wifi: WifiMacQueue needs to override some QueueBase methods

src/wifi/model/dca-txop.cc

@@ -240,7 +240,7 @@ DcaTxop::RestartAccessIfNeeded (void)
 {
   NS_LOG_FUNCTION (this);
   if ((m_currentPacket != 0
-       || m_queue->HasPackets ())
+       || !m_queue->IsEmpty ())
       && !m_dcf->IsAccessRequested ())
     {
       m_manager->RequestAccess (m_dcf);
@@ -252,7 +252,7 @@ DcaTxop::StartAccessIfNeeded (void)
 {
   NS_LOG_FUNCTION (this);
   if (m_currentPacket == 0
-      && m_queue->HasPackets ()
+      && !m_queue->IsEmpty ()
       && !m_dcf->IsAccessRequested ())
     {
       m_manager->RequestAccess (m_dcf);
@@ -360,7 +360,7 @@ bool
 DcaTxop::NeedsAccess (void) const
 {
   NS_LOG_FUNCTION (this);
-  return m_queue->HasPackets () || m_currentPacket != 0;
+  return !m_queue->IsEmpty () || m_currentPacket != 0;
 }
 
 void
@@ -369,7 +369,7 @@ DcaTxop::NotifyAccessGranted (void)
   NS_LOG_FUNCTION (this);
   if (m_currentPacket == 0)
     {
-      if (!m_queue->HasPackets ())
+      if (m_queue->IsEmpty ())
         {
           NS_LOG_DEBUG ("queue empty");
           return;

src/wifi/model/edca-txop-n.cc

@@ -153,7 +153,7 @@ bool
 EdcaTxopN::NeedsAccess (void) const
 {
   NS_LOG_FUNCTION (this);
-  return m_queue->HasPackets () || m_currentPacket != 0 || m_baManager->HasPackets ();
+  return !m_queue->IsEmpty () || m_currentPacket != 0 || m_baManager->HasPackets ();
 }
 
 uint16_t EdcaTxopN::GetNextSequenceNumberFor (WifiMacHeader *hdr)
@@ -186,7 +186,7 @@ EdcaTxopN::NotifyAccessGranted (void)
   m_startTxop = Simulator::Now ();
   if (m_currentPacket == 0)
     {
-      if (!m_queue->HasPackets () && !m_baManager->HasPackets ())
+      if (m_queue->IsEmpty () && !m_baManager->HasPackets ())
         {
           NS_LOG_DEBUG ("queue is empty");
           return;
@@ -724,7 +724,7 @@ EdcaTxopN::RestartAccessIfNeeded (void)
 {
   NS_LOG_FUNCTION (this);
   if ((m_currentPacket != 0
-       || m_queue->HasPackets () || m_baManager->HasPackets ())
+       || !m_queue->IsEmpty () || m_baManager->HasPackets ())
       && !m_dcf->IsAccessRequested ())
     {
       Ptr<const Packet> packet;
@@ -765,7 +765,7 @@ EdcaTxopN::StartAccessIfNeeded (void)
 {
   //NS_LOG_FUNCTION (this);
   if (m_currentPacket == 0
-      && (m_queue->HasPackets () || m_baManager->HasPackets ())
+      && (!m_queue->IsEmpty () || m_baManager->HasPackets ())
       && !m_dcf->IsAccessRequested ())
     {
       Ptr<const Packet> packet;

src/wifi/model/wifi-mac-queue.cc

@@ -403,7 +403,7 @@ WifiMacQueue::GetNPacketsByTidAndAddress (uint8_t tid, WifiMacHeader::AddressTyp
 
 template<>
 bool
-WifiMacQueue::HasPackets (void)
+WifiMacQueue::IsEmpty (void)
 {
   NS_LOG_FUNCTION (this);
 
@@ -411,12 +411,46 @@ WifiMacQueue::HasPackets (void)
     {
       if (!TtlExceeded (it))
         {
-          NS_LOG_DEBUG ("returns true");
-          return true;
+          NS_LOG_DEBUG ("returns false");
+          return false;
         }
     }
-  NS_LOG_DEBUG ("returns false");
-  return false;
+  NS_LOG_DEBUG ("returns true");
+  return true;
+}
+
+template<>
+uint32_t
+WifiMacQueue::GetNPackets (void)
+{
+  NS_LOG_FUNCTION (this);
+
+  // remove packets that stayed in the queue for too long
+  for (auto it = Head (); it != Tail (); )
+    {
+      if (!TtlExceeded (it))
+        {
+          it++;
+        }
+    }
+  return QueueBase::GetNPackets ();
+}
+
+template<>
+uint32_t
+WifiMacQueue::GetNBytes (void)
+{
+  NS_LOG_FUNCTION (this);
+
+  // remove packets that stayed in the queue for too long
+  for (auto it = Head (); it != Tail (); )
+    {
+      if (!TtlExceeded (it))
+        {
+          it++;
+        }
+    }
+  return QueueBase::GetNBytes ();
 }
 
 NS_OBJECT_TEMPLATE_CLASS_DEFINE (WifiQueue,WifiMacQueueItem);

src/wifi/model/wifi-mac-queue.h

@@ -284,13 +284,27 @@ public:
   uint32_t GetNPacketsByTidAndAddress (uint8_t tid,
                                        WifiMacHeader::AddressType type,
                                        Mac48Address addr);
+
   /**
-   * This method must be used (instead of the IsEmpty method of the base class)
-   * to check whether there are packets with unexpired time to live in the queue
+   * \return true if the queue is empty; false otherwise
    *
-   * \return true if there are packets with unexpired time to live
+   * Overrides the IsEmpty method provided by QueueBase
    */
-  bool HasPackets (void);
+  bool IsEmpty (void);
+
+  /**
+   * \return The number of packets currently stored in the Queue
+   *
+   * Overrides the GetNPackets method provided by QueueBase
+   */
+  uint32_t GetNPackets (void);
+
+  /**
+   * \return The number of bytes currently occupied by the packets in the Queue
+   *
+   * Overrides the GetNBytes method provided by QueueBase
+   */
+  uint32_t GetNBytes (void);
 
 private:
   /**
@@ -307,6 +321,11 @@ private:
   DropPolicy m_dropPolicy;                  //!< Drop behavior of queue
 };
 
+/// Forward declare overridden methods to avoid specializing after instantiation
+template<> bool WifiQueue<WifiMacQueueItem>::IsEmpty (void);
+template<> uint32_t WifiQueue<WifiMacQueueItem>::GetNPackets (void);
+template<> uint32_t WifiQueue<WifiMacQueueItem>::GetNBytes (void);
+
 /// Declare WifiMacQueue as a specialization of template class WifiQueue
 typedef WifiQueue<WifiMacQueueItem> WifiMacQueue;