7/6/25

As we have rounded up the message implementation on the template proxy, we can move ahead and do the same in the Vicon driver, as we have a demo coming up soon.

Short recap on getting JSON parameters

TL;DR

• Use .value(key, default) for safety and convenience
• Use contains() to check existence
• For optional/nested keys, combine .value or .contains
• Use .at() or operator[] only if you are sure the key exists => throws if not existing

So our config detect and hardware detect for Vicon are working.

When we try to run, there are still some problems:

• Do a hardware detection 2 times and there are two device threads

A bit of a struggle : communication thread pool

We had a crash closing the engine in the next scenario:

• Start engine, no UI
• Click 'h' to start a hardware detection
• Click 'q' to quit the engine => Boom we had a crash in the Destructor of the CProxyTestDevice that is statically created with NODE_REGISTER.

The reason is this: if we open a TCP communication through a CCommunicationObject (CProxyTestDevice has one through its inheritance from CProxyDevice), then a CCommunicationThread is created that runs a seperate thread to get telegrams and put these on a buffer. The communication object does not own this thread, it only has a std::weak_ptr<CCommunicationThread> to it. The actual owner of the thread is a static map that holds all communication threads for each port:

static std::map<UINT /*port*/, std::shared_ptr<CCommunicationThread>> &getMapThreads()
{
 static std::map<UINT /*port*/, std::shared_ptr<CCommunicationThread>> m_mapThreads;
 return m_mapThreads;
};

The purpose is to have shared threads per port.

The static map offers the next functions:

• AssignCommunicationThread : assigns a thread to a communicationobject, creates one if needed
• CloseCommunicationThread : when the communcation is closed
• CloseAllConnections : should be called in the main shutdown 

So in this case the problems started because of the next sequence:

• Hardwaredetect is called on the static CProxyTestDevice, that goes for all hardware detection
• This opens a communication port and a thread and it remains open
• when quitting the engine the communication on this static CProxyTestDevice is still open, but the map is already gone => boom

Finally these solutions where implemented:

• Communication objects hold a weak pointer to the communication thread, the map has the shared pointer. If the thread was deleted, the weak pointer will remain empty, so we know it is already closed
• Instead of declaring static map, we declared a static map& getStatic (The Phoenix Singleton ) 
• And we also protected the access to the map with a mutex, which was not done yet.
• Also changed in CCommunicationThread from raw CSocket* pointers to smart unique pointer: std::list<std::unique_ptr<CSocket>>

References:

• CCommunicationObject
• • AssignCommunicationThread
  • CloseCommunicationThread
  • CloseAllConnections
• Commit id of this fix bb0b4bae28abb316273f9a3026dd43ba8777bce8