C / C++ / MFC

1-Mar-02 6:21

The following is my code:

void CFilerecvDlg::OnStartServer()
{
m_button.EnableWindow(false);
CString s_name;
UINT port;
try {
g_sListen.Create(0);
g_sListen.GetSockName(s_name, port);
g_sListen.Bind(port);
g_sListen.Listen();
AfxBeginThread(ServerThreadProc, GetSafeHwnd());
}
catch(CException* e) {
e->Delete();
}
}

UINT ServerThreadProc(LPVOID pParam)
{
CSocket sConnect;
g_sListen.Accept(sConnect);
TRACE ("\nSocket connetced\n");
sConnect.Detach();
sConnect.Close();
return 0;
}

The run fails... A message is issued tellin something like "Thread 0x5425.. has exited with code -1. Memory leak detected!...". g_sListen is a global CSocket variable (in my serverdlg.cpp file). There are no warnings or errors at compile time...
Can anyone tell me where is my mistake???

"Needless redundancy is the hobgoblin of software engineering." - Peter Darnell

Nish Nishant1-Mar-02 6:26

Nish Nishant

1-Mar-02 6:26

Vladimir Georgiev wrote:
sConnect.Detach();
sConnect.Close();

When you detach, the underlying SOCKET is detached from your CSocket object and it's m_hSocket is cleared. This itself is a leak of sorts as you dont seem to be closesocket()-ing the detached SOCKET anywhere.

Nish

It's seven o'clock
On the dot
I'm in my drop top
Cruisin' the streets - Oh yeah
I got a real pretty, pretty little thing that's waiting for me

Vladimir Georgiev1-Mar-02 6:29

1-Mar-02 6:29

UINT ServerThreadProc(LPVOID pParam)
{

CSocket sConnect;

g_sListen.Accept(sConnect);
TRACE ("\nSocket acepted\n");
sConnect.Close();

return 0;
}

there is no TRACE in the debugger also after executing with this piece of code...

"Needless redundancy is the hobgoblin of software engineering." - Peter Darnell

Nish Nishant1-Mar-02 6:37

Nish Nishant

1-Mar-02 6:37

Vladimir

You are not doing this the right way at all.
You are calling GetSockName() on an unconnected socket. That will result in weird results. I suggest that you seriously take up a book and just browse through the basic. It should take you only 10-20 mins to get adjusted to it.

And one piece of advice :- The MFC socket classes are not thread-safe and you can run into all sorts of trouble using them. As far as possible use the native Winsock API.

Nish

It's seven o'clock
On the dot
I'm in my drop top
Cruisin' the streets - Oh yeah
I got a real pretty, pretty little thing that's waiting for me

Jon Hulatt1-Mar-02 7:15

Jon Hulatt

1-Mar-02 7:15

Nish [BusterBoy] wrote:
And one piece of advice :- The MFC socket classes are not thread-safe and you can run into all sorts of trouble using them. As far as possible use the native Winsock API.

This is sort of true, sort of not true. The MFX Socket classes don't work very well multi threaded. But they do work.

However, looks to me like you'd be far better off staying single threaded, but using CAsyncSocket.

Sorry to dissapoint you all with my lack of a witty or poignant signature.

Vladimir Georgiev1-Mar-02 6:31

1-Mar-02 6:31

All the traces lead to this piece of code:

// The same socket better not be blocking in more than one place.
ASSERT(m_pbBlocking == NULL);

_AFX_SOCK_THREAD_STATE* pState = _afxSockThreadState;

ASSERT(pState->m_hSocketWindow != NULL);

BOOL bBlocking = TRUE;
m_pbBlocking = &bBlocking;
CWinThread* pThread = AfxGetThread();
in a socketsomething.cpp

"Needless redundancy is the hobgoblin of software engineering." - Peter Darnell

Vladimir Georgiev1-Mar-02 6:34

1-Mar-02 6:34

ASSERT(pState->m_hSocketWindow != NULL);

this assertion failed... If you can think of something, please post it.

