From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Mon, 29 Feb 2016 17:43:33 -0600
Subject: [PATCH] Async Chunks API

Adds API's to load or generate chunks asynchronously.

Also adds utility methods to Entity to teleport asynchronously.

diff --git a/src/main/java/org/bukkit/World.java b/src/main/java/org/bukkit/World.java
index b3098ce9134acf24f49d23fc1babe79c6bf502f1..5efe33cef4d9c153d760fc71606721ff8abafbfc 100644
--- a/src/main/java/org/bukkit/World.java
+++ b/src/main/java/org/bukkit/World.java
@@ -950,6 +950,472 @@ public interface World extends RegionAccessor, WorldInfo, PluginMessageRecipient
     }
     // Paper end - additional getNearbyEntities API
 
+    // Paper start - async chunks API
+    /**
+     * This is the Legacy API before Java 8 was supported. Java 8 Consumer is provided,
+     * as well as future support
+     *
+     * Used by {@link World#getChunkAtAsync(Location,ChunkLoadCallback)} methods
+     * to request a {@link Chunk} to be loaded, with this callback receiving
+     * the chunk when it is finished.
+     *
+     * This callback will be executed on synchronously on the main thread.
+     *
+     * Timing and order this callback is fired is intentionally not defined and
+     * and subject to change.
+     *
+     * @deprecated Use either the Future or the Consumer based methods
+     */
+    @Deprecated
+    public static interface ChunkLoadCallback extends java.util.function.Consumer<Chunk> {
+        public void onLoad(@NotNull Chunk chunk);
+
+        // backwards compat to old api
+        @Override
+        default void accept(@NotNull Chunk chunk) {
+            onLoad(chunk);
+        }
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The {@link ChunkLoadCallback} will always be executed synchronously
+     * on the main Server Thread.
+     *
+     * @deprecated Use either the Future or the Consumer based methods
+     * @param x Chunk X-coordinate of the chunk - floor(world coordinate / 16)
+     * @param z Chunk Z-coordinate of the chunk - floor(world coordinate / 16)
+     * @param cb Callback to receive the chunk when it is loaded.
+     *           will be executed synchronously
+     */
+    @Deprecated
+    public default void getChunkAtAsync(int x, int z, @NotNull ChunkLoadCallback cb) {
+        getChunkAtAsync(x, z, true).thenAccept(cb::onLoad).exceptionally((ex) -> {
+            Bukkit.getLogger().log(java.util.logging.Level.WARNING, "Exception in chunk load callback", ex);
+            return null;
+        });
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given {@link Location}
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The {@link ChunkLoadCallback} will always be executed synchronously
+     * on the main Server Thread.
+     *
+     * @deprecated Use either the Future or the Consumer based methods
+     * @param loc Location of the chunk
+     * @param cb Callback to receive the chunk when it is loaded.
+     *           will be executed synchronously
+     */
+    @Deprecated
+    public default void getChunkAtAsync(@NotNull Location loc, @NotNull ChunkLoadCallback cb) {
+        getChunkAtAsync(loc, true).thenAccept(cb::onLoad).exceptionally((ex) -> {
+            Bukkit.getLogger().log(java.util.logging.Level.WARNING, "Exception in chunk load callback", ex);
+            return null;
+        });
+    }
+
+    /**
+     * Requests {@link Chunk} to be loaded that contains the given {@link Block}
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The {@link ChunkLoadCallback} will always be executed synchronously
+     * on the main Server Thread.
+     *
+     * @deprecated Use either the Future or the Consumer based methods
+     * @param block Block to get the containing chunk from
+     * @param cb Callback to receive the chunk when it is loaded.
+     *           will be executed synchronously
+     */
+    @Deprecated
+    public default void getChunkAtAsync(@NotNull Block block, @NotNull ChunkLoadCallback cb) {
+        getChunkAtAsync(block, true).thenAccept(cb::onLoad).exceptionally((ex) -> {
+            Bukkit.getLogger().log(java.util.logging.Level.WARNING, "Exception in chunk load callback", ex);
+            return null;
+        });
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The {@link java.util.function.Consumer} will always be executed synchronously
+     * on the main Server Thread.
