Fixed possible memory leak with projectiles, use owner/target metadata

src/pocketmine/entity/Arrow.php

@@ -37,14 +37,9 @@ class Arrow extends Projectile{
 	protected $gravity = 0.05;
 	protected $drag = 0.01;
 
-	protected $damage = 2;
+	public function __construct(Level $level, CompoundTag $nbt, Entity $shootingEntity = null, bool $critical = false){
-
-	protected $isCritical;
-
-	public function __construct(Level $level, CompoundTag $nbt, Entity $shootingEntity = null, $critical = false){
-		$this->isCritical = (bool) $critical;
 		parent::__construct($level, $nbt, $shootingEntity);
-		$this->setDataFlag(self::DATA_FLAGS, self::DATA_FLAG_CRITICAL, $critical);
+		$this->setCritical($critical);
 	}
 
 	public function isCritical() : bool{

src/pocketmine/entity/Entity.php

@@ -533,6 +533,80 @@ abstract class Entity extends Location implements Metadatable{
 		$this->setDataFlag(self::DATA_FLAGS, self::DATA_FLAG_WALLCLIMBING, $value);
 	}
 
+	/**
+	 * Returns the entity ID of the owning entity, or null if the entity doesn't have an owner.
+	 * @return int|string|null
+	 */
+	public function getOwningEntityId(){
+		return $this->getDataProperty(self::DATA_OWNER_EID);
+	}
+
+	/**
+	 * Returns the owning entity, or null if the entity was not found.
+	 * @return Entity|null
+	 */
+	public function getOwningEntity(){
+		$eid = $this->getOwningEntityId();
+		if($eid !== null){
+			return $this->server->findEntity($eid, $this->level);
+		}
+
+		return null;
+	}
+
+	/**
+	 * Sets the owner of the entity.
+	 *
+	 * @param Entity $owner
+	 *
+	 * @throws \InvalidArgumentException if the supplied entity is not valid
+	 */
+	public function setOwningEntity(Entity $owner){
+		if($owner->closed){
+			throw new \InvalidArgumentException("Supplied owning entity is garbage and cannot be used");
+		}
+
+		$this->setDataProperty(self::DATA_OWNER_EID, self::DATA_TYPE_LONG, $owner->getId());
+	}
+
+	/**
+	 * Returns the entity ID of the entity's target, or null if it doesn't have a target.
+	 * @return int|string|null
+	 */
+	public function getTargetEntityId(){
+		return $this->getDataProperty(self::DATA_TARGET_EID);
+	}
+
+	/**
+	 * Returns the entity's target entity, or null if not found.
+	 * This is used for things like hostile mobs attacking entities, and for fishing rods reeling hit entities in.
+	 *
+	 * @return Entity|null
+	 */
+	public function getTargetEntity(){
+		$eid = $this->getTargetEntityId();
+		if($eid !== null){
+			return $this->server->findEntity($eid, $this->level);
+		}
+
+		return null;
+	}
+
+	/**
+	 * Sets the entity's target entity.
+	 *
+	 * @param Entity $target
+	 *
+	 * @throws \InvalidArgumentException if the target entity is not valid
+	 */
+	public function setTargetEntity(Entity $target){
+		if($target->closed){
+			throw new \InvalidArgumentException("Supplied target entity is garbage and cannot be used");
+		}
+
+		$this->setDataProperty(self::DATA_TARGET_EID, self::DATA_TYPE_LONG, $target->getId());
+	}
+
 	/**
 	 * @return Effect[]
 	 */

src/pocketmine/entity/Projectile.php

@@ -36,16 +36,13 @@ abstract class Projectile extends Entity{
 
 	const DATA_SHOOTER_ID = 17;
 
-	/** @var Entity */
-	public $shootingEntity = null;
 	protected $damage = 0;
 
 	public $hadCollision = false;
 
 	public function __construct(Level $level, CompoundTag $nbt, Entity $shootingEntity = null){
-		$this->shootingEntity = $shootingEntity;
 		if($shootingEntity !== null){
-			$this->setDataProperty(self::DATA_SHOOTER_ID, self::DATA_TYPE_LONG, $shootingEntity->getId());
+			$this->setOwningEntity($shootingEntity);
 		}
 		parent::__construct($level, $nbt);
 	}
@@ -83,10 +80,10 @@ abstract class Projectile extends Entity{
 
 		$damage = $this->getResultDamage();
 
-		if($this->shootingEntity === null){
+		if($this->getOwningEntity() === null){
 			$ev = new EntityDamageByEntityEvent($this, $entity, EntityDamageEvent::CAUSE_PROJECTILE, $damage);
 		}else{
-			$ev = new EntityDamageByChildEntityEvent($this->shootingEntity, $this, $entity, EntityDamageEvent::CAUSE_PROJECTILE, $damage);
+			$ev = new EntityDamageByChildEntityEvent($this->getOwningEntity(), $this, $entity, EntityDamageEvent::CAUSE_PROJECTILE, $damage);
 		}
 
 		$entity->attack($ev->getFinalDamage(), $ev);
@@ -140,7 +137,7 @@ abstract class Projectile extends Entity{
 
 			foreach($list as $entity){
 				if(/*!$entity->canCollideWith($this) or */
-				($entity === $this->shootingEntity and $this->ticksLived < 5)
+				($entity->getId() === $this->getOwningEntityId() and $this->ticksLived < 5)
 				){
 					continue;
 				}