[1.8] Tile entity sometimes null

[SnowyEgret]

I have a block which provides a tile entity and is rendered by an ISmartBlockModel.

 

Method handleBlockState() is overidden to lookup a model given an IBlockState which is read from an unlisted property which is in turn set from a field on the block's tile entity. This is all based on TheGreyGhost's Minecraft by Example MBE04, and works fine, most of the time.

 

Here is my block:

 

public class BlockSelected extends Block implements ITileEntityProvider {

public static final PrevStateProperty prevStateProperty = new PrevStateProperty();

public BlockSelected() {
	super(Material.clay);
}

@Override
public boolean isOpaqueCube() {
	return false;
}

@SideOnly(Side.CLIENT)
public EnumWorldBlockLayer getBlockLayer() {
	return EnumWorldBlockLayer.CUTOUT_MIPPED;
}

@Override
protected BlockState createBlockState() {
	return new ExtendedBlockState(this, new IProperty[0], new IUnlistedProperty[] { prevStateProperty });
}

@Override
public IBlockState getExtendedState(IBlockState state, IBlockAccess world, BlockPos pos) {
	PrevStateTileEntity tileEntity = (PrevStateTileEntity) world.getTileEntity(pos);
	IBlockState prevState = null;
	if (tileEntity != null) {
		prevState = tileEntity.getPrevState();
	} else {
		System.out.println("tileEntity=" + tileEntity);
	}
	return ((IExtendedBlockState) state).withProperty(prevStateProperty, prevState);
}

@Override
public TileEntity createNewTileEntity(World worldIn, int meta) {
	return new PrevStateTileEntity();
}

}

 

and here is the ISmartBlockModel's relevent code:

 

public class BlockSelectedModel implements ISmartBlockModel {

private IBakedModel model;

@Override
public IBakedModel handleBlockState(IBlockState state) {
	IBlockState s = ((IExtendedBlockState) state).getValue(BlockSelected.prevStateProperty);
	model = Minecraft.getMinecraft().getBlockRendererDispatcher().getBlockModelShapes().getModelForState(s);
	return this;
}
}

 

Here is my tile entity with its IBlockState field:

 

public class PrevStateTileEntity extends TileEntity {

private IBlockState prevState;
private final String PREV_STATE_KEY = "b";

public IBlockState getPrevState() {
	return prevState;
}

public void setPrevState(IBlockState state) {
	prevState = state;
}

@Override
public void writeToNBT(NBTTagCompound tag) {
	tag.setInteger(PREV_STATE_KEY, Block.getStateId(prevState));
	super.writeToNBT(tag);
}

@Override
public void readFromNBT(NBTTagCompound tag) {
	prevState = Block.getStateById(tag.getInteger(PREV_STATE_KEY));
	super.readFromNBT(tag);
}

@Override
public Packet getDescriptionPacket() {
	NBTTagCompound tag = new NBTTagCompound();
	writeToNBT(tag);
	super.writeToNBT(tag);
	return new S35PacketUpdateTileEntity(pos, this.getBlockMetadata(), tag);
}

@Override
public void onDataPacket(NetworkManager net, S35PacketUpdateTileEntity pkt) {
	readFromNBT(pkt.getNbtCompound());
	super.readFromNBT(pkt.getNbtCompound());
}

}

 

I am placing the block in the world like this:

 

	world.setBlockState(pos, state, 1);
	world.markBlockForUpdate(pos);
	PrevStateTileEntity tileEntity = (PrevStateTileEntity) world.getTileEntity(pos);
	tileEntity.setPrevState(prevState);

 

The problem occurs when the tile entity in getExtendedState() occasionally comes up null during rendering. Without the tile entity, I can not set the unlisted property and the block can't render. This always happens when I set a range of blocks, and then set another adjacent range. The first range renders properly after being set, but then their tile entities come back null after the adjacent range is set. I know the tile entity is null, because I get the println in getExtendedState().

 

If I set the first range, then walk away into another chunk before coming back and setting the second range, things are ok, and world.getTileEntity(pos) comes back with a valid tile entity.

 

Here is an image of the problem. The outermost ring of blocks are the new setBlockStates. The inner blocks were rendering properly before the outer ring was added. I am guessing they cross a chunk boundary which would explain why some of the inner ones are rendering properly:

 

[/img]

 

 

[delpi]

I can't remember why, but i got in the habit of a null check anytime I grab and instance of a tile.

