Cap Entity Collisions - Resolves #577

Limit a single entity to colliding a max of configurable times per tick.
This will alleviate issues where living entities are hoarded in 1x1 pens

This is not tied to the maxEntityCramming rule. Cramming will still apply
just as it does in Vanilla, but entity pushing logic will be capped.

You can set this to 0 to disable collisions.

Spigot-Server-Patches/Cap-Entity-Collisions.patch

@@ -0,0 +1,58 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Sun, 22 Jan 2017 18:07:56 -0500
+Subject: [PATCH] Cap Entity Collisions
+
+Limit a single entity to colliding a max of configurable times per tick.
+This will alleviate issues where living entities are hoarded in 1x1 pens
+
+This is not tied to the maxEntityCramming rule. Cramming will still apply
+just as it does in Vanilla, but entity pushing logic will be capped.
+
+You can set this to 0 to disable collisions.
+
+diff --git a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+index e8762c487..dba1c477e 100644
+--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
++++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+@@ -0,0 +0,0 @@ public class PaperWorldConfig {
+     private void armorStandEntityLookups() {
+         armorStandEntityLookups = getBoolean("armor-stands-do-collision-entity-lookups", true);
+     }
++
++    public int maxCollisionsPerEntity;
++    private void maxEntityCollision() {
++        maxCollisionsPerEntity = getInt( "max-entity-collisions", this.spigotConfig.getInt("max-entity-collisions", 8) );
++        log( "Max Entity Collisions: " + maxCollisionsPerEntity );
++    }
+ }
+diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
+index a1d2233ba..37dc29f63 100644
+--- a/src/main/java/net/minecraft/server/Entity.java
++++ b/src/main/java/net/minecraft/server/Entity.java
+@@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener {
+     public final boolean defaultActivationState;
+     public long activatedTick = Integer.MIN_VALUE;
+     public boolean fromMobSpawner;
++    protected int numCollisions = 0; // Paper
+     public void inactiveTick() { }
+     // Spigot end
+ 
+diff --git a/src/main/java/net/minecraft/server/EntityLiving.java b/src/main/java/net/minecraft/server/EntityLiving.java
+index 07688b1ce..6ac6a4062 100644
+--- a/src/main/java/net/minecraft/server/EntityLiving.java
++++ b/src/main/java/net/minecraft/server/EntityLiving.java
+@@ -0,0 +0,0 @@ public abstract class EntityLiving extends Entity {
+                 }
+             }
+ 
+-            for (j = 0; j < list.size(); ++j) {
++            numCollisions = Math.max(0, numCollisions - world.paperConfig.maxCollisionsPerEntity); // Paper
++            for (j = 0; j < list.size() && numCollisions < world.paperConfig.maxCollisionsPerEntity; ++j) { // Paper
+                 Entity entity = (Entity) list.get(j);
++                entity.numCollisions++; // Paper
++                numCollisions++; // Paper
+ 
+                 this.C(entity);
+             }
+--

Spigot-Server-Patches/Paper-config-files.patch

@@ -6,7 +6,7 @@ Subject: [PATCH] Paper config files
 
 diff --git a/src/main/java/com/destroystokyo/paper/PaperConfig.java b/src/main/java/com/destroystokyo/paper/PaperConfig.java
 new file mode 100644
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
+index 000000000..c009c5f12
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java
 @@ -0,0 +0,0 @@
@@ -176,7 +176,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +}
 diff --git a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
 new file mode 100644
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
+index 000000000..dae60dcce
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
 @@ -0,0 +0,0 @@
@@ -253,7 +253,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    }
 +}
 diff --git a/src/main/java/net/minecraft/server/DedicatedServer.java b/src/main/java/net/minecraft/server/DedicatedServer.java
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+index 31756b80d..cb83e4f56 100644
 --- a/src/main/java/net/minecraft/server/DedicatedServer.java
 +++ b/src/main/java/net/minecraft/server/DedicatedServer.java
 @@ -0,0 +0,0 @@ public class DedicatedServer extends MinecraftServer implements IMinecraftServer
@@ -268,7 +268,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
              DedicatedServer.LOGGER.info("Generating keypair");
              this.a(MinecraftEncryption.b());
 diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+index d7cc8b60f..b29375a0c 100644
 --- a/src/main/java/net/minecraft/server/World.java
 +++ b/src/main/java/net/minecraft/server/World.java
 @@ -0,0 +0,0 @@ public abstract class World implements IBlockAccess {
@@ -289,7 +289,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
          this.world = new CraftWorld((WorldServer) this, gen, env);
          this.ticksPerAnimalSpawns = this.getServer().getTicksPerAnimalSpawns(); // CraftBukkit
 diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+index 312260764..791383fb3 100644
 --- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
 +++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
 @@ -0,0 +0,0 @@ public final class CraftServer implements Server {
@@ -316,7 +316,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
          overrideAllCommandBlockCommands = commandsConfiguration.getStringList("command-block-overrides").contains("*");
  
 diff --git a/src/main/java/org/bukkit/craftbukkit/Main.java b/src/main/java/org/bukkit/craftbukkit/Main.java
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+index b931cd5c3..788bf6617 100644
 --- a/src/main/java/org/bukkit/craftbukkit/Main.java
 +++ b/src/main/java/org/bukkit/craftbukkit/Main.java
 @@ -0,0 +0,0 @@ public class Main {
@@ -334,4 +334,45 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
              }
          };
  
+diff --git a/src/main/java/org/spigotmc/SpigotWorldConfig.java b/src/main/java/org/spigotmc/SpigotWorldConfig.java
+index fd859f1a6..be003ce65 100644
+--- a/src/main/java/org/spigotmc/SpigotWorldConfig.java
++++ b/src/main/java/org/spigotmc/SpigotWorldConfig.java
+@@ -0,0 +0,0 @@ public class SpigotWorldConfig
+         config.set( "world-settings.default." + path, val );
+     }
+ 
+-    private boolean getBoolean(String path, boolean def)
++    public boolean getBoolean(String path, boolean def)
+     {
+         config.addDefault( "world-settings.default." + path, def );
+         return config.getBoolean( "world-settings." + worldName + "." + path, config.getBoolean( "world-settings.default." + path ) );
+     }
+ 
+-    private double getDouble(String path, double def)
++    public double getDouble(String path, double def)
+     {
+         config.addDefault( "world-settings.default." + path, def );
+         return config.getDouble( "world-settings." + worldName + "." + path, config.getDouble( "world-settings.default." + path ) );
+     }
+ 
+-    private int getInt(String path, int def)
++    public int getInt(String path, int def)
+     {
+         config.addDefault( "world-settings.default." + path, def );
+         return config.getInt( "world-settings." + worldName + "." + path, config.getInt( "world-settings.default." + path ) );
+     }
+ 
+-    private <T> List getList(String path, T def)
++    public <T> List getList(String path, T def)
+     {
+         config.addDefault( "world-settings.default." + path, def );
+         return (List<T>) config.getList( "world-settings." + worldName + "." + path, config.getList( "world-settings.default." + path ) );
+     }
+ 
+-    private String getString(String path, String def)
++    public String getString(String path, String def)
+     {
+         config.addDefault( "world-settings.default." + path, def );
+         return config.getString( "world-settings." + worldName + "." + path, config.getString( "world-settings.default." + path ) );
 --