Fire entity dismount/vehicle events (but supress their cancellation) for player teleportation

Entities must be dismounted before teleportation in order to avoid
multiple issues in the server with regards to teleportation, shamefully,
too many plugins rely on the events firing, which means that not firing
these events caues more issues than it solves;

In order to counteract this, Entity dismount/exit vehicle events have
been modified to supress cancellation (and has a method to allow plugins
to check if this has been set), noting that cancellation will be silently
surpressed given that plugins are not expecting this event to not be cancellable.

This is a far from ideal scenario, however: given the current state of this
event and other alternatives causing issues elsewhere, I believe that
this is going to be the best soultion all around.

Improvements/suggestions welcome!

Spigot-API-Patches/0167-Support-cancellation-supression-of-EntityDismount-Ve.patch

@@ -0,0 +1,112 @@
+From f1d6f2a88ce9419dcfc9ae177fd077c1e60c6eb6 Mon Sep 17 00:00:00 2001
+From: Shane Freeder <theboyetronic@gmail.com>
+Date: Sun, 18 Nov 2018 15:53:43 +0000
+Subject: [PATCH] Support cancellation supression of EntityDismount/VehicleExit
+ events"
+
+Entities must be dismounted before teleportation in order to avoid
+multiple issues in the server with regards to teleportation, shamefully,
+too many plugins rely on the events firing, which means that not firing
+these events caues more issues than it solves;
+
+In order to counteract this, Entity dismount/exit vehicle events have
+been modified to supress cancellation (and has a method to allow plugins
+to check if this has been set), noting that cancellation will be silently
+surpressed given that plugins are not expecting this event to not be cancellable.
+
+This is a far from ideal scenario, however: given the current state of this
+event and other alternatives causing issues elsewhere, I believe that
+this is going to be the best soultion all around.
+
+Improvements/suggestions welcome!
+
+diff --git a/src/main/java/org/bukkit/event/vehicle/VehicleExitEvent.java b/src/main/java/org/bukkit/event/vehicle/VehicleExitEvent.java
+index 364451b56..b3269db2e 100644
+--- a/src/main/java/org/bukkit/event/vehicle/VehicleExitEvent.java
++++ b/src/main/java/org/bukkit/event/vehicle/VehicleExitEvent.java
+@@ -12,10 +12,18 @@ public class VehicleExitEvent extends VehicleEvent implements Cancellable {
+     private static final HandlerList handlers = new HandlerList();
+     private boolean cancelled;
+     private final LivingEntity exited;
++    private final boolean isCancellable; // Paper
+ 
+-    public VehicleExitEvent(final Vehicle vehicle, final LivingEntity exited) {
++    public VehicleExitEvent(Vehicle vehicle, LivingEntity exited, boolean isCancellable) { // Paper
+         super(vehicle);
+         this.exited = exited;
++        // Paper start
++        this.isCancellable = isCancellable;
++    }
++
++    public VehicleExitEvent(final Vehicle vehicle, final LivingEntity exited) {
++        this(vehicle, exited, true);
++        // Paper end
+     }
+ 
+     /**
+@@ -32,9 +40,18 @@ public class VehicleExitEvent extends VehicleEvent implements Cancellable {
+     }
+ 
+     public void setCancelled(boolean cancel) {
++        // Paper start
++        if (cancel && !isCancellable) {
++            return;
++        }
+         this.cancelled = cancel;
+     }
+ 
++    public boolean isCancellable() {
++        return isCancellable;
++        // paper end
++    }
++
+     @Override
+     public HandlerList getHandlers() {
+         return handlers;
+diff --git a/src/main/java/org/spigotmc/event/entity/EntityDismountEvent.java b/src/main/java/org/spigotmc/event/entity/EntityDismountEvent.java
+index 4110d3bb2..555899efc 100644
+--- a/src/main/java/org/spigotmc/event/entity/EntityDismountEvent.java
++++ b/src/main/java/org/spigotmc/event/entity/EntityDismountEvent.java
+@@ -15,11 +15,20 @@ public class EntityDismountEvent extends EntityEvent implements Cancellable
+     private static final HandlerList handlers = new HandlerList();
+     private boolean cancelled;
+     private final Entity dismounted;
++    private final boolean isCancellable; // Paper
+ 
+     public EntityDismountEvent(Entity what, Entity dismounted)
+     {
++        // Paper start
++        this(what, dismounted, true);
++    }
++
++    public EntityDismountEvent(Entity what, Entity dismounted, boolean isCancellable)
++    {
++        // Paper end
+         super( what );
+         this.dismounted = dismounted;
++        this.isCancellable = isCancellable; // Paper
+     }
+ 
+     public Entity getDismounted()
+@@ -36,9 +45,18 @@ public class EntityDismountEvent extends EntityEvent implements Cancellable
+     @Override
+     public void setCancelled(boolean cancel)
+     {
++        // Paper start
++        if (cancel && !isCancellable) {
++            return;
++        }
+         this.cancelled = cancel;
+     }
+ 
++    public boolean isCancellable() {
++        return isCancellable;
++        // Paper end
++    }
++
+     @Override
+     public HandlerList getHandlers()
+     {
+-- 
+2.19.1
+

