net-device-queue-interface.h

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2017 Universita' degli Studi di Napoli Federico II
 *
 * 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: Stefano Avallone <stefano.avallone@.unina.it>
 */
#ifndef NET_DEVICE_QUEUE_INTERFACE_H
#define NET_DEVICE_QUEUE_INTERFACE_H

#include <vector>
#include <map>
#include "ns3/callback.h"
#include "ns3/object.h"
#include "ns3/ptr.h"
#include "ns3/queue-item.h"
#include "ns3/queue.h"
#include "ns3/net-device.h"

namespace ns3 {

class QueueLimits;
class NetDeviceQueueInterface;

// This header file is included by all the queue discs and all the netdevices
// using a Queue object. The following explicit template instantiation
// declarations enables them to suppress implicit template instantiations
extern template class Queue<Packet>;
extern template class Queue<QueueDiscItem>;


class NetDeviceQueue : public SimpleRefCount<NetDeviceQueue>
{
public:
  NetDeviceQueue ();
  virtual ~NetDeviceQueue();

  virtual void Start (void);

  virtual void Stop (void);

  virtual void Wake (void);

  bool IsStopped (void) const;

  typedef Callback< void > WakeCallback;

  virtual void SetWakeCallback (WakeCallback cb);

  void NotifyQueuedBytes (uint32_t bytes);

  void NotifyTransmittedBytes (uint32_t bytes);

  void ResetQueueLimits ();

  void SetQueueLimits (Ptr<QueueLimits> ql);

  Ptr<QueueLimits> GetQueueLimits ();

  template <typename Item>
  static void PacketEnqueued (Ptr<Queue<Item> > queue,
                              Ptr<NetDeviceQueueInterface> ndqi,
                              uint8_t txq, Ptr<const Item> item);

  template <typename Item>
  static void PacketDequeued (Ptr<Queue<Item> > queue,
                              Ptr<NetDeviceQueueInterface> ndqi,
                              uint8_t txq, Ptr<const Item> item);

  template <typename Item>
  static void PacketDiscarded (Ptr<Queue<Item> > queue,
                               Ptr<NetDeviceQueueInterface> ndqi,
                               uint8_t txq, Ptr<const Item> item);

private:
  bool m_stoppedByDevice;         
  bool m_stoppedByQueueLimits;    
  Ptr<QueueLimits> m_queueLimits; 
  WakeCallback m_wakeCallback;    
};


class NetDeviceQueueInterface : public Object
{
public:
  static TypeId GetTypeId (void);

  NetDeviceQueueInterface ();
  virtual ~NetDeviceQueueInterface ();

  Ptr<NetDeviceQueue> GetTxQueue (uint8_t i) const;

  uint8_t GetNTxQueues (void) const;

  void SetTxQueuesN (uint8_t numTxQueues);

  void CreateTxQueues (void);

  bool GetLateTxQueuesCreation (void) const;

  void SetLateTxQueuesCreation (bool value);

  typedef Callback< uint8_t, Ptr<QueueItem> > SelectQueueCallback;

  void SetSelectQueueCallback (SelectQueueCallback cb);

  SelectQueueCallback GetSelectQueueCallback (void) const;

  template <typename Item>
  void ConnectQueueTraces (Ptr<Queue<Item> > queue, uint8_t txq);

protected:
  virtual void DoDispose (void);

private:
  std::vector< Ptr<NetDeviceQueue> > m_txQueuesVector;   
  SelectQueueCallback m_selectQueueCallback;   
  uint8_t m_numTxQueues;   
  bool m_lateTxQueuesCreation;   
  std::map<Ptr<QueueBase>, std::vector<CallbackBase> > m_traceMap;   
};


template <typename Item>
void
NetDeviceQueueInterface::ConnectQueueTraces (Ptr<Queue<Item> > queue, uint8_t txq)
{
  NS_ASSERT (queue != 0);
  NS_ASSERT (txq < GetNTxQueues ());

  m_traceMap.emplace (queue, std::initializer_list<CallbackBase> {
                               MakeBoundCallback (&NetDeviceQueue::PacketEnqueued<Item>, queue, this, txq),
                               MakeBoundCallback (&NetDeviceQueue::PacketDequeued<Item>, queue, this, txq),
                               MakeBoundCallback (&NetDeviceQueue::PacketDiscarded<Item>, queue, this, txq) });

