Re: Worker thread

From:
Bill Snyder <bsnyder@airmail.net>
Newsgroups:
microsoft.public.vc.mfc
Date:
Thu, 08 Mar 2012 10:42:48 -0600
Message-ID:
<djnhl79at2hg61arbe5cc7tlkbi66ct51e@4ax.com>
On Thu, 8 Mar 2012 11:18:58 -0500, Me <me@right.her> wrote:

I am experimenting with worker threads and seeing id I can start/stop it
from running
With the code below the worker thread does start and stop with the buttons.
BUT, when you press the stop button the thread still completes the full
cycle before exiting.
How do I get the thread to stop immediatly with the stop button?
I pasted the main .h and .cpp for review.
Also how do I pass a unsigned char array into the thread for processing?
How do I return the processed unsigned char array back to the main Dlg?
Thanks

// AdelDlg.h : header file

#if
!defined(AFX_ADELDLG_H__CB0DCF35_E38B_4013_B978_A696202F8736__INCLUDED_)
#define AFX_ADELDLG_H__CB0DCF35_E38B_4013_B978_A696202F8736__INCLUDED_

#define RunMsg (WM_APP + 1)

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

/////////////////////////////////////////////////////////////////////////////
// CAdelDlg dialog

class CAdelDlg : public CDialog
{
// Construction
public:
    CAdelDlg(CWnd* pParent = NULL); // standard constructor

// Dialog Data
 //{{AFX_DATA(CAdelDlg)
 enum { IDD = IDD_ADEL_DIALOG };
 CStatic c_Info;
 //}}AFX_DATA

 // ClassWizard generated virtual function overrides
 //{{AFX_VIRTUAL(CAdelDlg)
 protected:
 virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
 //}}AFX_VIRTUAL

 afx_msg LRESULT ShowMessage(UINT wParam, LONG lParam);

// Implementation

protected:
 HICON m_hIcon;

 // Generated message map functions
 //{{AFX_MSG(CAdelDlg)
 virtual BOOL OnInitDialog();
 afx_msg HCURSOR OnQueryDragIcon();
 afx_msg void OnStop();
 //}}AFX_MSG
 DECLARE_MESSAGE_MAP()
};

//{{AFX_INSERT_LOCATION}}
// Microsoft Visual C++ will insert additional declarations immediately
before the previous line.

#endif //
!defined(AFX_ADELDLG_H__CB0DCF35_E38B_4013_B978_A696202F8736__INCLUDED_)

==================================================================================================
==================================================================================================

// AdelDlg.cpp : implementation file

#include "stdafx.h"
#include "Adel.h"
#include "AdelDlg.h"
#include "io.h"

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

int MessCode;
volatile bool KillThread;
UINT runThread( LPVOID Param );

/////////////////////////////////////////////////////////////////////////////
// CAdelDlg dialog

CAdelDlg::CAdelDlg(CWnd* pParent /*=NULL*/)
    : CDialog(CAdelDlg::IDD, pParent)
{
 //{{AFX_DATA_INIT(CAdelDlg)
 //}}AFX_DATA_INIT
 // Note that LoadIcon does not require a subsequent DestroyIcon in Win32
 m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);
}

void CAdelDlg::DoDataExchange(CDataExchange* pDX)
{
 CDialog::DoDataExchange(pDX);
 //{{AFX_DATA_MAP(CAdelDlg)
 DDX_Control(pDX, IDC_INFO, c_Info);
 //}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CAdelDlg, CDialog)
 //{{AFX_MSG_MAP(CAdelDlg)
 ON_WM_QUERYDRAGICON()
 ON_BN_CLICKED(IDC_TEST, OnTest)
 ON_BN_CLICKED(IDC_STOP, OnStop)
 ON_WM_PAINT()
 //}}AFX_MSG_MAP
 ON_MESSAGE(RunMsg, ShowMessage)
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CAdelDlg message handlers

BOOL CAdelDlg::OnInitDialog()
{
 CDialog::OnInitDialog();

 SetIcon(m_hIcon, TRUE); // Set big icon
 SetIcon(m_hIcon, FALSE); // Set small icon

 return TRUE;
}

void CAdelDlg::OnTest() //button to start thread
{
 KillThread = false;
 AfxBeginThread(runThread,(LPVOID)m_hWnd);
 c_Info.SetWindowText("Thread Started...");
}

void CAdelXDlg::OnStop() //button to stop thread
{
 KillThread = true;
}

LRESULT CAdelDlg::ShowMessage(UINT wParam, LONG lParam) //display message
depending on code from thread
{
 if(MessCode == 0)
   c_Info.SetWindowText("MessageCode = 0");
 if(MessCode == 1)
   c_Info.SetWindowText("MessageCode = 1");
 if(MessCode == 2)
   c_Info.SetWindowText("MessageCode = 2");
 if(MessCode == 3)
   c_Info.SetWindowText("MessageCode = 3");
 return 0;
}

UINT runThread( LPVOID Param ) //test thread just sends a message
each second until stopped
{
 HWND hDlg = (HWND)Param;

 KillThread = false;
 do{
   MessCode = 0;
   ::PostMessage(hDlg, RunMsg, (WPARAM)0, (LPARAM)0);
   Sleep(1000);
   MessCode = 1;
   ::PostMessage(hDlg, RunMsg, (WPARAM)0, (LPARAM)0);
   Sleep(1000);
   MessCode = 2;
   ::PostMessage(hDlg, RunMsg, (WPARAM)0, (LPARAM)0);
   Sleep(1000);
   MessCode = 3;
   ::PostMessage(hDlg, RunMsg, (WPARAM)0, (LPARAM)0);
   Sleep(1000);
 }while(!KillThread);

 return 0;
}


Why aren't you sending MsgCode as one of the message parameters?

Anyway, you can make KillThread a semaphore rather than a boolean,
do a ReleaseSemaphore() to kill the worker thread, and re-code the
worker thread itself something like this:

UINT runThread( LPVOID Param )
{
  HWND hDlg = (HWND)Param ;
  int msgnum = -1 ;

  do{
    if( ++msgnum > 3 )
      msgnum = 0 ;
      MessCode = msgnum ;
     ::PostMessage(hDlg, RunMsg, (WPARAM)0, (LPARAM)0);
  } while( WaitForSingleObject( KillThread,1000 )==WAIT_TIMEOUT)

return 0;
}

--
Bill Snyder [This space unintentionally left blank]

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