Ns-3 Nix-vector Routing

src/common/packet-metadata.cc

 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
  * Copyright (c) 2006,2007 INRIA
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation;
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 1177 matching lines @@
       size -= 4;
       NS_LOG_LOGIC ("size=" << size << ", typeUid="<<item.typeUid <<
         ", size="<<item.size<<", chunkUid="<<item.chunkUid<<
         ", fragmentStart="<<extraItem.fragmentStart<<", fragmentEnd="<<
         extraItem.fragmentEnd<< ", packetUid="<<extraItem.packetUid);
       uint32_t tmp = AddBig (0xffff, m_tail, &item, &extraItem);
       UpdateTail (tmp);
     }
   NS_ASSERT (size == 0);
   return totalSize;
+}
+
+void
+PacketMetadata::SetNixVector (Ptr<NixVector> nixVector)

[craigdo, 2009/09/11 22:38:17]

I'm a bit concerned about this.  PacketMetadata is generic.  We are adding a
strongly typed pointer to this generic object to support Nix vectors.  What
happens if I want to do something a little different.  Do I add a NickVector
pointer to PacketMetadata?  How about a NackVector to the PacketMetadata later
on.  Why isn't this generic?  Does this point to a weakness in PacketMetadata
that needs to be addressed?

[jpelkey, 2009/09/12 18:34:14]

On 2009/09/11 22:38:17, craigdo wrote:
> I'm a bit concerned about this.  PacketMetadata is generic.  We are adding a
> strongly typed pointer to this generic object to support Nix vectors.  What
> happens if I want to do something a little different.  Do I add a NickVector
> pointer to PacketMetadata?  How about a NackVector to the PacketMetadata later
> on.  Why isn't this generic?  Does this point to a weakness in PacketMetadata
> that needs to be addressed?

I understand the concern.  It is my understanding the packet-metadata is for
things such as unique ID, which is useful for the simulation but doesn't belong
inside the packet.  The main issue is the nix-vector is something that must
travel along with the packet (much like the unique id).  To me, packet-metadata
was the appropriate place for this.  I am open to other suggestions.  We tried
packet tags a while back, but we were unable to use them because of a limiting
tag size.

+{
+    m_nixVector = nixVector;
+}
+
+Ptr<NixVector>
+PacketMetadata::GetNixVector (void) const
+{
+    return m_nixVector;
 }
 
 
 } // namespace ns3