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1.when a thread complete its execution ,can we restart its execution using same handle ?
2.when a thread complete its execution is it cosuming resources?
3.I need to do multiple tasks at the same time ,so I need to work in threads.as i have to repeate these tasks at regular interval so i have to start same threads ,time is critical so i m using multimedia timer to start threads at regular interval .
problem is I have to create a new thread after a regular interval.I think it will consume resources . How could I use same threads to run at regular interval ????????????????
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anilaabc wrote: 1.when a thread complete its execution ,can we restart its execution using same handle ?
I don't think so. Once a thread is finished, it's handle should become invalid.
anilaabc wrote: 2.when a thread complete its execution is it cosuming resources?
Yes. Also when it starts its execution. It has to allocate/deallocate its stack, at least.
anilaabc wrote: 3.I need to do multiple tasks at the same time ,so I need to work in threads.as i have to repeate these tasks at regular interval so i have to start same threads ,time is critical so i m using multimedia timer to start threads at regular interval .
problem is I have to create a new thread after a regular interval.I think it will consume resources . How could I use same threads to run at regular interval ????????????????
AFAIK there's no simple way to do that. You can create a thread that waits for a message or an event, and then executes a task in response to that message (or event). But you have to take care of the communication mechanism yourself.
There is sufficient light for those who desire to see, and there is sufficient darkness for those of a contrary disposition.
Blaise Pascal
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1. AFAIK no
2. After it terminated -unless it leaks memory or GDI resources- no.
3. I think what you could do is to use 1 or 2 events do control your thread (or threads), so your thread routine would look something like this:
HANDLE Events[] = {TerminateEvent, RepeatEvent};
BOOL Continue = TRUE;
while (Continue)
{
switch (WaitForMultipleObjects(2, Events, FALSE, INFINITE))
{
case WAIT_OBJECT_0:
Continue = FALSE;
break;
case WAIT_OBJECT_0 + 1:
continue;
default:
Continue = FALSE;
break;
}
}
The TherminateEvent and RepeatEvent you would create using the CreateEvent API call and signal them from another thread. You would probably need to add some more synchronization too. Does this help?
> The problem with computers is that they do what you tell them to do and not what you want them to do. <
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anilaabc wrote: 1.when a thread complete its execution ,can we restart its execution using same handle ?
No.
anilaabc wrote: 2.when a thread complete its execution is it cosuming resources?
Yes. From the docs:
"The thread object remains in the system until the thread has terminated
and all handles to it have been closed through a call to CloseHandle"
anilaabc wrote: i m using multimedia timer to start threads at regular interval
Is there a reason you can't just use the timer thread?
You may want to look into creating a pool of threads so you don't have to create
and destroy them rapidly.
Mark Salsbery
Microsoft MVP - Visual C++
![Java | [Coffee]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/coffee.gif)
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I could n't understan ...IS timer not execute in the main thread?
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Multimedia timers execute on their own thread.
Mark Salsbery
Microsoft MVP - Visual C++
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I want to do two to three tasks at the same time at regular interval ,time is important so i m using multimedia timer .
problem is ....timer run the thread only once .code is below
when I click button thread is created and multimedia timer is set.
count is an integer initialized with 0.
I suspend thread to resume at regular interval .
void CTimerDlg::Onbtnstart()
{
Thread=AfxBeginThread(ThreadDisplay, this, THREAD_PRIORITY_TIME_CRITICAL,0 ,CREATE_SUSPENDED);
handle=Thread->m_hThread;
Thread->m_bAutoDelete=false;
timeSetEvent(100, 0, TimeProcVideo, (DWORD)this, TIME_PERIODIC);
}
//thread analyzing data
UINT ThreadDisplay(LPVOID lParam)
{
CTimerDlg *obj=(CTimerDlg*) lParam;
obj->abc();
return 1;
}
void CTimerDlg::abc()
{
count++;
char a[20];
GetDlgItem(IDC_STATIC)->SetWindowText("");
CString s=itoa(count,a,10);
GetDlgItem(IDC_STATIC)->SetWindowText(s);
SuspendThread(handle);
}
void CALLBACK TimeProcVideo(UINT uID, UINT uMsg, DWORD dwUser, DWORD dw1, DWORD dw2)
{
CTimerDlg* timer=(CTimerDlg*) dwUser;
timer->ControlThreads();
}
void CTimerDlg::ControlThreads()
{
ResumeThread(handle);
}
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you were given an answer by Roger the first time you asked this question (some 21 hrs ago as I see it). If you cant be bothered answering him/explaining what you're trying to do, dont post the same question again !!!
'g'
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I think you didn't noticed.I modified the question and explained ...
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CStringList *ListData,SetOfList;
ListData = new CStringList;
ListData->AddTail(str1);
ListData->AddTail(str2);
SetOfList.AddTail(ListData1);
ListData = new CStringList;
ListData->AddTail(str1);
ListData->AddTail(str2);
SetOfList.AddTail(ListData2);
ListData = new CStringList;
ListData->AddTail(str1);
ListData->AddTail(str2);
SetOfList.AddTail(ListData3);
...
from code above when finish the program
how can I write the code for delete all allocation memory.
please advise
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Max++ wrote: how can I write the code for delete all allocation memory.
Allocated as shown, you can't.
All your "new"s need to be matched with a "delete". You can't possibly do that
because you overwrite the existing pointers with newly allocated values.
As far as the contents of the lists, the CStringList destuctor will take care of that.
