// NewDHT creates a new DHT object with the given peer as the 'local' host
func NewDHT(ctx context.Context, h host.Host, dstore ds.ThreadSafeDatastore) *IpfsDHT {
dht := new(IpfsDHT)
dht.datastore = dstore
dht.self = h.ID()
dht.peerstore = h.Peerstore()
dht.host = h
// register for network notifs.
dht.host.Network().Notify((*netNotifiee)(dht))
dht.proc = goprocess.WithTeardown(func() error {
// remove ourselves from network notifs.
dht.host.Network().StopNotify((*netNotifiee)(dht))
return nil
})
dht.ctx = ctx
h.SetStreamHandler(ProtocolDHT, dht.handleNewStream)
dht.providers = NewProviderManager(dht.ctx, dht.self)
dht.proc.AddChild(dht.providers.proc)
goprocessctx.CloseAfterContext(dht.proc, ctx)
dht.routingTable = kb.NewRoutingTable(20, kb.ConvertPeerID(dht.self), time.Minute, dht.peerstore)
dht.birth = time.Now()
dht.Validator = make(record.Validator)
dht.Validator["pk"] = record.PublicKeyValidator
return dht
}
func (s *Swarm) dialAddrs(ctx context.Context, d *conn.Dialer, p peer.ID, remoteAddrs []ma.Multiaddr) (conn.Conn, error) {
// try to connect to one of the peer's known addresses.
// we dial concurrently to each of the addresses, which:
// * makes the process faster overall
// * attempts to get the fastest connection available.
// * mitigates the waste of trying bad addresses
log.Debugf("%s swarm dialing %s %s", s.local, p, remoteAddrs)
ctx, cancel := context.WithCancel(ctx)
defer cancel() // cancel work when we exit func
foundConn := make(chan struct{})
conns := make(chan conn.Conn, len(remoteAddrs))
errs := make(chan error, len(remoteAddrs))
// dialSingleAddr is used in the rate-limited async thing below.
dialSingleAddr := func(addr ma.Multiaddr) {
connC, err := s.dialAddr(ctx, d, p, addr)
// check parent still wants our results
select {
case <-foundConn:
if connC != nil {
connC.Close()
}
return
default:
}
if err != nil {
errs <- err
} else if connC == nil {
errs <- fmt.Errorf("failed to dial %s %s", p, addr)
} else {
conns <- connC
}
}
// this whole thing is in a goroutine so we can use foundConn
// to end early.
go func() {
// rate limiting just in case. at most 10 addrs at once.
limiter := ratelimit.NewRateLimiter(process.Background(), 10)
limiter.Go(func(worker process.Process) {
// permute addrs so we try different sets first each time.
for _, i := range rand.Perm(len(remoteAddrs)) {
select {
case <-foundConn: // if one of them succeeded already
break
case <-worker.Closing(): // our context was cancelled
break
default:
}
workerAddr := remoteAddrs[i] // shadow variable to avoid race
limiter.LimitedGo(func(worker process.Process) {
dialSingleAddr(workerAddr)
})
}
})
processctx.CloseAfterContext(limiter, ctx)
}()
// wair fot the results.
exitErr := fmt.Errorf("failed to dial %s", p)
for i := 0; i < len(remoteAddrs); i++ {
select {
case exitErr = <-errs: //
log.Debug("dial error: ", exitErr)
case connC := <-conns:
// take the first + return asap
close(foundConn)
return connC, nil
}
}
return nil, exitErr
}