Added support for partial chunk/region load

src/main/java/net/querz/mca/Chunk.java

@@ -12,6 +12,7 @@
 import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.util.Arrays;
+import static net.querz.mca.LoadFlags.*;
 
 public class Chunk {
 
@@ -49,10 +50,10 @@ public class Chunk {
 	 */
 	public Chunk(CompoundTag data) {
 		this.data = data;
-		initReferences();
+		initReferences(ALL_DATA);
 	}
 
-	private void initReferences() {
+	private void initReferences(long loadFlags) {
 		if (data == null) {
 			throw new NullPointerException("data cannot be null");
 		}
@@ -63,17 +64,39 @@ private void initReferences() {
 		this.dataVersion = data.getInt("DataVersion");
 		this.inhabitedTime = level.getLong("InhabitedTime");
 		this.lastUpdate = level.getLong("LastUpdate");
-		this.biomes = level.getIntArray("Biomes");
-		this.heightMaps = level.getCompoundTag("Heightmaps");
-		this.carvingMasks = level.getCompoundTag("CarvingMasks");
-		this.entities = level.containsKey("Entities") ? level.getListTag("Entities").asCompoundTagList() : null;
-		this.tileEntities = level.containsKey("TileEntities") ? level.getListTag("TileEntities").asCompoundTagList() : null;
-		this.tileTicks = level.containsKey("TileTicks") ? level.getListTag("TileTicks").asCompoundTagList() : null;
-		this.liquidTicks = level.containsKey("LiquidTicks") ? level.getListTag("LiquidTicks").asCompoundTagList() : null;
-		this.lights = level.containsKey("Lights") ? level.getListTag("Lights").asListTagList() : null;
-		this.liquidsToBeTicked = level.containsKey("LiquidsToBeTicked") ? level.getListTag("LiquidsToBeTicked").asListTagList() : null;
-		this.toBeTicked = level.containsKey("ToBeTicked") ? level.getListTag("ToBeTicked").asListTagList() : null;
-		this.postProcessing = level.containsKey("PostProcessing") ? level.getListTag("PostProcessing").asListTagList() : null;
+		if((loadFlags | BIOMES) != 0) {
+			this.biomes = level.getIntArray("Biomes");
+		}
+		if((loadFlags | HEIGHTMAPS) != 0) {
+			this.heightMaps = level.getCompoundTag("Heightmaps");
+		}
+		if((loadFlags | CARVING_MARKS) != 0) {
+			this.carvingMasks = level.getCompoundTag("CarvingMasks");
+		}
+		if((loadFlags | ENTITIES) != 0) {
+			this.entities = level.containsKey("Entities") ? level.getListTag("Entities").asCompoundTagList() : null;
+		}
+		if((loadFlags | TILE_ENTITIES) != 0) {
+			this.tileEntities = level.containsKey("TileEntities") ? level.getListTag("TileEntities").asCompoundTagList() : null;
+		}
+		if((loadFlags | TILE_TICKS) != 0) {
+			this.tileTicks = level.containsKey("TileTicks") ? level.getListTag("TileTicks").asCompoundTagList() : null;
+		}
+		if((loadFlags | LIQUID_TILE_TICKS) != 0) {
+			this.liquidTicks = level.containsKey("LiquidTicks") ? level.getListTag("LiquidTicks").asCompoundTagList() : null;
+		}
+		if((loadFlags | LIGHTS) != 0) {
+			this.lights = level.containsKey("Lights") ? level.getListTag("Lights").asListTagList() : null;
+		}
+		if((loadFlags | LIQUIDS_TO_BE_TICKED) != 0) {
+			this.liquidsToBeTicked = level.containsKey("LiquidsToBeTicked") ? level.getListTag("LiquidsToBeTicked").asListTagList() : null;
+		}
+		if((loadFlags | TO_BE_TICKED) != 0) {
+			this.toBeTicked = level.containsKey("ToBeTicked") ? level.getListTag("ToBeTicked").asListTagList() : null;
+		}
+		if((loadFlags | POST_PROCESSING) != 0) {
+			this.postProcessing = level.containsKey("PostProcessing") ? level.getListTag("PostProcessing").asListTagList() : null;
+		}
 		this.status = level.getString("Status");
 		this.structures = level.getCompoundTag("Structures");
 		if (level.containsKey("Sections")) {
@@ -86,10 +109,14 @@ private void initReferences() {
 				if (newSection.isEmpty()) {
 					continue;
 				}
-
 				this.sections[sectionIndex] = newSection;
 			}
 		}
+
+		// If we haven't requested the full set of data we can drop the underlying raw data to let the GC handle it.
+		if(loadFlags != ALL_DATA) {
+			this.data = null;
+		}
 	}
 
