nsc: Fix build problem if gtk config store is disabled
gtk config store pulled in libdl.so for us, so things fail
to link of the config store isn't enabled. This makes nsc
pull in libdl itself when its enabled.
/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
* Copyright (c) 2008 University of Washington
*
* 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
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Author: Tom Henderson <tomh@tomh.org>
*/
#include "ns3/log.h"
#include "ns3/command-line.h"
#include "ns3/ptr.h"
#include "ns3/config.h"
#include "ns3/uinteger.h"
#include "ns3/string.h"
#include "ns3/pointer.h"
#include "ns3/simulator.h"
#include "ns3/node.h"
#include "ns3/queue.h"
#include "ns3/drop-tail-queue.h"
#include "ns3/point-to-point-net-device.h"
using namespace ns3;
NS_LOG_COMPONENT_DEFINE ("AttributeValueSample");
//
// This is a basic example of how to use the attribute system to
// set and get a value in the underlying system; namely, an unsigned
// integer of the maximum number of packets in a queue
//
int
main (int argc, char *argv[])
{
LogComponentEnable ("AttributeValueSample", LOG_LEVEL_INFO);
// By default, the MaxPackets attribute has a value of 100 packets
// (this default can be observed in the function DropTailQueue::GetTypeId)
//
// Here, we set it to 80 packets. We could use one of two value types:
// a string-based value or a UintegerValue value
Config::SetDefault ("ns3::DropTailQueue::MaxPackets", StringValue ("80"));
// The below function call is redundant
Config::SetDefault ("ns3::DropTailQueue::MaxPackets", UintegerValue (80));
// Allow the user to override any of the defaults and the above
// SetDefaults() at run-time, via command-line arguments
CommandLine cmd;
cmd.Parse (argc, argv);
// Now, we will create a few objects using the low-level API
Ptr<Node> n0 = CreateObject<Node> ();
Ptr<PointToPointNetDevice> net0 = CreateObject<PointToPointNetDevice> ();
n0->AddDevice (net0);
Ptr<Queue> q = CreateObject<DropTailQueue> ();
net0->SetQueue(q);
// At this point, we have created a single node (Node 0) and a
// single PointToPointNetDevice (NetDevice 0) and added a
// DropTailQueue to it.
// Now, we can manipulate the MaxPackets value of the already
// instantiated DropTailQueue. Here are various ways to do that.
// We assume that a smart pointer (Ptr) to a relevant network device
// is in hand; here, it is the net0 pointer.
// 1. Pointer-based access
//
// One way to change the value is to access a pointer to the
// underlying queue and modify its attribute.
//
// First, we observe that we can get a pointer to the (base class)
// queue via the PointToPointNetDevice attributes, where it is called
// TxQueue
PointerValue ptr;
net0->GetAttribute ("TxQueue", ptr);
Ptr<Queue> txQueue = ptr.Get<Queue> ();
// Using the GetObject function, we can perform a safe downcast
// to a DropTailQueue, where MaxPackets is a member
Ptr<DropTailQueue> dtq = txQueue->GetObject <DropTailQueue> ();
NS_ASSERT (dtq);
// Next, we can get the value of an attribute on this queue
// We have introduced wrapper "Value" classes for the underlying
// data types, similar to Java wrappers around these types, since
// the attribute system stores values and not disparate types.
// Here, the attribute value is assigned to a Uinteger, and
// the Get() method on this value produces the (unwrapped) uint32_t.
UintegerValue limit;
dtq->GetAttribute ("MaxPackets", limit);
NS_LOG_INFO ("1. dtq limit: " << limit.Get () << " packets");
// Note that the above downcast is not really needed; we could have
// done the same using the Ptr<Queue> even though the attribute
// is a member of the subclass
txQueue->GetAttribute ("MaxPackets", limit);
NS_LOG_INFO ("2. txQueue limit: " << limit.Get () << " packets");
// Now, let's set it to another value (60 packets)
txQueue->SetAttribute("MaxPackets", UintegerValue (60));
txQueue->GetAttribute ("MaxPackets", limit);
NS_LOG_INFO ("3. txQueue limit changed: " << limit.Get () << " packets");
// 2. Namespace-based access
//
// An alternative way to get at the attribute is to use the configuration
// namespace. Here, this attribute resides on a known path in this
// namespace; this approach is useful if one doesn't have access to
// the underlying pointers and would like to configure a specific
// attribute with a single statement.
Config::Set ("/NodeList/0/DeviceList/0/TxQueue/MaxPackets", UintegerValue (25));
txQueue->GetAttribute ("MaxPackets", limit);
NS_LOG_INFO ("4. txQueue limit changed through namespace: " <<
limit.Get () << " packets");
// we could have also used wildcards to set this value for all nodes
// and all net devices (which in this simple example has the same
// effect as the previous Set())
Config::Set ("/NodeList/*/DeviceList/*/TxQueue/MaxPackets", UintegerValue (15));
txQueue->GetAttribute ("MaxPackets", limit);
NS_LOG_INFO ("5. txQueue limit changed through wildcarded namespace: " <<
limit.Get () << " packets");
Simulator::Destroy ();
}