About select() in multithread - C / C++ / MFC Discussion Boards

Re: win7 & vista's problem

nenfa5-Feb-10 15:24

nenfa

5-Feb-10 15:24

thanks for your advice Smile | :)

Converting TCHAR to LPSTR to be used in CreateProcess [modified]

lazy_panther28-Jan-10 0:57

lazy_panther

28-Jan-10 0:57

Hi,

I need to create a process like

LPTSTR szCmdline[] = TEXT("ffmpeg -i " + ofn.lpstrFile + " -r 1 -ss 00:00:10 -vframes 1 -f image2 " + Buffer + "\\Initframe10.bmp");

For this I will be using CreateProcess API but problem is how to convert TCHAR to a LPTSTR lpCommandLine to be passed to CreateProcess?

ofn.lpstrFile (LPTSTR type) is obtained as outcome of GetOpenFileName API Call and Buffer (TCHAR type) is obtained as GetTempPath.

I get compilation errors which I am not able to fix. (I am new to Win32 programming so this may sound naive).

Can someone please help me in fixing the errors?

Thanks

modified on Thursday, January 28, 2010 7:30 AM

Re: Converting TCHAR to LPSTR to be used in CreateProcess

Rajesh R Subramanian28-Jan-10 1:04

Rajesh R Subramanian

28-Jan-10 1:04

Hi,

I strongly recommend that you read this two part article. It's well worth the time you'll spend:

The Complete Guide to C++ Strings, Part I - Win32 Character Encodings[^]
The Complete Guide to C++ Strings, Part II - String Wrapper Classes[^]

“Follow your bliss.” – Joseph Campbell

Re: Converting TCHAR to LPSTR to be used in CreateProcess

lazy_panther28-Jan-10 1:30

lazy_panther

28-Jan-10 1:30

Thanks, I have gone over first link and is really informative. Thumbs Up | :thumbsup:

I will go over second link now.

Re: Converting TCHAR to LPSTR to be used in CreateProcess

Rajesh R Subramanian28-Jan-10 2:05

Rajesh R Subramanian

28-Jan-10 2:05

I'm glad it helped you. Smile | :)

“Follow your bliss.” – Joseph Campbell

Re: Converting TCHAR to LPSTR to be used in CreateProcess

KingsGambit28-Jan-10 1:06

KingsGambit

28-Jan-10 1:06

WideCharToMultiByte() function can be used for conversion. You can also use a _bstr_t class which has an operator char* which can convert unicode to char*

Re: Converting TCHAR to LPSTR to be used in CreateProcess

Richard MacCutchan28-Jan-10 1:47

Richard MacCutchan

28-Jan-10 1:47

As well as the other suggestions you should study the basics of arrays and pointers in C and how they are used.

MVP 2010 - are they mad?

About select() in multithread

luderjane28-Jan-10 0:10

luderjane

28-Jan-10 0:10

Dear all,

I have a question about Winsock.

My program is a TCP client which manipulates lots of socket connection concurrently.

One socket for each thread.

I use blocking mode at most of time, except creating a new connection to server.

I turn socket into non-blocking mode first, then use select() to check the socket before turning back.

I really don't want to waste time on uncertain blocking timeout and make sure the connection is established in the specific time.

Everything works well when most of server are reachable.

But here comes the question.

If the number of unreachable server increases(more than 5), the rest reachable server will fail on creating connection.

In this case, select() always return 0(means timeout) even though the server is originally reachable.

Here is the portion of my program to create connection:

Open(LPCTSTR addr, int port, DWORD dwTimeout)
{
    _socket = 0;

    SOCKET theSocket;
    int nRet;
    // Store information about the server
    LPHOSTENT lpHostEntry;
    lpHostEntry = gethostbyname(addr); // Specifying server by its name
    if (lpHostEntry == NULL) {
    return;
    }

    // Create the socket
    theSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (theSocket == INVALID_SOCKET) {
        return;
    }

    // Set socket to non-blocking mode
    unsigned long ul = 1;
    nRet = ioctlsocket(theSocket, FIONBIO, (unsigned long*)&ul);
    if (nRet == SOCKET_ERROR) {
        closesocket(theSocket);
        return;
    }

