sync.c

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	if (pTrigger->test_type != XSyncPositiveTransition &&
	    pTrigger->test_type != XSyncNegativeTransition &&
	    pTrigger->test_type != XSyncPositiveComparison &&
	    pTrigger->test_type != XSyncNegativeComparison)
	{
	    client->errorValue = pTrigger->test_type;
	    return BadValue;
	}
	/* select appropriate CheckTrigger function */

	switch (pTrigger->test_type)
	{
        case XSyncPositiveTransition: 
	    pTrigger->CheckTrigger = SyncCheckTriggerPositiveTransition;
	    break;
        case XSyncNegativeTransition: 
	    pTrigger->CheckTrigger = SyncCheckTriggerNegativeTransition;
	    break;
        case XSyncPositiveComparison: 
	    pTrigger->CheckTrigger = SyncCheckTriggerPositiveComparison;
	    break;
        case XSyncNegativeComparison: 
	    pTrigger->CheckTrigger = SyncCheckTriggerNegativeComparison;
	    break;
	}
    }

    if (changes & (XSyncCAValueType | XSyncCAValue))
    {
	if (pTrigger->value_type == XSyncAbsolute)
	    pTrigger->test_value = pTrigger->wait_value;
	else /* relative */
	{
	    Bool overflow;
	    if (pCounter == NULL)
		return BadMatch;

	    XSyncValueAdd(&pTrigger->test_value, pCounter->value, 
			  pTrigger->wait_value, &overflow);
	    if (overflow)
	    {
		client->errorValue = XSyncValueHigh32(pTrigger->wait_value);
		return BadValue;
	    }
	}
    }

    /*  we wait until we're sure there are no errors before registering
     *  a new counter on a trigger
     */
    if (newcounter)
    {
	if ((status = SyncAddTriggerToCounter(pTrigger)) != Success)
	    return status;
    }
    else if (IsSystemCounter(pCounter))
    {
	SyncComputeBracketValues(pCounter, /*startOver*/ TRUE);
    }
    
    return Success;
}

/*  AlarmNotify events happen in response to actions taken on an Alarm or
 *  the counter used by the alarm.  AlarmNotify may be sent to multiple 
 *  clients.  The alarm maintains a list of clients interested in events.
 */
static void
SyncSendAlarmNotifyEvents(pAlarm)
    SyncAlarm *pAlarm;
{
    SyncAlarmClientList *pcl;
    xSyncAlarmNotifyEvent ane;
    SyncTrigger *pTrigger = &pAlarm->trigger;

    UpdateCurrentTime();

    ane.type = SyncEventBase + XSyncAlarmNotify;
    ane.kind = XSyncAlarmNotify;
    ane.sequenceNumber = pAlarm->client->sequence;
    ane.alarm = pAlarm->alarm_id;
    if (pTrigger->pCounter)
    {
	ane.counter_value_hi = XSyncValueHigh32(pTrigger->pCounter->value);
	ane.counter_value_lo = XSyncValueLow32(pTrigger->pCounter->value);
    }
    else
    { /* XXX what else can we do if there's no counter? */
	ane.counter_value_hi = ane.counter_value_lo = 0;
    }

    ane.alarm_value_hi = XSyncValueHigh32(pTrigger->test_value);
    ane.alarm_value_lo = XSyncValueLow32(pTrigger->test_value);
    ane.time = currentTime.milliseconds;
    ane.state = pAlarm->state;

    /* send to owner */
    if (pAlarm->events && !pAlarm->client->clientGone) 
	WriteEventsToClient(pAlarm->client, 1, (xEvent *) &ane);

    /* send to other interested clients */
    for (pcl = pAlarm->pEventClients; pcl; pcl = pcl->next)
    {
	if (!pAlarm->client->clientGone)
	{
	    ane.sequenceNumber = pcl->client->sequence;
	    WriteEventsToClient(pcl->client, 1, (xEvent *) &ane);
	}
    }
}