"Needless redundancy is the hobgoblin of software engineering." - Peter Darnell

Nish Nishant1-Mar-02 6:43

Nish Nishant

1-Mar-02 6:43

// this part is okay 
g_sListen.Create(0); 

//not okay. you cannot call this function on 
//an unconnected socket
g_sListen.GetSockName(s_name, port); 
					
//the port you got from the previous call is invalid
//your Bind() call will fail
g_sListen.Bind(port);

//this function fails too cause everything previous to 
//it has also failed
g_sListen.Listen();

Nish

It's seven o'clock
On the dot
I'm in my drop top
Cruisin' the streets - Oh yeah
I got a real pretty, pretty little thing that's waiting for me

how could i keep the value of a specific pointer?

lucy1-Mar-02 8:08

lucy

1-Mar-02 8:08

Hmm, I think the sequence here should be:
g_sListen.Create(0);
g_sListen.Bind(....);
g_sListen.GetSockName();

You can pass NULL to Bind, and let system give you the IP address of local computer as well as assign a free port number to you. Since both are assigned by the system, you want to call GetSockName to retrieve these two parameters.

Gérald Mercet1-Mar-02 3:13

Gérald Mercet

1-Mar-02 3:13

In my dialog app i have 2 functions which use ADO connection to catch value from a database, and which put them into a "C" pointer of pointer and a regular pointer. I want after in a third function use the 2 pointers, which represent some of the input data. As i do it with 3 different button which each of them call one and only one function.

For example the first, called OnLoadCorrel, put a whole matrix into a **pCorrel, the second one called On LoadVol, put a whole array into a *pVol. And, finally, the 3 function use the values needed coming from the matrix and the array. It's at this point of my app that there's a pb, because when i call the third function, the app doesn't recognize (or know) the value into both the pointers (perhaps the value have been lost?!?)

So you could see the following lost, and i hope that soeone could find if what is wron in my app.

/////////////////////////////////////////////////////////
So, in the CalcRiskPortDlg.cpp::

void CCalcRiskPortDlg::OnLoadVol()
{
UpdateData(TRUE);
::CoInitialize(NULL);
LoadTables Table(m_dlgSector);
int i;
// _variant_t IndexCol;
CString strValue;

try
{
_ConnectionPtr pConnection=NULL;
CString strTemp;
strTemp.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\\CalcRiskPort\\vol_correl1.mdb;");
_bstr_t strCnn(strTemp);
TESTHR(pConnection.CreateInstance(__uuidof(Connection)));
pConnection->Open(strCnn,"","",adConnectUnspecified);

_RecordsetPtr pTp("ADODB.Recordset");
try
{

pTp->Open("Volatilité",strCnn,adOpenStatic,adLockOptimistic,adCmdTableDirect);

if(!pTp->EndOfFile)
{
for(i=1;i<=m_dlgSector;i++)
{
pTp->MoveFirst();
pTp->Move(i-1);
//strIndexCol=Table.ConvIntToVar((double)j);
//strIndexCol=strIndexCol+strT;
//_variant_t IndexCol(strIndexCol);
*(Table.pVol+i)=pTp->Fields->GetItem("Volatilité")->Value;
}
}

//dValue=pTp->Fields->GetItem("N° Titre")->Value;
//Parameter2=pTp->Fields->GetItem(IndexColumn)->Value;

pTp->Close();
}
catch(_com_error &e)
{
AfxMessageBox("a pas bon");
}
m_dlgValue=Table.pVol[3];
strValue.Format("%.9f",m_dlgValue);
CEdit* PEdit=(CEdit*)GetDlgItem(IDC_VALUE);
PEdit->SetWindowText(strValue);
//Table.free_dmatrix(Table.pCorrel,1,m_dlgPortWeight,1,m_dlgPortWeight);
pConnection->Close();

}
catch(_com_error &e)
{
AfxMessageBox("a pas bon");
}

::CoUninitialize();

// TODO: Add your control notification handler code here

}

void CCalcRiskPortDlg::OnLoadCorrel()
{
UpdateData(TRUE);
::CoInitialize(NULL);
LoadTables Table(1,m_dlgSector,1,m_dlgSector);
int i,j;
// _variant_t IndexCol;
CString strValue,strT,strIndexCol;
strT="t";

//Table.pCorrel=Table.dmatrix(1,m_dlgPortWeight,1,m_dlgPortWeight);
try
{
_ConnectionPtr pConnection=NULL;
CString strTemp;
strTemp.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\\CalcRiskPort\\vol_correl1.mdb;");
_bstr_t strCnn(strTemp);
TESTHR(pConnection.CreateInstance(__uuidof(Connection)));
pConnection->Open(strCnn,"","",adConnectUnspecified);

