getCurrentVersionNumber() of VirtualModule crashes due to missing owner

[zenker]

I guess that should not happen when using ApplicationCore in the correct way, but currently my application crashes at this point since owner is a nullptr in my case:

ApplicationCore/include/Module.h

Line 146 in 43b4e47

VersionNumber getCurrentVersionNumber() const override { return _owner->getCurrentVersionNumber(); }

Better throw an exception and if possible give a hint how to solve the problem.

[mhier]

Why does your module not have an owner? What type of module are you talking about?

[zenker]

I found out how the owner is a nullptr. In my ApplicationModule in the mainLoop method I call findTag("SYS").writeAll(). Here findTag will create a VirtualModule:

ApplicationCore/src/EntityOwner.cc

Line 99 in 43b4e47

VirtualModule module{_name, _description, getModuleType()};

This VirtualModule has no owner:

ApplicationCore/include/VirtualModule.h

Line 25 in 43b4e47

: Module(nullptr, name, description), _moduleType(moduleType) {

And finally when writeAll() is called the problem descibed above happens:

ApplicationCore/src/Module.cc

Line 108 in 43b4e47

auto versionNumber = getCurrentVersionNumber();

[mhier]

Ah ok, so we have to somehow override getCurrentVersionNumber() in VirtualModules to obtain the version number properly from the corresponding ApplicationModule.

Btw: findTag() might be very slow. I would recommend running it once at the beginning of mainLoop() and then later only use the VirtualModule to run writeAll() on. I had not foreseen this use case, but it might be nice and handy, so we should support it.

[mhier]

I think this is fixed, but a test is still missing. So the task is to write a small test that writeAll() and readAll() properly work and get/set the version number from the true owner.

[zenker]

I just tested with the master branch and the problem is still present.

[mhier]

Now tracked on redmine: #8361