/* 

 * tclWinNotify.c --

 *

 *	This file contains Windows-specific procedures for the notifier,

 *	which is the lowest-level part of the Tcl event loop.  This file

 *	works together with ../generic/tclNotify.c.

 *

 * Copyright (c) 1995-1997 Sun Microsystems, Inc.

 *

 * See the file "license.terms" for information on usage and redistribution

 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.

 *

 * RCS: @(#) $Id: tclWinNotify.c,v 1.11.2.1 2003/03/21 03:24:09 dgp Exp $

 */

#include "tclWinInt.h"

/*

 * The follwing static indicates whether this module has been initialized.

 */

#define INTERVAL_TIMER 1	/* Handle of interval timer. */

#define WM_WAKEUP WM_USER	/* Message that is send by

				 * Tcl_AlertNotifier. */

/*

 * The following static structure contains the state information for the

 * Windows implementation of the Tcl notifier.  One of these structures

 * is created for each thread that is using the notifier.  

 */

typedef struct ThreadSpecificData {

    CRITICAL_SECTION crit;	/* Monitor for this notifier. */

    DWORD thread;		/* Identifier for thread associated with this

				 * notifier. */

    HANDLE event;		/* Event object used to wake up the notifier

				 * thread. */

    int pending;		/* Alert message pending, this field is

				 * locked by the notifierMutex. */

    HWND hwnd;			/* Messaging window. */

    int timeout;		/* Current timeout value. */

    int timerActive;		/* 1 if interval timer is running. */

} ThreadSpecificData;

static Tcl_ThreadDataKey dataKey;

extern TclStubs tclStubs;

extern Tcl_NotifierProcs tclOriginalNotifier;

/*

 * The following static indicates the number of threads that have

 * initialized notifiers.  It controls the lifetime of the TclNotifier

 * window class.

 *

 * You must hold the notifierMutex lock before accessing this variable.

 */

static int notifierCount = 0;

TCL_DECLARE_MUTEX(notifierMutex)

/*

 * Static routines defined in this file.

 */

static LRESULT CALLBACK	NotifierProc(HWND hwnd, UINT message,

			    WPARAM wParam, LPARAM lParam);

/*

 *----------------------------------------------------------------------

 *

 * Tcl_InitNotifier --

 *

 *	Initializes the platform specific notifier state.

 *

 * Results:

 *	Returns a handle to the notifier state for this thread..

 *

 * Side effects:

 *	None.

 *

 *----------------------------------------------------------------------

 */

ClientData

Tcl_InitNotifier()

{

    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    WNDCLASS class;

    /*

     * Register Notifier window class if this is the first thread to

     * use this module.

     */

    Tcl_MutexLock(&notifierMutex);

    if (notifierCount == 0) {

	class.style = 0;

	class.cbClsExtra = 0;

	class.cbWndExtra = 0;

	class.hInstance = TclWinGetTclInstance();

	class.hbrBackground = NULL;

	class.lpszMenuName = NULL;

	class.lpszClassName = "TclNotifier";

	class.lpfnWndProc = NotifierProc;

	class.hIcon = NULL;

	class.hCursor = NULL;

	if (!RegisterClassA(&class)) {

	    panic("Unable to register TclNotifier window class");

	}

    }

    notifierCount++;

    Tcl_MutexUnlock(&notifierMutex);

    tsdPtr->pending = 0;

    tsdPtr->timerActive = 0;

    InitializeCriticalSection(&tsdPtr->crit);

    tsdPtr->hwnd = NULL;

    tsdPtr->thread = GetCurrentThreadId();

    tsdPtr->event = CreateEvent(NULL, TRUE /* manual */,

	    FALSE /* !signaled */, NULL);

    return (ClientData) tsdPtr;

}

/*

 *----------------------------------------------------------------------

 *

 * Tcl_FinalizeNotifier --

 *

 *	This function is called to cleanup the notifier state before

 *	a thread is terminated.

