C / C++ / MFC

3-Oct-04 23:51

Hi All,
I am working on a multi-threaded appln.In that I want to create an array of worker threads (like CWinThread *multthreads[maxsize]), which manipulates on some data until i ask them to stop(Using waitForSingle/MultipleObject) PEACEFULLY(not terminating). Say if i may want to stop the thread @ the 5th position.
I am awaiting for your comments
Thanx in advance
SUjan

Neville Franks4-Oct-04 0:11

Neville Franks

4-Oct-04 0:11

I suggest you look at and use http://www.codeproject.com/threads/threadlibrary.asp[^]

Neville Franks, Author of ED for Windows www.getsoft.com and coming soon: Surfulater www.surfulater.com

Sujan Christo4-Oct-04 0:29

4-Oct-04 0:29

Hi Franks,
Thanx 4 the link. I'll look into it.

Sujan Christo4-Oct-04 1:01

4-Oct-04 1:01

Hi Franks,
I tried a dialog based program 4 multithreading. Here i am adding the sourcing which i have created.

#define MAX_CONNECTIONS 5
#include <afxmt.h>
static CWinThread *multthreads[MAX_CONNECTIONS];
static CEvent m_eventShutdown[MAX_CONNECTIONS];
static HANDLE hShutDown[MAX_CONNECTIONS];
static int shutdownWait[MAX_CONNECTIONS];
static int ShutThreadIndex;
int tableCount = 0;

//OnInitDialog
for (int count=0;count<max_connections;count++)
{
hshutdown[count]="NULL;
" shutdownwait[count]="0;
}
hShutDown[0]" =="" wait_object_0;

="" worker="" thread="" function
uint="" dataaccessthreading(lpvoid="" pparam)
{

="" dword="" dwret="WaitForMultipleObjects(MAX_CONNECTIONS,hShutDown,FALSE," infinite);

="" switch(dwret)
="" {
="" case="" wait_timeout:
="" break;
="" wait_failed:
="" while="" (true)
="" trace1("\ncaching="" 0x%x="" ",getcurrentthreadid());
="" switch(::waitforsingleobject(m_eventshutdown[shutthreadindex].m_hobject,shutdownwait[shutthreadindex]))
="" wait_object_0:
="" this="" is="" what="" we="" want="" to="" happen.
="" trace("wait_object_0");
="" break;

="" wait_timeout:="" something="" bad="" happened="" -="" force="" the="" termination
="" trace("timeout");
="" ::terminatethread(*i,="" 1);
="" wait_abandoned:="" has="" been="" terminated="" already!?="" maybe...
="" trace("wait_abandoned");
="" default:
="" trace("other");
="" }

="" sleep(2000);
="" trace("exit="" \n");
="" wait_object_0="" +="" 1:
="" trace("userobject="" trace("defalut="" }
=""
="" return="" 0;
}

="" start="" a="" i="" am="" using
void="" cmultitestingdlg::onbuttonstart()
{
="" multthreads[0]="AfxBeginThread(DataAccessThreading,p,0,0,CREATE_SUSPENDED);
" multthreads[0]-="">m_bAutoDelete = FALSE;
multthreads[0]->ResumeThread();
hShutDown[1] = multthreads[0]->m_hThread;
}

//To Shutdown the thread i am using
void CMultiTestingDlg::ShutdownThread(int i)
{
ShutThreadIndex = i;
shutdownWait[ShutThreadIndex] = INFINITE;
m_eventShutdown[ShutThreadIndex].SetEvent();
TRACE1("\nShutdown Index %d\n",i);
}
The problem i am facing is, when i give shutdownthread, sometimes it is closing the correct thread, sometimes it is not closing the correct thread.
PLEASE HELP ME. AM I GOING ON THE RIGHT DIRECTION.
SORRY FOR TROUBLING YOU MUCH.
THANX IN ADVANCE
Sujan

Neville Franks4-Oct-04 2:40

Neville Franks

4-Oct-04 2:40

All thread functions DataAccessThreading() are accessing the same global data and they don't know which instance of the thread they are. So the first thread to check eventShutdown[ShutThreadIndex] which see it and behave as requested.

I would wrap:

static CWinThread *multthreads[MAX_CONNECTIONS];
static CEvent m_eventShutdown[MAX_CONNECTIONS];
static HANDLE hShutDown[MAX_CONNECTIONS];
static int shutdownWait[MAX_CONNECTIONS];
static int ShutThreadIndex;

in a class and create an array of these. The pass the array instance address into the DataAccessThreading() function. Each thread knows which intance it is and only needs to check its specific eventShutdown.

