Re: Passing message to thread - C / C++ / MFC Discussion Boards

Samrah Saulat Mirza28-Jun-03 5:51

28-Jun-03 5:51

Firends i am having a problem and i like your advice in this regard. I would appreciate the non-MFC answer.

I've a thread. The purpose of this thread is to read string from somewhere and then display it on the console. Lets call it thread A. So simple, so easy.

I've two other threads. The purpose of these threads is to get some data from internet.

Now, what i want is that the two threads getting data from internet should "send" the string to thread A, so that it can be displayed. But i don't want those two threads to block. And this is the problem. Of course two threads should write string somewhere and then thread A get those strings periodically. As such critical section is necessary which i like to prevent because as such there is a blocking.

In order to overcome the problem i am using IO completion ports. But the problem is that IOCP is not available in Win9X family operating systems.

So what you like to advice me.

Re: Passing message to thread

Nitron28-Jun-03 6:02

Nitron

28-Jun-03 6:02

If it's simply a reader/writer paradigm, why not use a volatile string in the calling thread and write static Get/Set member functions that can be called via a pointer to the calling thread?

- Nitron

"Those that say a task is impossible shouldn't interrupt the ones who are doing it." - Chinese Proverb

Re: Passing message to thread

Shah Shehpori28-Jun-03 6:56

Shah Shehpori

28-Jun-03 6:56

Nitron wrote:
If it's simply a reader/writer paradigm,

No, its not simply like that. I need to implement some sort of message queue just like IO completion port.

Re: Passing message to thread

valikac28-Jun-03 6:53

valikac

28-Jun-03 6:53

One solution is a queue STL container. Pop and insert new messages as string objects.

Kuphryn

Re: Passing message to thread

Shah Shehpori28-Jun-03 6:59

Shah Shehpori

28-Jun-03 6:59

kuphryn wrote:
One solution is a queue STL container.

But as such i need to make this queue thread safe using critical section; otherwise two different threads may want to read and write at this object the same time.

Re: Passing message to thread

valikac28-Jun-03 7:46

valikac

28-Jun-03 7:46

Correct.

Kuphryn

Re: Passing message to thread

Peter Weyzen28-Jun-03 17:26

Peter Weyzen

28-Jun-03 17:26

You can't avoid that...

Though the other cheap way, is to post messages to your own window. You can pass the strings by converting them to atom's (see GlobalAddAtom). If you don't have a window, then go back to plan A as mentioned above.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br />
Peter Weyzen<br />
Staff Engineer<br />
Santa Cruz Networks

Re: Passing message to thread

cmk28-Jun-03 18:11

cmk

28-Jun-03 18:11

Read the docs for PostThreadMessage().
It will explain how to create a message queue for your thread A (dead easy).

Threads B, C can then call PostThreadMessage(thread_A, MY_STR_MSG, char*, length).

Thread A (even though it doesn't have a window) can use the normal window GetMessage() loop to pull the strings from the message queue.

Probably want to alloc memory for strings in threads B,C and delete in thread A.

...cmk

How to set the position of a progress bar

FlyingDancer28-Jun-03 3:54

FlyingDancer

28-Jun-03 3:54

Can I set a ProgressBar's postion in a static CALLBACK function? For instance:
......
//{{AFX_DATA(CFormatNT)
enum { IDD = IDD_DIALOG_FORMAT };
CProgressCtrl m_progress;
//}}AFX_DATA
.....
static BOOL CALLBACK FormatDiskCallback( ...);
.......
BOOL CALLBACK CFormatNT::FormatDiskCallback(..)
{
......
m_progress.SetPos(10);
......
}
When I compile it, there is an error as below:
error C2228: left of '.SetPos' must have class/struct/union type

What is the problem? How to solve it?

Thank you in advance!

Re: How to set the position of a progress bar

Michael Dunn28-Jun-03 5:20

Michael Dunn

28-Jun-03 5:20

A static method can't access non-static member variables. You'll need to pass a pointer to either this or just the CProgressCtrl to the callback function.

--Mike--
"So where does that leave us? Well, it leaves us right back where we started, only more confused than before." -- Matt Gullett
Ericahist | Homepage | RightClick-Encrypt | 1ClickPicGrabber

Re: How to set the position of a progress bar

FlyingDancer29-Jun-03 15:35

FlyingDancer

29-Jun-03 15:35

In the head file----------------
//{{AFX_DATA(CFormatNT)
enum { IDD = IDD_DIALOG_FORMAT };
CProgressCtrl m_progress;
//}}AFX_DATA
.....
-------------------------------------
static BOOL CALLBACK FormatDiskCallback( ...,CProgressCtrl progressBar);
static void PrintOut(...PFMIFSCALLBACK FormatExCallback,CProgressCtrl m_progress);
.......
In the implementation file-----------------------------------------
typedef BOOL (CALLBACK *PFMIFSCALLBACK)( ...,CProgressCtrl progressBar );
-------------------------
BOOL CALLBACK CFormatNT::FormatDiskCallback(...,CProgressCtrl progressBar)
{
......
m_progress.SetPos(10);
......
}

void CFormatNT::PrintOut(..., PFMIFSCALLBACK FormatExCallback,CProgressCtrl m_progress)
{
....
FormatExCallback(...,m_progress);
}
...
PrintOut(...,m_progress);
...
Compile it, and the result is:
error C2664: 'PrintOut' : cannot convert parameter 3 from 'class CProgressCtrl' to 'class CProgressCtrl'
What is the problem? And how to solve it?

