This reverts commit 0081e30a896a730f9598353353f6ee258803850e.
The logic introduced by this commit is correct in MC JAVA 1.9+. Unfortunately, nobody likes 1.9+ for combat.
Some testing in MCPE vanilla made it apparent that this logic isn't correct for MCPE. The old logic is correct for pre-1.9 knockback.
it's possible to walk off a tower while flying without moving vertically, and this code previously wouldn't detect that, leaving a gaping hole in the anti-cheat.
Under normal circumstances, none of the boxed code will throw exceptions. Under exceptional circumstances, the caller should know about it. Usually the caller is the server. We don't want to catch unexpected exceptions because those should crash the server and generate a crashdump.
this was an interesting bug.
This was discovered by making a projectile's drag 0, making its gravity a factor of its throw force (such that force / gravity = integer value), and then throwing it directly up. At the apex, an error would occur due to trying to do a ray trace with a zero vector.
This also led me to realize that there's an edge case in the current movement system - if an entity's motion reaches 0, it will stop getting movement updates. This can be undesirable when things such as gravity cause motion to become zero when throwing a projectile directly upwards. This will need to be fixed separately.
As discussed in #2297:
Honestly I don't see a fit purpose for async saving at all. It should either always be synchronous or always asynchronous, and at the user's own option. However, this isn't currently possible because Config doesn't enable you to get the serialized content without writing it to disk.
Consider the following code:
```php
for($i = 0, $size = $this->getServer()->getAsyncPool()->getSize(); $i < $size; ++$i){
$this->getServer()->getAsyncPool()->submitTask(new class extends AsyncTask{
public function onRun(){
sleep(5);
}
});
}
$config = $this->getConfig();
$config->set("steve", "hi");
$config->save(true);
$config->set("steve", "bye");
$config->save(false);
```
Output:
```yml
---
steve: hi
...
```
Expected output:
```yml
---
steve: bye
...
```
Additionally, if your configs are causing you performance issues when you're saving, it's a clear sign that
a) you're saving too much
b) you're abusing configs and should consider using a database.
Configs should be used for _simple_ data which does not change much. Configuration is such that the _user_ is expected to be able to modify it. As such, it should never be an issue to save synchronously.
In the future, something like ReactPHP may be introduced to allow proper async saving. When this happens, async saving would always be sequential but non blocking. Using threads for this makes no sense.
