I have developed managed C++ application which return an object of ManagedSubscription
to C# clients.
ManagedSubscription
receives a callback from C# clients, internally makes its own callback to communicate to native C++ code.
While crossing boundaries from native to managed, I observe a crash.
I have put try-catch
in native as well as managed callbacks, but it is not caught.
This is my managed C++ code:
struct NativeCallbackWrapper
{
public:
typedef std::function<bool(const std::vector<Sample>&, bool)> Callback_t;
typedef bool(*CallbackPtr)(const std::vector<Sample>&, bool);
NativeCallbackWrapper(Callback_t callback)
: m_callback(callback)
{
}
~NativeCallbackWrapper()
{
}
const Callback_t m_callback;
};
//Here is decalred variables in ManagedSubscription.h file
typedef std::function<bool(const std::vector<DFS::Chart::Misc::Sample>&, bool)> Callback_t;
typedef bool(*CallbackPtr)(const std::vector<DFS::Chart::Misc::Sample>&, bool);
delegate bool DelegateFunc(const std::vector<DFS::Chart::Misc::Sample>&, bool);
NativeCallbackWrapper *m_nativeCallbackWrapper;
System::Action<TradeResponse, bool>^ m_callback;
DelegateFunc^ m_delegate;
System::Runtime::InteropServices::GCHandle m_delegateHandle;
//This object is returned to C# application
ManagedSubscription::ManagedSubscription(
Action<BidAskResponse, bool>^ callback)
{
m_delegate = gcnew DelegateFunc(this, &ManagedSubscription::OnCallback);
m_delegateHandle = System::Runtime::InteropServices::GCHandle::Alloc(m_delegate);
m_nativeCallbackWrapper = new NativeCallbackWrapper(static_cast<CallbackPtr>(Marshal::GetFunctionPointerForDelegate(m_delegate).ToPointer()));
m_callback = callback;
}
bool ManagedSubscription::OnCallback(const std::vector<Sample>& result, bool disconnected)
{
try
{
m_callback(samplesData, disconnected);
return true;
}
catch (Exception^ ex)
{
return false;
}
catch (Object^ ex)
{
return false;
}
}
//This is given to natice class which actually calls this callback (ManagedSubscription::OnCallback mentioned above)
const ManagedSubscription::Callback_t& ManagedSubscription::GetNativeCallback()
{
return m_nativeCallbackWrapper->m_callback;
}
This is my native C++ code:
bool Publish(const std::vector<SampleType>& samples, bool disconnected)
{
try
{
//This actually calls managed callback (ManagedSubscription::OnCallback)
return m_subscriptionCallback(samples, disconnected);
}
catch (std::exception& e)
{
return false;
}
catch (...)
{
return false;
}
}
This is stack trace of crash:
KERNELBASE!RaiseException+68 cdb52105 00007ffb 00000001
clr!RaiseTheExceptionInternalOnly+33b cdee43f4 00007ffb 00000000
clr!RaiseTheException+a4 cdee4460 00007ffb 00000002
clr!RealCOMPlusThrow+69 cdeb6d72 00007ffb 43d60b70
clr!Thread::RaiseCrossContextException+333 cdcd24cb 00007ffb 2fbadcf8
clr!Thread::DoADCallBack+1a8 cdb69535 00007ffb 2fbade01
clr!UM2MDoADCallBack+b3 cdb681dd 00007ffb 8a988a50
clr!UMThunkStub+26d bc090516 00007ffb 2fbaef70
ManagedChartFeedInterface!DFS::Chart::HistoricalCache::TypedSubscription<DFS::Chart::ChartCache::ForexInstrumentInfo>::Publish+66
First line of stack trace represents call from native code return m_subscriptionCallback(samples, disconnected);
in Publish
mentioned above.
Am I doing anything wrong in marshaling of callback?
Is it something related to App-Domains as client app used app-domain concept?
I got quiet helpful answer from other sites on my same problem: I thought to share this here as well. Here is link for that:
[https://msdn.microsoft.com/en-us/library/367eeye0.aspx][1] says it is not necessary to pin the delegate; the function pointer will remain valid even if the GC relocates the delegate.
In the CoreCLR sources, it looks like Thread::DoADCallBack
calls Thread::RaiseCrossContextException
only via the END_DOMAIN_TRANSITION
macro, after a different exception has been caught. And Thread::DoADCallback
uses that macro only if the application domain does not match.