How to correctly use PluginContextFactory::instance().getPluginContext()?

SunshineDreaming · October 9, 2024, 4:01am

I use PluginContextFactory::instance().getPluginContext() for all instances of the plugin (in parallel, module loaded after unloaded, instaniating).
Do I need such a PluginContextFactory instance for each plugin instance independently?
My own VST3-SDK-based host can load VST3 plugins and run them.
The first few times its initialized anything works fine. But when adding/removing instances of the same plugin, it sometimes (not always) crashes on a later instaniating of the plugin instance and I suspected this plugin-context-factor-instance to be the reason.

it crashed here:

github.com

steinbergmedia/vst3_public_sdk/blob/master/source/vst/hosting/plugprovider.cpp#L198


      
          			// ask for the associated controller class ID
          			if (component->getControllerClassId (controllerCID) == kResultTrue)
          			{
          				// create its controller part created from the factory
          				controller = factory.createInstance<IEditController> (VST3::UID (controllerCID));
          				if (controller)
          				{
          					// initialize the component with our context
          					if (auto plugCtrlBase = U::cast<IPluginBase> (controller))
          					{
          						res = (plugCtrlBase->initialize (hostContext) == kResultOk);
          						if (res == false)
          						{
          							printError ([&] (std::ostream& stream) {
          								stream << "Failed to initialize controller of " << classInfo.name ()
          								       << "!\n";
          							});
          						}
          					}
          					else
          					{

SunshineDreaming · October 10, 2024, 4:03am

After lot more testing now it seems that I cannot reproduce the crash anymore. Some unrelated reason maybe resolved after some changes.

So using PluginContextFactory::instance().getPluginContext()
for any instances (of the same and for any plugins) seems to be valid, right?

Yvan · October 10, 2024, 9:37am

the hostContext could be global… maybe there was a refcounting issue… you could secure your hostContext by disabling the refcounting, just overwrite like this:
uint32 PLUGIN_API addRef () override { return 1; }
uint32 PLUGIN_API release () override { return 1; }

SunshineDreaming · October 10, 2024, 9:30pm

Thank you for your answer.

in class HostApplication here in file hostclasses.h I added the 2 lines of your previous post. But the compiler complains:
error C2535: “Steinberg::uint32 Steinberg::Vst::HostApplication::addRef(void)”: member function already defined or declared,
cause its already defined here this way in hostclasses.cpp

So the refcounting seems not to be the reason. Will investigate further, when the crash again occurs. Thanks for your help!