 *

 * Results:

 *	None.

 *

 * Side effects:

 *	May dispose of the notifier window and class.

 *

 *----------------------------------------------------------------------

 */

void

Tcl_FinalizeNotifier(clientData)

    ClientData clientData;	/* Pointer to notifier data. */

{

    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) clientData;

    /*

     * Only finalize the notifier if a notifier was installed in the

     * current thread; there is a route in which this is not

     * guaranteed to be true (when tclWin32Dll.c:DllMain() is called

     * with the flag DLL_PROCESS_DETACH by the OS, which could be

     * doing so from a thread that's never previously been involved

     * with Tcl, e.g. the task manager) so this check is important.

     *

     * Fixes Bug #217982 reported by Hugh Vu and Gene Leache.

     */

    if (tsdPtr == NULL) {

	return;

    }

    DeleteCriticalSection(&tsdPtr->crit);

    CloseHandle(tsdPtr->event);

    /*

     * Clean up the timer and messaging window for this thread.

     */

    if (tsdPtr->hwnd) {

	KillTimer(tsdPtr->hwnd, INTERVAL_TIMER);

	DestroyWindow(tsdPtr->hwnd);

    }

    /*

     * If this is the last thread to use the notifier, unregister

     * the notifier window class.

     */

    Tcl_MutexLock(&notifierMutex);

    notifierCount--;

    if (notifierCount == 0) {

	UnregisterClassA("TclNotifier", TclWinGetTclInstance());

    }

    Tcl_MutexUnlock(&notifierMutex);

}

/*

 *----------------------------------------------------------------------

 *

 * Tcl_AlertNotifier --

 *

 *	Wake up the specified notifier from any thread. This routine

 *	is called by the platform independent notifier code whenever

 *	the Tcl_ThreadAlert routine is called.  This routine is

 *	guaranteed not to be called on a given notifier after

 *	Tcl_FinalizeNotifier is called for that notifier.  This routine

 *	is typically called from a thread other than the notifier's

 *	thread.

 *

 * Results:

 *	None.

 *

 * Side effects:

 *	Sends a message to the messaging window for the notifier

 *	if there isn't already one pending.

 *

 *----------------------------------------------------------------------

 */

void

Tcl_AlertNotifier(clientData)

    ClientData clientData;	/* Pointer to thread data. */

{

    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) clientData;

    /*

     * Note that we do not need to lock around access to the hwnd

     * because the race condition has no effect since any race condition

     * implies that the notifier thread is already awake.

     */

    if (tsdPtr->hwnd) {

	/*

	 * We do need to lock around access to the pending flag.

	 */

	EnterCriticalSection(&tsdPtr->crit);

	if (!tsdPtr->pending) {

	    PostMessage(tsdPtr->hwnd, WM_WAKEUP, 0, 0);

	}

	tsdPtr->pending = 1;

	LeaveCriticalSection(&tsdPtr->crit);

    } else {

	SetEvent(tsdPtr->event);

    }

}

/*

 *----------------------------------------------------------------------

 *

 * Tcl_SetTimer --

 *

 *	This procedure sets the current notifier timer value.  The

 *	notifier will ensure that Tcl_ServiceAll() is called after

 *	the specified interval, even if no events have occurred.

 *

 * Results:

 *	None.

 *

 * Side effects:

 *	Replaces any previous timer.

 *

 *----------------------------------------------------------------------

 */

void

Tcl_SetTimer(

    Tcl_Time *timePtr)		/* Maximum block time, or NULL. */

{

    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    UINT timeout;

    /*

     * Allow the notifier to be hooked.  This may not make sense

     * on Windows, but mirrors the UNIX hook.

     */

    if (tclStubs.tcl_SetTimer != tclOriginalNotifier.setTimerProc) {

	tclStubs.tcl_SetTimer(timePtr);

	return;

    }

    /*

     * We only need to set up an interval timer if we're being called

     * from an external event loop.  If we don't have a window handle

     * then we just return immediately and let Tcl_WaitForEvent handle

     * timeouts.

