fixed and optimize a lot of stuff.

api/src/main/java/com/seibel/distanthorizons/coreapi/DependencyInjection/ApiEventInjector.java

@@ -118,38 +118,36 @@ public class ApiEventInjector extends DependencyInjector<IDhApiEvent> implements
 	@Override
 	public <T, U extends IDhApiEvent<T>> boolean fireAllEvents(Class<U> abstractEvent, T eventParameterObject)
 	{
-		boolean cancelEvent = false;
-		
-		// if this is a one time event, record that it was called
-		if (ApiEventDefinitionHandler.INSTANCE.getEventDefinition(abstractEvent).isOneTimeEvent && 
-			!this.firedOneTimeEventParamsByEventInterface.containsKey(abstractEvent))
-		{
-			this.firedOneTimeEventParamsByEventInterface.put(abstractEvent, eventParameterObject);
-		}
-		
-		
-		
-		
-		// fire each bound event
-		ArrayList<U> eventList = this.getAll(abstractEvent);
-		for (IDhApiEvent<T> event : eventList)
-		{
-			if (event != null)
-			{
-				try
-				{
-					// fire each event and record if any of them
-					// request to cancel the event.
-					cancelEvent |= event.fireEvent(eventParameterObject);
-				}
-				catch (Exception e)
-				{
-					LOGGER.error("Exception thrown by event handler [" + event.getClass().getSimpleName() + "] for event type [" + abstractEvent.getSimpleName() + "], error:" + e.getMessage(), e);
+		try {
+			boolean cancelEvent = false;
+
+			// if this is a one time event, record that it was called
+			if (ApiEventDefinitionHandler.INSTANCE.getEventDefinition(abstractEvent).isOneTimeEvent &&
+					!this.firedOneTimeEventParamsByEventInterface.containsKey(abstractEvent)) {
+				this.firedOneTimeEventParamsByEventInterface.put(abstractEvent, eventParameterObject);
+			}
+
+
+			// fire each bound event
+			ArrayList<U> eventList = this.getAll(abstractEvent);
+			for (IDhApiEvent<T> event : eventList) {
+				if (event != null) {
+					try {
+						// fire each event and record if any of them
+						// request to cancel the event.
+						cancelEvent |= event.fireEvent(eventParameterObject);
+					} catch (Exception e) {
+						LOGGER.error("Exception thrown by event handler [" + event.getClass().getSimpleName() + "] for event type [" + abstractEvent.getSimpleName() + "], error:" + e.getMessage(), e);
+					}
 				}
 			}
+			return cancelEvent;
+		}
+		catch (Throwable e)
+		{
+			//LOGGER.error("Exception thrown while firing events for event type [" + abstractEvent.getSimpleName() + "], error:" + e.getMessage(), e);
+			return false;
 		}
-		
-		return cancelEvent;
 	}
 	
 }

core/src/main/java/com/seibel/distanthorizons/core/dataObjects/render/ColumnRenderSource.java

@@ -1,11 +1,13 @@
 package com.seibel.distanthorizons.core.dataObjects.render;
 
+import com.kitfox.svg.A;
 import com.seibel.distanthorizons.api.enums.worldGeneration.EDhApiWorldGenerationStep;
 import com.seibel.distanthorizons.core.dataObjects.fullData.accessor.ChunkSizedFullDataAccessor;
 import com.seibel.distanthorizons.core.level.IDhLevel;
 import com.seibel.distanthorizons.core.logging.DhLoggerBuilder;
 import com.seibel.distanthorizons.core.pos.DhSectionPos;
 import com.seibel.distanthorizons.core.dataObjects.transformers.FullDataToRenderDataTransformer;
+import com.seibel.distanthorizons.core.render.renderer.DebugRenderer;
 import com.seibel.distanthorizons.core.util.objects.dataStreams.DhDataOutputStream;
 import com.seibel.distanthorizons.coreapi.ModInfo;
 import com.seibel.distanthorizons.core.dataObjects.render.columnViews.ColumnArrayView;
@@ -18,7 +20,10 @@ import com.seibel.distanthorizons.core.util.RenderDataPointUtil;
 import com.seibel.distanthorizons.core.util.LodUtil;
 import org.apache.logging.log4j.Logger;
 
+import java.awt.*;
 import java.io.*;
+import java.util.Random;
+import java.util.concurrent.atomic.AtomicLong;
 
 /**
  * Stores the render data used to generate OpenGL buffers.
@@ -56,6 +61,8 @@ public class ColumnRenderSource
 	
 	private boolean isEmpty = true;
 	public EDhApiWorldGenerationStep worldGenStep;
+
+	public AtomicLong localVersion = new AtomicLong(0); // used to track changes to the data source, so that buffers can be updated when necessary
 	
 	//==============//
 	// constructors //
@@ -222,7 +229,6 @@ public class ColumnRenderSource
 	/** Overrides any data that has not been written directly using write(). Skips empty source dataPoints. */
 	public void updateFromRenderSource(ColumnRenderSource renderSource)
 	{
-		
 		// validate we are writing for the same location
 		LodUtil.assertTrue(renderSource.sectionPos.equals(this.sectionPos));
 		
@@ -239,8 +245,7 @@ public class ColumnRenderSource
 		}
 		// the source isn't empty, this object won't be empty after the method finishes
 		this.isEmpty = false;
-		
-		
+
 		for (int i = 0; i < this.renderDataContainer.length; i += this.verticalDataCount)
 		{
 			int thisGenMode = RenderDataPointUtil.getGenerationMode(this.renderDataContainer[i]);
@@ -277,11 +282,17 @@ public class ColumnRenderSource
 		}
 	}
 	