/*  CounterNotify events only occur in response to an Await.  The events 
 *  go only to the Awaiting client.
 */
static void
SyncSendCounterNotifyEvents(client, ppAwait, num_events)
    ClientPtr client;
    SyncAwait **ppAwait;
    int num_events;
{
    xSyncCounterNotifyEvent *pEvents, *pev;
    int i;

    if (client->clientGone)
	return;
    pev = pEvents = (xSyncCounterNotifyEvent *)
		 ALLOCATE_LOCAL(num_events * sizeof(xSyncCounterNotifyEvent));
    if (!pEvents) 
	return;
    UpdateCurrentTime();
    for (i = 0; i < num_events; i++, ppAwait++, pev++)
    {
	SyncTrigger *pTrigger = &(*ppAwait)->trigger;
	pev->type = SyncEventBase + XSyncCounterNotify;
	pev->kind = XSyncCounterNotify;
	pev->sequenceNumber = client->sequence;
	pev->counter = pTrigger->pCounter->id;
	pev->wait_value_lo = XSyncValueLow32(pTrigger->test_value);
	pev->wait_value_hi = XSyncValueHigh32(pTrigger->test_value);
	pev->counter_value_lo = XSyncValueLow32(pTrigger->pCounter->value);
	pev->counter_value_hi = XSyncValueHigh32(pTrigger->pCounter->value);
	pev->time = currentTime.milliseconds;
	pev->count = num_events - i - 1; /* events remaining */
	pev->destroyed = pTrigger->pCounter->beingDestroyed;
    }
    /* swapping will be taken care of by this */
    WriteEventsToClient(client, num_events, (xEvent *)pEvents);
    DEALLOCATE_LOCAL(pEvents);
}


/* This function is called when an alarm's counter is destroyed.
 * It is plugged into pTrigger->CounterDestroyed (for alarm triggers).
 */
void
SyncAlarmCounterDestroyed(pTrigger)
    SyncTrigger *pTrigger;
{
    SyncAlarm *pAlarm = (SyncAlarm *)pTrigger;

    pAlarm->state = XSyncAlarmInactive;
    SyncSendAlarmNotifyEvents(pAlarm);
    pTrigger->pCounter = NULL;
}


/*  This function is called when an alarm "goes off."  
 *  It is plugged into pTrigger->TriggerFired (for alarm triggers).
 */
static void
SyncAlarmTriggerFired(pTrigger)
    SyncTrigger *pTrigger;
{
    SyncAlarm *pAlarm = (SyncAlarm *)pTrigger;
    CARD64 new_test_value;

    /* no need to check alarm unless it's active */
    if (pAlarm->state != XSyncAlarmActive)
	return;

    /*  " if the counter value is None, or if the delta is 0 and
     *    the test-type is PositiveComparison or NegativeComparison,
     *    no change is made to value (test-value) and the alarm
     *    state is changed to Inactive before the event is generated."
     */
    if (pAlarm->trigger.pCounter == NULL
	|| (XSyncValueIsZero(pAlarm->delta)
	    && (pAlarm->trigger.test_type == XSyncPositiveComparison
		|| pAlarm->trigger.test_type == XSyncNegativeComparison)))
	pAlarm->state = XSyncAlarmInactive;

    new_test_value = pAlarm->trigger.test_value;

    if (pAlarm->state == XSyncAlarmActive)
    {
	Bool overflow;
	CARD64 oldvalue;
	SyncTrigger *paTrigger = &pAlarm->trigger;

	/* "The alarm is updated by repeatedly adding delta to the
	 *  value of the trigger and re-initializing it until it
	 *  becomes FALSE."
	 */
	oldvalue = paTrigger->test_value;

	/* XXX really should do something smarter here */

	do
	{
	    XSyncValueAdd(&paTrigger->test_value, paTrigger->test_value,
			  pAlarm->delta, &overflow);
	} while (!overflow && 
	      (*paTrigger->CheckTrigger)(paTrigger,
					paTrigger->pCounter->value));

	new_test_value = paTrigger->test_value;
	paTrigger->test_value = oldvalue;

	/* "If this update would cause value to fall outside the range
	 *  for an INT64...no change is made to value (test-value) and
	 *  the alarm state is changed to Inactive before the event is
	 *  generated."
	 */
	if (overflow)
	{
	    new_test_value = oldvalue;
	    pAlarm->state = XSyncAlarmInactive;
	}
    }
    /*  The AlarmNotify event has to have the "new state of the alarm"
     *  which we can't be sure of until this point.  However, it has
     *  to have the "old" trigger test value.  That's the reason for
     *  all the newvalue/oldvalue shuffling above.  After we send the
     *  events, give the trigger its new test value.
     */
    SyncSendAlarmNotifyEvents(pAlarm);
    pTrigger->test_value = new_test_value;
}