+     *
+     * @param x Chunk X-coordinate of the chunk - floor(world coordinate / 16)
+     * @param z Chunk Z-coordinate of the chunk - floor(world coordinate / 16)
+     * @param cb Callback to receive the chunk when it is loaded.
+     *           will be executed synchronously
+     */
+    default void getChunkAtAsync(final int x, final int z, final @NotNull Consumer<? super Chunk> cb) {
+        this.getChunkAtAsync(x, z, true).thenAccept(cb).exceptionally((ex) -> {
+            Bukkit.getLogger().log(java.util.logging.Level.WARNING, "Exception in chunk load callback", ex);
+            return null;
+        });
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The {@link java.util.function.Consumer} will always be executed synchronously
+     * on the main Server Thread.
+     *
+     * @param x Chunk X-coordinate of the chunk - floor(world coordinate / 16)
+     * @param z Chunk Z-coordinate of the chunk - floor(world coordinate / 16)
+     * @param gen Should we generate a chunk if it doesn't exist or not
+     * @param cb Callback to receive the chunk when it is loaded.
+     *           will be executed synchronously
+     */
+    default void getChunkAtAsync(final int x, final int z, final boolean gen, final @NotNull Consumer<? super Chunk> cb) {
+        this.getChunkAtAsync(x, z, gen).thenAccept(cb).exceptionally((ex) -> {
+            Bukkit.getLogger().log(java.util.logging.Level.WARNING, "Exception in chunk load callback", ex);
+            return null;
+        });
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given {@link Location}
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The {@link java.util.function.Consumer} will always be executed synchronously
+     * on the main Server Thread.
+     *
+     * @param loc Location of the chunk
+     * @param cb Callback to receive the chunk when it is loaded.
+     *           will be executed synchronously
+     */
+    default void getChunkAtAsync(final @NotNull Location loc, final @NotNull Consumer<? super Chunk> cb) {
+        this.getChunkAtAsync((int) Math.floor(loc.getX()) >> 4, (int) Math.floor(loc.getZ()) >> 4, true, cb);
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given {@link Location}
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The {@link java.util.function.Consumer} will always be executed synchronously
+     * on the main Server Thread.
+     *
+     * @param loc Location of the chunk
+     * @param gen Should the chunk generate if it doesn't exist
+     * @param cb Callback to receive the chunk when it is loaded.
+     *           will be executed synchronously
+     */
+    default void getChunkAtAsync(final @NotNull Location loc, final boolean gen, final @NotNull Consumer<? super Chunk> cb) {
+        this.getChunkAtAsync((int) Math.floor(loc.getX()) >> 4, (int) Math.floor(loc.getZ()) >> 4, gen, cb);
+    }
+
+    /**
+     * Requests {@link Chunk} to be loaded that contains the given {@link Block}
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The {@link java.util.function.Consumer} will always be executed synchronously
+     * on the main Server Thread.
+     *
+     * @param block Block to get the containing chunk from
+     * @param cb Callback to receive the chunk when it is loaded.
+     *           will be executed synchronously
+     */
+    default void getChunkAtAsync(final @NotNull Block block, final @NotNull Consumer<? super Chunk> cb) {
+        this.getChunkAtAsync(block.getX() >> 4, block.getZ() >> 4, true, cb);
+    }
+
+    /**
+     * Requests {@link Chunk} to be loaded that contains the given {@link Block}
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The {@link java.util.function.Consumer} will always be executed synchronously
+     * on the main Server Thread.
+     *
+     * @param block Block to get the containing chunk from
+     * @param gen Should the chunk generate if it doesn't exist
+     * @param cb Callback to receive the chunk when it is loaded.
+     *           will be executed synchronously
+     */
+    default void getChunkAtAsync(final @NotNull Block block, final boolean gen, final @NotNull Consumer<? super Chunk> cb) {
+        this.getChunkAtAsync(block.getX() >> 4, block.getZ() >> 4, gen, cb);
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The future will always be executed synchronously
+     * on the main Server Thread.
