neo-go/pkg/rpc/server/subscription.go

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package server
import (
"github.com/gorilla/websocket"
"github.com/nspcc-dev/neo-go/pkg/core/transaction"
"github.com/nspcc-dev/neo-go/pkg/rpc/request"
"github.com/nspcc-dev/neo-go/pkg/rpc/response"
"github.com/nspcc-dev/neo-go/pkg/rpc/response/result"
"go.uber.org/atomic"
)
type (
// subscriber is an event subscriber.
subscriber struct {
writer chan<- *websocket.PreparedMessage
ws *websocket.Conn
overflown atomic.Bool
// These work like slots as there is not a lot of them (it's
// cheaper doing it this way rather than creating a map),
// pointing to EventID is an obvious overkill at the moment, but
// that's not for long.
feeds [maxFeeds]feed
}
feed struct {
event response.EventID
filter interface{}
}
)
const (
// Maximum number of subscriptions per one client.
maxFeeds = 16
// This sets notification messages buffer depth, it may seem to be quite
// big, but there is a big gap in speed between internal event processing
// and networking communication that is combined with spiky nature of our
// event generation process, which leads to lots of events generated in
// short time and they will put some pressure to this buffer (consider
// ~500 invocation txs in one block with some notifications). At the same
// time this channel is about sending pointers, so it's doesn't cost
// a lot in terms of memory used.
notificationBufSize = 1024
)
func (f *feed) Matches(r *response.Notification) bool {
if r.Event != f.event {
return false
}
if f.filter == nil {
return true
}
switch f.event {
case response.TransactionEventID:
filt := f.filter.(request.TxFilter)
tx := r.Payload[0].(*transaction.Transaction)
return tx.Type == filt.Type
case response.NotificationEventID:
filt := f.filter.(request.NotificationFilter)
notification := r.Payload[0].(result.NotificationEvent)
return notification.Contract.Equals(filt.Contract)
case response.ExecutionEventID:
filt := f.filter.(request.ExecutionFilter)
applog := r.Payload[0].(result.ApplicationLog)
return len(applog.Executions) != 0 && applog.Executions[0].VMState == filt.State
}
return false
}