Spigot-Server-Patches/0409-force-entity-dismount-during-teleportation.patch

@@ -1,21 +1,26 @@
-From eb51274be66ea5528f88a96fb47566325f46b0ce Mon Sep 17 00:00:00 2001
+From 61a77f36f64990073b33f4d0e0ab942060e044d3 Mon Sep 17 00:00:00 2001
 From: Shane Freeder <theboyetronic@gmail.com>
 Date: Thu, 15 Nov 2018 13:38:37 +0000
 Subject: [PATCH] force entity dismount during teleportation
 
 Entities must be dismounted before teleportation in order to avoid
-multiple issues in the server with regards to teleportation, while
-we now lose the ability for plugins to monitor this specific case
-of entity dismount, the alternative is that we allow a cancellable
-event, but silently ignore the cancelled status, which might cause
-further issues for plugins tracking state
+multiple issues in the server with regards to teleportation, shamefully,
+too many plugins rely on the events firing, which means that not firing
+these events caues more issues than it solves;
 
-Given that nobody can be relying on the Cancellable state of those
-events during teleportation due to the issues that arise from this,
-this is a small trade off
+In order to counteract this, Entity dismount/exit vehicle events have
+been modified to supress cancellation (and has a method to allow plugins
+to check if this has been set), noting that cancellation will be silently
+surpressed given that plugins are not expecting this event to not be cancellable.
+
+This is a far from ideal scenario, however: given the current state of this
+event and other alternatives causing issues elsewhere, I believe that
+this is going to be the best soultion all around.
+
+Improvements/suggestions welcome!
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index 32b90f30d9..2377175f83 100644
+index 32b90f30d9..78ec842f29 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -2096,12 +2096,15 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
@@ -25,43 +30,49 @@ index 32b90f30d9..2377175f83 100644
 -    public void stopRiding() {
 +    // Paper start
 +    public void stopRiding() { stopRiding(false); }
-+    public void stopRiding(boolean force) {
++    public void stopRiding(boolean suppressCancellation) {
 +    // Paper end
          if (this.vehicle != null) {
              Entity entity = this.vehicle;
  
              this.vehicle = null;
 -            if (!entity.removePassenger(this)) this.vehicle = entity; // CraftBukkit
-+            if (!entity.removePassenger(this, force)) this.vehicle = entity; // CraftBukkit // Paper
++            if (!entity.removePassenger(this, suppressCancellation)) this.vehicle = entity; // CraftBukkit // Paper
          }
  
      }
-@@ -2146,10 +2149,14 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
+@@ -2146,7 +2149,10 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
          return true; // CraftBukkit
      }
  
