[Mono-dev] DirectFB and Mono

[Csaba Balazs]

Hello,

I minimized the C++ and C# codes. The C++ part inits the DirectFB.

Compiling / Running:

1. g++ -shared -D_REENTRANT -o libprobawrap.so probawrap.cpp
-I/usr/include/glib-2.0/ -I/usr/lib/glib-2.0/include/ -I/usr/include/directfb
-ldirectfb
2. gmcs Proba.cs
3. mono Proba.exe

The C# application inits first the DirectFB (with C++ library), and starts
making with Proba_Function garbage string and printing then to screen. .
If I use the DirectFBCreate command, the whole application fails and 
exit, when
the mono GC starts, usually after 60-70 garbages.

Why can it happen? The sources are enclosed.

Thanks.

Csaba

Proba.cs:
---------------------------------------------------------------------------
using System;
using System.Runtime.InteropServices;

class Proba {

	[DllImport("probawrap")]
	private static extern void proba_init();

	public Proba() {
		proba_init();
	}

	private void Proba_Function() {
		int i = 0;
		while (true) {
			string garbage = "garbage: " + i;
			i++;
			Console.WriteLine("C# Proba_Function - " + garbage);
		}
	}

	public static void Main() {
		Proba proba = new Proba();
		proba.Proba_Function();
	}
}


probawrap.cpp
---------------------------------------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

#include <directfb/directfb.h>
#include <directfb/directfb_version.h>

/* macro for a safe call to DirectFB functions */
#define DFBCHECK(x...) \
      {                                                                \
           err = x;                                                    \
           if (err != DFB_OK) {                                        \
                fprintf( stderr, "%s <%d>:\n\t", __FILE__, __LINE__ ); \
                DirectFBErrorFatal( #x, err );                         \
           }                                                           \
      }

IDirectFB *evas_gui_dfb;

extern "C" {

	void proba_init() {
		DFBResult err;
		int argc = 2;
		char* arg0 = "directfb";
		char* arg1 = "--dfb:system=x11";

		char** argv = new char*[2];
		argv[0] = arg0;
		argv[1] = arg1;

		IDirectFB	      *evas_gui_dfb;

		DFBCHECK( DirectFBInit(&argc, &argv) );
		DFBCHECK( DirectFBCreate(&evas_gui_dfb) );	// <--- problem, if we use

		delete argv;

	}

}

---------------------------------------------------------------------------




Quoting Csaba Balazs <csaba.balazs at researchstudio.at>:

> Hello,
>
> I have found an interesting "bug". I wrote a simple C# sample, which 
> calls a C
> function.
> This C function sets up the DirectFB (DirectFBInit and DirectFBCreate) and
> returns. And whenever the Garbage Collector starts running, it kills 
> the whole
> application.
> I think they somehow interfere, and GC kills the directFB. Has anyone 
> met this
> problem?
> What can be the solution?
>
> Thanks in advance:
>
> Csaba
>
>
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