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topicResolverSender.go
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topicResolverSender.go
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package topicResolverSender
import (
"github.com/ElrondNetwork/elrond-go/dataRetriever"
"github.com/ElrondNetwork/elrond-go/marshal"
"github.com/ElrondNetwork/elrond-go/p2p"
)
// topicRequestSuffix represents the topic name suffix
const topicRequestSuffix = "_REQUEST"
// NumPeersToQuery number of peers to send the message
const NumPeersToQuery = 2
type topicResolverSender struct {
messenger dataRetriever.MessageHandler
marshalizer marshal.Marshalizer
topicName string
peerListCreator dataRetriever.PeerListCreator
randomizer dataRetriever.IntRandomizer
targetShardId uint32
}
// NewTopicResolverSender returns a new topic resolver instance
func NewTopicResolverSender(
messenger dataRetriever.MessageHandler,
topicName string,
peerListCreator dataRetriever.PeerListCreator,
marshalizer marshal.Marshalizer,
randomizer dataRetriever.IntRandomizer,
targetShardId uint32,
) (*topicResolverSender, error) {
if messenger == nil || messenger.IsInterfaceNil() {
return nil, dataRetriever.ErrNilMessenger
}
if marshalizer == nil || marshalizer.IsInterfaceNil() {
return nil, dataRetriever.ErrNilMarshalizer
}
if randomizer == nil || randomizer.IsInterfaceNil() {
return nil, dataRetriever.ErrNilRandomizer
}
if peerListCreator == nil || peerListCreator.IsInterfaceNil() {
return nil, dataRetriever.ErrNilPeerListCreator
}
resolver := &topicResolverSender{
messenger: messenger,
topicName: topicName,
peerListCreator: peerListCreator,
marshalizer: marshalizer,
randomizer: randomizer,
targetShardId: targetShardId,
}
return resolver, nil
}
// SendOnRequestTopic is used to send request data over channels (topics) to other peers
// This method only sends the request, the received data should be handled by interceptors
func (trs *topicResolverSender) SendOnRequestTopic(rd *dataRetriever.RequestData) error {
buff, err := trs.marshalizer.Marshal(rd)
if err != nil {
return err
}
peerList := trs.peerListCreator.PeerList()
if len(peerList) == 0 {
return dataRetriever.ErrNoConnectedPeerToSendRequest
}
topicToSendRequest := trs.topicName + topicRequestSuffix
indexes := createIndexList(len(peerList))
shuffledIndexes, err := fisherYatesShuffle(indexes, trs.randomizer)
if err != nil {
return err
}
msgSentCounter := 0
for idx := range shuffledIndexes {
peer := peerList[idx]
err = trs.messenger.SendToConnectedPeer(topicToSendRequest, buff, peer)
if err != nil {
continue
}
msgSentCounter++
if msgSentCounter == NumPeersToQuery {
break
}
}
if msgSentCounter == 0 {
return err
}
return nil
}
func createIndexList(listLength int) []int {
indexes := make([]int, listLength)
for i := 0; i < listLength; i++ {
indexes[i] = i
}
return indexes
}
// Send is used to send an array buffer to a connected peer
// It is used when replying to a request
func (trs *topicResolverSender) Send(buff []byte, peer p2p.PeerID) error {
return trs.messenger.SendToConnectedPeer(trs.topicName, buff, peer)
}
// TopicRequestSuffix returns the suffix that will be added to create a new channel for requests
func (trs *topicResolverSender) TopicRequestSuffix() string {
return topicRequestSuffix
}
// TargetShardID returns the target shard ID for this resolver should serve data
func (trs *topicResolverSender) TargetShardID() uint32 {
return trs.targetShardId
}
func fisherYatesShuffle(indexes []int, randomizer dataRetriever.IntRandomizer) ([]int, error) {
newIndexes := make([]int, len(indexes))
copy(newIndexes, indexes)
for i := len(newIndexes) - 1; i > 0; i-- {
j, err := randomizer.Intn(i + 1)
if err != nil {
return nil, err
}
newIndexes[i], newIndexes[j] = newIndexes[j], newIndexes[i]
}
return newIndexes, nil
}
// IsInterfaceNil returns true if there is no value under the interface
func (trs *topicResolverSender) IsInterfaceNil() bool {
if trs == nil {
return true
}
return false
}