fluencelabs/go-libp2p-kad-dht
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Avoid blocking in notification handlers.

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This isn't the correct fix but the correct fix is probably not worth it.

introduces #70
This commit is contained in:
Steven Allen 2017-07-26 04:40:53 -07:00
parent 4e8a520479
commit 796e96c95f
1 changed files with 41 additions and 20 deletions
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61
notif.go
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@ -1,13 +1,23 @@
package dht
import (
"context"
"io"
"time"
inet "github.com/libp2p/go-libp2p-net"
ma "github.com/multiformats/go-multiaddr"
mstream "github.com/multiformats/go-multistream"
)
// TODO: There is a race condition here where we could process notifications
// out-of-order and incorrectly mark some peers as DHT nodes (or not DHT nodes).
// The correct fix for this is nasty so I'm not really sure it's worth it.
// Incorrectly recording or failing to record a DHT node in the routing table
// isn't a big issue.
const dhtCheckTimeout = 10 * time.Second
// netNotifiee defines methods to be used with the IpfsDHT
type netNotifiee IpfsDHT
@ -23,25 +33,36 @@ func (nn *netNotifiee) Connected(n inet.Network, v inet.Conn) {
default:
}
// Note: We *could* just check the peerstore to see if the remote side supports the dht
// protocol, but its not clear that that information will make it into the peerstore
// by the time this notification is sent. So just to be very careful, we brute force this
// and open a new stream
s, err := dht.host.NewStream(dht.Context(), v.RemotePeer(), ProtocolDHT, ProtocolDHTOld)
switch err {
case nil:
s.Close()
// connected fine? full dht node
dht.Update(dht.Context(), v.RemotePeer())
case mstream.ErrNotSupported:
// Client mode only, don't bother adding them to our routing table
case io.EOF:
// This is kindof an error, but it happens someone often so make it a warning
log.Warningf("checking dht client type: %s", err)
default:
// real error? thats odd
log.Errorf("checking dht client type: %s", err)
}
go func() {
// Note: We *could* just check the peerstore to see if the remote side supports the dht
// protocol, but its not clear that that information will make it into the peerstore
// by the time this notification is sent. So just to be very careful, we brute force this
// and open a new stream
// TODO: There's a race condition here where the connection may
// not be open (and we may sit here trying to connect). I've
// added a timeout but that's not really the correct fix.
ctx, cancel := context.WithTimeout(dht.Context(), dhtCheckTimeout)
defer cancel()
s, err := dht.host.NewStream(ctx, v.RemotePeer(), ProtocolDHT, ProtocolDHTOld)
switch err {
case nil:
s.Close()
// connected fine? full dht node
dht.Update(dht.Context(), v.RemotePeer())
case mstream.ErrNotSupported:
// Client mode only, don't bother adding them to our routing table
case io.EOF:
// This is kindof an error, but it happens someone often so make it a warning
log.Warningf("checking dht client type: %s", err)
default:
// real error? thats odd
log.Errorf("checking dht client type: %s", err)
}
}()
}
func (nn *netNotifiee) Disconnected(n inet.Network, v inet.Conn) {
@ -51,7 +72,7 @@ func (nn *netNotifiee) Disconnected(n inet.Network, v inet.Conn) {
return
default:
}
dht.routingTable.Remove(v.RemotePeer())
go dht.routingTable.Remove(v.RemotePeer())
}
func (nn *netNotifiee) OpenedStream(n inet.Network, v inet.Stream) {}