Invoke C# delegate asynchronously from unmanaged C++

[Yoni Rabinovitch]

Is it possible to invoke a C# delegate/event handler asynchronously,
from unmanaged C++ ?

I assume this requires a Managed C++ wrapper, which would call
BeginInvoke on the delegate ?

Is this correct, and if so, does anyone have an example ?

Thanks !!

 

[Nicholas Paldino [.NET/C# MVP]]

Yoni,

It is not possible from unmanaged C. You will either have to use the
#pragma managed and #pragma unmanaged directives to enter into managed code
and make the call, or you will have to marshal the delegate as a function
pointer, in which case you would have to call it asynchronously, creating
your own thread, etc, etc. Or, you could export the type as a COM object
and use that, calling the BeginInvoke method yourself.

Hope this helps.

 

[Nicholas Paldino [.NET/C# MVP]]

Assaf,

How are you doing it? Which method are you using?


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Nicholas, maybe i don't understand you,

but, I'm doing it!

However, my app crashes after about 15 minutes of doing it intesively.

I fear that since i am not locking down the manged code in any way,
it gets moved around.
The Unmanaged code not being aware of this change, invokes the Managed code.
However it is using the wrong address. And this leads to a crash -
"ExecutionEngineException".

assaf




in message news:[email protected]...

Yoni,

It is not possible from unmanaged C. You will either have to use the
#pragma managed and #pragma unmanaged directives to enter into managed code
and make the call, or you will have to marshal the delegate as a function
pointer, in which case you would have to call it asynchronously, creating
your own thread, etc, etc. Or, you could export the type as a COM object
and use that, calling the BeginInvoke method yourself.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Is it possible to invoke a C# delegate/event handler asynchronously,
from unmanaged C++ ?

I assume this requires a Managed C++ wrapper, which would call
BeginInvoke on the delegate ?

Is this correct, and if so, does anyone have an example ?

Thanks !!

 

[Guest]

Nicholas, maybe i don't understand you,

but, I'm doing it!

However, my app crashes after about 15 minutes of doing it intesively.

I fear that since i am not locking down the manged code in any way,
it gets moved around.
The Unmanaged code not being aware of this change, invokes the Managed code.
However it is using the wrong address. And this leads to a crash -
"ExecutionEngineException".

assaf

Yoni,

It is not possible from unmanaged C. You will either have to use the
#pragma managed and #pragma unmanaged directives to enter into managed code
and make the call, or you will have to marshal the delegate as a function
pointer, in which case you would have to call it asynchronously, creating
your own thread, etc, etc. Or, you could export the type as a COM object
and use that, calling the BeginInvoke method yourself.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Is it possible to invoke a C# delegate/event handler asynchronously,
from unmanaged C++ ?

I assume this requires a Managed C++ wrapper, which would call
BeginInvoke on the delegate ?

Is this correct, and if so, does anyone have an example ?

Thanks !!

 

[José Joye]

I do not know if I'm off topic. However, I had a crash problem (after a
about 1000 calls) when using a callback from C to C# (having delegate in
C#).
The problem was in the C declaration. Here is a correct sample (watch for
the 2nd WINAPI)

// in C header file:
DLLEXPORT void WINAPI PassExitFnPtr (void (WINAPI * pExit)(int exit_code));



José

Nicholas, maybe i don't understand you,

but, I'm doing it!

However, my app crashes after about 15 minutes of doing it intesively.

I fear that since i am not locking down the manged code in any way,
it gets moved around.
The Unmanaged code not being aware of this change, invokes the Managed code.
However it is using the wrong address. And this leads to a crash -
"ExecutionEngineException".

assaf




in message news:[email protected]...

Yoni,

It is not possible from unmanaged C. You will either have to use the
#pragma managed and #pragma unmanaged directives to enter into managed code
and make the call, or you will have to marshal the delegate as a function
pointer, in which case you would have to call it asynchronously, creating
your own thread, etc, etc. Or, you could export the type as a COM object
and use that, calling the BeginInvoke method yourself.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Is it possible to invoke a C# delegate/event handler asynchronously,
from unmanaged C++ ?

I assume this requires a Managed C++ wrapper, which would call
BeginInvoke on the delegate ?

Is this correct, and if so, does anyone have an example ?

Thanks !!

 

[José Joye]

BTW, I had a second problem as well.
You have to make sure that you keep a live reference to your delegate in
your C# code (this has to be kept as long as the callback could be fired)

José

I do not know if I'm off topic. However, I had a crash problem (after a
about 1000 calls) when using a callback from C to C# (having delegate in
C#).
The problem was in the C declaration. Here is a correct sample (watch for
the 2nd WINAPI)

// in C header file:
DLLEXPORT void WINAPI PassExitFnPtr (void (WINAPI * pExit)(int exit_code));



José

Nicholas, maybe i don't understand you,

but, I'm doing it!

However, my app crashes after about 15 minutes of doing it intesively.

I fear that since i am not locking down the manged code in any way,
it gets moved around.
The Unmanaged code not being aware of this change, invokes the Managed code.
However it is using the wrong address. And this leads to a crash -
"ExecutionEngineException".

assaf




in message news:[email protected]...

Yoni,

It is not possible from unmanaged C. You will either have to use the
#pragma managed and #pragma unmanaged directives to enter into managed code
and make the call, or you will have to marshal the delegate as a function
pointer, in which case you would have to call it asynchronously, creating
your own thread, etc, etc. Or, you could export the type as a COM object
and use that, calling the BeginInvoke method yourself.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Is it possible to invoke a C# delegate/event handler asynchronously,
from unmanaged C++ ?

I assume this requires a Managed C++ wrapper, which would call
BeginInvoke on the delegate ?

Is this correct, and if so, does anyone have an example ?

Thanks !!

