Add ability to change biome in unloaded chunks (#28).

Create new object that stores information about pending biome change operation per chunk.
Add new ChunkLoadListener that fires on ChunkLoadEvent and changes biome in given chunk, if it is in pending list.
Add new operation that force-load chunk once per 5 ticks and change biome in it.

pom.xml

@@ -46,8 +46,8 @@
         <java.version>1.8</java.version>
         <powermock.version>1.7.4</powermock.version>
         <!-- More visible way how to change dependency versions -->
-        <spigot.version>1.13.2-R0.1-SNAPSHOT</spigot.version>
-        <bentobox.version>1.5.2</bentobox.version>
+        <spigot.version>1.14.3-R0.1-SNAPSHOT</spigot.version>
+        <bentobox.version>1.5.3</bentobox.version>
         <level.version>1.5.0</level.version>
         <vault.version>1.7</vault.version>
         <anvilgui.version>a07c9b64f7</anvilgui.version>

src/main/java/world/bentobox/biomes/BiomesAddon.java

@@ -3,23 +3,24 @@
 
 import org.bukkit.Bukkit;
 import org.bukkit.Material;
-import java.util.ArrayList;
-import java.util.List;
+import org.bukkit.World;
+import java.util.Iterator;
 import java.util.Optional;
 
 import world.bentobox.bentobox.api.addons.Addon;
-import world.bentobox.bentobox.api.addons.GameModeAddon;
 import world.bentobox.bentobox.api.configuration.Config;
 import world.bentobox.bentobox.api.flags.Flag;
 import world.bentobox.bentobox.hooks.VaultHook;
 import world.bentobox.bentobox.managers.RanksManager;
 import world.bentobox.biomes.commands.admin.AdminCommand;
 import world.bentobox.biomes.commands.user.BiomesCommand;
+import world.bentobox.biomes.database.objects.BiomeChunkUpdateObject;
 import world.bentobox.biomes.handlers.BiomeDataRequestHandler;
 import world.bentobox.biomes.handlers.BiomeListRequestHandler;
 import world.bentobox.biomes.handlers.ChangeBiomeRequestHandler;
 import world.bentobox.biomes.listeners.ChangeOwnerListener;
 import world.bentobox.biomes.config.Settings;
+import world.bentobox.biomes.listeners.ChunkLoadListener;
 import world.bentobox.level.Level;
 
 
@@ -121,6 +122,7 @@ public void onEnable()
 
 			// Register the reset listener
 			this.registerListener(new ChangeOwnerListener(this));
+			this.registerListener(new ChunkLoadListener(this));
 
 			// Register Flags
 			this.registerFlag(BIOMES_WORLD_PROTECTION);
@@ -131,6 +133,38 @@ public void onEnable()
 			this.registerRequestHandler(new BiomeListRequestHandler(this));
 
 			this.registerRequestHandler(new ChangeBiomeRequestHandler(this));
+
+			// This task will force-load chunk every 5th tick if its biome is not updated.
+			Bukkit.getScheduler().runTaskTimer(this.getPlugin(), () -> {
+				Iterator<BiomeChunkUpdateObject> iterator = this.addonManager.getBiomeUpdaterCollection().iterator();
+
+				// if there is nothing to load, then skip.
+				if (!iterator.hasNext())
+				{
+					return;
+				}
+
+				BiomeChunkUpdateObject updater = iterator.next();
+
+				// if chunk is already force-loaded, then skip.
+				while (iterator.hasNext() && updater.isForceLoaded())
+				{
+					updater = iterator.next();
+				}
+
+				World world = updater.getWorld();
+
+				// if chunk is loaded then skip.
+				if (!world.isChunkLoaded(updater.getChunkX(), updater.getChunkZ()))
+				{
+					// Set flag as force-loaded.
+					updater.setForceLoaded(true);
+
+					// force-load chunk.
+					world.setChunkForceLoaded(updater.getChunkX(), updater.getChunkZ(), true);
+					world.loadChunk(updater.getChunkX(), updater.getChunkZ());
+				}
+			}, 5L, 5L);
 		}
 		else
 		{

src/main/java/world/bentobox/biomes/BiomesAddonManager.java

@@ -16,6 +16,7 @@
 import world.bentobox.bentobox.database.Database;
 import world.bentobox.bentobox.util.ItemParser;
 import world.bentobox.bentobox.util.Util;
+import world.bentobox.biomes.database.objects.BiomeChunkUpdateObject;
 import world.bentobox.biomes.database.objects.BiomesObject;
 import world.bentobox.biomes.config.Settings.VisibilityMode;
 import world.bentobox.biomes.panels.GuiUtils;
@@ -45,6 +46,9 @@ protected BiomesAddonManager(BiomesAddon addon)
 			this.addon.saveResource("biomes.yml", false);
 		}
 
+		this.biomePendingChunkUpdateDatabase = new Database<>(addon, BiomeChunkUpdateObject.class);
+		this.biomePendingChunkUpdateMap = new HashMap<>();
+
 		this.load();
 