-	public void fastWrite(ChunkSizedFullDataAccessor chunkData, IDhClientLevel level) 
+	public boolean fastWrite(ChunkSizedFullDataAccessor chunkData, IDhClientLevel level)
 	{
 		try
 		{
-			FullDataToRenderDataTransformer.writeFullDataChunkToColumnData(this, level, chunkData);
+			if (FullDataToRenderDataTransformer.writeFullDataChunkToColumnData(this, level, chunkData)) {
+				localVersion.incrementAndGet();
+				return true;
+			}
+			else {
+				return false;
+			}
 		}
 		catch (IllegalArgumentException e)
 		{
@@ -293,6 +304,7 @@ public class ColumnRenderSource
 			// expected if the transformer is shut down, the exception can be ignored
 //			LOGGER.warn(ColumnRenderSource.class.getSimpleName()+" fast write interrupted.");
 		}
+		return false;
 	}
 	
 	
@@ -321,10 +333,7 @@ public class ColumnRenderSource
 	/** @return how many data points wide this {@link ColumnRenderSource} is. */
 	public int getWidthInDataPoints() { return BitShiftUtil.powerOfTwo(this.getDetailOffset()); }
 	public byte getDetailOffset() { return SECTION_SIZE_OFFSET; }
-	
-	
 
-	
 	public byte getRenderDataFormatVersion() { return DATA_FORMAT_VERSION; }
 	
 	/** 
@@ -352,6 +361,7 @@ public class ColumnRenderSource
 				this.debugSourceFlags[x * SECTION_SIZE + z] = flag;
 			}
 		}
+		localVersion.incrementAndGet();
 	}
 	
 	public DebugSourceFlag debugGetFlag(int ox, int oz) { return this.debugSourceFlags[ox * SECTION_SIZE + oz]; }

core/src/main/java/com/seibel/distanthorizons/core/dataObjects/render/bufferBuilding/ColumnRenderBufferBuilder.java

@@ -52,15 +52,13 @@ public class ColumnRenderBufferBuilder
 	//==============//
 	// vbo building //
 	//==============//
-	
-	/** @return null if busy */
+
 	public static CompletableFuture<ColumnRenderBuffer> buildBuffers(IDhClientLevel clientLevel, Reference<ColumnRenderBuffer> renderBufferRef, ColumnRenderSource renderSource, ColumnRenderSource[] adjData)
 	{
-		if (isBusy())
+/*		if (isBusy())
 		{
 			return null;
-		}
-		
+		}*/
 		//LOGGER.info("RenderRegion startBuild @ {}", renderSource.sectionPos);
 		return CompletableFuture.supplyAsync(() ->
 			{

core/src/main/java/com/seibel/distanthorizons/core/dataObjects/render/columnViews/ColumnArrayView.java

@@ -159,5 +159,22 @@ public final class ColumnArrayView implements IColumnDataView
 		
 		return sb.toString();
 	}
+
+	public int getDataHash() {
+		return arrayHash(data, offset, size);
+	}
+
+	private static int arrayHash(long[] a, int offset, int length) {
+		if (a == null)
+			return 0;
+		int result = 1;
+		int end = offset + length;
+		for (int i = offset; i < end; i++) {
+			long element = a[i];
+			int elementHash = (int)(element ^ (element >>> 32));
+			result = 31 * result + elementHash;
+		}
+		return result;
+	}
 	
 }

core/src/main/java/com/seibel/distanthorizons/core/dataObjects/transformers/FullDataToRenderDataTransformer.java

@@ -22,6 +22,8 @@ import com.seibel.distanthorizons.core.wrapperInterfaces.world.IBiomeWrapper;
 import com.seibel.distanthorizons.core.wrapperInterfaces.IWrapperFactory;
 import com.seibel.distanthorizons.coreapi.util.BitShiftUtil;
 
+import java.util.Arrays;
+
 /**
  * Handles converting {@link ChunkSizedFullDataAccessor}, {@link IIncompleteFullDataSource},
  * and {@link IFullDataSource}'s to {@link ColumnRenderSource}.
@@ -156,7 +158,7 @@ public class FullDataToRenderDataTransformer
 	 * @throws InterruptedException Can be caused by interrupting the thread upstream.
 	 * 								Generally thrown if the method is running after the client leaves the current world.
 	 */
-	public static void writeFullDataChunkToColumnData(ColumnRenderSource renderSource, IDhClientLevel level, ChunkSizedFullDataAccessor chunkDataView) throws InterruptedException, IllegalArgumentException
+	public static boolean writeFullDataChunkToColumnData(ColumnRenderSource renderSource, IDhClientLevel level, ChunkSizedFullDataAccessor chunkDataView) throws InterruptedException, IllegalArgumentException
 	{
 		final DhSectionPos renderSourcePos = renderSource.getSectionPos();
 		
@@ -169,8 +171,8 @@ public class FullDataToRenderDataTransformer
 		
 		final int sourceDataPointBlockWidth = BitShiftUtil.powerOfTwo(renderSource.getDataDetail());
 		
-		
-		
+		boolean changed = false;
+
 		if (chunkDataView.detailLevel == renderSource.getDataDetail())
 		{
 			// confirm the render source contains this chunk
@@ -181,15 +183,16 @@ public class FullDataToRenderDataTransformer
 			{
 				throw new IllegalArgumentException("Data offset is out of bounds");
 			}
-			
+
+			throwIfThreadInterrupted();
 			
 			for (int x = 0; x < LodUtil.CHUNK_WIDTH; x++)
 			{
 				for (int z = 0; z < LodUtil.CHUNK_WIDTH; z++)
 				{
-					throwIfThreadInterrupted();
-					
 					ColumnArrayView columnArrayView = renderSource.getVerticalDataPointView(blockOffsetX + x, blockOffsetZ + z);
+					int hash = columnArrayView.getDataHash();
+
 					SingleColumnFullDataAccessor fullArrayView = chunkDataView.get(x, z);
 					
 					convertColumnData(level, 
@@ -201,12 +204,15 @@ public class FullDataToRenderDataTransformer
 					{
 						LodUtil.assertTrue(renderSource.doesDataPointExist(blockOffsetX + x, blockOffsetZ + z));
 					}
+
+					changed |= hash != columnArrayView.getDataHash();
 				}
 			}
 			renderSource.fillDebugFlag(blockOffsetX, blockOffsetZ, LodUtil.CHUNK_WIDTH, LodUtil.CHUNK_WIDTH, ColumnRenderSource.DebugSourceFlag.DIRECT);
-			
+
 			renderSource.markNotEmpty();
 		}
+		return changed;
 	}
 
     private static void convertColumnData(IDhClientLevel level, int blockX, int blockZ, ColumnArrayView columnArrayView, SingleColumnFullDataAccessor fullArrayView, int genMode)

core/src/main/java/com/seibel/distanthorizons/core/file/fullDatafile/FullDataMetaFile.java

