mirror of https://github.com/status-im/go-waku.git
117 lines
2.9 KiB
Go
117 lines
2.9 KiB
Go
package utils
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import (
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"context"
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"errors"
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"math/rand"
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"sync"
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"time"
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"github.com/libp2p/go-libp2p-core/host"
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"github.com/libp2p/go-libp2p-core/peer"
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"github.com/libp2p/go-libp2p/p2p/protocol/ping"
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"github.com/status-im/go-waku/logging"
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"go.uber.org/zap"
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)
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// ErrNoPeersAvailable is emitted when no suitable peers are found for
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// some protocol
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var ErrNoPeersAvailable = errors.New("no suitable peers found")
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// SelectPeer is used to return a random peer that supports a given protocol.
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func SelectPeer(host host.Host, protocolId string, log *zap.Logger) (*peer.ID, error) {
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// @TODO We need to be more strategic about which peers we dial. Right now we just set one on the service.
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// Ideally depending on the query and our set of peers we take a subset of ideal peers.
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// This will require us to check for various factors such as:
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// - which topics they track
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// - latency?
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// - default store peer?
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var peers peer.IDSlice
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for _, peer := range host.Peerstore().Peers() {
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protocols, err := host.Peerstore().SupportsProtocols(peer, protocolId)
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if err != nil {
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log.Error("obtaining protocols supported by peers", zap.Error(err), logging.HostID("peer", peer))
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return nil, err
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}
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if len(protocols) > 0 {
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peers = append(peers, peer)
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}
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}
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if len(peers) >= 1 {
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// TODO: proper heuristic here that compares peer scores and selects "best" one. For now a random peer for the given protocol is returned
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return &peers[rand.Intn(len(peers))], nil // nolint: gosec
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}
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return nil, ErrNoPeersAvailable
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}
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type pingResult struct {
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p peer.ID
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rtt time.Duration
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}
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// SelectPeerWithLowestRTT will select a peer that supports a specific protocol with the lowest reply time
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func SelectPeerWithLowestRTT(ctx context.Context, host host.Host, protocolId string, log *zap.Logger) (*peer.ID, error) {
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var peers peer.IDSlice
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for _, peer := range host.Peerstore().Peers() {
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protocols, err := host.Peerstore().SupportsProtocols(peer, protocolId)
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if err != nil {
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log.Error("error obtaining the protocols supported by peers", zap.Error(err))
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return nil, err
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}
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if len(protocols) > 0 {
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peers = append(peers, peer)
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}
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}
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wg := sync.WaitGroup{}
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waitCh := make(chan struct{})
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pingCh := make(chan pingResult, 1000)
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wg.Add(len(peers))
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go func() {
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for _, p := range peers {
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go func(p peer.ID) {
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defer wg.Done()
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ctx, cancel := context.WithTimeout(ctx, 3*time.Second)
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defer cancel()
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result := <-ping.Ping(ctx, host, p)
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if result.Error == nil {
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pingCh <- pingResult{
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p: p,
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rtt: result.RTT,
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}
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}
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}(p)
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}
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wg.Wait()
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close(waitCh)
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close(pingCh)
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}()
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select {
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case <-waitCh:
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var min *pingResult
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for p := range pingCh {
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if min == nil {
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min = &p
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} else {
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if p.rtt < min.rtt {
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min = &p
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}
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}
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}
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if min == nil {
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return nil, ErrNoPeersAvailable
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}
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return &min.p, nil
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case <-ctx.Done():
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return nil, ErrNoPeersAvailable
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}
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}
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