_RecordsetPtr pTp("ADODB.Recordset");
try
{

pTp->Open("Correlation",strCnn,adOpenStatic,adLockOptimistic,adCmdTableDirect);

if(!pTp->EndOfFile)
{
for(i=1;i<=m_dlgSector;i++)
{
for(j=1;j<=m_dlgSector;j++)
{
pTp->MoveFirst();
pTp->Move(i-1);
strIndexCol=Table.ConvIntToVar((double)j);
strIndexCol=strIndexCol+strT;
_variant_t IndexCol(strIndexCol);
*(*(Table.pCorrel+i)+j)=pTp->Fields->GetItem(IndexCol)->Value;
}
}
}

//dValue=pTp->Fields->GetItem("N° Titre")->Value;
//Parameter2=pTp->Fields->GetItem(IndexColumn)->Value;

pTp->Close();
}
catch(_com_error &e)
{
AfxMessageBox("a pas bon");
}
m_dlgValue=Table.pCorrel[3][7];
strValue.Format("%.9f",m_dlgValue);
CEdit* PEdit=(CEdit*)GetDlgItem(IDC_VALUE);
PEdit->SetWindowText(strValue);
//Table.free_dmatrix(Table.pCorrel,1,m_dlgPortWeight,1,m_dlgPortWeight);
pConnection->Close();

}
catch(_com_error &e)
{
AfxMessageBox("a pas bon");
}

::CoUninitialize();
// TODO: Add your control notification handler code here

}

void CCalcRiskPortDlg::OnCalcvar()
{
UpdateData(TRUE);
::CoInitialize(NULL);

LoadTables Table;
double Var;
double *pTabVar=new double[pow(2,m_dlgSector)];
CString strValue;

int *pTabBinPort=new int[m_dlgAsset];
int *pTabNumPort=new int[m_dlgAsset];

int k,i;
i=0;

for(k=0;k<=m_dlgAsset-1;k++)
{
*(pTabBinPort+k)=0;

Table.ConvertBinToNum(k,pTabBinPort,pTabNumPort);
}
*pTabVar=Table.CalcVar(pTabNumPort,m_dlgAsset);

for(i=1;i<=pow(2,m_dlgSector);i++)
{
k=m_dlgSector-1;

while(*(pTabBinPort+k)==1)
{
*(pTabBinPort+k)=0;
Table.ConvertBinToNum(k,pTabBinPort,pTabNumPort);
k--;
}
*(pTabBinPort+k)=1;
Table.ConvertBinToNum(k,pTabBinPort,pTabNumPort);

*(pTabVar+i)=Table.CalcVar(pTabNumPort,m_dlgAsset);
}
m_dlgValue=pTabVar[2];
strValue.Format("%.9f",m_dlgValue);
CEdit* PEdit=(CEdit*)GetDlgItem(IDC_VALUE);
PEdit->SetWindowText(strValue);
delete []pTabVar;
delete []pTabNumPort;
delete []pTabBinPort;
::CoUninitialize();

// TODO: Add your control notification handler code here

}
///////////////////////////////////////////////////////////
and for information the LoadTable.cpp code where you could find others function's definitions:

#include "stdafx.h"
#include "CalcRiskPort.h"
#include "LoadTables.h"

#define NR_END 1
#define FREE_ARG char*
#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////
LoadTables::LoadTables()
{

}

LoadTables::LoadTables(long a,long b,long c,long d)
{
//free_dmatrix(pCorrel,a,b,c,d);

pCorrel=dmatrix(a,b,c,d);