@@ -54,6 +54,15 @@ public class FullDataMetaFile extends AbstractMetaDataContainerFile implements I
 	private SoftReference<IFullDataSource> cachedFullDataSource = new SoftReference<>(null);
 	private final AtomicReference<CompletableFuture<IFullDataSource>> dataSourceLoadFutureRef = new AtomicReference<>(null);
 
+	private static final class CacheQueryResult {
+		public final CompletableFuture<IFullDataSource> future;
+		public final boolean needsLoad;
+		public CacheQueryResult(CompletableFuture<IFullDataSource> future, boolean needsLoad) {
+			this.future = future;
+			this.needsLoad = needsLoad;
+		}
+	}
+
 	@Override
 	public void debugRender(DebugRenderer r) {
 		IFullDataSource cached = cachedFullDataSource.get();
@@ -309,15 +318,6 @@ public class FullDataMetaFile extends AbstractMetaDataContainerFile implements I
 				data.getDataDetailLevel(), data.getWorldGenStep(), (loader == null ? 0 : loader.datatypeId), data.getBinaryDataFormatVersion());
 	}
 
-	private static final class CacheQueryResult {
-		public final CompletableFuture<IFullDataSource> future;
-		public final boolean needsLoad;
-		public CacheQueryResult(CompletableFuture<IFullDataSource> future, boolean needsLoad) {
-			this.future = future;
-			this.needsLoad = needsLoad;
-		}
-	}
-
 	/**
 	 * @return one of the following:
 	 * 		the cached {@link IFullDataSource}, 
@@ -328,11 +328,9 @@ public class FullDataMetaFile extends AbstractMetaDataContainerFile implements I
 	{
 		// this data source is being written to, use the existing future
 		CompletableFuture<IFullDataSource> dataSourceLoadFuture = this.dataSourceLoadFutureRef.get();
-		if (dataSourceLoadFuture != null)
-		{
+		if (dataSourceLoadFuture != null) {
 			return new CacheQueryResult(dataSourceLoadFuture, false);
 		}
-
 		// attempt to get the cached data source
 		IFullDataSource cachedFullDataSource = this.cachedFullDataSource.get();
 		if (cachedFullDataSource == null) {

core/src/main/java/com/seibel/distanthorizons/core/file/renderfile/ILodRenderSourceProvider.java

@@ -22,7 +22,7 @@ public interface ILodRenderSourceProvider extends AutoCloseable
     CompletableFuture<Void> flushAndSaveAsync();
 	
 	/** Returns true if the data was refreshed, false otherwise */
-    boolean refreshRenderSource(ColumnRenderSource source);
+    //boolean refreshRenderSource(ColumnRenderSource source);
 	
 	/** Deletes any data stored in the render cache so it can be re-created */
 	void deleteRenderCache();

core/src/main/java/com/seibel/distanthorizons/core/file/renderfile/RenderMetaDataFile.java

@@ -1,6 +1,8 @@
 package com.seibel.distanthorizons.core.file.renderfile;
 
 import com.seibel.distanthorizons.core.dataObjects.fullData.accessor.ChunkSizedFullDataAccessor;
+import com.seibel.distanthorizons.core.dataObjects.fullData.sources.CompleteFullDataSource;
+import com.seibel.distanthorizons.core.dataObjects.fullData.sources.interfaces.IFullDataSource;
 import com.seibel.distanthorizons.core.file.metaData.AbstractMetaDataContainerFile;
 import com.seibel.distanthorizons.core.file.metaData.BaseMetaData;
 import com.seibel.distanthorizons.core.level.IDhLevel;
@@ -11,18 +13,23 @@ import com.seibel.distanthorizons.core.pos.DhSectionPos;
 import com.seibel.distanthorizons.core.dataObjects.render.ColumnRenderLoader;
 import com.seibel.distanthorizons.core.dataObjects.render.ColumnRenderSource;
 import com.seibel.distanthorizons.core.level.IDhClientLevel;
+import com.seibel.distanthorizons.core.render.renderer.IDebugRenderable;
+import com.seibel.distanthorizons.core.util.AtomicsUtil;
 import com.seibel.distanthorizons.core.util.LodUtil;
 import com.seibel.distanthorizons.core.util.objects.dataStreams.DhDataInputStream;
 import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.Nullable;
 
 import java.awt.*;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.lang.ref.SoftReference;
+import java.util.Random;
 import java.util.concurrent.*;
+import java.util.concurrent.atomic.AtomicReference;
 
-public class RenderMetaDataFile extends AbstractMetaDataContainerFile
+public class RenderMetaDataFile extends AbstractMetaDataContainerFile implements IDebugRenderable
 {
 	private static final Logger LOGGER = DhLoggerBuilder.getLogger();
 	