+     * @param loc Location to load the corresponding chunk from
+     * @return Future that will resolve when the chunk is loaded
+     */
+    default @NotNull java.util.concurrent.CompletableFuture<Chunk> getChunkAtAsync(final @NotNull Location loc) {
+        return this.getChunkAtAsync((int) Math.floor(loc.getX()) >> 4, (int) Math.floor(loc.getZ()) >> 4, true);
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The future will always be executed synchronously
+     * on the main Server Thread.
+     * @param loc Location to load the corresponding chunk from
+     * @param gen Should the chunk generate if it doesn't exist
+     * @return Future that will resolve when the chunk is loaded
+     */
+    default @NotNull java.util.concurrent.CompletableFuture<Chunk> getChunkAtAsync(final @NotNull Location loc, final boolean gen) {
+        return this.getChunkAtAsync((int) Math.floor(loc.getX()) >> 4, (int) Math.floor(loc.getZ()) >> 4, gen);
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The future will always be executed synchronously
+     * on the main Server Thread.
+     * @param block Block to load the corresponding chunk from
+     * @return Future that will resolve when the chunk is loaded
+     */
+    default @NotNull java.util.concurrent.CompletableFuture<Chunk> getChunkAtAsync(final @NotNull Block block) {
+        return this.getChunkAtAsync(block.getX() >> 4, block.getZ() >> 4, true);
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The future will always be executed synchronously
+     * on the main Server Thread.
+     * @param block Block to load the corresponding chunk from
+     * @param gen Should the chunk generate if it doesn't exist
+     * @return Future that will resolve when the chunk is loaded
+     */
+    default @NotNull java.util.concurrent.CompletableFuture<Chunk> getChunkAtAsync(final @NotNull Block block, final boolean gen) {
+        return this.getChunkAtAsync(block.getX() >> 4, block.getZ() >> 4, gen);
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The future will always be executed synchronously
+     * on the main Server Thread.
+     *
+     * @param x Chunk X-coordinate of the chunk - floor(world coordinate / 16)
+     * @param z Chunk Z-coordinate of the chunk - floor(world coordinate / 16)
+     * @return Future that will resolve when the chunk is loaded
+     */
+    default @NotNull java.util.concurrent.CompletableFuture<Chunk> getChunkAtAsync(final int x, final int z) {
+        return this.getChunkAtAsync(x, z, true);
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The future will always be executed synchronously
+     * on the main Server Thread.
+     *
+     * @param x Chunk X-coordinate of the chunk - floor(world coordinate / 16)
+     * @param z Chunk Z-coordinate of the chunk - floor(world coordinate / 16)
+     * @param gen Should we generate a chunk if it doesn't exist or not
+     * @return Future that will resolve when the chunk is loaded
+     */
+    default @NotNull java.util.concurrent.CompletableFuture<Chunk> getChunkAtAsync(final int x, final int z, final boolean gen) {
+        return this.getChunkAtAsync(x, z, gen, false);
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The future will always be executed synchronously
+     * on the main Server Thread.
+     * @param loc Location to load the corresponding chunk from
+     * @return Future that will resolve when the chunk is loaded
+     */
+    default @NotNull java.util.concurrent.CompletableFuture<Chunk> getChunkAtAsyncUrgently(final @NotNull Location loc) {
+        return this.getChunkAtAsync((int) Math.floor(loc.getX()) >> 4, (int) Math.floor(loc.getZ()) >> 4, true, true);
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The future will always be executed synchronously
+     * on the main Server Thread.
+     * @param loc Location to load the corresponding chunk from
+     * @param gen Should the chunk generate if it doesn't exist
+     * @return Future that will resolve when the chunk is loaded
+     */
+    default @NotNull java.util.concurrent.CompletableFuture<Chunk> getChunkAtAsyncUrgently(final @NotNull Location loc, final boolean gen) {
+        return this.getChunkAtAsync((int) Math.floor(loc.getX()) >> 4, (int) Math.floor(loc.getZ()) >> 4, gen, true);
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The future will always be executed synchronously
+     * on the main Server Thread.
+     * @param block Block to load the corresponding chunk from
+     * @return Future that will resolve when the chunk is loaded
+     */
+    default @NotNull java.util.concurrent.CompletableFuture<Chunk> getChunkAtAsyncUrgently(final @NotNull Block block) {
+        return this.getChunkAtAsync(block.getX() >> 4, block.getZ() >> 4, true, true);
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The future will always be executed synchronously
+     * on the main Server Thread.