 

If it only happens in a rare tick, skipping the render for the null isn't going to matter much.

 

 

On your end, have you tried error trapping it or using the debug to see what is going on? 

[SnowyEgret]

I have placed this line with a breakpoint after the test for a null tile entity (just gets the tile entity again)

 

		
world.getTileEntity(pos);

 

it takes me here in class RegionRenderCache:

 

		
    public TileEntity getTileEntity(BlockPos pos)
    {
        int i = (pos.getX() >> 4) - this.chunkX;
        int j = (pos.getZ() >> 4) - this.chunkZ;
        return this.chunkArray[i][j].getTileEntity(pos, Chunk.EnumCreateEntityType.QUEUED);
    }

 

to here in class Chunk:

    public TileEntity getTileEntity(BlockPos pos, Chunk.EnumCreateEntityType p_177424_2_)
    {
        TileEntity tileentity = (TileEntity)this.chunkTileEntityMap.get(pos);

        if (tileentity != null && tileentity.isInvalid())
        {
            chunkTileEntityMap.remove(pos);
            tileentity = null;
        }

        if (tileentity == null)
        {
            if (p_177424_2_ == Chunk.EnumCreateEntityType.IMMEDIATE)
            {
                tileentity = this.createNewTileEntity(pos);
                this.worldObj.setTileEntity(pos, tileentity);
            }
            else if (p_177424_2_ == Chunk.EnumCreateEntityType.QUEUED)
            {
                this.field_177447_w.add(pos);
            }
        }

        return tileentity;
    }

 

tileentity comes back null from chunkTileEntityMap then when p_177424_2_ == Chunk.EnumCreateEntityType.QUEUED, the position is added to field_177447_w which is of type ConcurrentLinkedQueue.

 

 

[delpi]

Something looks odd with your tile entity, but I don't have access to anything right now, so can't figure it out.

 

Why are you doing this?

 

 

world.setBlockState(pos, state, 1);

world.markBlockForUpdate(pos);

PrevStateTileEntity tileEntity = (PrevStateTileEntity) world.getTileEntity(pos);

tileEntity.setPrevState(prevState);

 

 

 

Did you get that from someone as an example?

 

 

 

[SnowyEgret]

After I set my block (BTW, world.setBlock(pos, state, 3) without marking the position for update seems to behave identically) I need to set field prevState (type IBlockState) on the tile entity. When the tile entity is created by my block, field prevState is uninitialized:

 

@Override
public TileEntity createNewTileEntity(World worldIn, int meta) {
	return new PrevStateTileEntity();
}

 

 

 

[delpi]

I'm going to have to let someone else chime in that has set a block/tile in 1.8 via java.  I have working blocks, but I'm always setting them with the player.

[SnowyEgret]

Thanks delpi.

 

BTW, I have modified my original post so that the image in the spoiler correctly shows the problem.

[SnowyEgret]

Something else that may be relevant. I sometimes get this warning in the console when the tile entity is coming up null:

 

[12:47:43] [Client thread/WARN]: Needed to grow BufferBuilder buffer: Old size 524288 bytes, new size 2621440 bytes.

 

Does anyone know which class is printing this warning?

[SnowyEgret]

Ok, I have found a fix for my problem, but I have no idea of it's consequences, nor do I understand why it's working. Poking around in Chunk.setBlockState() I came across this block of code which removes tile entities:

 

                if (!this.worldObj.isRemote)
                {
                    if (iblockstate1.getBlock() != state.getBlock()) //Only fire block breaks when the block changes.
                    block1.breakBlock(this.worldObj, pos, iblockstate1);
                    TileEntity te = this.getTileEntity(pos, Chunk.EnumCreateEntityType.CHECK);
                    if (te != null && te.shouldRefresh(this.worldObj, pos, iblockstate1, state)) this.worldObj.removeTileEntity(pos);
                }
                else if (block1.hasTileEntity(iblockstate1))
                {
                    TileEntity te = this.getTileEntity(pos, Chunk.EnumCreateEntityType.CHECK);
                    if (te != null && te.shouldRefresh(this.worldObj, pos, iblockstate1, state))
                    this.worldObj.removeTileEntity(pos);
                }

