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.

1 files changed, 54 insertions, 0 deletions

diff --git a/patches/server/0454-Fix-Not-a-string-Map-Conversion-spam.patch b/patches/server/0454-Fix-Not-a-string-Map-Conversion-spam.patch
new file mode 100644
index 0000000000..5b2328afe8
--- /dev/null
+++ b/patches/server/0454-Fix-Not-a-string-Map-Conversion-spam.patch
@@ -0,0 +1,54 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Aikar <[email protected]>
+Date: Thu, 8 Oct 2020 00:00:25 -0400
+Subject: [PATCH] Fix "Not a string" Map Conversion spam
+
+The maps did convert successfully, but had noisy logs due to Spigot
+implementing this logic incorrectly.
+
+This stops the spam by converting the old format to new before
+requesting the world.
+
+Track spigot issue to see when fixed: https://hub.spigotmc.org/jira/browse/SPIGOT-6181
+
+diff --git a/src/main/java/net/minecraft/world/level/saveddata/maps/MapItemSavedData.java b/src/main/java/net/minecraft/world/level/saveddata/maps/MapItemSavedData.java
+index 5e469bd4d9ca428abdd9d758993164635dc86f27..d6a0a882331226c3ae4ced09e449eb7931740f8f 100644
+--- a/src/main/java/net/minecraft/world/level/saveddata/maps/MapItemSavedData.java
++++ b/src/main/java/net/minecraft/world/level/saveddata/maps/MapItemSavedData.java
+@@ -21,6 +21,8 @@ import net.minecraft.core.component.DataComponents;
+ import net.minecraft.nbt.CompoundTag;
+ import net.minecraft.nbt.ListTag;
+ import net.minecraft.nbt.NbtOps;
++import net.minecraft.nbt.NumericTag;
++import net.minecraft.nbt.StringTag;
+ import net.minecraft.nbt.Tag;
+ import net.minecraft.network.FriendlyByteBuf;
+ import net.minecraft.network.chat.Component;
+@@ -121,7 +123,26 @@ public class MapItemSavedData extends SavedData {
+     }
+ 
+     public static MapItemSavedData load(CompoundTag nbt, HolderLookup.Provider registryLookup) {
+-        DataResult<ResourceKey<Level>> dataresult = DimensionType.parseLegacy(new Dynamic(NbtOps.INSTANCE, nbt.get("dimension"))); // CraftBukkit - decompile error
++        // Paper start - fix "Not a string" spam
++        Tag dimension = nbt.get("dimension");
++        if (dimension instanceof NumericTag && ((NumericTag) dimension).getAsInt() >= CraftWorld.CUSTOM_DIMENSION_OFFSET) {
++            long least = nbt.getLong("UUIDLeast");
++            long most = nbt.getLong("UUIDMost");
++
++            if (least != 0L && most != 0L) {
++                UUID uuid = new UUID(most, least);
++                CraftWorld world = (CraftWorld) Bukkit.getWorld(uuid);
++                if (world != null) {
++                    dimension = StringTag.valueOf("minecraft:" + world.getName().toLowerCase(java.util.Locale.ENGLISH));
++                } else {
++                    dimension = StringTag.valueOf("bukkit:_invalidworld_");
++                }
++            } else {
++                dimension = StringTag.valueOf("bukkit:_invalidworld_");
++            }
++        }
++        DataResult<ResourceKey<Level>> dataresult = DimensionType.parseLegacy(new Dynamic(NbtOps.INSTANCE, dimension)); // CraftBukkit - decompile error
++        // Paper end - fix "Not a string" spam
+         Logger logger = MapItemSavedData.LOGGER;
+ 
+         Objects.requireNonNull(logger);