Neville Franks, Author of ED for Windows www.getsoft.com and coming soon: Surfulater www.surfulater.com

Thanx a lot Franks

Sujan Christo4-Oct-04 18:27

4-Oct-04 18:27

Dear Franks,
THANX A LOT.
I was literally struggling with this. I'll try as per your suggestion. Incase of need i'll trouble(SORRY 4 that) again.
Moreover i was having a doubt that whether i am going in the right direction.So your reply helps me a lot.
THANX A LOT
Yours
Sujan

Sujan Christo5-Oct-04 0:10

5-Oct-04 0:10

Dear Franks,
I tried by creating a class and used it as you have said, still getting the same problem. Do you have any sample code, which does this. If you do have, will you please post it. I am in deep trouble.
SORRY FOR DISTURBING YOU AGAIN.
if the code is too large you can send it to my mail id also
AWAITING YOUR REPLY
Yours
Sujan

Bob Stanneveld4-Oct-04 4:25

Bob Stanneveld

4-Oct-04 4:25

Hello,

I started a multithreaded application a few weeks ago and I find this[^] class extremely usefull.

Your code would look like this:

<br />
CThread threads[maxsize];<br />
// some code<br />
threads[4].Stop(); // Function Kill also applies...<br />
// more code<br />

Hope this helps..

Multiply it by infinity and take it beyond eternity and you'll still have no idea about what I'm talking about.

Sujan Christo4-Oct-04 21:36

4-Oct-04 21:36

Hi Bob,
Just now only i saw your reply. Thanx, i'll go through the article.
Sujan

Changing color of the Edit box

valikac4-Oct-04 6:29

valikac

4-Oct-04 6:29

What data and how are the threads processing the data?

Kuphryn

Neelesh K J Jain3-Oct-04 23:25

Neelesh K J Jain

3-Oct-04 23:25

Hello Friends,
I want to change the back ground color of the edit box at the time of initialization only. Even though i had used SetBkColor() and the SetBkMode() I couldn't able to change the color of the edit box.

Please help.
Thank you,

Neelesh J Jain.

stopwatch, timer....

marcomars3-Oct-04 23:16

marcomars

3-Oct-04 23:16

Hello,
my mfc application is performing a time consuming operation.

Before this I want to prompt the user with an approximate estimate of the execution time.

For this my idea was to execute some (eg 100) cycles, get the elapsed time
and multiply this for the number of total needed executions.

In MATLAB (for MATLAB users) it would be a simple tic - toc command.

Is there something similar for VC++?

Or do you have an idea for another approach?

Thanks,
Marco.

Re: stopwatch, timer....

Neville Franks4-Oct-04 0:24

Neville Franks

4-Oct-04 0:24

Have a look at the CRT function clock(). A quick Google located:

http://msdn.microsoft.com/msdnmag/issues/04/09/CQA/default.aspx[^]

which should head you in the right direction. Also search CP for performance monitoring code.

And maybe profile you code to speed it up as much as possible. Smile | :)

Neville Franks, Author of ED for Windows www.getsoft.com and coming soon: Surfulater www.surfulater.com

Re: stopwatch, timer....

David Crow4-Oct-04 4:09

David Crow

4-Oct-04 4:09

marcomars wrote:
my mfc application is performing a time consuming operation.

Estimations aside, can you put this time-consuming operation in a separate thread? That way, no matter how long it takes or how off your estimations are, your main UI thread is not being blocked and remains responsive.

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

BYTE array and lists

mcsherry3-Oct-04 23:01

mcsherry

3-Oct-04 23:01

Hi,

My program needs to take a pointer to BYTE array (unsigned char*) and convert it into a STL list so that each BYTE in the array has its own element in the list, i.e. if the array has hundred bytes then the list needs to have a hundred entries, at present when I try to do this each element in my list points to the entire BYTE array, when what I really need is copies of each single BYTE in its own part of the list.

Does anyone know how I can do this?

cheers,
Andy

Antony M Kancidrowski4-Oct-04 0:37

Antony M Kancidrowski

4-Oct-04 0:37

You could have something like

std::list<char> m_STLList;
for (int nByteCount = 0; nByteCount < entries_in_array; nByteCount++)
{
  char* pByte = (pByteArray + nByteCount);
  m_STLList.push_back(*pByte);
}

Hope this helps

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)

mcsherry4-Oct-04 2:32

mcsherry

4-Oct-04 2:32

cheers Ant for your reply. Unfortunatly when I use:

char* pByte = (pByteArray + nByteCount);

all I get is pByte pointing to the actual data in memory instead of making a copy of that particular byte.

Andy,

Antony M Kancidrowski4-Oct-04 3:52

Antony M Kancidrowski

4-Oct-04 3:52

It is the line that adds it to the list that makes the copy (notice the *pByte)

m_STLList.push_back(*pByte);

if you like it can be changed to

char Byte = *(pByteArray + nByteCount);
m_STLList.push_back(Byte);

char Byte = pByteArray[nByteCount];
m_STLList.push_back(Byte);

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)

mcsherry4-Oct-04 4:30

mcsherry

4-Oct-04 4:30

Hi Ant,

I see what you mean now (I'm being a bit dense today! Dead | X|

)