    // Use SOCKADDR_IN to fill in address information
    SOCKADDR_IN saServer;
    saServer.sin_family = AF_INET;
    saServer.sin_addr = *((LPIN_ADDR)*lpHostEntry->h_addr_list);
    // ^ Address of the server being inserted into the address field
    saServer.sin_port = htons(port);

    // Connect to the server
    nRet = connect(theSocket,
                    (LPSOCKADDR)&saServer, // Server address
                    sizeof(struct sockaddr)); // Length of address structure
    if (nRet == SOCKET_ERROR && WSAGetLastError() != WSAEWOULDBLOCK) {
        closesocket(theSocket);
        return;
    }

    struct timeval timeout;
    fd_set r;
    FD_ZERO(&r);
    FD_SET(theSocket, &r);
    timeout.tv_sec = dwTimeout / 1000;
    timeout.tv_usec = (dwTimeout % 1000) * 1000;

    nRet = select(0, 0, &r, 0, &timeout);
    if (nRet <= 0 ) {
        closesocket(theSocket);
        return;
    }

    // Set socket to blocking mode
    ul= 0;
    nRet = ioctlsocket(theSocket, FIONBIO, (unsigned long*)&ul);
    if (nRet == SOCKET_ERROR){
        closesocket(theSocket);
        return;
    }

    _socket = theSocket;
}

Is there anything wrong in this code?

Or any constraint on the number of unreachable socket select() concurrently in multithread?

Re: About select() in multithread

Moak28-Jan-10 8:00

Moak

28-Jan-10 8:00

luderjane wrote:
I use blocking mode at most of time, except creating a new connection to server.

I turn socket into non-blocking mode first, then use select() to check the socket before turning back.

Just an idea, you could use a "master thread" to check for timeouts and close socket handles. This should make threads return from blocking connect() calls if necessary... and you can remove the select-timeout-code (untested).

/M

Webchat in Europe Java | [Coffee]

(only 4K)

Re: About select() in multithread

luderjane1-Feb-10 20:16

luderjane

1-Feb-10 20:16

I wrote a simple testbed to exclude other factor in my program as follows(builds in VC2005, must depends on Ws2_32.lib):

#include <stdio.h>
#include <tchar.h>
#include <Winsock2.h>

typedef struct ServerInfo {
    char sIP[32];
    int iPort;
    DWORD dwTimeout;
    BOOL bPrintable;
} ServerInfo, *pServerInfo;

DWORD WINAPI OpenThreadProc(void* lpParam);
void BlockingOpen(pServerInfo pServer);
void NonBlockingOpen(pServerInfo pServer);

int _tmain(int argc, _TCHAR* argv[])
{
    int iNumOfURServer = 0;
    char sIP[32];
    int iPort = 80;
    DWORD dwTimeout = 5000;
    
    printf("Number of unreachable server: ");
    scanf("%d", &iNumOfURServer);
    printf("Reachable server IP: ");
    scanf("%s", sIP);
    printf("Reachable server port: ");
    scanf("%d", &iPort);
    printf("Timeout(in millisecond, 0 indicates blocking mode): ");
    scanf("%u", &dwTimeout);

    WSADATA wsaData;
    WORD version = MAKEWORD(2,2);
    WSAStartup(version, &wsaData);

    pServerInfo ServerArray = new ServerInfo[iNumOfURServer+1];
    char sURIP[32];

    for (int i = 0; i < iNumOfURServer; i++)
    {
        sprintf(sURIP, "192.168.1.1%02d", i);
        strcpy_s(ServerArray[i].sIP, sURIP);
        ServerArray[i].iPort = 3456;
        ServerArray[i].dwTimeout = dwTimeout;
        ServerArray[i].bPrintable = FALSE;

