[mesh-forwarder] update and simplify Counters tracking (#11419)

src/core/thread/indirect_sender.cpp

@@ -516,17 +516,7 @@ void IndirectSender::HandleSentFrameToChild(const Mac::TxFrame &aFrame,
             Get<MeshForwarder>().LogMessage(MeshForwarder::kMessageTransmit, *message, txError, &macDest);
         }
 
-        if (message->GetType() == Message::kTypeIp6)
-        {
-            if (aChild.GetIndirectTxSuccess())
-            {
-                Get<MeshForwarder>().mIpCounters.mTxSuccess++;
-            }
-            else
-            {
-                Get<MeshForwarder>().mIpCounters.mTxFailure++;
-            }
-        }
+        Get<MeshForwarder>().mCounters.UpdateOnTxDone(*message, aChild.GetIndirectTxSuccess());
 
         if (message->GetIndirectTxChildMask().Has(childIndex))
         {

src/core/thread/mesh_forwarder.cpp

@@ -90,6 +90,30 @@ void ThreadLinkInfo::SetFrom(const Mac::RxFrame &aFrame)
 #endif
 }
 
+void MeshForwarder::Counters::UpdateOnTxDone(const Message &aMessage, bool aTxSuccess)
+{
+    if (aMessage.GetType() == Message::kTypeIp6)
+    {
+        aTxSuccess ? mTxSuccess++ : mTxFailure++;
+    }
+}
+
+void MeshForwarder::Counters::UpdateOnRx(const Message &aMessage)
+{
+    if (aMessage.GetType() == Message::kTypeIp6)
+    {
+        mRxSuccess++;
+    }
+}
+
+void MeshForwarder::Counters::UpdateOnDrop(const Message &aMessage)
+{
+    if (aMessage.GetType() == Message::kTypeIp6)
+    {
+        mRxFailure++;
+    }
+}
+
 MeshForwarder::MeshForwarder(Instance &aInstance)
     : InstanceLocator(aInstance)
     , mMessageNextOffset(0)
@@ -112,8 +136,6 @@ MeshForwarder::MeshForwarder(Instance &aInstance)
 {
     mFragTag = Random::NonCrypto::GetUint16();
 
-    ResetCounters();
-
 #if OPENTHREAD_CONFIG_TX_QUEUE_STATISTICS_ENABLE
     mTxQueueStats.Clear();
 #endif
@@ -1303,10 +1325,7 @@ void MeshForwarder::FinalizeMessageDirectTx(Message &aMessage, Error aError)
         aMessage.SetTxSuccess(false);
     }
 
-    if (aMessage.GetType() == Message::kTypeIp6)
-    {
-        aMessage.GetTxSuccess() ? mIpCounters.mTxSuccess++ : mIpCounters.mTxFailure++;
-    }
+    mCounters.UpdateOnTxDone(aMessage, aMessage.GetTxSuccess());
 
     if (aMessage.IsMleCommand(Mle::kCommandDiscoveryRequest))
     {
@@ -1561,12 +1580,7 @@ void MeshForwarder::ClearReassemblyList(void)
     for (Message &message : mReassemblyList)
     {
         LogMessage(kMessageReassemblyDrop, message, kErrorNoFrameReceived);
-
-        if (message.GetType() == Message::kTypeIp6)
-        {
-            mIpCounters.mRxFailure++;
-        }
-
+        mCounters.UpdateOnDrop(message);
         mReassemblyList.DequeueAndFree(message);
     }
 }
@@ -1596,12 +1610,7 @@ bool MeshForwarder::UpdateReassemblyList(void)
         if (now - message.GetTimestamp() >= TimeMilli::SecToMsec(kReassemblyTimeout))
         {
             LogMessage(kMessageReassemblyDrop, message, kErrorReassemblyTimeout);
-
-            if (message.GetType() == Message::kTypeIp6)
-            {
-                mIpCounters.mRxFailure++;
-            }
-
+            mCounters.UpdateOnDrop(message);
             mReassemblyList.DequeueAndFree(message);
         }
     }
@@ -1669,10 +1678,7 @@ Error MeshForwarder::HandleDatagram(Message &aMessage, const Mac::Address &aMacS
 
     LogMessage(kMessageReceive, aMessage, kErrorNone, &aMacSource);
 
-    if (aMessage.GetType() == Message::kTypeIp6)
-    {
-        mIpCounters.mRxSuccess++;
-    }
+    mCounters.UpdateOnRx(aMessage);
 
     aMessage.SetLoopbackToHostAllowed(true);
     aMessage.SetOrigin(Message::kOriginThreadNetif);

src/core/thread/mesh_forwarder.hpp

@@ -163,6 +163,22 @@ class MeshForwarder : public InstanceLocator, private NonCopyable
     friend class TimeTicker;
 
 public:
+    /**
+     * Represents the IPv6 message counters, tracking the number IPv6 message TX and RX that succeeded or failed.
+     */
+    class Counters : public otIpCounters, public Clearable<Counters>
+    {
+        friend class MeshForwarder;
+        friend class IndirectSender;
+
+    private:
+        Counters(void) { Clear(); }
+
+        void UpdateOnTxDone(const Message &aMessage, bool aTxSuccess);
+        void UpdateOnRx(const Message &aMessage);
+        void UpdateOnDrop(const Message &aMessage);
+    };
+
     /**
      * Initializes the object.
      *
@@ -269,12 +285,12 @@ public:
      *
      * @returns A reference to the IP level counters.
      */
-    const otIpCounters &GetCounters(void) const { return mIpCounters; }
+    const Counters &GetCounters(void) const { return mCounters; }
 
     /**
      * Resets the IP level counters.
      */
-    void ResetCounters(void) { ClearAllBytes(mIpCounters); }
+    void ResetCounters(void) { mCounters.Clear(); }
 
 #if OPENTHREAD_CONFIG_TX_QUEUE_STATISTICS_ENABLE
     /**
@@ -642,7 +658,7 @@ private:
 
     TxTask mScheduleTransmissionTask;
 
-    otIpCounters mIpCounters;
+    Counters mCounters;
 
 #if OPENTHREAD_FTD || OPENTHREAD_CONFIG_MAC_CSL_TRANSMITTER_ENABLE
     IndirectSender mIndirectSender;