/*  This function is called when an Await unblocks, either as a result
 *  of the trigger firing OR the counter being destroyed.
 *  It goes into pTrigger->TriggerFired AND pTrigger->CounterDestroyed
 *  (for Await triggers).
 */
static void
SyncAwaitTriggerFired(pTrigger)
    SyncTrigger *pTrigger;
{
    SyncAwait *pAwait = (SyncAwait *)pTrigger;
    int numwaits;
    SyncAwaitUnion *pAwaitUnion;
    SyncAwait **ppAwait;
    int num_events = 0;

    pAwaitUnion = (SyncAwaitUnion *)pAwait->pHeader;
    numwaits = pAwaitUnion->header.num_waitconditions;
    ppAwait = (SyncAwait **)ALLOCATE_LOCAL(numwaits * sizeof(SyncAwait *));
    if (!ppAwait)
	goto bail;

    pAwait = &(pAwaitUnion+1)->await;

    /* "When a client is unblocked, all the CounterNotify events for
     *  the Await request are generated contiguously. If count is 0
     *  there are no more events to follow for this request. If
     *  count is n, there are at least n more events to follow."
     *
     *  Thus, it is best to find all the counters for which events
     *  need to be sent first, so that an accurate count field can
     *  be stored in the events.
     */
    for ( ; numwaits; numwaits--, pAwait++)
    {
	CARD64 diff;
	Bool overflow, diffgreater, diffequal;

	/* "A CounterNotify event with the destroyed flag set to TRUE is
	 *  always generated if the counter for one of the triggers is
	 *  destroyed."
	 */
	if (pAwait->trigger.pCounter->beingDestroyed)
	{
	    ppAwait[num_events++] = pAwait;
	    continue;
	}

	/* "The difference between the counter and the test value is
	 *  calculated by subtracting the test value from the value of
	 *  the counter."
	 */
	XSyncValueSubtract(&diff, pAwait->trigger.pCounter->value,
			   pAwait->trigger.test_value, &overflow);

	/* "If the difference lies outside the range for an INT64, an
	 *  event is not generated."
	 */
	if (overflow)
	    continue;
	diffgreater = XSyncValueGreaterThan(diff, pAwait->event_threshold);
	diffequal   = XSyncValueEqual(diff, pAwait->event_threshold);

	/* "If the test-type is PositiveTransition or
	 *  PositiveComparison, a CounterNotify event is generated if
	 *  the difference is at least event-threshold. If the test-type
	 *  is NegativeTransition or NegativeComparison, a CounterNotify
	 *  event is generated if the difference is at most
	 *  event-threshold."
	 */

	if ( ((pAwait->trigger.test_type == XSyncPositiveComparison ||
	       pAwait->trigger.test_type == XSyncPositiveTransition)
	       && (diffgreater || diffequal))
	     ||
	     ((pAwait->trigger.test_type == XSyncNegativeComparison ||
	       pAwait->trigger.test_type == XSyncNegativeTransition)
	      && (!diffgreater) /* less or equal */
	      )
	   )
	{
	    ppAwait[num_events++] = pAwait;
	}
    }
    if (num_events)
	SyncSendCounterNotifyEvents(pAwaitUnion->header.client, ppAwait,
				    num_events);
    DEALLOCATE_LOCAL(ppAwait);

bail:
    /* unblock the client */
    AttendClient(pAwaitUnion->header.client);
    /* delete the await */
    FreeResource(pAwaitUnion->header.delete_id, RT_NONE);
}


/*  This function should always be used to change a counter's value so that
 *  any triggers depending on the counter will be checked.
 */
void
SyncChangeCounter(pCounter, newval)
    SyncCounter    *pCounter;
    CARD64         newval;
{
    SyncTriggerList       *ptl, *pnext;
    CARD64 oldval;

    oldval = pCounter->value;
    pCounter->value = newval;

    /* run through triggers to see if any become true */
    for (ptl = pCounter->pTriglist; ptl; ptl = pnext)
    {
	pnext = ptl->next;
	if ((*ptl->pTrigger->CheckTrigger)(ptl->pTrigger, oldval))
	    (*ptl->pTrigger->TriggerFired)(ptl->pTrigger);
    }

    if (IsSystemCounter(pCounter))
    {
	SyncComputeBracketValues(pCounter, /* startOver */ FALSE);
    }
}


