I'm currently dealing with a system that stores LivingEntity instances and some related data in a map, based on certain conditions.
In order to prevent memory leakage, I need to remove entries from said map as appropriate.

 

This *could* be accomplished by iterating through every map entry * every entity in every world and seeing if any world contains it, on a timer, but that's a bit inefficient compared to an event-based system.

 

As far as events go, I have not been able to find an event specifically for "any time an entity is unloaded" (latest stable forge release; 2768), but if one exists, please tell me!

 

For now, I tried the next best thing, and used a combination of other events.  This is working for *some* cases but not all.  For example, if I spawn a zombie in an enclosed structure (not in a permanently loaded chunk / "spawn chunk") and move very far away, I receive no messages involving said zombie.  If I place a llama outside the structure, I *do* receive a message for that in the chunk unload.  Also, even if the zombie has a name via nametag, I still receive no message.

Current code:
 

Spoiler

    @SubscribeEvent
    public static void despawn(LivingSpawnEvent.AllowDespawn event)
    {
        EntityLivingBase livingBase = event.getEntityLiving();
        Event.Result result = event.getResult();
        if (livingBase instanceof EntityLiving && result != Event.Result.DENY && result != Event.Result.DEFAULT)
        {
            System.out.println("Despawn " + event.getEntity().getName());
        }
    }

    @SubscribeEvent
    public static void entityDead(LivingDeathEvent event)
    {
        System.out.println("Dead " + event.getEntity().getName());
    }

    @SubscribeEvent
    public static void chunkUnload(ChunkEvent.Unload event)
    {
        Chunk chunk = event.getChunk();
        Set<Entity>[] sets = chunk.getEntityLists();
        for (Set<Entity> set : sets)
        {
            for (Entity entity : set)
            {
                if (entity instanceof EntityLiving) System.out.println("Chunk Unload (saved) " + entity.getName());
            }
        }
    }

    @SubscribeEvent
    public static void worldUnload(WorldEvent.Unload event)
    {
        for (Entity entity : event.getWorld().loadedEntityList)
        {
            if (entity instanceof EntityLiving)
            {
                System.out.println("World Unload " + entity.getName());
            }
        }
    }

 

 

 

Edit: For now, I've supplemented this with the periodic double-iteration I was trying to avoid.  I'm still using the above methods to keep the map size to a minimum and reduce processing due to the periodic iterations.

Edited December 24, 20186 yr by Laike_Endaril
Update

Thanks for the reply, and sorry for my late response!  I will look into capabilities.