Alexander,
I found something in the lazarus package for vortex :
{ FPC specific thread create function to replace Vortex's thread create.
This is required because FPC doesn't work when C libraries create their own
threads}
This may lead us to a solution I guess.
Some more background about that would be nice. Is this documented anywhere ?
Maik
Alexander Grau schrieb:
Hello Maik!
I have tried out your test program, and I get the crash too. However
your program is already doing 10 things at the same time ;-) - This is
too difficult to find out the real problem - you need to scale down
everything ... So, I have written a minimal test program for you here
to start with - it works for me (no crash), how does it work at your
side?
Regards,
Alexander
program project1;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,
sysutils
{ you can add units after this };
{$R project1.res}
type
MT_THREAD_HANDLE = Pointer;
tdummy = class
name: string;
constructor create(aname: string);
procedure test;
end;
function vcmtdll_NewThread: MT_THREAD_HANDLE; stdcall; external
'vcmtdll.dll';
procedure vcmtdll_DeleteThread(ahandle : MT_THREAD_HANDLE); stdcall;
external 'vcmtdll.dll';
procedure vcmtdll_RegisterCallback(ahandle : MT_THREAD_HANDLE; pCBFunc
: Pointer; pCBData : Pointer); stdcall; external 'vcmtdll.dll';
procedure vcmtdll_StartThread(ahandle : MT_THREAD_HANDLE; iDelay :
Cardinal); stdcall; external 'vcmtdll.dll';
var
handle: MT_THREAD_HANDLE;
constructor tdummy.create(aname: string);
begin
inherited create;
name:=aname;
end;
procedure tdummy.test;
begin
writeln('tdummy.test: ', name);
end;
procedure OnExecuteClb(pCBData : Pointer); cdecl;
var
dummy: tdummy;
i: integer;
begin
writeln('onExecuteClb');
dummy:=tdummy.create('callbackdummy');
tdummy(pCBData).test;
for i:=1 to 30 do
dummy.test();
dummy.free;
end;
var
globaldummy: tdummy;
begin
globaldummy:=tdummy.create('globaldummy');
writeln('start');
Handle := vcmtdll_NewThread();
writeln('handle=', hexStr(handle));
vcmtdll_RegisterCallback(Handle, @OnExecuteClb, globaldummy);
vcmtdll_StartThread(handle, 0);
sleep(1000);
vcmtdll_DeleteThread(handle);
writeln('bye');
globaldummy.free;
end.
Maik Wojcieszak schrieb:
Hi,
After my holiday I've done done more research on this problem and hope I
can get an answer while continuing this thread.
My Versions (again)
Lazarus IDE v0.9.28.2 Beta
MS Windows XP Prof DE sp3
FPC Version 2.2.4
What I basically do is passing a pointer to a calback funtion to a dll
writte in c++ (Visual Studio 2005) and call it from there.
** The follwing code is from the example attached to this mail **
procedure OnExecuteClb(pCBData : Pointer); cdecl;
begin
...
end;
The function is passed to the dll like this
...
FHandle := uVCMTDLL.vcmtdll_NewThread();
uVCMTDLL.vcmtdll_RegisterCallback(FHandle,@OnExecuteClb,self);
...
The test includes a dll which has the following interface
...
#define VCMTDLL_API __declspec(dllexport)
namespace VCMTDLL {
typedef void* MT_THREAD_HANDLE;
extern "C" {
VCMTDLL_API MT_THREAD_HANDLE vcmtdll_NewThread(); // create a new
thread object
VCMTDLL_API void vcmtdll_DeleteThread(MT_THREAD_HANDLE ahandle); //
delete an existing thread object
VCMTDLL_API void vcmtdll_RegisterCallback(MT_THREAD_HANDLE ahandle,
void* pCBFunc, void* pCBData); // pass a callback to execute inside the
thread context
VCMTDLL_API void vcmtdll_StartThread(MT_THREAD_HANDLE ahandle, unsigned
int iDelay); // start the execution with a delay of <iDelay>
milliseconds
}// extern "C"
...
with a loop in the callback function everything is fine
...
x := 0;
while x < 100 do
begin
x := x + 1;
end;
...
I can execute it without problems.
BUT if I create and destroy an object inside the procedure the app
crahes or hangs after several runs of the test (between 1 an 10 starts).
the object:
...
TVCMTDummyObject = class
private
public
Tag : Integer;
end;
...
the code in the callback
...
a := TVCMTDummyObject.Create;
a.Free;
...
Another problem is that a PostMessage from the callback's thread context
immediatly crashes the app. But this may be resolved later.
If there is anybody who uses a similar mechanism in his lazarus project
and knows how to solve this problem it'd be great.
The demo project together with dll is attached too.
Best Regards
Maik
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