wifi: (fixes #1034) WifiMac::m_macTxDropTrace is fed with packets dropped in the wifi MAC queues

RELEASE_NOTES

@@ -34,6 +34,7 @@ New user-visible features
 
 Bugs fixed
 ----------
+- Bug 1034 - No trace source for packet dropping from WifiMacQueue
 - Bug 2007 - uan: Remove deprecation on SetRxThresholdDb
 - Bug 2214 - tcp: Use of ScheduleNow only in selected part of the code
 - Bug 2221 - network: Remove constraint on size of ns3::Packet Tag objects

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

@@ -352,6 +352,10 @@ ApWifiMac::Enqueue (Ptr<const Packet> packet, Mac48Address to, Mac48Address from
     {
       ForwardDown (packet, from, to);
     }
+  else
+    {
+      NotifyTxDrop (packet);
+    }
 }
 
 void

src/wifi/model/dca-txop.cc

@@ -142,6 +142,23 @@ DcaTxop::SetTxFailedCallback (TxFailed callback)
   m_txFailedCallback = callback;
 }
 
+void
+DcaTxop::SetTxDroppedCallback (TxDropped callback)
+{
+  NS_LOG_FUNCTION (this << &callback);
+  m_txDroppedCallback = callback;
+  m_queue->TraceConnectWithoutContext ("Drop", MakeCallback (&DcaTxop::TxDroppedPacket, this));
+}
+
+void
+DcaTxop::TxDroppedPacket (Ptr<const WifiMacQueueItem> item)
+{
+  if (!m_txDroppedCallback.IsNull ())
+    {
+      m_txDroppedCallback (item->GetPacket ());
+    }
+}
+
 Ptr<WifiMacQueue >
 DcaTxop::GetQueue () const
 {

src/wifi/model/dca-txop.h

@@ -80,6 +80,11 @@ public:
    * packet transmission was failed.
    */
   typedef Callback <void, const WifiMacHeader&> TxFailed;
+  /**
+   * typedef for a callback to invoke when a
+   * packet is dropped.
+   */
+  typedef Callback <void, Ptr<const Packet> > TxDropped;
 
   /**
    * Check for EDCA.
@@ -123,6 +128,11 @@ public:
    * packet transmission was completed unsuccessfully.
    */
   void SetTxFailedCallback (TxFailed callback);
+  /**
+   * \param callback the callback to invoke when a
+   * packet is dropped.
+   */
+  void SetTxDroppedCallback (TxDropped callback);
 
   /**
    * Return the MacLow associated with this DcaTxop.
@@ -382,11 +392,20 @@ protected:
    *         false otherwise.
    */
   virtual bool IsLastFragment (void) const;
+  /**
+   *
+   * Pass the packet included in the wifi MAC queue item to the
+   * packet dropped callback.
+   *
+   * \param item the wifi MAC queue item.
+   */
+  void TxDroppedPacket (Ptr<const WifiMacQueueItem> item);
 
   DcfState *m_dcf; //!< the DCF state
   DcfManager *m_manager; //!< the DCF manager
   TxOk m_txOkCallback; //!< the transmit OK callback
   TxFailed m_txFailedCallback; //!< the transmit failed callback
+  TxDropped m_txDroppedCallback; //!< the packet dropped callback
   Ptr<WifiMacQueue> m_queue; //!< the wifi MAC queue
   MacTxMiddle *m_txMiddle; //!< the MacTxMiddle
   Ptr <MacLow> m_low; //!< the MacLow

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

@@ -59,6 +59,7 @@ RegularWifiMac::RegularWifiMac ()
   m_dca->SetTxMiddle (m_txMiddle);
   m_dca->SetTxOkCallback (MakeCallback (&RegularWifiMac::TxOk, this));
   m_dca->SetTxFailedCallback (MakeCallback (&RegularWifiMac::TxFailed, this));
+  m_dca->SetTxDroppedCallback (MakeCallback (&RegularWifiMac::NotifyTxDrop, this));
 
   //Construct the EDCAFs. The ordering is important - highest
   //priority (Table 9-1 UP-to-AC mapping; IEEE 802.11-2012) must be created
@@ -425,6 +426,7 @@ RegularWifiMac::SetupEdcaQueue (AcIndex ac)
   edca->SetTxMiddle (m_txMiddle);
   edca->SetTxOkCallback (MakeCallback (&RegularWifiMac::TxOk, this));
   edca->SetTxFailedCallback (MakeCallback (&RegularWifiMac::TxFailed, this));
+  edca->SetTxDroppedCallback (MakeCallback (&RegularWifiMac::NotifyTxDrop, this));
   edca->SetAccessCategory (ac);
   edca->CompleteConfig ();
 

src/wifi/model/wifi-mac.cc

@@ -209,7 +209,7 @@ WifiMac::GetTypeId (void)
                      MakeTraceSourceAccessor (&WifiMac::m_macTxTrace),
                      "ns3::Packet::TracedCallback")
     .AddTraceSource ("MacTxDrop",
-                     "A packet has been dropped in the MAC layer before being queued for transmission.",
+                     "A packet has been dropped in the MAC layer before transmission.",
                      MakeTraceSourceAccessor (&WifiMac::m_macTxDropTrace),
                      "ns3::Packet::TracedCallback")
     .AddTraceSource ("MacPromiscRx",