When converting things in Minecraft to use wall time instead of ticks I
realized we'd run into integer division rounding issues and could have
updates that end up counting as zero ticks. To compensate for this the
code ensures we always process at least one tick. However, every time we
end up with zero ticks the next time we have an extra tick due to rounding
the other way with the leftovers. This means we are going far too fast and
should not have this at least one tick logic at all.
On top of this some potions rely on the number of ticks they run and not
just the amount of time they last and so potions were put back to running
with ticks entirely.
Currently furnace smelting and the item pickup delay timer use wall time
(aka actual time passed) to emulate a constant tick rate so run at the
same speed regardless of the server's actual tick rate. There are several
other places this makes sense so this commit converts them.
The item despawn timer is converted so now always takes 5 minutes. Users
know this 5 minute number well so keeping this constant helps to avoid
confusion. This also helps alleviate lag because if a large number of item
drops is the reason your server is running slowly having them stay around
longer just means your server is slow longer.
Potion brewing and the zombie villager conversion timer are now constant.
These match the furnace criteria of being useful for hiding lag and not
having a detrimental effect on gameplay.
Potion effects are now also using wall time. The client is told about effect
times in ticks and displays this information to the user as minutes and
seconds assuming a solid 20 ticks per second. The server does have
code for updating the client with the current time remaining to help
avoid skew due to differing tick rates but making this a constant makes
sense due to this display.
We know these updates (can) break plugins bypassing Bukkit. They are needed for
smooth updates however. There will be another one right before before 1.1-R1.
