PaperMC/patches/server/0786-Fix-sticky-pistons-and-BlockPistonRetractEvent.patch
Spottedleaf 01a13871de
Rewrite chunk system (#8177)
Patch documentation to come

Issues with the old system that are fixed now:
- World generation does not scale with cpu cores effectively.
- Relies on the main thread for scheduling and maintaining chunk state, dropping chunk load/generate rates at lower tps.
- Unreliable prioritisation of chunk gen/load calls that block the main thread.
- Shutdown logic is utterly unreliable, as it has to wait for all chunks to unload - is it guaranteed that the chunk system is in a state on shutdown that it can reliably do this? Watchdog shutdown also typically failed due to thread checks, which is now resolved.
- Saving of data is not unified (i.e can save chunk data without saving entity data, poses problems for desync if shutdown is really abnormal.
- Entities are not loaded with chunks. This caused quite a bit of headache for Chunk#getEntities API, but now the new chunk system loads entities with chunks so that they are ready whenever the chunk loads in. Effectively brings the behavior back to 1.16 era, but still storing entities in their own separate regionfiles.

The above list is not complete. The patch documentation will complete it.

New chunk system hard relies on starlight and dataconverter, and most importantly the new concurrent utilities in ConcurrentUtil.

Some of the old async chunk i/o interface (i.e the old file io thread reroutes _some_ calls to the new file io thread) is kept for plugin compat reasons. It will be removed in the next major version of minecraft.

The old legacy chunk system patches have been moved to the removed folder in case we need them again.
2022-09-26 01:02:51 -07:00

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Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Wed, 22 Dec 2021 09:51:48 -0800
Subject: [PATCH] Fix sticky pistons and BlockPistonRetractEvent
There is an explicit check in the handling code for empty pistons that
prevents sticky pistons from firing the event. However when we look back
at the history we see that this check was originally added so that ONLY
sticky pistons would fire the retract event. I'm not sure why.
https://hub.spigotmc.org/stash/projects/SPIGOT/repos/craftbukkit/commits/1092acbddf07edfa4100bc6824504ac75088e913
Over the course of several updates, the meaning of that field appears to
have changed from "is NOT sticky" to "is sticky". So now its having the
opposite effect. Only normal pistons fire the retraction event. And like
all things in CB, it's just been carried around since.
If we are to believe the history, the correct fix for this issue is to
flip it so it only fires for sticky pistons, but that puts us in a
bind. It's already firing for non-sticky pistons, changing it now would
likely result in breakage. Furthermore, there is little documentation as
to WHY that was ever intended to be the case.
Instead we opt to remove the check entirely so that the event fires for
all piston types.
Co-authored-by: Zach Brown <zach@zachbr.io>
Co-authored-by: Madeline Miller <mnmiller1@me.com>
diff --git a/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java b/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java
index 24a822ade17849a083161216c184f02c30b5cb1f..f456ad8a74464414f69b616a48ee9a2c1cee4d90 100644
--- a/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java
+++ b/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java
@@ -146,15 +146,15 @@ public class PistonBaseBlock extends DirectionalBlock {
}
// CraftBukkit start
- if (!this.isSticky) {
- org.bukkit.block.Block block = world.getWorld().getBlockAt(pos.getX(), pos.getY(), pos.getZ());
- BlockPistonRetractEvent event = new BlockPistonRetractEvent(block, ImmutableList.<org.bukkit.block.Block>of(), CraftBlock.notchToBlockFace(enumdirection));
- world.getCraftServer().getPluginManager().callEvent(event);
-
- if (event.isCancelled()) {
- return;
- }
- }
+ // if (!this.isSticky) { // Paper - Move further down
+ // org.bukkit.block.Block block = world.getWorld().getBlockAt(pos.getX(), pos.getY(), pos.getZ());
+ // BlockPistonRetractEvent event = new BlockPistonRetractEvent(block, ImmutableList.<org.bukkit.block.Block>of(), CraftBlock.notchToBlockFace(enumdirection));
+ // world.getCraftServer().getPluginManager().callEvent(event);
+ //
+ // if (event.isCancelled()) {
+ // return;
+ // }
+ // }
// PAIL: checkME - what happened to setTypeAndData?
// CraftBukkit end
world.blockEvent(pos, this, b0, enumdirection.get3DDataValue());
@@ -236,6 +236,13 @@ public class PistonBaseBlock extends DirectionalBlock {
BlockState iblockdata1 = (BlockState) ((BlockState) Blocks.MOVING_PISTON.defaultBlockState().setValue(MovingPistonBlock.FACING, enumdirection)).setValue(MovingPistonBlock.TYPE, this.isSticky ? PistonType.STICKY : PistonType.DEFAULT);
+ // Paper start - Move empty piston retract call to fix multiple event fires
+ if (!this.isSticky) {
+ if (!new BlockPistonRetractEvent(CraftBlock.at(world, pos), java.util.Collections.emptyList(), CraftBlock.notchToBlockFace(enumdirection)).callEvent()) {
+ return false;
+ }
+ }
+ // Paper end
world.setBlock(pos, iblockdata1, 20);
world.setBlockEntity(MovingPistonBlock.newMovingBlockEntity(pos, iblockdata1, (BlockState) this.defaultBlockState().setValue(PistonBaseBlock.FACING, Direction.from3DDataValue(data & 7)), enumdirection, false, true)); // Paper - diff on change
world.blockUpdated(pos, iblockdata1.getBlock());
@@ -262,6 +269,13 @@ public class PistonBaseBlock extends DirectionalBlock {
if (type == 1 && !iblockdata2.isAir() && PistonBaseBlock.isPushable(iblockdata2, world, blockposition1, enumdirection.getOpposite(), false, enumdirection) && (iblockdata2.getPistonPushReaction() == PushReaction.NORMAL || iblockdata2.is(Blocks.PISTON) || iblockdata2.is(Blocks.STICKY_PISTON))) {
this.moveBlocks(world, pos, enumdirection, false);
} else {
+ // Paper start - fire BlockPistonRetractEvent for sticky pistons retracting nothing (air)
+ if (type == TRIGGER_CONTRACT && iblockdata2.isAir()) {
+ if (!new BlockPistonRetractEvent(CraftBlock.at(world, pos), java.util.Collections.emptyList(), CraftBlock.notchToBlockFace(enumdirection)).callEvent()) {
+ return false;
+ }
+ }
+ // Paper end
world.removeBlock(pos.relative(enumdirection), false);
}
}