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c5a10665b8
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.
91 lines
4.5 KiB
Diff
91 lines
4.5 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Aikar <aikar@aikar.co>
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Date: Sat, 21 Jul 2018 14:27:34 -0400
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Subject: [PATCH] Duplicate UUID Resolve Option
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Due to a bug in https://github.com/PaperMC/Paper/commit/2e29af3df05ec0a383f48be549d1c03200756d24
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which was added all the way back in March of 2016, it was unknown (potentially not at the time)
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that an entity might actually change the seed of the random object.
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At some point, EntitySquid did start setting the seed. Due to this shared random, this caused
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every entity to use a Random object with a predictable seed.
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This has caused entities to potentially generate with the same UUID....
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Over the years, servers have had entities disappear, but no sign of trouble
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because CraftBukkit removed the log lines indicating that something was wrong.
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We have fixed the root issue causing duplicate UUID's, however we now have chunk
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files full of entities that have the same UUID as another entity!
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When these chunks load, the 2nd entity will not be added to the world correctly.
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If that chunk loads in a different order in the future, then it will reverse and the
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missing one is now the one added to the world and not the other. This results in very
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inconsistent entity behavior.
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This change allows you to recover any duplicate entity by generating a new UUID for it.
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This also lets you delete them instead if you don't want to risk having new entities added to
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the world that you previously did not see.
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But for those who are ok with leaving this inconsistent behavior, you may use WARN or NOTHING options.
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It is recommended you regenerate the entities, as these were legit entities, and deserve your love.
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diff --git a/src/main/java/net/minecraft/world/level/chunk/status/ChunkStatusTasks.java b/src/main/java/net/minecraft/world/level/chunk/status/ChunkStatusTasks.java
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index 82fc5133325a127890984d51c1381883759eb444..ae16cf5c803caae636860dd9b1a83abe479ca5a4 100644
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--- a/src/main/java/net/minecraft/world/level/chunk/status/ChunkStatusTasks.java
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+++ b/src/main/java/net/minecraft/world/level/chunk/status/ChunkStatusTasks.java
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@@ -189,10 +189,51 @@ public class ChunkStatusTasks {
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entity.discard(null); // CraftBukkit - add Bukkit remove cause
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needsRemoval = true;
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}
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+ checkDupeUUID(world, entity); // Paper - duplicate uuid resolving
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return !needsRemoval;
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}));
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// CraftBukkit end
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}
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}
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+
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+ // Paper start - duplicate uuid resolving
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+ // rets true if to prevent the entity from being added
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+ public static boolean checkDupeUUID(ServerLevel level, net.minecraft.world.entity.Entity entity) {
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+ io.papermc.paper.configuration.WorldConfiguration.Entities.Spawning.DuplicateUUID.DuplicateUUIDMode mode = level.paperConfig().entities.spawning.duplicateUuid.mode;
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+ if (mode != io.papermc.paper.configuration.WorldConfiguration.Entities.Spawning.DuplicateUUID.DuplicateUUIDMode.WARN
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+ && mode != io.papermc.paper.configuration.WorldConfiguration.Entities.Spawning.DuplicateUUID.DuplicateUUIDMode.DELETE
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+ && mode != io.papermc.paper.configuration.WorldConfiguration.Entities.Spawning.DuplicateUUID.DuplicateUUIDMode.SAFE_REGEN) {
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+ return false;
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+ }
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+ net.minecraft.world.entity.Entity other = level.getEntity(entity.getUUID());
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+
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+ if (other == null || other == entity) {
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+ return false;
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+ }
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+
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+ if (mode == io.papermc.paper.configuration.WorldConfiguration.Entities.Spawning.DuplicateUUID.DuplicateUUIDMode.SAFE_REGEN && other != null && !other.isRemoved()
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+ && Objects.equals(other.getEncodeId(), entity.getEncodeId())
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+ && entity.getBukkitEntity().getLocation().distance(other.getBukkitEntity().getLocation()) < level.paperConfig().entities.spawning.duplicateUuid.safeRegenDeleteRange
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+ ) {
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+ entity.discard(null);
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+ return true;
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+ }
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+ if (!other.isRemoved()) {
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+ switch (mode) {
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+ case SAFE_REGEN: {
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+ entity.setUUID(java.util.UUID.randomUUID());
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+ break;
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+ }
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+ case DELETE: {
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+ entity.discard(org.bukkit.event.entity.EntityRemoveEvent.Cause.DISCARD);
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+ return true;
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+ }
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+ default:
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+ break;
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+ }
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+ }
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+ return false;
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+ }
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+ // Paper end - duplicate uuid resolving
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}
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