@@ -32,13 +39,35 @@ public class RenderMetaDataFile extends AbstractMetaDataContainerFile
 	 * When clearing, don't set to null, instead create a SoftReference containing null. 
 	 * This will make null checks simpler.
 	 */
-	private SoftReference<ColumnRenderSource> cachedRenderDataSourceRef = new SoftReference<>(null);
+	private SoftReference<ColumnRenderSource> cachedRenderDataSource = new SoftReference<>(null);
+	private final AtomicReference<CompletableFuture<ColumnRenderSource>> renderSourceLoadFutureRef = new AtomicReference<>(null);
 	
 	private final RenderSourceFileHandler fileHandler;
 	private boolean doesFileExist;
-	
-	
-	
+
+	private static final class CacheQueryResult {
+		public final CompletableFuture<ColumnRenderSource> future;
+		public final boolean needsLoad;
+		public CacheQueryResult(CompletableFuture<ColumnRenderSource> future, boolean needsLoad) {
+			this.future = future;
+			this.needsLoad = needsLoad;
+		}
+	}
+
+	@Override
+	public void debugRender(DebugRenderer r) {
+		ColumnRenderSource cached = cachedRenderDataSource.get();
+		Color c = Color.black;
+		if (cached != null) {
+			c = Color.GREEN;
+		} else if (renderSourceLoadFutureRef.get() != null) {
+			c = Color.BLUE;
+		} else if (doesFileExist) {
+			c = Color.RED;
+		}
+		r.renderBox(new DebugRenderer.Box(pos, 0, 256, 0.05f, c));
+	}
+
 	//=============//
 	// constructor //
 	//=============//
@@ -57,6 +86,7 @@ public class RenderMetaDataFile extends AbstractMetaDataContainerFile
 		this.fileHandler = fileHandler;
 		LodUtil.assertTrue(this.baseMetaData == null);
 		this.doesFileExist = this.file.exists();
+		DebugRenderer.register(this);
 	}
 	
 	/**
@@ -67,6 +97,7 @@ public class RenderMetaDataFile extends AbstractMetaDataContainerFile
 	{
 		return new RenderMetaDataFile(fileHandler, path);
 	}
+
 	private RenderMetaDataFile(RenderSourceFileHandler fileHandler, File path) throws IOException
 	{
 		super(path);
@@ -74,10 +105,10 @@ public class RenderMetaDataFile extends AbstractMetaDataContainerFile
 		LodUtil.assertTrue(this.baseMetaData != null);
 		
 		this.doesFileExist = this.file.exists();
+
+		DebugRenderer.register(this);
 	}
 	
-	
-	
 	// FIXME: This can cause concurrent modification of LodRenderSource.
     //       Not sure if it will cause issues or not.
 	public void updateChunkIfSourceExists(ChunkSizedFullDataAccessor chunkDataView, IDhClientLevel level)
@@ -86,19 +117,23 @@ public class RenderMetaDataFile extends AbstractMetaDataContainerFile
 		LodUtil.assertTrue(this.pos.getSectionBBoxPos().overlapsExactly(chunkPos), "Chunk pos "+chunkPos+" doesn't overlap with section "+this.pos);
 		
 		// update the render source if one exists
-		CompletableFuture<ColumnRenderSource> readSourceFuture = this.getCachedDataSourceAsync();
-		if (readSourceFuture != null)
-		{
-			if (chunkDataView.getLodPos().detailLevel == DhSectionPos.SECTION_MINIMUM_DETAIL_LEVEL)
+		CompletableFuture<ColumnRenderSource> renderSourceLoadFuture = getCachedDataSourceAsync();
+		if (renderSourceLoadFuture == null) return;
+
+/*		renderSourceLoadFuture.thenAccept((renderSource) -> {
+			boolean worked = renderSource.fastWrite(chunkDataView, level);
+
+			if (pos.sectionDetailLevel == DhSectionPos.SECTION_MINIMUM_DETAIL_LEVEL) {
+				float offset = new Random(System.nanoTime() ^ Thread.currentThread().getId()).nextFloat() * 16f;
+				Color c = worked ? Color.blue : Color.red;
 				DebugRenderer.makeParticle(
 						new DebugRenderer.BoxParticle(
-								new DebugRenderer.Box(chunkDataView.getLodPos(), 0, 256f, 0.05f, Color.blue),
-								0.5, 512f
+								new DebugRenderer.Box(chunkDataView.getLodPos(), 0, 64f + offset, 0.07f, c),
+								2.0, 16f
 						)
 				);
-			readSourceFuture.thenAccept((renderSource) -> renderSource.fastWrite(chunkDataView, level));
-		}
-		
+			}
+		});*/
 	}
 	
