus.NumClients() >= env.Config.MaxSubscriptionClients {
    27  		return nil, fmt.Errorf("max_subscription_clients %d reached", env.Config.MaxSubscriptionClients)
    28  	} else if env.EventBus.NumClientSubscriptions(addr) >= env.Config.MaxSubscriptionsPerClient {
    29  		return nil, fmt.Errorf("max_subscriptions_per_client %d reached", env.Config.MaxSubscriptionsPerClient)
    30  	} else if len(query) > maxQueryLength {
    31  		return nil, errors.New("maximum query length exceeded")
    32  	}
    33  
    34  	env.Logger.Info("Subscribe to query", "remote", addr, "query", query)
    35  
    36  	q, err := tmquery.New(query)
    37  	if err != nil {
    38  		return nil, fmt.Errorf("failed to parse query: %w", err)
    39  	}
    40  
    41  	subCtx, cancel := context.WithTimeout(ctx.Context(), SubscribeTimeout)
    42  	defer cancel()
    43  
    44  	sub, err := env.EventBus.Subscribe(subCtx, addr, q, env.Config.SubscriptionBufferSize)
    45  	if err != nil {
    46  		return nil, err
    47  	}
    48  
    49  	closeIfSlow := env.Config.CloseOnSlowClient
    50  
    51  	// Capture the current ID, since it can change in the future.
    52  	subscriptionID := ctx.JSONReq.ID
    53  	go func() {
    54  		for {
    55  			select {
    56  			case msg := <-sub.Out():
    57  				var (
    58  					resultEvent = &ctypes.ResultEvent{Query: query, Data: msg.Data(), Events: msg.Events()}
    59  					resp        = rpctypes.NewRPCSuccessResponse(subscriptionID, resultEvent)
    60  				)
    61  				writeCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
    62  				defer cancel()
    63  				if err := ctx.WSConn.WriteRPCResponse(writeCtx, resp); err != nil {
    64  					env.Logger.Info("Can't write response (slow client)",
    65  						"to", addr, "subscriptionID", subscriptionID, "err", err)
    66  
    67  					if closeIfSlow {
    68  						var (
    69  							err  = errors.New("subscription was cancelled (reason: slow client)")
    70  							resp = rpctypes.RPCServerError(subscriptionID, err)
    71  						)
    72  						if !ctx.WSConn.TryWriteRPCResponse(resp) {
    73  							env.Logger.Info("Can't write response (slow client)",
    74  								"to", addr, "subscriptionID", subscriptionID, "err", err)
    75  						}
    76  						return
    77  					}
    78  				}
    79  			case <-sub.Cancelled():
    80  				if sub.Err() != tmpubsub.ErrUnsubscribed {
    81  					var reason string
    82  					if sub.Err() == nil {
    83  						reason = "Tendermint exited"
    84  					} else {
    85  						reason = sub.Err().Error()
    86  					}
    87  					var (
    88  						err  = fmt.Errorf("subscription was cancelled (reason: %s)", reason)
    89  						resp = rpctypes.RPCServerError(subscriptionID, err)
    90  					)
    91  					if !ctx.WSConn.TryWriteRPCResponse(resp) {
    92  						env.Logger.Info("Can't write response (slow client)",
    93  							"to", addr, "subscriptionID", subscriptionID, "err", err)
    94  					}
    95  				}
    96  				return
    97  			}
    98  		}
    99  	}()
   100  
   101  	return &ctypes.ResultSubscribe{}, nil
   102  }
   103  
   104  // Unsubscribe from events via WebSocket.
   105  // More: https://docs.tendermint.com/v0.34/rpc/#/Websocket/unsubscribe
   106  func Unsubscribe(ctx *rpctypes.Context, query string) (*ctypes.ResultUnsubscribe, error) {
   107  	addr := ctx.RemoteAddr()
   108  	env.Logger.Info("Unsubscribe from query", "remote", addr, "query", query)
   109  	q, err := tmquery.New(query)
   110  	if err != nil {
   111  		return nil, fmt.Errorf("failed to parse query: %w", err)
   112  	}
   113  	err = env.EventBus.Unsubscribe(context.Background(), addr, q)
   114  	if err != nil {
   115  		return nil, err
   116  	}
   117  	return &ctypes.ResultUnsubscribe{}, nil
   118  }
   119  
   120  // UnsubscribeAll from all events via WebSocket.
   121  // More: https://docs.tendermint.com/v0.34/rpc/#/Websocket/unsubscribe_all
   122  func UnsubscribeAll(ctx *rpctypes.Context) (*ctypes.ResultUnsubscribe, error) {
   123  	addr := ctx.RemoteAddr()
   124  	env.Logger.Info("Unsubscribe from all", "remote", addr)
   125  	err := env.EventBus.UnsubscribeAll(context.Background(), addr)
   126  	if err != nil {
   127  		return nil, err
   128  	}
   129  	return &ctypes.ResultUnsubscribe{}, nil
   130  }