        CreateThread(NULL, 0, OpenThreadProc, &ServerArray[i], 0, NULL);
    }

    strcpy_s(ServerArray[iNumOfURServer].sIP, sIP);
    ServerArray[iNumOfURServer].iPort = iPort;
    ServerArray[iNumOfURServer].dwTimeout = dwTimeout;
    ServerArray[iNumOfURServer].bPrintable = TRUE;
    CreateThread(NULL, 0, OpenThreadProc, &ServerArray[iNumOfURServer], 0, NULL);

    scanf("%d", &iPort);

    return 0;
}

DWORD WINAPI OpenThreadProc(void* lpParam)
{
    pServerInfo pServer = (pServerInfo)lpParam;
    
    while (true)
    {
        if (pServer->dwTimeout == 0)
        {
            BlockingOpen(pServer);
        } 
        else
        {
            NonBlockingOpen(pServer);
        }
        
        Sleep(1000);
    }

    return 0;
}

void BlockingOpen(pServerInfo pServer)
{
    SOCKET theSocket;
    int nRet;

    //
    // Store information about the server
    //
    LPHOSTENT lpHostEntry;

    lpHostEntry = gethostbyname(pServer->sIP);		// Specifying server by its name
    if (lpHostEntry == NULL) {
       return;
    }

    //
    // Create the socket
    //
    theSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    if (theSocket == INVALID_SOCKET) {
        return;
    }

    //
    // Use SOCKADDR_IN to fill in address information
    //
    SOCKADDR_IN saServer;

    saServer.sin_family = AF_INET;
    saServer.sin_addr = *((LPIN_ADDR)*lpHostEntry->h_addr_list);
    // ^ Address of the server being inserted into the address field
    saServer.sin_port = htons(pServer->iPort);

    //
    // Connect to the server
    //
    DWORD dwStartTime = GetTickCount();
    nRet = connect(theSocket,
        (LPSOCKADDR)&saServer,		// Server address
        sizeof(struct sockaddr));	// Length of address structure
    if (pServer->bPrintable)
    {
        if (nRet == SOCKET_ERROR) 
        {
            printf("%s:%d blocking open failed takes %d ms\n", pServer->sIP, pServer->iPort, 
                      GetTickCount()-dwStartTime);
        }
        else
        {
            printf("%s:%d blocking open successful takes %d ms\n", pServer->sIP, pServer->iPort,  
                      GetTickCount()-dwStartTime);
        }
    }

    closesocket(theSocket);
}

void NonBlockingOpen(pServerInfo pServer)
{
    SOCKET theSocket;
    int nRet;
    //
    // Store information about the server
    //
    LPHOSTENT lpHostEntry;

    lpHostEntry = gethostbyname(pServer->sIP);		// Specifying server by its name
    if (lpHostEntry == NULL) {
        return;
    }

    //
    // Create the socket
    //
    theSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    if (theSocket == INVALID_SOCKET) {
        return;
    }

    // Set socket to non-blocking mode
    //
    unsigned long ul = 1;
    nRet = ioctlsocket(theSocket, FIONBIO, (unsigned long*)&ul);
    if (nRet == SOCKET_ERROR) {
        closesocket(theSocket);
        return;
    }

    // Use SOCKADDR_IN to fill in address information
    //
    SOCKADDR_IN saServer;

    saServer.sin_family = AF_INET;
    saServer.sin_addr = *((LPIN_ADDR)*lpHostEntry->h_addr_list);
    // ^ Address of the server being inserted into the address field
    saServer.sin_port = htons(pServer->iPort);

    // Connect to the server
    //
    nRet = connect(theSocket,
        (LPSOCKADDR)&saServer,		// Server address
        sizeof(struct sockaddr));	// Length of address structure

    if (nRet == SOCKET_ERROR && WSAGetLastError() != WSAEWOULDBLOCK) {
        closesocket(theSocket);
        return;
    }

    struct timeval timeout;
    fd_set r;

    FD_ZERO(&r);
    FD_SET(theSocket, &r);
    timeout.tv_sec = pServer->dwTimeout / 1000;
    timeout.tv_usec = (pServer->dwTimeout % 1000) * 1000;
    DWORD dwStartTime = GetTickCount();
    nRet = select(0, 0, &r, 0, &timeout);
    if (pServer->bPrintable)
    {
        if ( nRet <= 0 ) 
        {
            printf("%s:%d non-blocking open failed takes %d ms\n", pServer->sIP, pServer->iPort, 
                      GetTickCount()-dwStartTime);
        }
        else
        {
            printf("%s:%d non-blocking open successful takes %d ms\n", pServer->sIP, 
                      pServer->iPort, GetTickCount()-dwStartTime);
        }
    }

    closesocket(theSocket);
}

This testbed simply creates multiple thread which opens a socket repeatedly.

