1 Thread Pooling #

2 Scenario 1: Call Functions Asynchronously #

BOOL QueueUserWorkItem(
	PTHREAD_START_ROUTINE pfnCallback,
	PVOID pvContext,
	ULONG dwFlags
);

DWORD WINAPI WorkItemFunc( PVOID pvContext );

3 Scenario 2: Call Functions at Timed Intervals #

HANDLE CreateTimerQueue();

BOOL CreateTimerQueueTimer(
	PHANDLE phNewTimer,
	HANDLE hTimerQueue,
	WAITORTIMERCALLBACK pfnCallback,
	PVOID pvContext,
	DWORD dwDueTime,
	DWORD dwPeriod,
	ULONG dwFlags
);

VOID WINAPI WaitOrTimerCallback(
	PVOID pvContext,
	BOOL fTimerOrWaitFired
);

BOOL DeleteTimerQueueTimer(
	HANDLE hTimerQueue,
	HANDLE hTimer,
	HANDLE hCompletionEvent
);

BOOL ChangeTimerQueueTimer(
	HANDLE hTimerQueue,
	HANDLE hTimer,
	ULONG dwDueTime,
	ULONG dwPeriod
);

BOOL DeleteTimerQueueEx(
	HANDLE hTimerQueue,
	HANDLE hCompletionEvent
);

3.1 The TimedMsgBox Sample Application #

TimedMsgBox.cpp

/******************************************************************************
Module:  TimedMsgBox.cpp
Notices: Copyright (c) 2000 Jeffrey Richter
******************************************************************************/


#include "..\CmnHdr.h"      /* See Appendix A. */
#include <tchar.h>


//////////////////////////////////////////////////////////////////////////////


// The caption of our message box
TCHAR g_szCaption[] = TEXT( "Timed Message Box" );


// How many seconds we'll display the message box
int g_nSecLeft = 0;


// This is STATIC window control ID for a message box
#define ID_MSGBOX_STATIC_TEXT       0x0000ffff


//////////////////////////////////////////////////////////////////////////////


VOID WINAPI MsgBoxTimeout( PVOID pvContext, BOOLEAN fTimeout )
{
    // NOTE: Due to a thread race condition, it is possible (but very unlikely)
    // that the message box will not be created when we get here.
    HWND hwnd = FindWindow( NULL, g_szCaption );

    if( hwnd != NULL ) {
        // The window does exist; update the time remaining.
        TCHAR sz[100];
        wsprintf( sz, TEXT( "You have %d seconds to respond" ), g_nSecLeft-- );
        SetDlgItemText( hwnd, ID_MSGBOX_STATIC_TEXT, sz );

        if( g_nSecLeft == 0 ) {
            // The time is up; force the message box to exit.
            EndDialog( hwnd, IDOK );
        }
    } else {

        // The window does not exist yet; do nothing this time.
        // We'll try again in another second.
    }
}


//////////////////////////////////////////////////////////////////////////////


int WINAPI _tWinMain( HINSTANCE hinstExe, HINSTANCE, PTSTR pszCmdLine, int )
{
    chWindows9xNotAllowed();

    // How many seconds we'll give the user to respond
    g_nSecLeft = 10;

    // Create a multishot 1-second timer that begins firing after 1 second.
    HANDLE hTimerQTimer;
    CreateTimerQueueTimer( &hTimerQTimer, NULL, MsgBoxTimeout, NULL,
        1000, 1000, 0 );

    // Display the message box.
    MessageBox( NULL, TEXT( "You have 10 seconds to respond" ),
        g_szCaption, MB_OK );

    // Cancel the timer & delete the timer queue
    DeleteTimerQueueTimer( NULL, hTimerQTimer, NULL );

    // Let us know if the user responded or if we timed out.
    MessageBox(NULL,
        ( g_nSecLeft == 0 ) ? TEXT( "Timeout" ) : TEXT( "User responded" ),
            TEXT( "Result" ), MB_OK );

    return ( 0 );
}


//////////////////////////////// End of File /////////////////////////////////

TimedMsgBox.rc

//Microsoft Developer Studio generated resource script.
//
#include "resource.h"

#define APSTUDIO_READONLY_SYMBOLS
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE 2 resource.
//
#include "afxres.h"

/////////////////////////////////////////////////////////////////////////////
#undef APSTUDIO_READONLY_SYMBOLS

/////////////////////////////////////////////////////////////////////////////
// English (U.S.) resources

#if !defined(AFX_RESOURCE_DLL) || defined(AFX_TARG_ENU)
#ifdef _WIN32
LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US
#pragma code_page(1252)
#endif //_WIN32

/////////////////////////////////////////////////////////////////////////////
//
// Icon
//

// Icon with lowest ID value placed first to ensure application icon
// remains consistent on all systems.
IDI_TIMEDMSGBOX         ICON    DISCARDABLE     "TimedMsgBox.ico"

#ifdef APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// TEXTINCLUDE
//

1 TEXTINCLUDE DISCARDABLE
BEGIN
    "resource.h\0"
END

2 TEXTINCLUDE DISCARDABLE
BEGIN
    "#include ""afxres.h""\r\n"
    "\0"
END

3 TEXTINCLUDE DISCARDABLE
BEGIN
    "\r\n"
    "\0"
END

#endif  // APSTUDIO_INVOKED

#endif  // English (U.S.) resources
/////////////////////////////////////////////////////////////////////////////



#ifndef APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE 3 resource.
//


/////////////////////////////////////////////////////////////////////////////
#endif  // not APSTUDIO_INVOKED

4 Scenario 3: Call Functions When Single Kernel Objects Become Signaled #

BOOL RegisterWaitForSingleObject(
	PHANDLE phNewWaitObject,
	HANDLE hObject,
	WAITORTIMERCALLBACK pfnCallback,
	PVOID pvContext,
	ULONG dwMilliseconds,
	ULONG dwFlags
);

VOID WINAPI WaitOrTimerCallbackFunc(
	PVOID pvContext,
	BOOLEAN fTimerOrWaitFired
);

BOOL UnregisterWaitEx(
	HANDLE hWaitHandle,
	HANDLE hCompletionEvent
);

5 Scenario 4: Call Functions When Asynchronous I/O Requests Complete #

BOOL BindIoCompletionCallback(
	HANDLE hDevice,
	POVERLAPPED_COMPLETION_ROUTINE pfnCallback,
	ULONG dwFlags
);

VOID WINAPI OverlappedCompletionRoutine(
	DWORD dwErrorCode,
	DWORD dwNumberOfBytesTransferred,
	POVERLAPPED pOverlapped
);