traffic-control: (merges !121) Add functors for chaining of ECN Mark trace

src/traffic-control/doc/queue-discs.rst

@@ -60,7 +60,7 @@ is stopped. Waking a queue disc is equivalent to make it run.
 Every queue disc collects statistics about the total number of packets/bytes
 received from the upper layers (in case of root queue disc) or from the parent
 queue disc (in case of child queue disc), enqueued, dequeued, requeued, dropped,
-dropped before enqueue, dropped after dequeue, stored in the queue disc and
+dropped before enqueue, dropped after dequeue, marked, and stored in the queue disc and
 sent to the netdevice or to the parent queue disc. Note that packets that are
 dequeued may be requeued, i.e., retained by the traffic control infrastructure,
 if the netdevice is not ready to receive them. Requeued packets are not part
@@ -126,6 +126,7 @@ The base class QueueDisc provides many trace sources:
 * ``Dequeue``
 * ``Requeue``
 * ``Drop``
+* ``Mark``
 * ``PacketsInQueue``
 * ``BytesInQueue``
 

src/traffic-control/model/queue-disc.cc

@@ -360,6 +360,11 @@ QueueDisc::QueueDisc (QueueDiscSizePolicy policy)
       return DropAfterDequeue (item,
                                m_childQueueDiscDropMsg.assign (CHILD_QUEUE_DISC_DROP).append (r).data ());
     };
+  m_childQueueDiscMarkFunctor = [this] (Ptr<const QueueDiscItem> item, const char* r)
+    {
+      return Mark (const_cast<QueueDiscItem *> (PeekPointer (item)),
+                   m_childQueueDiscMarkMsg.assign (CHILD_QUEUE_DISC_MARK).append (r).data ());
+    };
 }
 
 QueueDisc::QueueDisc (QueueDiscSizePolicy policy, QueueSizeUnit unit)
@@ -636,7 +641,7 @@ QueueDisc::AddQueueDiscClass (Ptr<QueueDiscClass> qdClass)
                    "A queue disc with WAKE_CHILD as wake mode can only be a root queue disc");
 
   // set the parent callbacks on the child queue disc, so that it can notify
-  // the parent queue disc of packets enqueued, dequeued or dropped
+  // the parent queue disc of packets enqueued, dequeued, dropped, or marked
   qdClass->GetQueueDisc ()->TraceConnectWithoutContext ("Enqueue",
                                      MakeCallback (&QueueDisc::PacketEnqueued, this));
   qdClass->GetQueueDisc ()->TraceConnectWithoutContext ("Dequeue",
@@ -647,6 +652,9 @@ QueueDisc::AddQueueDiscClass (Ptr<QueueDiscClass> qdClass)
   qdClass->GetQueueDisc ()->TraceConnectWithoutContext ("DropAfterDequeue",
                                      MakeCallback (&ChildQueueDiscDropFunctor::operator(),
                                                    &m_childQueueDiscDadFunctor));
+  qdClass->GetQueueDisc ()->TraceConnectWithoutContext ("Mark",
+                                     MakeCallback (&ChildQueueDiscMarkFunctor::operator(),
+                                                   &m_childQueueDiscMarkFunctor));
   m_classes.push_back (qdClass);
 }
 

src/traffic-control/model/queue-disc.h

@@ -515,6 +515,7 @@ public:
   // Reasons for dropping packets
   static constexpr const char* INTERNAL_QUEUE_DROP = "Dropped by internal queue";    //!< Packet dropped by an internal queue
   static constexpr const char* CHILD_QUEUE_DISC_DROP = "(Dropped by child queue disc) "; //!< Packet dropped by a child queue disc
+  static constexpr const char* CHILD_QUEUE_DISC_MARK = "(Marked by child queue disc) "; //!< Packet marked by a child queue disc
 
 protected:
   /**
@@ -709,6 +710,7 @@ private:
   Ptr<QueueDiscItem> m_requeued;    //!< The last packet that failed to be transmitted
   bool m_peeked;                    //!< A packet was dequeued because Peek was called
   std::string m_childQueueDiscDropMsg;  //!< Reason why a packet was dropped by a child queue disc
+  std::string m_childQueueDiscMarkMsg;  //!< Reason why a packet was marked by a child queue disc
   QueueDiscSizePolicy m_sizePolicy;     //!< The queue disc size policy
   bool m_prohibitChangeMode;            //!< True if changing mode is prohibited
 
@@ -731,6 +733,8 @@ private:
   typedef std::function<void (Ptr<const QueueDiscItem>)> InternalQueueDropFunctor;
   /// Type for the function objects notifying that a packet has been dropped by a child queue disc
   typedef std::function<void (Ptr<const QueueDiscItem>, const char*)> ChildQueueDiscDropFunctor;
+  /// Type for the function objects notifying that a packet has been marked by a child queue disc
+  typedef std::function<void (Ptr<const QueueDiscItem>, const char*)> ChildQueueDiscMarkFunctor;
 
   /// Function object called when an internal queue dropped a packet before enqueue
   InternalQueueDropFunctor m_internalQueueDbeFunctor;
@@ -740,6 +744,8 @@ private:
   ChildQueueDiscDropFunctor m_childQueueDiscDbeFunctor;
   /// Function object called when a child queue disc dropped a packet after dequeue
   ChildQueueDiscDropFunctor m_childQueueDiscDadFunctor;
+  /// Function object called when a child queue disc marked a packet
+  ChildQueueDiscMarkFunctor m_childQueueDiscMarkFunctor;
 };
 
 /**