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, 21 insertions, 0 deletions

diff --git a/patches/server/0442-Fix-CraftSound-backwards-compatibility.patch b/patches/server/0442-Fix-CraftSound-backwards-compatibility.patch
new file mode 100644
index 0000000000..9ca7f86992
--- /dev/null
+++ b/patches/server/0442-Fix-CraftSound-backwards-compatibility.patch
@@ -0,0 +1,21 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: BillyGalbreath <[email protected]>
+Date: Thu, 17 Dec 2020 15:25:49 -0600
+Subject: [PATCH] Fix CraftSound backwards compatibility
+
+
+diff --git a/src/main/java/org/bukkit/craftbukkit/CraftSound.java b/src/main/java/org/bukkit/craftbukkit/CraftSound.java
+index 260a738d5d61cf931b939502ea9c66451855b91e..dce716b6ac407d1e1ae07272ee5c8b14f891f5fa 100644
+--- a/src/main/java/org/bukkit/craftbukkit/CraftSound.java
++++ b/src/main/java/org/bukkit/craftbukkit/CraftSound.java
+@@ -40,4 +40,10 @@ public class CraftSound {
+         throw new IllegalArgumentException("No Reference holder found for " + bukkit
+                 + ", this can happen if a plugin creates its own sound effect with out properly registering it.");
+     }
++
++    // Paper start
++    public static String getSound(Sound sound) {
++        return sound.getKey().getKey();
++    }
++    // Paper end
+ }