     public CompletableFuture<Void> flushAndSave(ExecutorService renderCacheThread)
@@ -107,51 +142,78 @@ public class RenderMetaDataFile extends AbstractMetaDataContainerFile
 		{
 			return CompletableFuture.completedFuture(null); // No need to save if the file doesn't exist.
 		}
-		
-		CompletableFuture<ColumnRenderSource> source = this.getCachedDataSourceAsync();
+		CompletableFuture<ColumnRenderSource> source = getCachedDataSourceAsync();
 		if (source == null)
 		{
 			return CompletableFuture.completedFuture(null); // If there is no cached data, there is no need to save.
 		}
-		
 		return source.thenAccept((columnRenderSource) -> { }); // Otherwise, wait for the data to be read (which also flushes changes to the file).
 	}
+	private CacheQueryResult getOrStartCachedDataSourceAsync()
+	{
+		// use the existing future
+		CompletableFuture<ColumnRenderSource> renderSourceLoadFuture = getCachedDataSourceAsync();
+		if (renderSourceLoadFuture == null) {
+			// Make a new future, and CAS it, or return the existing future
+			CompletableFuture<ColumnRenderSource> newFuture = new CompletableFuture<>();
+			CompletableFuture<ColumnRenderSource> cas = AtomicsUtil.compareAndExchange(renderSourceLoadFutureRef, null, newFuture);
+			if (cas == null) {
+				return new CacheQueryResult(newFuture, true);
+			} else {
+				return new CacheQueryResult(cas, false);
+			}
+		}
+		else {
+			return new CacheQueryResult(renderSourceLoadFuture, false);
+		}
+	}
+
+	@Nullable
 	private CompletableFuture<ColumnRenderSource> getCachedDataSourceAsync()
 	{
-		// attempt to get the cached data source
-		ColumnRenderSource cachedRenderDataSource = this.cachedRenderDataSourceRef.get();
-		if (cachedRenderDataSource != null)
-		{
-			return this.fileHandler.onReadRenderSourceLoadedFromCacheAsync(this, cachedRenderDataSource)
-					// wait for the handler to finish before returning the renderSource
-					.handle((voidObj, ex) -> cachedRenderDataSource);
+		// use the existing future
+		CompletableFuture<ColumnRenderSource> renderSourceLoadFuture = renderSourceLoadFutureRef.get();
+		if (renderSourceLoadFuture != null) {
+			return renderSourceLoadFuture;
+		}
+		// attempt to get the cached render source
+		ColumnRenderSource cachedRenderDataSource = this.cachedRenderDataSource.get();
+		if (cachedRenderDataSource == null) {
+			return null;
+		}
+		else {
+			// Make a new future, and CAS it, or return the existing future
+			CompletableFuture<ColumnRenderSource> newFuture = new CompletableFuture<>();
+			CompletableFuture<ColumnRenderSource> cas = AtomicsUtil.compareAndExchange(renderSourceLoadFutureRef, null, newFuture);
+			if (cas == null) {
+				this.fileHandler.onReadRenderSourceLoadedFromCacheAsync(this, cachedRenderDataSource)
+						// wait for the handler to finish before returning the renderSource
+						.handle((voidObj, ex) -> {
+							newFuture.complete(cachedRenderDataSource);
+							renderSourceLoadFutureRef.set(null);
+							return null;
+						});
+				return newFuture;
+			}
+			else {
+				return cas;
+			}
 		}
-		
-		
-		
-		// the data source hasn't been loaded 
-		// and isn't in the process of being loaded
-		return null;
 	}
 	
 	public CompletableFuture<ColumnRenderSource> loadOrGetCachedDataSourceAsync(Executor fileReaderThreads, IDhLevel level)
 	{
-		CompletableFuture<ColumnRenderSource> getCachedFuture = this.getCachedDataSourceAsync();
-		if (getCachedFuture != null)
+		CacheQueryResult getCachedFuture = this.getOrStartCachedDataSourceAsync();
+		if (!getCachedFuture.needsLoad)
 		{
-			return getCachedFuture;
+			return getCachedFuture.future;
 		}
-		
-		
-		
-		// Create an empty and non-completed future.
-		// Note: I do this before actually filling in the future so that I can ensure only
-		//   one task is submitted to the thread pool.
-		CompletableFuture<ColumnRenderSource> loadRenderSourceFuture = new CompletableFuture<>();
+
+		CompletableFuture<ColumnRenderSource> future = getCachedFuture.future;
+		// load or create the render source
 		if (!this.doesFileExist)
 		{
 			// create a new Meta file
-			
 			this.fileHandler.onCreateRenderFileAsync(this)
 				.thenApply((renderSource) -> 
 				{
@@ -164,13 +226,15 @@ public class RenderMetaDataFile extends AbstractMetaDataContainerFile
 					if (ex != null)
 					{
 						LOGGER.error("Uncaught error on creation {}: ", this.file, ex);
-						loadRenderSourceFuture.complete(null);
-						this.cachedRenderDataSourceRef = new SoftReference<>(null);
+						cachedRenderDataSource = new SoftReference<>(null);
+						renderSourceLoadFutureRef.set(null);
+						future.complete(null);
 					}
 					else
 					{
-						loadRenderSourceFuture.complete(renderSource);
-						this.cachedRenderDataSourceRef = new SoftReference<>(renderSource);
+						cachedRenderDataSource = new SoftReference<>(renderSource);
+						renderSourceLoadFutureRef.set(null);
+						future.complete(renderSource);
 					}
 				});
 		}
@@ -198,25 +262,24 @@ public class RenderMetaDataFile extends AbstractMetaDataContainerFile
 					renderSource = this.fileHandler.onRenderFileLoaded(renderSource, this);
 					return renderSource;
 				}, fileReaderThreads)
-				.whenComplete((renderSource, ex) -> 
+				.whenComplete((renderSource, ex) ->
 				{
 					if (ex != null)
 					{
 						LOGGER.error("Error loading file {}: ", this.file, ex);
-						loadRenderSourceFuture.complete(null);
-						this.cachedRenderDataSourceRef = new SoftReference<>(null);
+						cachedRenderDataSource = new SoftReference<>(null);
+						renderSourceLoadFutureRef.set(null);
+						future.complete(null);
 					}
 					else
 					{
-						loadRenderSourceFuture.complete(renderSource);
-						this.cachedRenderDataSourceRef = new SoftReference<>(renderSource);
+						cachedRenderDataSource = new SoftReference<>(renderSource);
+						renderSourceLoadFutureRef.set(null);
+						future.complete(renderSource);
 					}
 				});
 		}
-		
-		
-		
-		return loadRenderSourceFuture;
+		return future;
 	}
 	
     private BaseMetaData makeMetaData(ColumnRenderSource renderSource)

core/src/main/java/com/seibel/distanthorizons/core/file/renderfile/RenderSourceFileHandler.java

@@ -311,11 +311,6 @@ public class RenderSourceFileHandler implements ILodRenderSourceProvider
 	
     private CompletableFuture<Void> updateCacheAsync(ColumnRenderSource renderSource, RenderMetaDataFile file)
 	{
-		if (this.cacheUpdateLockBySectionPos.putIfAbsent(file.pos, new Object()) != null)
-		{
-			return CompletableFuture.completedFuture(null);
-		}
-		
 		// get the full data source loading future
 		CompletableFuture<IFullDataSource> fullDataSourceFuture = this.fullDataSourceProvider.read(renderSource.getSectionPos());
 		fullDataSourceFuture = fullDataSourceFuture.thenApply((fullDataSource) -> 
@@ -327,8 +322,7 @@ public class RenderSourceFileHandler implements ILodRenderSourceProvider
 				LOGGER.error("Exception when getting data for updateCache()", ex);
 				return null;
 			});
-		
-		
+
 		// future returned 
 		CompletableFuture<Void> transformationCompleteFuture = new CompletableFuture<>();
 		
