private void acceptor(ref UdpPacket udp_p, ref Paxos_Packet paxos_p)
{
switch (paxos_p.MsgType)
{
case ((ushort)Phase.Paxos_1A):
paxos_p.MsgType = (ushort)Phase.Paxos_1B;
paxos_p.Voted_Round = vrounds_register[paxos_p.Instance];
paxos_p.Value = value_register[paxos_p.Instance];
paxos_p.Accept_ID = datapath_id;
rounds_register[paxos_p.Instance] = paxos_p.Voted_Round;
udp_p.DestinationPort = Paxos.Learner_Port;
udp_p.UpdateUDPChecksum();
break;
case ((ushort)Phase.Paxos_2A):
paxos_p.MsgType = (ushort)Phase.Paxos_2B;
rounds_register[paxos_p.Instance] = paxos_p.Round;
vrounds_register[paxos_p.Instance] = paxos_p.Round;
value_register[paxos_p.Instance] = paxos_p.Value;
paxos_p.Accept_ID = datapath_id;
udp_p.DestinationPort = Paxos.Learner_Port;
udp_p.UpdateUDPChecksum();
break;
default:
throw (new Exception("Unknown Paxos phase"));
}
}
override public ForwardingDecision process_packet(int in_port, ref Packet packet)
{
if (packet is EthernetPacket &&
packet.Encapsulates(typeof(IPv4Packet), typeof(UdpPacket), typeof(Paxos_Packet)))
{
IpPacket ip_p = ((IpPacket)(packet.PayloadPacket));
UdpPacket udp_p = ((UdpPacket)(ip_p.PayloadPacket));
if (udp_p.DestinationPort == Paxos.Paxos_Coordinator_Port)
{
Paxos_Packet paxos_p = ((Paxos_Packet)(udp_p.PayloadPacket));
instance_register++;
paxos_p.Instance = instance_register;
udp_p.DestinationPort = Paxos.Paxos_Acceptor_Port;
udp_p.UpdateUDPChecksum(); // NOTE we could use "udp_p.Checksum = 0" to
// follows the P4 implementation,
// avoiding the (optional) UDP checksum.
// Same applies to instances of
// checksum-setting below.
}
}
// We assume that we receive from in_port and send to in_port+1.
// NOTE that we implicitly forward all non-Paxos packets onwards,
// unmmodified. The downstream processor then decides how to forward
// them along the network.
return(new ForwardingDecision.SinglePortForward(in_port + 1));
}
override public ForwardingDecision process_packet(int in_port, ref Packet packet)
{
//Check if the packet is of the form we're interested in.
if (packet is EthernetPacket &&
packet.Encapsulates(typeof(IPv4Packet), typeof(UdpPacket), typeof(Paxos_Packet)))
{
IpPacket ip_p = ((IpPacket)(packet.PayloadPacket));
UdpPacket udp_p = ((UdpPacket)(ip_p.PayloadPacket));
if (udp_p.DestinationPort == Paxos.Paxos_Acceptor_Port)
{
Paxos_Packet paxos_p = ((Paxos_Packet)(udp_p.PayloadPacket));
ingress_metadata_t local_metadata;
read_round(out local_metadata, paxos_p);
if (local_metadata.round <= paxos_p.Round)
{
acceptor(ref udp_p, ref paxos_p);
}
}
}
// We follow the same forwarding policy as the Coordinator.
return(new ForwardingDecision.SinglePortForward(in_port + 1));
}
private void read_round(out ingress_metadata_t local_metadata, Paxos_Packet paxos_p)
{
local_metadata = new ingress_metadata_t();
local_metadata.round = rounds_register[paxos_p.Instance];
local_metadata.set_drop = true;
}
