waku-org/go-waku

package rendezvous

import (
    "math/rand"
    "sync"
    "time"

    "github.com/libp2p/go-libp2p/core/peer"
    "github.com/libp2p/go-libp2p/p2p/discovery/backoff"
)

// RendezvousPoint is a structure that represent a node that can be used to discover new peers
type RendezvousPoint struct {
    sync.RWMutex

    id     peer.ID
    cookie []byte

    bkf     backoff.BackoffStrategy
    nextTry time.Time
}

// NewRendezvousPoint is used to create a RendezvousPoint
func NewRendezvousPoint(peerID peer.ID) *RendezvousPoint {
    rngSrc := rand.NewSource(rand.Int63())
    minBackoff, maxBackoff := time.Second*30, time.Hour
    bkf := backoff.NewExponentialBackoff(minBackoff, maxBackoff, backoff.FullJitter, time.Second, 5.0, 0, rand.New(rngSrc))

    now := time.Now()

    rp := &RendezvousPoint{
        id:      peerID,
        nextTry: now,
        bkf:     bkf(),
    }

    return rp
}

// Delay is used to indicate that the connection to a rendezvous point failed
func (rp *RendezvousPoint) Delay() {
    rp.Lock()
    defer rp.Unlock()

    rp.nextTry = time.Now().Add(rp.bkf.Delay())
}

// SetSuccess is used to indicate that a connection to a rendezvous point was succesful
func (rp *RendezvousPoint) SetSuccess(cookie []byte) {
    rp.Lock()
    defer rp.Unlock()

    rp.bkf.Reset()
    rp.nextTry = time.Now()
    rp.cookie = cookie
}

// NextTry returns when can a rendezvous point be used again
func (rp *RendezvousPoint) NextTry() time.Time {
    rp.RLock()
    defer rp.RUnlock()
    return rp.nextTry
}