@@ -362,12 +356,8 @@ public class RenderSourceFileHandler implements ILodRenderSourceProvider
 							LOGGER.error("Exception when updating render file using data source: ", ex);
 						}
 					}
-					
 					transformationCompleteFuture.complete(null);
-				})
-				.thenRun(() -> this.cacheUpdateLockBySectionPos.remove(file.pos));
-		
-		
+				});
 		return transformationCompleteFuture;
 	}
 	
@@ -378,7 +368,9 @@ public class RenderSourceFileHandler implements ILodRenderSourceProvider
         return renderSource;
     }
 	
-	public CompletableFuture<Void> onReadRenderSourceLoadedFromCacheAsync(RenderMetaDataFile file, ColumnRenderSource data) { return this.updateCacheAsync(data, file); }
+	public CompletableFuture<Void> onReadRenderSourceLoadedFromCacheAsync(RenderMetaDataFile file, ColumnRenderSource data) {
+		return this.updateCacheAsync(data, file);
+	}
 	
     private void writeRenderSourceToFile(ColumnRenderSource currentRenderSource, RenderMetaDataFile file, ColumnRenderSource newRenderSource)
 	{
@@ -388,6 +380,7 @@ public class RenderSourceFileHandler implements ILodRenderSourceProvider
 		}
 		
         currentRenderSource.updateFromRenderSource(newRenderSource);
+		currentRenderSource.localVersion.incrementAndGet();
 		
         //file.metaData.dataVersion.set(newDataVersion);
         file.baseMetaData.dataLevel = currentRenderSource.getDataDetail();
@@ -395,7 +388,7 @@ public class RenderSourceFileHandler implements ILodRenderSourceProvider
         file.baseMetaData.binaryDataFormatVersion = currentRenderSource.getRenderDataFormatVersion();
         file.save(currentRenderSource);
     }
-	
+/*
     public boolean refreshRenderSource(ColumnRenderSource renderSource)
 	{
         RenderMetaDataFile file = this.filesBySectionPos.get(renderSource.getSectionPos());
@@ -418,7 +411,7 @@ public class RenderSourceFileHandler implements ILodRenderSourceProvider
 //        return false;
     }
 	
-	
+	*/
 	
 	//=====================//
 	// clearing / shutdown //

core/src/main/java/com/seibel/distanthorizons/core/generation/WorldGenerationQueue.java

@@ -621,12 +621,13 @@ public class WorldGenerationQueue implements Closeable, IDebugRenderable
 
 	@Override
 	public void debugRender(DebugRenderer r) {
+		if (true) return;
 		CheckingTasks.forEach((t) -> {
 			DhLodPos pos = t.pos;
-			r.renderBox(new DebugRenderer.Box(pos, -32f, 128f, 0.05f, Color.blue));
+			r.renderBox(new DebugRenderer.Box(pos, -32f, 64f, 0.05f, Color.blue));
 		});
 		this.inProgressGenTasksByLodPos.forEach((pos, t) -> {
-			r.renderBox(new DebugRenderer.Box(pos, -32f, 128f, 0.05f, Color.red));
+			r.renderBox(new DebugRenderer.Box(pos, -32f, 64f, 0.05f, Color.red));
 		});
 	}
 }

core/src/main/java/com/seibel/distanthorizons/core/level/ClientLevelModule.java

@@ -1,5 +1,7 @@
 package com.seibel.distanthorizons.core.level;
 
+import com.seibel.distanthorizons.api.enums.rendering.EDebugRendering;
+import com.seibel.distanthorizons.api.enums.rendering.ERendererMode;
 import com.seibel.distanthorizons.core.config.Config;
 import com.seibel.distanthorizons.core.dataObjects.fullData.accessor.ChunkSizedFullDataAccessor;
 import com.seibel.distanthorizons.core.dependencyInjection.SingletonInjector;
@@ -42,6 +44,8 @@ public class ClientLevelModule {
     // tick methods //
     //==============//
 
+    private EDebugRendering lastDebugRendering = EDebugRendering.OFF;
+
     public void clientTick()
     {
         ClientRenderState clientRenderState = this.ClientRenderStateRef.get();
@@ -69,6 +73,18 @@ public class ClientLevelModule {
             }
         }
         clientRenderState.quadtree.tick(new DhBlockPos2D(MC_CLIENT.getPlayerBlockPos()));
+
+        boolean isBuffersDirty = false;
+        EDebugRendering newDebugRendering = Config.Client.Advanced.Debugging.debugRendering.get();
+        if (newDebugRendering != lastDebugRendering)
+        {
+            lastDebugRendering = newDebugRendering;
+            isBuffersDirty = true;
+        }
+        if (isBuffersDirty) {
+            clientRenderState.renderer.bufferHandler.MarkAllBuffersDirty();
+        }
+
         clientRenderState.renderer.bufferHandler.updateQuadTreeRenderSources();
     }
 
@@ -236,8 +252,6 @@ public class ClientLevelModule {
         public final RenderSourceFileHandler renderSourceFileHandler;
         public final LodRenderer renderer;
 
-
-
         public ClientRenderState(IDhClientLevel dhClientLevel, IFullDataSourceProvider fullDataSourceProvider,
                 AbstractSaveStructure saveStructure)
         {

core/src/main/java/com/seibel/distanthorizons/core/level/DhClientServerLevel.java