}

LoadTables::LoadTables(long a)
{
pVol=NULL;
Delete_pVol();
pVol=new double [a];
}

void LoadTables::Delete_pVol()
{
if(pVol!=NULL)
{
delete[] pVol;
pVol=NULL;
}
}

LoadTables::~LoadTables()
{

}

void LoadTables::nrerror(char error_text[])
{
AfxMessageBox("Ca marche moyen");
exit(1);
}

double **LoadTables::dmatrix(long LowRow,long HighRow,long LowCol,long HighCol)
{
long i, RowSize=HighRow-LowRow+1,ColSize=HighCol-LowCol+1;

double **m;

m=(double **)malloc((size_t)((RowSize+NR_END)*sizeof(double*)));
if(!m)nrerror("pb allocation1 in matrix()");

m +=NR_END;
m -=LowRow;

m[LowRow]=(double *)malloc((size_t)((RowSize*ColSize+NR_END)*sizeof(double)));
if(!m[LowRow])nrerror("pb allocation2 in matrix()");

m[LowRow] +=NR_END;
m[LowRow] -=LowCol;

for(i=LowRow+1;i<=HighRow;i++)
m[i]=m[i-1]+ColSize;

return m;
}

void LoadTables::free_dmatrix(double **m,long LowRow,long HighRow,long LowCol,long HighCol)
{

free((FREE_ARG)(m[LowRow]+LowCol-NR_END));
free((FREE_ARG)(m+LowRow-NR_END));

}

CString LoadTables::ConvIntToVar(double j)
{
CString strIndexCol;
int decimal,sign;

strIndexCol=_fcvt(j,0,&decimal,&sign);

//_variant_t IndexCol(strIndexCol);

return strIndexCol;

}

double LoadTables::ReturnValue(long Row,_variant_t IndexCol, _variant_t ParamTable)
{

double dValue;
CString strTemp;
strTemp.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\\CalcRiskPort\\vol_correl1.mdb;");
_bstr_t strcnn(strTemp);
_RecordsetPtr pTp("ADODB.Recordset");

try
{
pTp->Open(ParamTable,strcnn,adOpenStatic,adLockOptimistic,adCmdTableDirect);
pTp->MoveFirst();
pTp->Move(Row-1);
if(!pTp->EndOfFile)
dValue=pTp->Fields->GetItem(IndexCol)->Value;
//dValue=pTp->Fields->GetItem("N° Titre")->Value;
//Parameter2=pTp->Fields->GetItem(IndexColumn)->Value;

pTp->Close();

}

catch(_com_error &e)
{

AfxMessageBox("Table non atteinte");
pTp->Close();

}

return dValue;

}

double LoadTables::CalcVar(int* pTabNumPort,int NbOfAsset)
{
int i,j;
double sum1,sum2,sum;

sum=sum1=sum2=0;

for(i=1,j=0;i<=NbOfAsset,j

Net Send Message

1-Mar-02 0:21

Hi,

I want to create a Winpopup type in VC Dialog Based one.
How to send a message from one system to anothere system.

Regards,
Mani.

Guarding delete

Joe Moldovan28-Feb-02 23:49

Joe Moldovan

28-Feb-02 23:49

Does anyone know of a way to guard a delete operator from trying to release a non-allocated block, as in the following trivial example.

short x[ 100 ];

try
{
delete []x;
}

catch( ... )
{
return MDERROR;
}

This does not work as the exception is caught somewhere in the bowels of the system and I get either an assert or a user breakpoint box. I have looked at RTTI but it doesn't help me. How can I prevent a crash if I'm passed a pointer to a global or static block?

Thanks all!

Joaquín M López Muñoz1-Mar-02 0:35

Joaquín M López Muñoz

1-Mar-02 0:35

This function determines whether a given pointer belongs in the stack or not:

bool is_stack_memory(void * p)
{
  char check;
  MEMORY_BASIC_INFORMATION m1,m2;
 
  ::ZeroMemory(&m1,sizeof(m1));
  ::ZeroMemory(&m2,sizeof(m2));
  ::VirtualQuery(p,&m1,sizeof(m1));
  ::VirtualQuery(&check,&m2,sizeof(m2));
 
  return m1.BaseAddress==m2.BaseAddress;
}

So you can write code like

if(is_stack_memory(x)){
  printf("x has not been dynamically allocated\n");
  return MDERROR; // or whatever
}
else{
  delete [] x;
}

Anyway, IMHO designing functions around this feature is not a very good idea. I'd restrict the ability to determine whether a pointer is deleteable to doing error checking in debug mode.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

PS: There's a limitation in is_stack_memory, namely that it fails to identify pointers on other threads' stacks. This could be worked around, however.

Jon Hulatt1-Mar-02 4:12

Jon Hulatt

1-Mar-02 4:12

or, if you ALWAYS init pointers to NULL, and ALWAYS reset them to NULL after delete, like I do, then:

if (pointer)
  delete [] pointer;
pointer = NULL;

Sorry to dissapoint you all with my lack of a witty or poignant signature.