/* loosely based on dix/events.c/EventSelectForWindow */
static Bool
SyncEventSelectForAlarm(pAlarm, client, wantevents)
    SyncAlarm *pAlarm;
    ClientPtr client;
    Bool      wantevents;
{
    SyncAlarmClientList *pClients;

    if (client == pAlarm->client) /* alarm owner */
    {
	pAlarm->events = wantevents;
	return Success;
    }

    /* see if the client is already on the list (has events selected) */

    for (pClients = pAlarm->pEventClients; pClients;
	 pClients = pClients->next)
    {
	if (pClients->client == client)
	{
	    /* client's presence on the list indicates desire for 
	     * events.  If the client doesn't want events, remove it 
	     * from the list.  If the client does want events, do
	     * nothing, since it's already got them.
	     */
	    if (!wantevents)
	    {
		FreeResource(pClients->delete_id, RT_NONE);
	    }
	    return Success;
	}
    }

    /*  if we get here, this client does not currently have
     *  events selected on the alarm
     */

    if (!wantevents)
	/* client doesn't want events, and we just discovered that it 
	 * doesn't have them, so there's nothing to do.
	 */
	return Success;

    /* add new client to pAlarm->pEventClients */

    pClients = (SyncAlarmClientList *) xalloc(sizeof(SyncAlarmClientList));
    if (!pClients)
	return BadAlloc;

    /*  register it as a resource so it will be cleaned up 
     *  if the client dies
     */

    pClients->delete_id = FakeClientID(client->index);
    if (!AddResource(pClients->delete_id, RTAlarmClient, pAlarm))
    {
	xfree(pClients);
	return BadAlloc;
    }

    /* link it into list after we know all the allocations succeed */

    pClients->next = pAlarm->pEventClients;
    pAlarm->pEventClients = pClients;
    pClients->client = client;
    return Success;
}

/*
 * ** SyncChangeAlarmAttributes ** This is used by CreateAlarm and ChangeAlarm
 */
static int 
SyncChangeAlarmAttributes(client, pAlarm, mask, values)
    ClientPtr       client;
    SyncAlarm      *pAlarm;
    Mask	    mask;
    CARD32	    *values;
{
    int		   status;
    XSyncCounter   counter;
    Mask	   origmask = mask;

    counter = pAlarm->trigger.pCounter ? pAlarm->trigger.pCounter->id : None;

    while (mask)
    {
	int    index2 = lowbit(mask);
	mask &= ~index2;
	switch (index2)
	{
	  case XSyncCACounter:
	    mask &= ~XSyncCACounter;
	    /* sanity check in SyncInitTrigger */
	    counter = *values++;
	    break;

	  case XSyncCAValueType:
	    mask &= ~XSyncCAValueType;
	    /* sanity check in SyncInitTrigger */
	    pAlarm->trigger.value_type = *values++;
	    break;

	  case XSyncCAValue:
	    mask &= ~XSyncCAValue;
	    XSyncIntsToValue(&pAlarm->trigger.wait_value, values[1], values[0]);
	    values += 2;
	    break;

	  case XSyncCATestType:
	    mask &= ~XSyncCATestType;
	    /* sanity check in SyncInitTrigger */
	    pAlarm->trigger.test_type = *values++;
	    break;

	  case XSyncCADelta:
	    mask &= ~XSyncCADelta;
	    XSyncIntsToValue(&pAlarm->delta, values[1], values[0]);
	    values += 2;
	    break;

	  case XSyncCAEvents:
	    mask &= ~XSyncCAEvents;
	    if ((*values != xTrue) && (*values != xFalse))
	    {
		client->errorValue = *values;
		return BadValue;
	    }
	    status = SyncEventSelectForAlarm(pAlarm, client,
					     (Bool)(*values++));
	    if (status != Success)
		return status;
	    break;

	  default:
	    client->errorValue = mask;
	    return BadValue;
	}
    }

    /* "If the test-type is PositiveComparison or PositiveTransition
     *  and delta is less than zero, or if the test-type is
     *  NegativeComparison or NegativeTransition and delta is
     *  greater than zero, a Match error is generated."
     */