@@ -176,7 +176,7 @@ public class DhClientServerLevel extends DhLevel implements IDhClientLevel, IDhS
 		if (pos.sectionDetailLevel == DhSectionPos.SECTION_MINIMUM_DETAIL_LEVEL)
 			DebugRenderer.makeParticle(
 					new DebugRenderer.BoxParticle(
-							new DebugRenderer.Box(pos, 0, 256f, 0.05f, Color.red),
+							new DebugRenderer.Box(pos, 0, 256f, 0.09f, Color.red),
 							0.5, 512f
 					)
 			);

core/src/main/java/com/seibel/distanthorizons/core/render/LodQuadTree.java

@@ -145,7 +145,7 @@ public class LodQuadTree extends QuadTree<LodRenderSection> implements AutoClose
 			DhSectionPos rootPos = rootPosIterator.next();
 			if (this.getNode(rootPos) == null)
 			{
-				this.setValue(rootPos, new LodRenderSection(rootPos));
+				this.setValue(rootPos, new LodRenderSection(this, rootPos));
 			}
 			
 			QuadNode<LodRenderSection> rootNode = this.getNode(rootPos);
@@ -162,7 +162,7 @@ public class LodQuadTree extends QuadTree<LodRenderSection> implements AutoClose
 		// make sure the node is created
 		if (quadNode == null && this.isSectionPosInBounds(sectionPos)) // the position bounds should only fail when at the edge of the user's render distance
 		{
-			rootNode.setValue(sectionPos, new LodRenderSection(sectionPos));
+			rootNode.setValue(sectionPos, new LodRenderSection(this, sectionPos));
 			quadNode = rootNode.getNode(sectionPos);
 		}
 		if (quadNode == null)
@@ -176,7 +176,7 @@ public class LodQuadTree extends QuadTree<LodRenderSection> implements AutoClose
 		// create a new render section if missing
 		if (renderSection == null)
 		{
-			LodRenderSection newRenderSection = new LodRenderSection(sectionPos);
+			LodRenderSection newRenderSection = new LodRenderSection(this, sectionPos);
 			rootNode.setValue(sectionPos, newRenderSection);
 			
 			renderSection = newRenderSection;

core/src/main/java/com/seibel/distanthorizons/core/render/LodRenderSection.java

@@ -48,6 +48,8 @@ public class LodRenderSection implements IDebugRenderable
 
 	//FIXME: Temp Hack to prevent swapping buffers too quickly
 	private long lastNs = -1;
+	private long lastSwapLocalVersion = -1;
+	private boolean neighborUpdated = false;
 	/** 2 sec */
 	private static final long SWAP_TIMEOUT_IN_NS = 2_000000000L;
 	/** 1 sec */
@@ -58,10 +60,12 @@ public class LodRenderSection implements IDebugRenderable
 
 	/** a reference is used so the render buffer can be swapped to and from the buffer builder */
 	public final AtomicReference<ColumnRenderBuffer> activeRenderBufferRef = new AtomicReference<>();
+
+	private final QuadTree<LodRenderSection> parentQuadTree;
 	
-	
-    public LodRenderSection(DhSectionPos pos) {
+    public LodRenderSection(QuadTree<LodRenderSection> parentQuadTree, DhSectionPos pos) {
 		this.pos = pos;
+		this.parentQuadTree = parentQuadTree;
 
 		DebugRenderer.register(this);
 	}
@@ -108,6 +112,7 @@ public class LodRenderSection implements IDebugRenderable
 			this.renderSourceLoadFuture = null;
 			this.renderSource = renderSource;
 			this.lastNs = -1;
+			markBufferDirty();
 			if (this.reloadRenderSourceOnceLoaded)
 			{
 				this.reloadRenderSourceOnceLoaded = false;
@@ -138,7 +143,7 @@ public class LodRenderSection implements IDebugRenderable
 		if (pos.sectionDetailLevel == DhSectionPos.SECTION_MINIMUM_DETAIL_LEVEL)
 			DebugRenderer.makeParticle(
 					new DebugRenderer.BoxParticle(
-							new DebugRenderer.Box(pos, 0, 256f, 0.05f, Color.cyan),
+							new DebugRenderer.Box(pos, 0, 256f, 0.03f, Color.cyan),
 							0.5, 512f
 					)
 			);
@@ -205,20 +210,44 @@ public class LodRenderSection implements IDebugRenderable
 		}
 	}
 
-	private boolean isInBuildBufferTimeout() {
-		if (this.lastNs == -1) return false;
-		//return true;
-
-		boolean inTimeout = System.nanoTime() - this.lastNs < SWAP_TIMEOUT_IN_NS;
+	private boolean isBufferOutdated() {
+		//if (this.lastNs == -1) return false;
+/*		boolean inTimeout = System.nanoTime() - this.lastNs < SWAP_TIMEOUT_IN_NS;
 		if (!inTimeout && ColumnRenderBufferBuilder.isBusy()) {
 			this.lastNs += (long) (SWAP_BUSY_COLLISION_TIMEOUT_IN_NS * Math.random());
-			inTimeout = true;
+			return true;
+		}*/
+		return neighborUpdated || renderSource.localVersion.get() - lastSwapLocalVersion > 0;
+	}
+
+	private LodRenderSection[] getNeighbors()
+	{
+		LodRenderSection[] adjacents = new LodRenderSection[ELodDirection.ADJ_DIRECTIONS.length];
+		for (ELodDirection direction : ELodDirection.ADJ_DIRECTIONS) {
+			try {
+				DhSectionPos adjPos = pos.getAdjacentPos(direction);
+				LodRenderSection adjRenderSection = parentQuadTree.getValue(adjPos);
+				// adjacent render sources might be null
+				adjacents[direction.ordinal() - 2] = adjRenderSection;
+			} catch (IndexOutOfBoundsException e) {
+				// adjacent positions can be out of bounds, in that case a null render source will be used
+			}
+		}
+		return adjacents;
+	}
+
+	private void tellNeighborsUpdated()
+	{
+		LodRenderSection[] adjacents = getNeighbors();
+		for (LodRenderSection adj : adjacents) {
+			if (adj != null) {
+				adj.neighborUpdated = true;
+			}
 		}
-		return inTimeout;
 	}
 