There is only one reachable server and the rest are unreachable.

When I use non-blocking mode(timeout = 5000) and 2 unreachable servers, the open procedure takes 0 ms at most of time.

If I gradually increase the number of unreachable server and keep the same timeout, the open procedure takes more and more time.

In the end(about 16 unreachable servers), the open procedure failed every time(except first 5 times).

Even in blocking mode(timeout = 0), the opening time consuming will increase with the number of unreachable server.

There seems to be a constraint on the socket connection in multithread.

But I cannot google any official document about it...

Painting in Win32, MFC and WPF ?

Sameerkumar Namdeo27-Jan-10 23:19

Sameerkumar Namdeo

27-Jan-10 23:19

hello everybody,

Have gone through some application made in WPF and saw their painting means, drawing of controls, image etc..
They were just amazing.
One thing to be asked is how internally they are managing such fast, flicker free painting.
I tried to achieve such kind of optimized painting in Win32 or MFC applications, but to no success.
Please tell me which all points I am missing. Where I should look for concerned resources.

Thanks for your time.

Re: Painting in Win32, MFC and WPF ?

KingsGambit28-Jan-10 0:06

KingsGambit

28-Jan-10 0:06

Following link discusses some commonly used techniques:http://www.catch22.net/tuts/flicker[^]

CDocTemplate labelling a file yesAlreadyOpen after a document close

maycockt27-Jan-10 23:02

maycockt

27-Jan-10 23:02

Hi,

Following on from a question I asked yesterday, I am left with my document being closed and my view being reverted to default (empty) state, but being unable to open the file I was last viewing because the CDocTemplate has the file marked "yesAlreadyOpen".
The file is not open as I read the content of the file and then close it, but a I am uanble to re-view teh file again until I have opened another file and then come back to it.

Is there a flag or reset I need to apply in my OnFileClose function to clear that CDocTemplate flag?
If so, what would would I need to call?

TIA

Tony

Re: CDocTemplate labelling a file yesAlreadyOpen after a document close

Richard MacCutchan28-Jan-10 1:51

Richard MacCutchan

28-Jan-10 1:51

I'm not totally sure of this as I am not a regular user of MFC but you might try looking at RemoveDocument()[^].

MVP 2010 - are they mad?

Re: CDocTemplate labelling a file yesAlreadyOpen after a document close

krmed28-Jan-10 2:47

krmed

28-Jan-10 2:47

Hi again.

I just looked at the code in one of my SDI apps that does not exhibit the problem you're seeing, and I notice in the OnNewDocument function, it uses

if (!CDocument::OnNewDocument())
    return FALSE;

Perhaps you can call that when you close your first document and it might reset your flag.

Hope that helps.

Karl - WK5M
PP-ASEL-IA (N43CS)
PGP Key: 0xDB02E193
PGP Key Fingerprint: 8F06 5A2E 2735 892B 821C 871A 0411 94EA DB02 E193

Problem in loading custom menu

Anu_Bala27-Jan-10 21:31

Anu_Bala

27-Jan-10 21:31

Hi,
In my applcaition the menu is default like
------------------
File. View. Help.
------------------
But i dont want this.I want like
------------------
Applicaitionname
-------------------
To get this,i delete Help menu first and the applcaiton works fine.I delete Statusbar from View,works fine.Then i delete Toolbar from view menu but it shows the assertion error in
atmfc\src\mfc\winmdi.cpp on Line 132.

How can i get my custom menu.
Even i cannot these IDR_MAINFRAME menu and using new IDR_MAINFRAME with my menu.THis also creates same assertion problem.
Pls help me.
Im using VS2008.

Anu

Re: Problem in loading custom menu

KingsGambit28-Jan-10 0:09

KingsGambit

28-Jan-10 0:09

If you are removing resources then you may have to remove some parts of the source code as well which might be using these deleted resources. May be you can debug and check the call stack to see which call leads to the assertion.