 		// TODO: Remove this code after some time, as this is just a protective code against invalid world names.
@@ -56,7 +60,9 @@ protected BiomesAddonManager(BiomesAddon addon)
 					biomesObject.setWorld(biomesObject.getWorld().toLowerCase());
 					biomesObject.setUniqueId(biomesObject.getUniqueId().toLowerCase());
 
-					this.addon.logWarning("Biomes addon fixed your data for biome " + biomesObject.getUniqueId() + ". 1.14 does not allow to use capital letters in world names.");
+					this.addon.logWarning("Biomes addon fixed your data for biome "
+						+ biomesObject.getUniqueId() +
+						". 1.14 does not allow to use capital letters in world names.");
 				}
 			});
 		}
@@ -74,9 +80,12 @@ protected BiomesAddonManager(BiomesAddon addon)
 	private void load()
 	{
 		this.biomesCacheData.clear();
+		this.biomePendingChunkUpdateMap.clear();
+
 		this.addon.getLogger().info("Loading biomes...");
 
 		this.biomesDatabase.loadObjects().forEach(this::loadBiomes);
+		this.biomePendingChunkUpdateDatabase.loadObjects().forEach(this::addChunkUpdateObject);
 	}
 
 
@@ -89,6 +98,9 @@ public void reload()
 
 		this.biomesDatabase = new Database<>(this.addon, BiomesObject.class);
 		this.biomesDatabase.loadObjects().forEach(this::loadBiomes);
+
+		this.biomePendingChunkUpdateDatabase = new Database<>(this.addon, BiomeChunkUpdateObject.class);
+		this.biomePendingChunkUpdateDatabase.loadObjects().forEach(this::addChunkUpdateObject);
 	}
 
 
@@ -113,6 +125,19 @@ public void saveBiome(BiomesObject biome)
 	public void save()
 	{
 		this.biomesCacheData.values().forEach(this.biomesDatabase::saveObject);
+
+		// Clear Database.
+		List<BiomeChunkUpdateObject> objectList =
+			this.biomePendingChunkUpdateDatabase.loadObjects();
+		objectList.forEach(object -> this.biomePendingChunkUpdateDatabase.
+			deleteID(object.getUniqueId()));
+
+		// Save cache into database.
+		if (!this.biomePendingChunkUpdateMap.isEmpty())
+		{
+			this.biomePendingChunkUpdateMap.values().forEach(
+				this.biomePendingChunkUpdateDatabase::saveObject);
+		}
 	}
 
 	/**
@@ -581,6 +606,60 @@ public boolean hasAnyBiome(World world)
 	}
 
 
+// ---------------------------------------------------------------------
+// Section: Later Biome Updater
+// ---------------------------------------------------------------------
+
+
+	/**
+	 * This method finds and returns BiomeChunkUpdaterObject in given world with given
+	 * chunk X and Z coordinates.
+	 * @param world World where process will happen.
+	 * @param x Chunk X coordinate.
+	 * @param z Chunk Z coordinate.
+	 * @return BiomeChunkUpdateObject where update is pending or null.
+	 */
+	public BiomeChunkUpdateObject getPendingChunkUpdateObject(World world, int x, int z)
+	{
+		return this.biomePendingChunkUpdateMap.get(world.getName() + "-" + x + "-" + z);
+	}
+
+
+	/**
+	 * This method returns collection with all objects that contains information about
+	 * chunks where biome update is still not completed.
+	 * @return Collection of BiomeCHunkUpdateObjects.
+	 */
+	public Collection<BiomeChunkUpdateObject> getBiomeUpdaterCollection()
+	{
+		return this.biomePendingChunkUpdateMap.values();
+	}
+
+
+	/**
+	 * This method adds BiomeChunkUpdateObject to cache.
+	 * @param updateObject Object that must be added to cache.
+	 */
+	public void addChunkUpdateObject(BiomeChunkUpdateObject updateObject)
+	{
+		this.biomePendingChunkUpdateMap.put(updateObject.getUniqueId(), updateObject);
+	}
+
+
+	/**
+	 * This method removes given element form cache and database.
+	 * @param element Element that should be removed.
+	 */
+	public void removeUpdateObject(BiomeChunkUpdateObject element)
+	{
+		if (this.biomePendingChunkUpdateMap.containsKey(element.getUniqueId()))
+		{
+			this.biomePendingChunkUpdateMap.remove(element.getUniqueId());
+			this.biomePendingChunkUpdateDatabase.deleteObject(element);
+		}
+	}
+
+
 // ---------------------------------------------------------------------
 // Section: Variables
 // ---------------------------------------------------------------------
@@ -604,4 +683,15 @@ public boolean hasAnyBiome(World world)
 	 * Variable stores biomes.yml location
 	 */
 	private File biomesFile;
+
+	/**
+	 * Variable stores BiomeChunkUpdateObject objects that contains information about
+	 * chunk that is not updated yet.
+	 */
+	private Map<String, BiomeChunkUpdateObject> biomePendingChunkUpdateMap;
+
+	/**
+	 * Variable stores database of BiomeChunkUpdateObject.
+	 */
+	private Database<BiomeChunkUpdateObject> biomePendingChunkUpdateDatabase;
 }