network: ScheduleNow() not only the wake callback, but also the check on its condition

The wake callback is scheduled "now" to let the flow of operations associated with
dequeue/remove complete before the flow control mechanism is triggered. Move the check on
the conditions for calling the wake callback after the flow of operations is completed
as well, in case the latter affect such conditions.

src/network/utils/net-device-queue-interface.cc

@@ -22,7 +22,6 @@
 #include "ns3/abort.h"
 #include "ns3/queue-item.h"
 #include "ns3/queue-limits.h"
-#include "ns3/simulator.h"
 #include "ns3/uinteger.h"
 
 namespace ns3
@@ -89,7 +88,7 @@ NetDeviceQueue::Wake()
     // Request the queue disc to dequeue a packet
     if (wasStoppedByDevice && !m_wakeCallback.IsNull())
     {
-        Simulator::ScheduleNow(&NetDeviceQueue::m_wakeCallback, this);
+        m_wakeCallback();
     }
 }
 
@@ -142,7 +141,7 @@ NetDeviceQueue::NotifyTransmittedBytes(uint32_t bytes)
     // Request the queue disc to dequeue a packet
     if (wasStoppedByQueueLimits && !m_wakeCallback.IsNull())
     {
-        Simulator::ScheduleNow(&NetDeviceQueue::m_wakeCallback, this);
+        m_wakeCallback();
     }
 }
 

src/network/utils/net-device-queue-interface.h

@@ -25,6 +25,7 @@
 #include "ns3/object-factory.h"
 #include "ns3/object.h"
 #include "ns3/ptr.h"
+#include "ns3/simulator.h"
 
 #include <functional>
 #include <vector>
@@ -361,19 +362,21 @@ void
 NetDeviceQueue::PacketDequeued(QueueType* queue, Ptr<const typename QueueType::ItemType> item)
 {
     NS_LOG_FUNCTION(this << queue << item);
-
-    // Inform BQL
-    NotifyTransmittedBytes(item->GetSize());
-
     NS_ASSERT_MSG(m_device, "Aggregated NetDevice not set");
-    // 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->WouldOverflow(1, m_device->GetMtu()))
-    {
-        Wake();
-    }
+    Simulator::ScheduleNow([=]() {
+        // Inform BQL
+        NotifyTransmittedBytes(item->GetSize());
+
+        // 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->WouldOverflow(1, m_device->GetMtu()))
+        {
+            Wake();
+        }
+    });
 }
 
 template <typename QueueType>