 -    protected boolean removePassenger(Entity entity) { // CraftBukkit
 +    // Paper start
 +    protected boolean removePassenger(Entity entity) { return removePassenger(entity, false);}
-+    protected boolean removePassenger(Entity entity, boolean force) { // CraftBukkit
++    protected boolean removePassenger(Entity entity, boolean suppressCancellation) { // CraftBukkit
 +        // Paper end
          if (entity.getVehicle() == this) {
              throw new IllegalStateException("Use x.stopRiding(y), not y.removePassenger(x)");
          } else {
-+            if (!force) { // Paper
-             // CraftBukkit start
-             CraftEntity craft = (CraftEntity) entity.getBukkitEntity().getVehicle();
-             Entity orig = craft == null ? null : craft.getHandle();
-@@ -2172,6 +2179,7 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
+@@ -2156,7 +2162,7 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
+             if (getBukkitEntity() instanceof Vehicle && entity.getBukkitEntity() instanceof LivingEntity) {
+                 VehicleExitEvent event = new VehicleExitEvent(
+                         (Vehicle) getBukkitEntity(),
+-                        (LivingEntity) entity.getBukkitEntity()
++                        (LivingEntity) entity.getBukkitEntity(), !suppressCancellation // Paper
+                 );
+                 Bukkit.getPluginManager().callEvent(event);
+                 CraftEntity craftn = (CraftEntity) entity.getBukkitEntity().getVehicle();
+@@ -2167,7 +2173,7 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
+             }
+             // CraftBukkit end
+             // Spigot start
+-            org.spigotmc.event.entity.EntityDismountEvent event = new org.spigotmc.event.entity.EntityDismountEvent(entity.getBukkitEntity(), this.getBukkitEntity());
++            org.spigotmc.event.entity.EntityDismountEvent event = new org.spigotmc.event.entity.EntityDismountEvent(entity.getBukkitEntity(), this.getBukkitEntity(), !suppressCancellation); // Paper
+             Bukkit.getPluginManager().callEvent(event);
              if (event.isCancelled()) {
                  return false;
-             }
-+            } // Paper
-             // Spigot end
-             this.passengers.remove(entity);
-             entity.k = 60;
 diff --git a/src/main/java/net/minecraft/server/EntityPlayer.java b/src/main/java/net/minecraft/server/EntityPlayer.java
-index 4490b63258..4fcbbae7d4 100644
+index 4490b63258..388a20a21f 100644
 --- a/src/main/java/net/minecraft/server/EntityPlayer.java
 +++ b/src/main/java/net/minecraft/server/EntityPlayer.java
 @@ -776,10 +776,13 @@ public class EntityPlayer extends EntityHuman implements ICrafting {
@@ -71,28 +82,15 @@ index 4490b63258..4fcbbae7d4 100644
 -    public void stopRiding() {
 +    // Paper start
 +    public void stopRiding() { stopRiding(false);};
-+    public void stopRiding(boolean force) {
++    public void stopRiding(boolean suppressCancellation) {
 +    // paper end
          Entity entity = this.getVehicle();
  
 -        super.stopRiding();
-+        super.stopRiding(force); // Paper
++        super.stopRiding(suppressCancellation); // Paper
          Entity entity1 = this.getVehicle();
  
          if (entity1 != entity && this.playerConnection != null) {
-diff --git a/src/main/java/net/minecraft/server/PlayerList.java b/src/main/java/net/minecraft/server/PlayerList.java
-index 73bd0dc4a1..ec52f385eb 100644
---- a/src/main/java/net/minecraft/server/PlayerList.java
-+++ b/src/main/java/net/minecraft/server/PlayerList.java
-@@ -619,7 +619,7 @@ public abstract class PlayerList {
-     }
- 
-     public EntityPlayer moveToWorld(EntityPlayer entityplayer, DimensionManager dimensionmanager, boolean flag, Location location, boolean avoidSuffocation) {
--        entityplayer.stopRiding(); // CraftBukkit
-+        entityplayer.stopRiding(true); // CraftBukkit // Paper
-         entityplayer.getWorldServer().getTracker().untrackPlayer(entityplayer);
-         // entityplayer.getWorldServer().getTracker().untrackEntity(entityplayer); // CraftBukkit
-         entityplayer.getWorldServer().getPlayerChunkMap().removePlayer(entityplayer);
 -- 
 2.19.1