 

[Guest]

check this out.
it has some code.

in the visual studio .net:
ms-help://MS.VSCC.2003/MS.MSDNQTR.2003FEB.1033/cpguide/html/cpconcallbacksam
ple.htm

assaf

Assaf,

How are you doing it? Which method are you using?


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Nicholas, maybe i don't understand you,

but, I'm doing it!

However, my app crashes after about 15 minutes of doing it intesively.

I fear that since i am not locking down the manged code in any way,
it gets moved around.
The Unmanaged code not being aware of this change, invokes the Managed code.
However it is using the wrong address. And this leads to a crash -
"ExecutionEngineException".

assaf




in message news:[email protected]...

Yoni,

It is not possible from unmanaged C. You will either have to use the
#pragma managed and #pragma unmanaged directives to enter into managed code
and make the call, or you will have to marshal the delegate as a function
pointer, in which case you would have to call it asynchronously, creating
your own thread, etc, etc. Or, you could export the type as a COM object
and use that, calling the BeginInvoke method yourself.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Is it possible to invoke a C# delegate/event handler asynchronously,
from unmanaged C++ ?

I assume this requires a Managed C++ wrapper, which would call
BeginInvoke on the delegate ?

Is this correct, and if so, does anyone have an example ?

Thanks !!

 

[Guest]

actually your problem sounds very similar to mine.
i am actually running a test now.
with your modification!
if this works, it will end 3 months of chasing this bug.

tnx

assaf

I do not know if I'm off topic. However, I had a crash problem (after a
about 1000 calls) when using a callback from C to C# (having delegate in
C#).
The problem was in the C declaration. Here is a correct sample (watch for
the 2nd WINAPI)

// in C header file:
DLLEXPORT void WINAPI PassExitFnPtr (void (WINAPI * pExit)(int exit_code));



José

Nicholas, maybe i don't understand you,

but, I'm doing it!

However, my app crashes after about 15 minutes of doing it intesively.

I fear that since i am not locking down the manged code in any way,
it gets moved around.
The Unmanaged code not being aware of this change, invokes the Managed code.
However it is using the wrong address. And this leads to a crash -
"ExecutionEngineException".

assaf




in message news:[email protected]...

Yoni,

It is not possible from unmanaged C. You will either have to use the
#pragma managed and #pragma unmanaged directives to enter into managed code
and make the call, or you will have to marshal the delegate as a function
pointer, in which case you would have to call it asynchronously, creating
your own thread, etc, etc. Or, you could export the type as a COM object
and use that, calling the BeginInvoke method yourself.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Is it possible to invoke a C# delegate/event handler asynchronously,
from unmanaged C++ ?

I assume this requires a Managed C++ wrapper, which would call
BeginInvoke on the delegate ?

Is this correct, and if so, does anyone have an example ?

Thanks !!

 

[Leon Finker]

Hello,

Whenever doing p/invoke or interop under .NET 1.1+,
I suggest to use CLR SPY:
http://blogs.gotdotnet.com/anathan/PermaLink.aspx/976d1677-a6d1-4a25-9c7b-8448824b8267

This uses CDP - Customer Debug Probes. More information about these probes
can be found at:
X:\...\SDK\v1.1\Tool Developers Guide\Samples\cdp\Managed\ReadMe.txt
X:\...\SDK\v1.1\Tool Developers Guide\Samples\cdp\

These probes will help you find marshalling related bugs much faster. For
example,
let's say there is a calling convention mismatch. Here is what you can get
with CLR SPY
logging:
"...PInvoke Calling Convention Mismatch in ConsoleApplication.exe...: Stack
imbalance
may be caused by incorrect calling convention for method
TestFunc(win32dll.dll)"

I hope it helps

Nicholas, maybe i don't understand you,

but, I'm doing it!

However, my app crashes after about 15 minutes of doing it intesively.

I fear that since i am not locking down the manged code in any way,
it gets moved around.
The Unmanaged code not being aware of this change, invokes the Managed code.
However it is using the wrong address. And this leads to a crash -
"ExecutionEngineException".

assaf




in message news:[email protected]...

Yoni,

It is not possible from unmanaged C. You will either have to use the
#pragma managed and #pragma unmanaged directives to enter into managed code
and make the call, or you will have to marshal the delegate as a function
pointer, in which case you would have to call it asynchronously, creating
your own thread, etc, etc. Or, you could export the type as a COM object
and use that, calling the BeginInvoke method yourself.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Is it possible to invoke a C# delegate/event handler asynchronously,
from unmanaged C++ ?

I assume this requires a Managed C++ wrapper, which would call
BeginInvoke on the delegate ?

Is this correct, and if so, does anyone have an example ?

Thanks !!

 

[Yoni Rabinovitch]

Thanks, everyone, for your input.

I should have mentioned that a central requirement of mine was to be
able to do this without any DllImport stuff, just straight IJW.

In the end, I found an (albeit convoluted) way of doing this, at
http://www.codeproject.com/managedcpp/cbwijw.asp.

This shows how to synchronously invoke a C# delegate via a callback
from unmanaged C++, without any DllImports.

It is reasonably straightforward to extend this example to cover
asynchronous invocation (BeginInvoke...EndInvoke).

 

[José Joye]

I'm not too clear with what you said. To me, IJW is not available to C#.
Only to managed C++.
Am I wrong?

José

 

[Yoni Rabinovitch]

I'm not too clear with what you said. To me, IJW is not available to C#.
Only to managed C++.
Am I wrong?

No, you're right. However, what I meant is that I have unmanaged C++,
which I wrap with managed C++. The C# is only "aware" of the managed
C++.

Now, essentially what I'm doing is to get the unmanaged C++ to
callback the C# delegate asynchronously, without using any DllImports
in the plumbing for all this.