     */

    if (!tsdPtr->hwnd) {

	return;

    }

    if (!timePtr) {

	timeout = 0;

    } else {

	/*

	 * Make sure we pass a non-zero value into the timeout argument.

	 * Windows seems to get confused by zero length timers.

	 */

	timeout = timePtr->sec * 1000 + timePtr->usec / 1000;

	if (timeout == 0) {

	    timeout = 1;

	}

    }

    tsdPtr->timeout = timeout;

    if (timeout != 0) {

	tsdPtr->timerActive = 1;

	SetTimer(tsdPtr->hwnd, INTERVAL_TIMER,

		    (unsigned long) tsdPtr->timeout, NULL);

    } else {

	tsdPtr->timerActive = 0;

	KillTimer(tsdPtr->hwnd, INTERVAL_TIMER);

    }

}

/*

 *----------------------------------------------------------------------

 *

 * Tcl_ServiceModeHook --

 *

 *	This function is invoked whenever the service mode changes.

 *

 * Results:

 *	None.

 *

 * Side effects:

 *	If this is the first time the notifier is set into

 *	TCL_SERVICE_ALL, then the communication window is created.

 *

 *----------------------------------------------------------------------

 */

void

Tcl_ServiceModeHook(mode)

    int mode;			/* Either TCL_SERVICE_ALL, or

				 * TCL_SERVICE_NONE. */

{

    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    /*

     * If this is the first time that the notifier has been used from a

     * modal loop, then create a communication window.  Note that after

     * this point, the application needs to service events in a timely

     * fashion or Windows will hang waiting for the window to respond

     * to synchronous system messages.  At some point, we may want to

     * consider destroying the window if we leave the modal loop, but

     * for now we'll leave it around.

     */

    if (mode == TCL_SERVICE_ALL && !tsdPtr->hwnd) {

	tsdPtr->hwnd = CreateWindowA("TclNotifier", "TclNotifier", WS_TILED,

		0, 0, 0, 0, NULL, NULL, TclWinGetTclInstance(), NULL);

	/*

	 * Send an initial message to the window to ensure that we wake up the

	 * notifier once we get into the modal loop.  This will force the

	 * notifier to recompute the timeout value and schedule a timer

	 * if one is needed.

	 */

	Tcl_AlertNotifier((ClientData)tsdPtr);

    }

}

/*

 *----------------------------------------------------------------------

 *

 * NotifierProc --

 *

 *	This procedure is invoked by Windows to process events on

 *	the notifier window.  Messages will be sent to this window

 *	in response to external timer events or calls to

 *	TclpAlertTsdPtr->

 *

 * Results:

 *	A standard windows result.

 *

 * Side effects:

 *	Services any pending events.

 *

 *----------------------------------------------------------------------

 */

static LRESULT CALLBACK

NotifierProc(

    HWND hwnd,

    UINT message,

    WPARAM wParam,

    LPARAM lParam)

{

    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    if (message == WM_WAKEUP) {

	EnterCriticalSection(&tsdPtr->crit);

	tsdPtr->pending = 0;

	LeaveCriticalSection(&tsdPtr->crit);

    } else if (message != WM_TIMER) {

	return DefWindowProc(hwnd, message, wParam, lParam);

    }

    /*

     * Process all of the runnable events.

     */

    Tcl_ServiceAll();

    return 0;

}

/*

 *----------------------------------------------------------------------

 *

 * Tcl_WaitForEvent --

 *

 *	This function is called by Tcl_DoOneEvent to wait for new

 *	events on the message queue.  If the block time is 0, then

 *	Tcl_WaitForEvent just polls the event queue without blocking.

 *

 * Results:

 *	Returns -1 if a WM_QUIT message is detected, returns 1 if

 *	a message was dispatched, otherwise returns 0.

