Fix classicAttackSpeed makes server lag (#4676)

[gesior]

classicAttackSpeed algorithm is bugged and may generate infinite number of scheduler (dispatcher) events.

1. TFS calls Player::doAttacking every second for every player.
2. It creates new event g_scheduler.addEvent(task);, which calls Player::doAttacking again with getAttackSpeed() delay. So there is repeating event every 0.2 sec (with attack speed 200) and TFS still calls Player::doAttacking every second creating new event.
   That way server can create infinite number of events for 1 player. 1 new event every second.

Often it all stops on if ((OTSYS_TIME() - lastAttack) >= getAttackSpeed()) { - player cannot attack as fast as these events execute, so if there is more than 1 dispatcher event for given player, it won't re-create it after execution (addEvent is inside that IF).
But if player uses melee weapon and his target is not within 1 sqm, his attack will never execute and lastAttack will never update, so it will be able to re-create events, even if there is more than 1 running in same time.

Fixed code limits number of scheduled doAttacking events to 1 per player.

[EvilHero90]

Don't you have to check if the classicAttackEvent is even valid before trying to stop it?

[gesior]

Don't you have to check if the classicAttackEvent is even valid before trying to stop it?

No. If it's not set yet by script, it's set to 0 in player.h and stopEvent code checks, if it's not 0:

void Scheduler::stopEvent(uint32_t eventId)
{
	if (eventId == 0) {
		return;
	}
...

Even, if it's set to some invalid number, stopEvent code first checks, if event with given ID exists, so it's 100% safe.