+     * @param block Block to load the corresponding chunk from
+     * @param gen Should the chunk generate if it doesn't exist
+     * @return Future that will resolve when the chunk is loaded
+     */
+    default @NotNull java.util.concurrent.CompletableFuture<Chunk> getChunkAtAsyncUrgently(final @NotNull Block block, final boolean gen) {
+        return this.getChunkAtAsync(block.getX() >> 4, block.getZ() >> 4, gen, true);
+    }
+
+    /**
+     * Requests a {@link Chunk} to be loaded at the given coordinates
+     *
+     * This method makes no guarantee on how fast the chunk will load,
+     * and will return the chunk to the callback at a later time.
+     *
+     * You should use this method if you need a chunk but do not need it
+     * immediately, and you wish to let the server control the speed
+     * of chunk loads, keeping performance in mind.
+     *
+     * The future will always be executed synchronously
+     * on the main Server Thread.
+     *
+     * @param x X Coord
+     * @param z Z Coord
+     * @return Future that will resolve when the chunk is loaded
+     */
+    default @NotNull java.util.concurrent.CompletableFuture<Chunk> getChunkAtAsyncUrgently(final int x, final int z) {
+        return this.getChunkAtAsync(x, z, true, true);
+    }
+
+    java.util.concurrent.@NotNull CompletableFuture<Chunk> getChunkAtAsync(int x, int z, boolean gen, boolean urgent);
+    // Paper end - async chunks API
+
     /**
      * Get a list of all players in this World
      *
diff --git a/src/main/java/org/bukkit/entity/Entity.java b/src/main/java/org/bukkit/entity/Entity.java
index 1e43deadce5a1a0e97521b1f69fee3106f5a0b9e..f1fc42ad24648ee481b9a5d4c4cc58ae8c0a93c1 100644
--- a/src/main/java/org/bukkit/entity/Entity.java
+++ b/src/main/java/org/bukkit/entity/Entity.java
@@ -168,6 +168,39 @@ public interface Entity extends Metadatable, CommandSender, Nameable, Persistent
      */
     public boolean teleport(@NotNull Entity destination, @NotNull TeleportCause cause);
 
+    // Paper start
+    /**
+     * Loads/Generates(in 1.13+) the Chunk asynchronously, and then teleports the entity when the chunk is ready.
+     * @param loc Location to teleport to
+     * @return A future that will be completed with the result of the teleport
+     */
+    default java.util.concurrent.@NotNull CompletableFuture<Boolean> teleportAsync(final @NotNull Location loc) {
+        return this.teleportAsync(loc, TeleportCause.PLUGIN);
+    }
+
+    /**
+     * Loads/Generates(in 1.13+) the Chunk asynchronously, and then teleports the entity when the chunk is ready.
+     * @param loc Location to teleport to
+     * @param cause Reason for teleport
+     * @return A future that will be completed with the result of the teleport
+     */
+    default java.util.concurrent.@NotNull CompletableFuture<Boolean> teleportAsync(final @NotNull Location loc, final @NotNull TeleportCause cause) {
+        final class Holder {
+            static final io.papermc.paper.entity.TeleportFlag[] EMPTY_FLAGS = new io.papermc.paper.entity.TeleportFlag[0];
+        }
+        return this.teleportAsync(loc, cause, Holder.EMPTY_FLAGS);
+    }
+
+    /**
+     * Loads/Generates(in 1.13+) the Chunk asynchronously, and then teleports the entity when the chunk is ready.
+     * @param loc Location to teleport to
+     * @param cause Reason for teleport
+     * @param teleportFlags Flags to be used in this teleportation
+     * @return A future that will be completed with the result of the teleport
+     */
+    java.util.concurrent.@NotNull CompletableFuture<Boolean> teleportAsync(@NotNull Location loc, @NotNull TeleportCause cause, @NotNull io.papermc.paper.entity.TeleportFlag @NotNull... teleportFlags);
+    // Paper end
+
     /**
      * Returns a list of entities within a bounding box centered around this
      * entity