Z21 ClientKernel: do not propagate external changes

Decoder changes caused by Z21 should not be sent back to Z21

server/src/hardware/protocol/z21/clientkernel.cpp

@@ -173,9 +173,18 @@ void ClientKernel::receive(const Message& message)
 
                     if(changed)
                     {
+                      //Set the bool guard for each change
+                      isUpdatingDecoderFromKernel = true;
                       decoder->emergencyStop = isEStop;
+
+                      isUpdatingDecoderFromKernel = true;
                       decoder->direction = dir;
+
+                      isUpdatingDecoderFromKernel = true;
                       decoder->throttle = throttle;
+
+                      //Reset at end
+                      isUpdatingDecoderFromKernel = false;
                     }
 
                     for(int i = 0; i <= maxFunc; i++)
@@ -420,10 +429,23 @@ void ClientKernel::decoderChanged(const Decoder& decoder, DecoderChangeFlags cha
   if(const auto& f = decoder.getFunction(functionNumber))
     funcVal = toTriState(f->value);
 
+  if(isUpdatingDecoderFromKernel)
+  {
+    //This change was caused by Z21 message so there is not point
+    //on informing back Z21 with another message
+    //Skip updating LocoCache again which might already be
+    //at a new value (EventLoop is slower to process callbacks)
+    //But reset the guard to allow Train and other parts of code
+    //to react to this change and further edit decoder state
+    isUpdatingDecoderFromKernel = false;
+    return;
+  }
+
   m_ioContext.post([this, addr, longAddr, direction, throttle, speedSteps, isEStop, changes, functionNumber, funcVal]()
     {
       LanXSetLocoDrive cmd;
       cmd.setAddress(addr, longAddr);
+
       cmd.setSpeedSteps(speedSteps);
       int speedStep = Decoder::throttleToSpeedStep(throttle, cmd.speedSteps());
 

server/src/hardware/protocol/z21/clientkernel.hpp

@@ -119,6 +119,7 @@ class ClientKernel final : public Kernel
     };
 
     std::unordered_map<uint16_t, LocoCache> m_locoCache;
+    bool isUpdatingDecoderFromKernel = false;
 
     InputController* m_inputController = nullptr;
     std::array<TriState, rbusAddressMax - rbusAddressMin + 1> m_rbusFeedbackStatus;