Le centriste1-Mar-02 5:02

Le centriste

1-Mar-02 5:02

If I were you, I would review my design. By this I mean that an object shouldn't deallocate memory it didn't allocate (which is obviously the case here since your object can't figure out if it is stack or heap memory), unless you have a good reason.

If I am wrong or said something stupid, I apologize in advance Wink | ;)

Michel

Joe Moldovan1-Mar-02 11:56

Joe Moldovan

1-Mar-02 11:56

Thanks for your thoughts. I didn't design or write this stuff. I'm only trying to wrap an audio interface I got pre-cooked. I watch my own new's and delete's like a hawk and always have the leakage detector on.

The bit about nulling the pointer is very good (simple and obvious) and will be standard in my code from now on.

I do however find it strange that delete doesn't throw a catchable exception. There must be a good reason for it. I will try it on Linux and see if it tells me why.

Timers are as threads? (newbie)

Mukkie1-Mar-02 12:06

Mukkie

1-Mar-02 12:06

Hi!

Try using:

__try
{
}
__except(1)
{
}

Mukkie

Joan M28-Feb-02 22:18

Joan M

28-Feb-02 22:18

Hello,

First of all let me thank you for reading my question.

QUESTION:
Hello, I have a program that has one WM_TIMER missage (SetTimer...), This message is redistributed to some of my classes via SendMessage(...).

I know that postmessage differs from sendmessage in the fact that postmessage waits for the message to return, and sendmessage don't waits.

Do the messages that I redistribute work at the same time?

The problem is that all of them call functions in a non-thread safe DLL. (that I have not linked and I don't have the code).

As always thank you for your help.

Joaquín M López Muñoz28-Feb-02 23:41

Joaquín M López Muñoz

28-Feb-02 23:41

No, timers aren't like threads. They are just regular messages processed in the same way as the rest. Think of the sending of WM_TIMER as if an external user makes the timing by himself and then clicks on a button to generate the message. No threading problems, right?

You can apply a simple sanity check: If you don't have explicitly created any thread with AfxBeginThread, CreateThread or _beginthread(ex), then your program is single-threaded and you just cannot suffer any threading problem.
In a single-threaded Windows app, all of your messages are driven by a unique message pump, which in fact serializes message processing. Two situations can arise:

If you broadcast your message in your OnTimer handler with SendMessages, then each SendMessage executes directly (rather than thru the message pump) and completely. So, no concurrency problems here.
If you do the broadcasting with PostMessages, all the messages get queued and are serially executed by the message pump. No problem either.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Steen Krogsgaard1-Mar-02 3:34

Steen Krogsgaard

1-Mar-02 3:34

Although Joaquin has already answered your question I just want to emphasized that you have gotten the SendMessage/PostMessage difference all backwards.

SendMessage is synchronous, meaning that the function calling SendMessage will be blocked until SendMessage returns (as if SendMessage was just another C++ function)

PostMessage is asynchronous, and basically it just puts you message on the receiving window's message queue. However, the handler of the posted message will not be called until the function calling PostMessage returns control to Windows (this is usually done in the message pump through calls to GetMessage/PeekMessage).

Cheers
Steen.

"To claim that computer games influence children is rediculous. If Pacman had influenced children born in the 80'ies we would see a lot of youngsters running around in dark rooms eating pills while listening to monotonous music"

Joan M1-Mar-02 4:54

Joan M

1-Mar-02 4:54

I have a question then... (sorry for that).

The program that I'm talking about is a Numerical Control, then I need to ask for the coordinates of the machine and to look for possible errors that could have happened, and so on... (also I have to be able to send information to the DLL that allow me to retrieve and to send data to the Numerical Control Interface DLL).

I want this process to be as fastest as it can, and I have written a WM_TIMER message that is sent to everywhere in wich requiring data is needed: getting coordinates, errors, status...

The WM_TIMER handler is called each 10 Ms and re-sent to all those places that need the notification.

In this situation I believe that is the same that I use the SendMessage or the PostMessage because at the end I will be asking a lot of times the same information.

Wich one do you think that's the best choice? (SEND or POST)message?

As always thank you very much for your help and attention.