Moved light population to an async task when needed, improved empty chunks

src/pocketmine/level/generator/LightPopulationTask.php

@@ -0,0 +1,74 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+namespace pocketmine\level\generator;
+
+use pocketmine\block\Block;
+use pocketmine\level\format\FullChunk;
+use pocketmine\level\generator\biome\Biome;
+use pocketmine\level\Level;
+use pocketmine\level\SimpleChunkManager;
+use pocketmine\scheduler\AsyncTask;
+use pocketmine\Server;
+use pocketmine\utils\Random;
+
+class LightPopulationTask extends AsyncTask{
+
+	public $levelId;
+	public $chunk;
+	public $chunkClass;
+
+	public function __construct(Level $level, FullChunk $chunk){
+		$this->levelId = $level->getId();
+		$this->chunk = $chunk->toFastBinary();
+		$this->chunkClass = get_class($chunk);
+	}
+
+	public function onRun(){
+		/** @var FullChunk $chunk */
+		$chunk = $this->chunkClass;
+		$chunk = $chunk::fromFastBinary($this->chunk);
+		if($chunk === null){
+			//TODO error
+			return;
+		}
+
+		$chunk->recalculateHeightMap();
+		$chunk->populateSkyLight();
+		$chunk->setLightPopulated();
+
+		$this->chunk = $chunk->toFastBinary();
+	}
+
+	public function onCompletion(Server $server){
+		$level = $server->getLevel($this->levelId);
+		if($level !== null){
+			/** @var FullChunk $chunk */
+			$chunk = $this->chunkClass;
+			$chunk = $chunk::fromFastBinary($this->chunk, $level->getProvider());
+			if($chunk === null){
+				//TODO error
+				return;
+			}
+			$level->generateChunkCallback($chunk->getX(), $chunk->getZ(), $chunk);
+		}
+	}
+}