  queue->TraceConnectWithoutContext ("Enqueue", m_traceMap[queue][0]);
  queue->TraceConnectWithoutContext ("Dequeue", m_traceMap[queue][1]);
  queue->TraceConnectWithoutContext ("DropAfterDequeue", m_traceMap[queue][1]);
  queue->TraceConnectWithoutContext ("DropBeforeEnqueue", m_traceMap[queue][2]);
}

template <typename Item>
void
NetDeviceQueue::PacketEnqueued (Ptr<Queue<Item> > queue,
                                Ptr<NetDeviceQueueInterface> ndqi,
                                uint8_t txq, Ptr<const Item> item)
{
  NS_LOG_STATIC_TEMPLATE_DEFINE ("NetDeviceQueueInterface");

  NS_LOG_FUNCTION (queue << ndqi << txq << item);

  // Inform BQL
  ndqi->GetTxQueue (txq)->NotifyQueuedBytes (item->GetSize ());

  uint16_t mtu = ndqi->GetObject<NetDevice> ()->GetMtu ();

  // After enqueuing a packet, we need to check whether the queue is able to
  // store another packet. If not, we stop the queue

  if ((queue->GetMode () == QueueBase::QUEUE_MODE_PACKETS &&
       queue->GetNPackets () >= queue->GetMaxPackets ()) ||
      (queue->GetMode () == QueueBase::QUEUE_MODE_BYTES &&
       queue->GetNBytes () + mtu > queue->GetMaxBytes ()))
    {
      NS_LOG_DEBUG ("The device queue is being stopped (" << queue->GetNPackets ()
                    << " packets and " << queue->GetNBytes () << " bytes inside)");
      ndqi->GetTxQueue (txq)->Stop ();
    }
}

template <typename Item>
void
NetDeviceQueue::PacketDequeued (Ptr<Queue<Item> > queue,
                                Ptr<NetDeviceQueueInterface> ndqi,
                                uint8_t txq, Ptr<const Item> item)
{
  NS_LOG_STATIC_TEMPLATE_DEFINE ("NetDeviceQueueInterface");

  NS_LOG_FUNCTION (queue << ndqi << txq << item);

  // Inform BQL
  ndqi->GetTxQueue (txq)->NotifyTransmittedBytes (item->GetSize ());

  uint16_t mtu = ndqi->GetObject<NetDevice> ()->GetMtu ();

  // After dequeuing a packet, if there is room for another packet we
  // call Wake () that ensures that the queue is not stopped and restarts
  // the queue disc if the queue was stopped

  if ((queue->GetMode () == QueueBase::QUEUE_MODE_PACKETS &&
       queue->GetNPackets () < queue->GetMaxPackets ()) ||
      (queue->GetMode () == QueueBase::QUEUE_MODE_BYTES &&
       queue->GetNBytes () + mtu <= queue->GetMaxBytes ()))
    {
      ndqi->GetTxQueue (txq)->Wake ();
    }
}

template <typename Item>
void
NetDeviceQueue::PacketDiscarded (Ptr<Queue<Item> > queue,
                                 Ptr<NetDeviceQueueInterface> ndqi,
                                 uint8_t txq, Ptr<const Item> item)
{
  NS_LOG_STATIC_TEMPLATE_DEFINE ("NetDeviceQueueInterface");

  NS_LOG_FUNCTION (queue << ndqi << txq << item);

  // This method is called when a packet is discarded before being enqueued in the
  // device queue, likely because the queue is full. This should not happen if the
  // device correctly stops the queue. Anyway, stop the tx queue, so that the upper
  // layers do not send packets until there is room in the queue again.

  NS_LOG_ERROR ("BUG! No room in the device queue for the received packet! ("
                << queue->GetNPackets () << " packets and " << queue->GetNBytes () << " bytes inside)");

  ndqi->GetTxQueue (txq)->Stop ();
}

} // namespace ns3

#endif /* NET_DEVICE_QUEUE_INTERFACE_H */