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, 41 insertions, 0 deletions

diff --git a/patches/server/0940-Fix-bees-aging-inside-hives.patch b/patches/server/0940-Fix-bees-aging-inside-hives.patch
new file mode 100644
index 0000000000..400ede1160
--- /dev/null
+++ b/patches/server/0940-Fix-bees-aging-inside-hives.patch
@@ -0,0 +1,41 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Jake Potrebic <[email protected]>
+Date: Sat, 21 Aug 2021 21:54:16 -0700
+Subject: [PATCH] Fix bees aging inside hives
+
+Fixes bees incorrectly being aged up due to upstream's
+resetting the ticks inside hive on a failed release
+
+diff --git a/src/main/java/net/minecraft/world/level/block/entity/BeehiveBlockEntity.java b/src/main/java/net/minecraft/world/level/block/entity/BeehiveBlockEntity.java
+index 1a3d8755c8f6a7cfe06069e2082d8147aaaff097..f933fa419a4b55b0096ff42caf1b071d027b8e7e 100644
+--- a/src/main/java/net/minecraft/world/level/block/entity/BeehiveBlockEntity.java
++++ b/src/main/java/net/minecraft/world/level/block/entity/BeehiveBlockEntity.java
+@@ -314,7 +314,7 @@ public class BeehiveBlockEntity extends BlockEntity {
+                     iterator.remove();
+                     // CraftBukkit start
+                 } else {
+-                    tileentitybeehive_hivebee.ticksInHive = tileentitybeehive_hivebee.occupant.minTicksInHive / 2; // Not strictly Vanilla behaviour in cases where bees cannot spawn but still reasonable
++                    tileentitybeehive_hivebee.exitTickCounter = tileentitybeehive_hivebee.occupant.minTicksInHive / 2; // Not strictly Vanilla behaviour in cases where bees cannot spawn but still reasonable // Paper - Fix bees aging inside hives; use exitTickCounter to keep actual bee life
+                     // CraftBukkit end
+                 }
+             }
+@@ -474,15 +474,18 @@ public class BeehiveBlockEntity extends BlockEntity {
+     private static class BeeData {
+ 
+         private final BeehiveBlockEntity.Occupant occupant;
++        private int exitTickCounter; // Paper - Fix bees aging inside hives; separate counter for checking if bee should exit to reduce exit attempts
+         private int ticksInHive;
+ 
+         BeeData(BeehiveBlockEntity.Occupant data) {
+             this.occupant = data;
+             this.ticksInHive = data.ticksInHive();
++            this.exitTickCounter = this.ticksInHive; // Paper - Fix bees aging inside hives
+         }
+ 
+         public boolean tick() {
+-            return this.ticksInHive++ > this.occupant.minTicksInHive;
++            this.ticksInHive++; // Paper - Fix bees aging inside hives
++            return this.exitTickCounter++ > this.occupant.minTicksInHive; // Paper - Fix bees aging inside hives
+         }
+ 
+         public BeehiveBlockEntity.Occupant toOccupant() {