Re: How to set the position of a progress bar

FlyingDancer29-Jun-03 18:37

FlyingDancer

29-Jun-03 18:37

Now I have completed the function by using another new thread.
Not handling the CProgressCtl varible in the static function.

how to play *.ani file in MFC?

dxhdxh28-Jun-03 2:44

dxhdxh

28-Jun-03 2:44

how to play *.ani file in MFC?
I dont want to use the function "LoadCursorFromFile"
I want to use it as a resource.
How do i do!

Attn: Robert Brault

gweather28-Jun-03 2:03

gweather

28-Jun-03 2:03

Robert,
I am very interested in your code to change the static text and background colors. I have entered in the code to do that from your code, but the colors do not change. Could I send you the code and have you take a look and see what is wrong?

Thanks very much,
George

Subclassed Control

Hesham Amin28-Jun-03 1:38

Hesham Amin

28-Jun-03 1:38

hi..
I create a subclassed MFC ActiveX control .. Subclassed from the Listbox control .. a have a method that should add an item :

the code causes an assertion .. can anyone help ?

void CSubCtrl::AddItem(BSTR FAR* strItem) <br />
{<br />
	<br />
	CString st(*strItem);<br />
	//AfxMessageBox(st);<br />
	CListBox lb;<br />
	lb.Attach(COleControl::m_hWnd);<br />
	lb.AddString(st);<br />
	lb.Detach();<br />
<br />
}

Re: Subclassed Control

MAAK29-Jun-03 12:07

MAAK

29-Jun-03 12:07

When talking about assertion, it's needed to know what is its condition from the file it exists in.

However, I guess that the possible assertion that could occur in your code is the IsWindow() assertion (ASSERT(::IsWindow(hWnd)) which indicate the the HWND passed to the Attach() function is invalid.

When you get an assertion in debug mode, click retry to see the assertion condition.

Re: Subclassed Control

Hesham Amin29-Jun-03 22:19

Hesham Amin

29-Jun-03 22:19

Hi..
the asseion occures in Attach method .. when i step in the code i find that ASSERT(FromHandlePermanent(hWndNew) == NULL); causes an assetion..
any suggestion please ?

Generic serial port interface

NeoFeng28-Jun-03 0:03

NeoFeng

28-Jun-03 0:03

Hello!

I am an electronics hobyist, I am interested in writing programs for interfacing with my homebrew electronics projects. Is there a generic serial port driver for Win32 environment using open source for download? Big Grin | :-D

Re: Generic serial port interface

Trollslayer28-Jun-03 5:25

Trollslayer

28-Jun-03 5:25

There are several seial classes on CP, look under http://www.codeproject.com/system/[^].

Elaine Rose | [Rose]

The tigress is here Big Grin | :-D

Something like #error but without error?

Dominik Reichl27-Jun-03 20:56

Dominik Reichl

27-Jun-03 20:56

Hello,

I am looking for a directive like #error, but one that doesn't stop the compiler. So something like #message...

Does such a directive exist?

Confused | :confused:

-Dominik

_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??

Re: Something like #error but without error?

Ryan Binns27-Jun-03 23:24

Ryan Binns

27-Jun-03 23:24

Try #pragma message("My Message")

Ryan

Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2^nd April 2003, The Lounge)

Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"

Re: Something like #error but without error?

Dominik Reichl27-Jun-03 23:32

Dominik Reichl

27-Jun-03 23:32

Ah, thanks Smile | :)

-Dominik

_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??

Re: Something like #error but without error?

Ryan Binns28-Jun-03 0:10

Ryan Binns

28-Jun-03 0:10

You're welcome Smile | :)

Ryan

Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2^nd April 2003, The Lounge)

Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"

Database?

DaveE9th27-Jun-03 19:40

DaveE9th

27-Jun-03 19:40

I want to design an MFC program that processes part numbers, I'm not sure which is the best way to go. Could someone please give me some advice on creating this type of program. I've had two people recommend a database, but I'd like to hear a few more opinions.

Thanks much Big Grin | :-D

Re: Database?

Anonymous29-Jun-03 5:20

Anonymous

29-Jun-03 5:20

You can download mySQL at http://www.mysql.com
It's free for private use.

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