 

TileEntity.shouldRefresh() looks like this:

 

    /**
     * Called from Chunk.setBlockIDWithMetadata, determines if this tile entity should be re-created when the ID, or Metadata changes.
     * Use with caution as this will leave straggler TileEntities, or create conflicts with other TileEntities if not used properly.
     *
     * @param world Current world
     * @param pos Tile's world position
     * @param oldID The old ID of the block
     * @param newID The new ID of the block (May be the same)
     * @return True to remove the old tile entity, false to keep it in tact {and create a new one if the new values specify to}
     */
    public boolean shouldRefresh(World world, BlockPos pos, IBlockState oldState, IBlockState newSate)
    {
        return !isVanilla || (oldState.getBlock() != newSate.getBlock());
    }

 

In my tile entity class I have overidden it leaving out the test for isVanilla:

 

@Override
public boolean shouldRefresh(World world, BlockPos pos, IBlockState oldState, IBlockState newSate) {
	return oldState.getBlock() != newSate.getBlock();
}

 

and my problem (and it has been a problem for weeks - I have tried everything) has gone away.

 

Please, if anyone has some insight, please share it. I am wary of the caution in the javadoc comment.

 

[delpi]

I'm not sure, but I suspect you should just override that and have it return false for your block.

[SnowyEgret]

I put these printlns in my tile entity's shouldRefresh():

 

@Override
public boolean shouldRefresh(World world, BlockPos pos, IBlockState oldState, IBlockState newSate) {
	System.out.println("oldState="+oldState);
	System.out.println("newSate="+newSate);
	new Throwable().printStackTrace();
	return oldState.getBlock() != newSate.getBlock();
}

 

and get this in the console:

 

[16:26:44] [Client thread/INFO] [sTDOUT]: [org.snowyegret.mojo.block.PrevStateTileEntity:shouldRefresh:30]: oldState=mojo:block_selected
[16:26:44] [Client thread/INFO] [sTDOUT]: [org.snowyegret.mojo.block.PrevStateTileEntity:shouldRefresh:31]: newSate=mojo:block_selected
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: java.lang.Throwable
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at org.snowyegret.mojo.block.PrevStateTileEntity.shouldRefresh(PrevStateTileEntity.java:32)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.world.chunk.Chunk.fillChunk(Chunk.java:1425)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.client.network.NetHandlerPlayClient.handleChunkData(NetHandlerPlayClient.java:763)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.network.play.server.S21PacketChunkData.processPacket(S21PacketChunkData.java:64)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.network.play.server.S21PacketChunkData.processPacket(S21PacketChunkData.java:152)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.network.PacketThreadUtil$1.run(PacketThreadUtil.java:24)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraftforge.fml.common.FMLCommonHandler.callFuture(FMLCommonHandler.java:714)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.client.Minecraft.runGameLoop(Minecraft.java:1078)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.client.Minecraft.run(Minecraft.java:376)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.client.main.Main.main(Main.java:117)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at java.lang.reflect.Method.invoke(Method.java:497)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
[16:26:44] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

 

As it turns out, it is this block of code in Chunk.fillChunk() that is calling shouldRefresh():

 

        while (iterator.hasNext())
        {
            TileEntity tileentity = (TileEntity)iterator.next();
            if (tileentity.shouldRefresh(this.worldObj, tileentity.getPos(), tileentity.getBlockType().getStateFromMeta(tileentity.getBlockMetadata()), getBlockState(tileentity.getPos())))
                invalidList.add(tileentity);
            tileentity.updateContainingBlockInfo();
        }

        for (TileEntity te : invalidList) te.invalidate();

 

This must be where minecraft performs a sort of garbage collection by invalidating tile entities which are no longer "referenced" by a block at that position. When the block changes to one that has no new tile entity to overwite it, you don't want it left in the world. I am not sure why this decision is delegated to the tile entity, and why its default implementation returns true if the tile entity is not vanilla (from class TileEntity):

    private boolean isVanilla = getClass().getName().startsWith("net.minecraft.");

 

but my guess is that the I should be keeping the check for oldState.getBlock() != newSate.getBlock() or I will be populating the world with unused tile entities.