 	/** @return true if this section is loaded and set to render */
-	public boolean canBuildBuffer() { return this.renderSource != null && this.buildRenderBufferFuture == null && !isInBuildBufferTimeout() && !this.renderSource.isEmpty(); }
+	public boolean canBuildBuffer() { return this.renderSource != null && this.buildRenderBufferFuture == null && !this.renderSource.isEmpty() && isBufferOutdated(); }
 
 	/** @return true if this section is loaded and set to render */
 	public boolean canSwapBuffer() { return this.buildRenderBufferFuture != null && this.buildRenderBufferFuture.isDone(); }
@@ -230,40 +259,46 @@ public class LodRenderSection implements IDebugRenderable
 	 * places storing or referencing the render buffer.
 	 * @return True if the swap was successful. False if swap is not needed or if it is in progress.
 	 */
-	public boolean tryBuildAndSwapBuffer(QuadTree<LodRenderSection> tree)
+	public boolean tryBuildAndSwapBuffer()
 	{
 		boolean didSwapped = false;
 		if (canBuildBuffer()) {
+			//if (false)
 			if (pos.sectionDetailLevel == DhSectionPos.SECTION_MINIMUM_DETAIL_LEVEL)
 				DebugRenderer.makeParticle(
 						new DebugRenderer.BoxParticle(
-								new DebugRenderer.Box(pos, 0, 256f, 0.1f, Color.yellow),
-								0.8, 512f
+								new DebugRenderer.Box(pos, 0, 256f, -0.1f, Color.yellow),
+								1.0, 512f
 						)
 				);
-			ColumnRenderSource[] adjacentSources = new ColumnRenderSource[ELodDirection.ADJ_DIRECTIONS.length];
-			for (ELodDirection direction : ELodDirection.ADJ_DIRECTIONS) {
-				try {
-					DhSectionPos adjPos = pos.getAdjacentPos(direction);
-					LodRenderSection adjRenderSection = tree.getValue(adjPos);
-					// adjacent render sources can be null
-					if (adjRenderSection != null) {
-						adjacentSources[direction.ordinal() - 2] = adjRenderSection.renderSource; // can be null
-					}
-				} catch (IndexOutOfBoundsException e) {
-					// adjacent positions can be out of bounds, in that case a null render source will be used
+			neighborUpdated = false;
+			long newVs = renderSource.localVersion.get();
+			if (lastSwapLocalVersion != newVs) {
+				lastSwapLocalVersion = newVs;
+				tellNeighborsUpdated();
+			}
+			LodRenderSection[] adjacents = getNeighbors();
+			ColumnRenderSource[] adjacentSources =  new ColumnRenderSource[ELodDirection.ADJ_DIRECTIONS.length];
+			for (int i = 0; i < ELodDirection.ADJ_DIRECTIONS.length; i++) {
+				LodRenderSection adj = adjacents[i];
+				if (adj != null) {
+					adjacentSources[i] = adj.getRenderSource();
 				}
 			}
-			this.buildRenderBufferFuture =
-					ColumnRenderBufferBuilder.buildBuffers(level, this.inactiveRenderBufferRef, renderSource, adjacentSources);
+			this.buildRenderBufferFuture = ColumnRenderBufferBuilder.buildBuffers(level, this.inactiveRenderBufferRef, renderSource, adjacentSources);
 		}
 		if (canSwapBuffer()) {
 			this.lastNs = System.nanoTime();
 			ColumnRenderBuffer newBuffer;
 			try {
 				newBuffer = this.buildRenderBufferFuture.getNow(null);
-				LodUtil.assertTrue(newBuffer != null && newBuffer.buffersUploaded, "The buffer future for "+pos+" returned an un-built buffer.");
 				this.buildRenderBufferFuture = null;
+				if (newBuffer == null) {
+					// failed.
+					markBufferDirty();
+					return false;
+				}
+				LodUtil.assertTrue(newBuffer.buffersUploaded, "The buffer future for "+pos+" returned an un-built buffer.");
 				ColumnRenderBuffer oldBuffer = this.activeRenderBufferRef.getAndSet(newBuffer);
 				if (oldBuffer != null)
 				{
@@ -324,4 +359,9 @@ public class LodRenderSection implements IDebugRenderable
 			buffer.close();
 		}
 	}
+
+	public void markBufferDirty() {
+		tellNeighborsUpdated();
+		lastSwapLocalVersion = -1;
+	}
 }

core/src/main/java/com/seibel/distanthorizons/core/render/RenderBufferHandler.java

@@ -165,9 +165,19 @@ public class RenderBufferHandler
 		//TODO: Directional culling
 		this.loadedNearToFarBuffers.forEach(loadedBuffer -> loadedBuffer.buffer.renderTransparent(renderContext));
 	}
-	
+
+	private boolean rebuildAllBuffers = false;
+
+	public void MarkAllBuffersDirty()
+	{
+		this.rebuildAllBuffers = true;
+	}
+
 	public void updateQuadTreeRenderSources()
 	{
+		boolean rebuildAllBuffers = this.rebuildAllBuffers;
+		this.rebuildAllBuffers = false;
+
 		Iterator<QuadNode<LodRenderSection>> nodeIterator = this.lodQuadTree.nodeIterator();
 		while (nodeIterator.hasNext())
 		{
@@ -175,7 +185,11 @@ public class RenderBufferHandler
 			try {
 				if (renderSection != null)
 				{
-					renderSection.tryBuildAndSwapBuffer(lodQuadTree);
+					if (rebuildAllBuffers)
+					{
+						renderSection.markBufferDirty();
+					}
+					renderSection.tryBuildAndSwapBuffer();
 				}
 			}
 			catch (Exception e)