 *

 * Side effects:

 *	Dispatches a message to a window procedure, which could do

 *	anything.

 *

 *----------------------------------------------------------------------

 */

int

Tcl_WaitForEvent(

    Tcl_Time *timePtr)		/* Maximum block time, or NULL. */

{

    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    MSG msg;

    DWORD timeout, result;

    int status;

    /*

     * Allow the notifier to be hooked.  This may not make

     * sense on windows, but mirrors the UNIX hook.

     */

    if (tclStubs.tcl_WaitForEvent != tclOriginalNotifier.waitForEventProc) {

	return tclStubs.tcl_WaitForEvent(timePtr);

    }

    /*

     * Compute the timeout in milliseconds.

     */

    if (timePtr) {

	timeout = timePtr->sec * 1000 + timePtr->usec / 1000;

    } else {

	timeout = INFINITE;

    }

    /*

     * Check to see if there are any messages in the queue before waiting

     * because MsgWaitForMultipleObjects will not wake up if there are events

     * currently sitting in the queue.

     */

    if (!PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE)) {

	/*

	 * Wait for something to happen (a signal from another thread, a

	 * message, or timeout).

	 */

	result = MsgWaitForMultipleObjects(1, &tsdPtr->event, FALSE, timeout,

		QS_ALLINPUT);

    }

    /*

     * Check to see if there are any messages to process.

     */

    if (PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE)) {

	/*

	 * Retrieve and dispatch the first message.

	 */

	result = GetMessage(&msg, NULL, 0, 0);

	if (result == 0) {

	    /*

	     * We received a request to exit this thread (WM_QUIT), so

	     * propagate the quit message and start unwinding.

	     */

	    PostQuitMessage((int) msg.wParam);

	    status = -1;

	} else if (result == -1) {

	    /*

	     * We got an error from the system.  I have no idea why this would

	     * happen, so we'll just unwind.

	     */

	    status = -1;

	} else {

	    TranslateMessage(&msg);

	    DispatchMessage(&msg);

	    status = 1;

	}

    } else {

	status = 0;

    }

    ResetEvent(tsdPtr->event);

    return status;

}

/*

 *----------------------------------------------------------------------

 *

 * Tcl_Sleep --

 *

 *	Delay execution for the specified number of milliseconds.

 *

 * Results:

 *	None.

 *

 * Side effects:

 *	Time passes.

 *

 *----------------------------------------------------------------------

 */

void

Tcl_Sleep(ms)

    int ms;			/* Number of milliseconds to sleep. */

{

    /*

     * Simply calling 'Sleep' for the requisite number of milliseconds

     * can make the process appear to wake up early because it isn't

     * synchronized with the CPU performance counter that is used in

     * tclWinTime.c.  This behavior is probably benign, but messes

     * up some of the corner cases in the test suite.  We get around

     * this problem by repeating the 'Sleep' call as many times

     * as necessary to make the clock advance by the requisite amount.

     */

    Tcl_Time now;		/* Current wall clock time */

    Tcl_Time desired;		/* Desired wakeup time */

    DWORD sleepTime = ms;	/* Time to sleep */

    Tcl_GetTime( &now );

    desired.sec = now.sec + ( ms / 1000 );

    desired.usec = now.usec + 1000 * ( ms % 1000 );

    if ( desired.usec > 1000000 ) {

	++desired.sec;

	desired.usec -= 1000000;

    }

    for ( ; ; ) {

	Sleep( sleepTime );

	Tcl_GetTime( &now );

	if ( now.sec > desired.sec ) {

	    break;

	} else if ( ( now.sec == desired.sec )

	     && ( now.usec >= desired.usec ) ) {

	    break;

	}

	sleepTime = ( ( 1000 * ( desired.sec - now.sec ) )

		      + ( ( desired.usec - now.usec ) / 1000 ) );

    }

}