Mark
Mark Salsbery
Microsoft MVP - Visual C++
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Hello folks!
I have a DLL that is loaded into a process, in its DLLMain it starts a thread which does some initialization, creates a window and runs a message loop. This works fine. But when the DLL is unloaded i want to stop the thread cleanly, so what i do is post a certain message using PostThreadMessage (or simply PostMessage to the window) to which the thread is suposed to break the message loop, do cleanup and exit. I (try to) post the message when DLLMain is called with DLL_PROCESS_DETACH and then wait for the thread to terminate. The problem is, by the time DLL_PROCESS_DETACH runs the thread has already been terminated and never got the chanche to do any cleanup by "someone else".
So my question is, how could i terminate the thread cleanly when (before) the DLL is unloaded?
Thanks for any replies in advance.
> The problem with computers is that they do what you tell them to do and not what you want them to do. <
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You really shouldn't be doing that stuff in DLLMain.
It's much safer to add exported initialize and cleanup functions to
the DLL.
More info: DllMain Callback Function[^]
Mark
Mark Salsbery
Microsoft MVP - Visual C++
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Yeah, i know, but the problem is, i have no control over the loading process, so i can't make it call any exported functions in my DLL, all i get is a call to DLLMain upon load and unload. Thanks for the reply, any other ideas maybe?
> The problem with computers is that they do what you tell them to do and not what you want them to do. <
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Maybe you could hook FreeLibrary[^] and if hModule is equal to your DLL post your thread message and then call the original.
Best Wishes,
-David Delaune
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I have thought of that, but that seems a bit overkill to do, but i will keep it in mind, thank you. 
> The problem with computers is that they do what you tell them to do and not what you want them to do. <
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You did not mention when your DLL unloads but if the host process is exiting by way of the ExitProcess Function then the first thing that happens is termination of threads. ExitThread is never called, your thread is killed by the TerminateThread Function. Then your DLL is unloaded. At this point your thread is already dead. If you do not have any control ofer the source code/functionality of the host process then there is essentially nothing that you can do. Unless you hook the host process functions of course. Now that I think about it.. hooking FreeLibrary will get you nowhere. ExitProcess would perhaps be a better candidate.
Better yet, you could just design your DLL so it doesn't have to do all this crap when forcibly unloaded.
Best Wishes,
-David Delaune
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Code-o-mat wrote: The problem is, by the time DLL_PROCESS_DETACH runs the thread has already been terminated
By what means has the thread been terminated already?
Why not make it so that DLL_PROCESS_DETACH posts the quit message to the window and then the thread cleans up and exits?
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That's exactly what i did, but as said, when i get the DLL_PROCESS_DETACH the thread has already been killed. I think when the process calls FreeLibrary it automatically kills the threads created by the DLL and then calls the DLLMain function. So i guess it won't be possible to terminate the thread in DLLMain. I will have to find another way, thanks for the reply.
> The problem with computers is that they do what you tell them to do and not what you want them to do. <
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Just use an event object to synchronize.
1) Create an event object.
2) During Dll unload process, After posting the message to thread, wait for the event to be signaled.
3) When the thread finishes cleanup, it should signal the event and exit.
4) When the event is signaled, delete the event and just exit.
Does this helps?
Regards,
Jijo.
_____________________________________________________
http://weseetips.com[ ^] Visual C++ tips and tricks. Updated daily.
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I simply use WaitForSingleObject with the handle of the thread after posting the message to wait for its termination. This worked fine in other cases, althorough i never before tried it in a DLL.
> The problem with computers is that they do what you tell them to do and not what you want them to do. <
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There is a variation of the GDI+ Graphics class method "MeasureString" that has an optional parameter "codepointsFitted" that is a pointer to an INT. The documentation states that it is supposed to receive the number of code points that were actually fit into the layout rectangle.
When I try to use this "codepointsFitted" parameter, the INT that is pointed to always has the character count of the input string regardless of whether it indicates that the text bounding rect is larger than the text layout rect.
Has anyone ever gotten this variation of "MeasureString" using the "codepointsFitted" parameter to work? If so, what is the trick to getting that parameter to populate with the correct value?
Status MeasureString(
const WCHAR *string,
INT length,
const Font *font,
const SizeF &layoutRectSize,
const StringFormat *stringFormat,
SizeF *size,
INT *codepointsFitted,
INT *linesFilled
) const;
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Seems to be working fine for me. The layout rect you are passing probably has enough width + height to hold all of your characters. Keep in mind that MeasureString will utilize *all* available space including height. So when it runs out of width it continues to render the text onto the next line. Pass it a HUGE string with a BIG font and see if you get the same results.
My test code:
RectF rSize;
INT iFitted;
INT iLines;
StringFormat format;
format.SetAlignment(StringAlignmentNear);
Font fontBold(L"Arial", 32, FontStyleBold);
CRect rcWin;
GetWindowRect(&rcWin);
RectF rgd(rctWin.left,rctWin.top,rctWin.right,rctWin.top + 32);
graphics.MeasureString(L"Test-Test-Test",-1,&fontBold,rgd,&format,&rSize,&iFitted,&iLines);
I copied and pasted that "Test-Test-Test" string about 20 times back to back to make my string bigger. The function correctly returns how many characers it was able to fit into the rect.
Best Wishes,
-David Delaune
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I thought I had tried everything. You reminded me that I needed one additional tweak to my format flag. I had "StringFormatFlagsNoClip" in there and it was apparently causing the issue.
Thanks for taking the time to help me out. It is greatly appreciated.
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