Re: Problem in loading custom menu

krmed28-Jan-10 2:32

krmed

28-Jan-10 2:32

I'm going to guess that your application is an MFC MDI app. If that's the case, the MFC framework requires that the main menu MUST contain a minimum of 2 items (Normally File and View).

If you debug your application you should get a Debug Assertion. Click on the retry button and it will take you to the line that caused the problem. In my test case, it's on line 132 of winmdi.cpp (MFC source file). Look at the surrounding code and you'll see

int iMenu = pMenu->GetMenuItemCount() - 2;

// If this assertion fails, your menu bar does not follow the guidelines
// so you will have to override this function and call CreateClient
// appropriately or use the MFC V2 MDI functionality.
ASSERT(iMenu >= 0);

In the comments, it tells you how to handle this - override OnCreateClient.

Hope that helps.

Karl - WK5M
PP-ASEL-IA (N43CS)
PGP Key: 0xDB02E193
PGP Key Fingerprint: 8F06 5A2E 2735 892B 821C 871A 0411 94EA DB02 E193

Deselecting Tree Node Item in MFC

RS.Ratheesh27-Jan-10 19:53

RS.Ratheesh

27-Jan-10 19:53

How to deselect the tree item when clicking outside the tree node (i need to remove focusbox). I used the below code but i failed.

void CEditableView::OnLButtonDown(UINT nFlags, CPoint point)
{

TVHITTESTINFO tvInfo;
CPoint pt;
HTREEITEM m_pOldSel;
GetCursorPos(&pt);
m_treeCtrl.ScreenToClient(&pt);
tvInfo.pt = pt;
UINT uFlags = 1;
UINT flags;
HTREEITEM htItem = m_treeCtrl.HitTest(pt);
if ((htItem != NULL))
{
m_pOldSel = m_treeCtrl.GetSelectedItem();
m_treeCtrl.Select(htItem, TVGN_DROPHILITE);
m_treeCtrl.GetCheck(htItem);
}
else
{
m_treeCtrl.Select(htItem, TVGN_DROPHILITE);
}

CView::OnLButtonDown(nFlags, point);
}

Re: Deselecting Tree Node Item in MFC

David Crow28-Jan-10 3:42

David Crow

28-Jan-10 3:42

ratheeshnair123 wrote:
else
{
m_treeCtrl.Select(htItem, TVGN_DROPHILITE);
}

Why would you do this if htItem is NULL?

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"Man who follows car will be exhausted." - Confucius

How to use library files.

Paulraj G27-Jan-10 19:52

Paulraj G

27-Jan-10 19:52

Hi...

I have to some static library files.

I have added the library name in project setting.

but the library files are not working...

any help will be appriciated...

Thanks...

G.Paulraj

Re: How to use library files.

CPallini27-Jan-10 21:04

CPallini

27-Jan-10 21:04

Paulraj G wrote:
I have added the library name in project setting.

You should:

Add the .lib files as linker input (additional dependecies).
Make Visual Studio aware of the folder(s) wherein such library files are (add the folders in the VC++ directories list).
Include the appropriate headers in your source files.

Paulraj G wrote:
but the library files are not working...

What (the fresh hell) does it mean? Could you, please, be more specific?

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Re: How to use library files.

Nelek27-Jan-10 21:12

Nelek

27-Jan-10 21:12

tsk tsk, you don't know what "files not working" mean? It means, of course, they are playing cards or drinking cooffe insteads of answering the calls of the process and doing their job. Imagine it... they are so lazy that don't even give any error message.

Regards.
--------
M.D.V. Wink | ;)

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
Rating helpfull answers is nice, but saying thanks can be even nicer.

Re: How to use library files.

CPallini27-Jan-10 21:32

CPallini

27-Jan-10 21:32

Re: How to use library files.

Cedric Moonen27-Jan-10 21:47

Cedric Moonen

27-Jan-10 21:47

Those library files, always reading books when they should be working... Roll eyes | :rolleyes:

Cédric Moonen
Software developer

Charting control [v3.0]
OpenGL game tutorial in C++

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