wifi: Implement a WifiMacQueue-specific Flush() method

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

@@ -398,6 +398,17 @@ WifiMacQueue::Remove(Ptr<const WifiMpdu> mpdu)
     return DoRemove(it);
 }
 
+void
+WifiMacQueue::Flush()
+{
+    NS_LOG_FUNCTION(this);
+
+    // there may be some expired MPDUs in the container queue storing MPDUs with expired lifetime,
+    // which will not be flushed by the Flush() method of the base class.
+    WipeAllExpiredMpdus();
+    Queue<WifiMpdu, WifiMacQueueContainer>::Flush();
+}
+
 void
 WifiMacQueue::Replace(Ptr<const WifiMpdu> currentItem, Ptr<WifiMpdu> newItem)
 {

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

@@ -212,6 +212,11 @@ class WifiMacQueue : public Queue<WifiMpdu, ns3::WifiMacQueueContainer>
      */
     Ptr<WifiMpdu> Remove(Ptr<const WifiMpdu> item);
 
+    /**
+     * Flush the queue.
+     */
+    void Flush();
+
     /**
      * Replace the given current item with the given new item. Actually, the current
      * item is dequeued and the new item is enqueued in its place. In this way,