Method UpdateOrCreateTimer

source/script.cpp:4042–4116

ResultType Script::UpdateOrCreateTimer(IObject *aCallback
	, bool aUpdatePeriod, __int64 aPeriod, bool aUpdatePriority, int aPriority)
// Caller should specific a blank aPeriod to prevent the timer's period from being changed
// (i.e. if caller just wants to turn on or off an existing timer).  But if it does this
// for a non-existent timer, that timer will be created with the default period as specified in
// the constructor.
{
	ScriptTimer *timer;
	for (timer = mFirstTimer; timer != NULL; timer = timer->mNextTimer)
		if (timer->mCallback == aCallback) // Match found.
			break;
	bool timer_existed = (timer != NULL);
	if (!timer_existed)  // Create it.
	{
		if (   !(timer = new ScriptTimer(aCallback))   )
			return MemoryError();
		if (!mFirstTimer)
			mFirstTimer = mLastTimer = timer;
		else
		{
			mLastTimer->mNextTimer = timer;
			// This must be done after the above:
			mLastTimer = timer;
		}
		++mTimerCount;
	}

	if (!timer->mEnabled)
	{
		timer->mEnabled = true;
		++mTimerEnabledCount;
		SET_MAIN_TIMER  // Ensure the API timer is always running when there is at least one enabled timed subroutine.
		if (timer_existed)
		{
			// mEnabled is currently used to mark a running timer for deletion upon return.
			// Since the timer could be recreated by a different thread which just happens
			// to interrupt the timer thread, it seems best for consistency to reset Period
			// and Priority as though it had already been deleted.
			aUpdatePeriod = true;
			aUpdatePriority = true;
		}
	}

	if (aUpdatePeriod)
	{
		if (aPeriod < 0) // Support negative periods to mean "run only once".
		{
			timer->mRunOnlyOnce = true;
			timer->mPeriod = (DWORD)-aPeriod;
		}
		else // Positive number.
		{
			timer->mPeriod = (DWORD)aPeriod;
			timer->mRunOnlyOnce = false;
		}
	}

	if (aUpdatePriority)