[child-supervision] remove dummy implementation of child supervision (#6628)

This commit removes dummy implementation of ChildSupervisor and
SupervisionListener. And add macro to ensure that these data members
only exist in ThreadNetif when child supervisor option is enabled. In
particular, ChildSupervisor only exists when child supervisor option
is enabled and it is FTD.

src/core/api/child_supervision_api.cpp

@@ -42,6 +42,8 @@
 
 using namespace ot;
 
+#if OPENTHREAD_FTD
+
 uint16_t otChildSupervisionGetInterval(otInstance *aInstance)
 {
     Instance &instance = *static_cast<Instance *>(aInstance);
@@ -56,6 +58,8 @@ void otChildSupervisionSetInterval(otInstance *aInstance, uint16_t aInterval)
     instance.Get<Utils::ChildSupervisor>().SetSupervisionInterval(aInterval);
 }
 
+#endif
+
 uint16_t otChildSupervisionGetCheckTimeout(otInstance *aInstance)
 {
     Instance &instance = *static_cast<Instance *>(aInstance);

src/core/common/instance.hpp

@@ -780,15 +780,18 @@ template <> inline Sntp::Client &Instance::Get(void)
 }
 #endif
 
+#if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE
+#if OPENTHREAD_FTD
 template <> inline Utils::ChildSupervisor &Instance::Get(void)
 {
     return mThreadNetif.mChildSupervisor;
 }
-
+#endif
 template <> inline Utils::SupervisionListener &Instance::Get(void)
 {
     return mThreadNetif.mSupervisionListener;
 }
+#endif
 
 #if OPENTHREAD_CONFIG_PING_SENDER_ENABLE
 template <> inline Utils::PingSender &Instance::Get(void)

src/core/thread/indirect_sender.cpp

@@ -423,10 +423,12 @@ void IndirectSender::HandleSentFrameToChild(const Mac::TxFrame &aFrame,
 
     VerifyOrExit(mEnabled);
 
+#if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE
     if (aError == kErrorNone)
     {
         Get<Utils::ChildSupervisor>().UpdateOnSend(aChild);
     }
+#endif
 
     // A zero `nextOffset` indicates that the sent frame is an empty
     // frame generated by `PrepareFrameForChild()` when there was no

src/core/thread/mesh_forwarder.cpp

@@ -407,12 +407,16 @@ void MeshForwarder::SetRxOnWhenIdle(bool aRxOnWhenIdle)
     if (aRxOnWhenIdle)
     {
         mDataPollSender.StopPolling();
+#if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE
         Get<Utils::SupervisionListener>().Stop();
+#endif
     }
     else
     {
         mDataPollSender.StartPolling();
+#if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE
         Get<Utils::SupervisionListener>().Start();
+#endif
     }
 }
 
@@ -1111,7 +1115,9 @@ void MeshForwarder::HandleReceivedFrame(Mac::RxFrame &aFrame)
     payload       = aFrame.GetPayload();
     payloadLength = aFrame.GetPayloadLength();
 
+#if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE
     Get<Utils::SupervisionListener>().UpdateOnReceive(macSource, linkInfo.IsLinkSecurityEnabled());
+#endif
 
     switch (aFrame.GetType())
     {

src/core/thread/mesh_forwarder_ftd.cpp

@@ -117,6 +117,7 @@ Error MeshForwarder::SendMessage(Message &aMessage)
         break;
     }
 
+#if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE
     case Message::kTypeSupervision:
     {
         Child *child = Get<Utils::ChildSupervisor>().GetDestination(aMessage);
@@ -124,6 +125,7 @@ Error MeshForwarder::SendMessage(Message &aMessage)
         mIndirectSender.AddMessageForSleepyChild(aMessage, *child);
         break;
     }
+#endif
 
     default:
         aMessage.SetDirectTransmission();

src/core/thread/thread_netif.cpp

@@ -139,8 +139,12 @@ ThreadNetif::ThreadNetif(Instance &aInstance)
     , mSrpServer(aInstance)
 #endif
 
+#if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE
+#if OPENTHREAD_FTD
     , mChildSupervisor(aInstance)
+#endif
     , mSupervisionListener(aInstance)
+#endif
     , mAnnounceBegin(aInstance)
     , mPanIdQuery(aInstance)
     , mEnergyScan(aInstance)

src/core/thread/thread_netif.hpp

@@ -288,11 +288,15 @@ private:
     Srp::Server mSrpServer;
 #endif
 
-    Utils::ChildSupervisor     mChildSupervisor;
+#if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE
+#if OPENTHREAD_FTD
+    Utils::ChildSupervisor mChildSupervisor;
+#endif
     Utils::SupervisionListener mSupervisionListener;
-    AnnounceBeginServer        mAnnounceBegin;
-    PanIdQueryServer           mPanIdQuery;
-    EnergyScanServer           mEnergyScan;
+#endif
+    AnnounceBeginServer mAnnounceBegin;
+    PanIdQueryServer    mPanIdQuery;
+    EnergyScanServer    mEnergyScan;
 
 #if OPENTHREAD_CONFIG_TIME_SYNC_ENABLE
     TimeSync mTimeSync;

src/core/utils/child_supervision.hpp

@@ -85,7 +85,9 @@ namespace Utils {
  *
  */
 
-#if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE && OPENTHREAD_FTD
+#if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE
+
+#if OPENTHREAD_FTD
 
 /**
  * This class implements a child supervisor.
@@ -171,23 +173,7 @@ private:
     uint16_t mSupervisionInterval;
 };
 
-#else // #if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE && OPENTHREAD_FTD
-
-class ChildSupervisor
-{
-public:
-    explicit ChildSupervisor(otInstance &) {}
-    void     Start(void) {}
-    void     Stop(void) {}
-    void     SetSupervisionInterval(uint16_t) {}
-    uint16_t GetSupervisionInterval(void) const { return 0; }
-    Child *  GetDestination(const Message &) const { return nullptr; }
-    void     UpdateOnSend(Child &) {}
-};
-
-#endif // #if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE && OPENTHREAD_FTD
-
-#if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE
+#endif // #if OPENTHREAD_FTD
 
 /**
  * This class implements a child supervision listener.
@@ -262,19 +248,6 @@ private:
     TimerMilli mTimer;
 };
 
-#else // #if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE
-
-class SupervisionListener : private NonCopyable
-{
-public:
-    SupervisionListener(otInstance &) {}
-    void     Start(void) {}
-    void     Stop(void) {}
-    void     SetTimeout(uint16_t) {}
-    uint16_t GetTimeout(void) const { return 0; }
-    void     UpdateOnReceive(const Mac::Address &, bool) {}
-};
-
 #endif // #if OPENTHREAD_CONFIG_CHILD_SUPERVISION_ENABLE
 
 /**