Paper/patches/server/0398-Prevent-headless-pistons-from-being-created.patch
Bjarne Koll c5a10665b8
Remove wall-time / unused skip tick protection (#11412)
Spigot still maintains some partial implementation of "tick skipping", a
practice in which the MinecraftServer.currentTick field is updated not
by an increment of one per actual tick, but instead set to
System.currentTimeMillis() / 50. This behaviour means that the tracked
tick may "skip" a tick value in case a previous tick took more than the
expected 50ms.

To compensate for this in important paths, spigot/craftbukkit
implements "wall-time". Instead of incrementing/decrementing ticks on
block entities/entities by one for each call to their tick() method,
they instead increment/decrement important values, like
an ItemEntity's age or pickupDelay, by the difference of
`currentTick - lastTick`, where `lastTick` is the value of
`currentTick` during the last tick() call.

These "fixes" however do not play nicely with minecraft's simulation
distance as entities/block entities implementing the above behaviour
would "catch up" their values when moving from a non-ticking chunk to a
ticking one as their `lastTick` value remains stuck on the last tick in
a ticking chunk and hence lead to a large "catch up" once ticked again.

Paper completely removes the "tick skipping" behaviour (See patch
"Further-improve-server-tick-loop"), making the above precautions
completely unnecessary, which also rids paper of the previous described
incompatibility with non-ticking chunks.
2024-09-19 16:36:07 +02:00

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2.0 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: commandblockguy <commandblockguy1@gmail.com>
Date: Fri, 14 Aug 2020 14:44:14 -0500
Subject: [PATCH] Prevent headless pistons from being created
Prevent headless pistons from being created by explosions or tree/mushroom growth.
diff --git a/src/main/java/net/minecraft/world/level/Explosion.java b/src/main/java/net/minecraft/world/level/Explosion.java
index 8bbc5025f202be784db78401154038f1f70f0163..6a1e2614453bc3d6fe082c1fd43228c4a182442e 100644
--- a/src/main/java/net/minecraft/world/level/Explosion.java
+++ b/src/main/java/net/minecraft/world/level/Explosion.java
@@ -207,6 +207,15 @@ public class Explosion {
if (f > 0.0F && this.damageCalculator.shouldBlockExplode(this, this.level, blockposition, iblockdata, f)) {
set.add(blockposition);
+ // Paper start - prevent headless pistons from forming
+ if (!io.papermc.paper.configuration.GlobalConfiguration.get().unsupportedSettings.allowHeadlessPistons && iblockdata.getBlock() == Blocks.MOVING_PISTON) {
+ net.minecraft.world.level.block.entity.BlockEntity extension = this.level.getBlockEntity(blockposition);
+ if (extension instanceof net.minecraft.world.level.block.piston.PistonMovingBlockEntity blockEntity && blockEntity.isSourcePiston()) {
+ net.minecraft.core.Direction direction = iblockdata.getValue(net.minecraft.world.level.block.piston.PistonHeadBlock.FACING);
+ set.add(blockposition.relative(direction.getOpposite()));
+ }
+ }
+ // Paper end - prevent headless pistons from forming
}
d4 += d0 * 0.30000001192092896D;