Add method isTickingWorlds to Bukkit (#8316)

Co-authored-by: Shane Freeder <theboyetronic@gmail.com>

Also, restores un/loading worlds mid tick. This will not be officially supported API contract that such a routine is safe, and these restrictions may be restored in the future.

patches/api/Add-method-isTickingWorlds-to-Bukkit.patch

@@ -0,0 +1,117 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: BuildTools <46540330+willkroboth@users.noreply.github.com>
+Date: Fri, 19 Aug 2022 16:11:51 -0400
+Subject: [PATCH] Add method isTickingWorlds() to Bukkit.
+
+
+diff --git a/src/main/java/org/bukkit/Bukkit.java b/src/main/java/org/bukkit/Bukkit.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/Bukkit.java
++++ b/src/main/java/org/bukkit/Bukkit.java
+@@ -0,0 +0,0 @@ public final class Bukkit {
+         return server.getWorlds();
+     }
+ 
++    // Paper start
++    /**
++     * Gets whether the worlds are being ticked right not or not.
++     *
++     * @return true if the worlds are being ticked, false otherwise.
++     */
++    public static boolean isTickingWorlds(){
++        return server.isTickingWorlds();
++    }
++    // Paper end
++
+     /**
+      * Creates or loads a world with the given name using the specified
+      * options.
+      * <p>
+      * If the world is already loaded, it will just return the equivalent of
+      * getWorld(creator.name()).
++     * <p>
++     * Do note that un/loading worlds mid-tick may have potential side effects, we strongly recommend
++     * ensuring that you're not loading worlds midtick by checking {@link Bukkit#isTickingWorlds()}
+      *
+      * @param creator the options to use when creating the world
+      * @return newly created or loaded world
+@@ -0,0 +0,0 @@ public final class Bukkit {
+ 
+     /**
+      * Unloads a world with the given name.
++     * <p>
++     * Do note that un/loading worlds mid-tick may have potential side effects, we strongly recommend
++     * ensuring that you're not loading worlds midtick by checking {@link Bukkit#isTickingWorlds()}
+      *
+      * @param name Name of the world to unload
+      * @param save whether to save the chunks before unloading
+@@ -0,0 +0,0 @@ public final class Bukkit {
+ 
+     /**
+      * Unloads the given world.
++     * <p>
++     * Do note that un/loading worlds mid-tick may have potential side effects, we strongly recommend
++     * ensuring that you're not loading worlds midtick by checking {@link Bukkit#isTickingWorlds()}
+      *
+      * @param world the world to unload
+      * @param save whether to save the chunks before unloading
+diff --git a/src/main/java/org/bukkit/Server.java b/src/main/java/org/bukkit/Server.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/Server.java
++++ b/src/main/java/org/bukkit/Server.java
+@@ -0,0 +0,0 @@ public interface Server extends PluginMessageRecipient, net.kyori.adventure.audi
+     @NotNull
+     public List<World> getWorlds();
+ 
++    // Paper start
++    /**
++     * Gets whether the worlds are being ticked right not or not.
++     *
++     * @return true if the worlds are being ticked, false otherwise.
++     */
++    public boolean isTickingWorlds();
++    // Paper end
++
+     /**
+      * Creates or loads a world with the given name using the specified
+      * options.
+      * <p>
+      * If the world is already loaded, it will just return the equivalent of
+      * getWorld(creator.name()).
++     * <p>
++     * Do note that un/loading worlds mid-tick may have potential side effects, we strongly recommend
++     * ensuring that you're not loading worlds midtick by checking {@link Bukkit#isTickingWorlds()}
+      *
+      * @param creator the options to use when creating the world
+      * @return newly created or loaded world
++     * @throws IllegalStateException when {@link #isTickingWorlds() isTickingWorlds} is true
+      */
+     @Nullable
+     public World createWorld(@NotNull WorldCreator creator);
+ 
+     /**
+      * Unloads a world with the given name.
++     * <p>
++     * Do note that un/loading worlds mid-tick may have potential side effects, we strongly recommend
++     * ensuring that you're not loading worlds midtick by checking {@link Bukkit#isTickingWorlds()}
+      *
+      * @param name Name of the world to unload
+      * @param save whether to save the chunks before unloading
+      * @return true if successful, false otherwise
++     * @throws IllegalStateException when {@link #isTickingWorlds() isTickingWorlds} is true
+      */
+     public boolean unloadWorld(@NotNull String name, boolean save);
+ 
+     /**
+      * Unloads the given world.
++     * <p>
++     * Do note that un/loading worlds mid-tick may have potential side effects, we strongly recommend
++     * ensuring that you're not loading worlds midtick by checking {@link Bukkit#isTickingWorlds()}
+      *
+      * @param world the world to unload
+      * @param save whether to save the chunks before unloading
+      * @return true if successful, false otherwise
++     * @throws IllegalStateException when {@link #isTickingWorlds() isTickingWorlds} is true
+      */
+     public boolean unloadWorld(@NotNull World world, boolean save);
+ 

patches/server/Throw-exception-on-world-create-while-being-ticked.patch

@@ -48,11 +48,23 @@ diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/ja
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 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 {
+         return new ArrayList<World>(this.worlds.values());
+     }
+ 
++    @Override
++    public boolean isTickingWorlds() {
++        return console.isIteratingOverLevels;
++    }
++
+     public DedicatedPlayerList getHandle() {
+         return this.playerList;
+     }
 @@ -0,0 +0,0 @@ public final class CraftServer implements Server {
      @Override
      public World createWorld(WorldCreator creator) {
          Preconditions.checkState(this.console.getAllLevels().iterator().hasNext(), "Cannot create additional worlds on STARTUP");
-+        Preconditions.checkState(!this.console.isIteratingOverLevels, "Cannot create a world while worlds are being ticked"); // Paper
++        //Preconditions.checkState(!this.console.isIteratingOverLevels, "Cannot create a world while worlds are being ticked"); // Paper - Cat - Temp disable. We'll see how this goes.
          Validate.notNull(creator, "Creator may not be null");
  
          String name = creator.name();
@@ -60,7 +72,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
  
      @Override
      public boolean unloadWorld(World world, boolean save) {
-+        Preconditions.checkState(!this.console.isIteratingOverLevels, "Cannot unload a world while worlds are being ticked"); // Paper
++        //Preconditions.checkState(!this.console.isIteratingOverLevels, "Cannot unload a world while worlds are being ticked"); // Paper - Cat - Temp disable. We'll see how this goes.
          if (world == null) {
              return false;
          }