 	/**
@@ -118,6 +145,16 @@ public int serialize(RandomAccessFile raf, int xPos, int zPos) throws IOExceptio
 	 * @throws IOException When something went wrong during reading.
 	 */
 	public void deserialize(RandomAccessFile raf) throws IOException {
+		deserialize(raf, ALL_DATA);
+	}
+
+	/**
+	 * Reads chunk data from a RandomAccessFile. The RandomAccessFile must already be at the correct position.
+	 * @param raf The RandomAccessFile to read the chunk data from.
+	 * @param loadFlags A logical or of {@link LoadFlags} constants indicating what data should be loaded
+	 * @throws IOException When something went wrong during reading.
+	 */
+	public void deserialize(RandomAccessFile raf, long loadFlags) throws IOException {
 		byte compressionTypeByte = raf.readByte();
 		CompressionType compressionType = CompressionType.getFromID(compressionTypeByte);
 		if (compressionType == null) {
@@ -127,7 +164,7 @@ public void deserialize(RandomAccessFile raf) throws IOException {
 		NamedTag tag = new NBTDeserializer(false).fromStream(dis);
 		if (tag != null && tag.getTag() instanceof CompoundTag) {
 			data = (CompoundTag) tag.getTag();
-			initReferences();
+			initReferences(loadFlags);
 		} else {
 			throw new IOException("invalid data tag: " + (tag == null ? "null" : tag.getClass().getName()));
 		}

src/main/java/net/querz/mca/LoadFlags.java

@@ -0,0 +1,24 @@
+package net.querz.mca;
+
+public class LoadFlags {
+    public static long BIOMES               = 0x0001;
+    public static long HEIGHTMAPS           = 0x0002;
+    public static long CARVINGMARKS         = 0x0004;
+    public static long ENTITIES             = 0x0008;
+    public static long TILE_ENTITIES        = 0x0010;
+    public static long CARVING_MARKS        = 0x0020;
+    public static long TILE_TICKS           = 0x0040;
+    public static long LIQUID_TILE_TICKS    = 0x0040;
+    public static long TO_BE_TICKED         = 0x0080;
+    public static long POST_PROCESSING      = 0x0100;
+    public static long STRUCTURES           = 0x0200;
+    public static long BLOCK_LIGHTS         = 0x0400;
+    public static long BLOCK_STATES         = 0x0800;
+    public static long SKY_LIGHT            = 0x1000;
+    public static long LIGHTS               = 0x2000;
+    public static long LIQUIDS_TO_BE_TICKED = 0x2000;
+
+    public static long ALL_DATA             = 0xffffffffffffffffL;
+
+
+}

src/main/java/net/querz/mca/MCAFile.java

@@ -34,6 +34,17 @@ public MCAFile(int regionX, int regionZ) {
 	 * @throws IOException If something went wrong during deserialization.
 	 * */
 	public void deserialize(RandomAccessFile raf) throws IOException {
+		deserialize(raf, LoadFlags.ALL_DATA);
+	}
+
+	/**
+	 * Reads an .mca file from a {@code RandomAccessFile} into this object.
+	 * This method does not perform any cleanups on the data.
+	 * @param raf The {@code RandomAccessFile} to read from.
+	 * @param loadFlags A logical or of {@link LoadFlags} constants indicating what data should be loaded
+	 * @throws IOException If something went wrong during deserialization.
+	 * */
+	public void deserialize(RandomAccessFile raf, long loadFlags) throws IOException {
 		chunks = new Chunk[1024];
 		for (int i = 0; i < 1024; i++) {
 			raf.seek(i * 4);
@@ -47,7 +58,7 @@ public void deserialize(RandomAccessFile raf) throws IOException {
 			int timestamp = raf.readInt();
 			Chunk chunk = new Chunk(timestamp);
 			raf.seek(4096 * offset + 4); //+4: skip data size
-			chunk.deserialize(raf);
+			chunk.deserialize(raf, loadFlags);
 			chunks[i] = chunk;
 		}
 	}

src/main/java/net/querz/mca/Section.java

@@ -1,5 +1,7 @@
 package net.querz.mca;
 
+import static net.querz.mca.LoadFlags.*;
+
 import net.querz.nbt.tag.ByteArrayTag;
 import net.querz.nbt.tag.CompoundTag;
 import net.querz.nbt.tag.ListTag;
@@ -21,6 +23,10 @@ public class Section {
 	private int dataVersion;
 
 	public Section(CompoundTag sectionRoot, int dataVersion) {
+		this(sectionRoot, dataVersion, ALL_DATA);
+	}
+
+	public Section(CompoundTag sectionRoot, int dataVersion, long loadFlags) {
 		data = sectionRoot;
 		this.dataVersion = dataVersion;
 		ListTag<?> rawPalette = sectionRoot.getListTag("Palette");
@@ -37,9 +43,15 @@ public Section(CompoundTag sectionRoot, int dataVersion) {
 		LongArrayTag blockStates = sectionRoot.getLongArrayTag("BlockStates");
 		ByteArrayTag skyLight = sectionRoot.getByteArrayTag("SkyLight");
 
-		this.blockLight = blockLight != null ? blockLight.getValue() : null;
-		this.blockStates = blockStates != null ? blockStates.getValue() : null;
-		this.skyLight = skyLight != null ? skyLight.getValue() : null;
+		if((loadFlags | BLOCK_LIGHTS) != 0) {
+			this.blockLight = blockLight != null ? blockLight.getValue() : null;
+		}
+		if((loadFlags | BLOCK_STATES) != 0) {
+			this.blockStates = blockStates != null ? blockStates.getValue() : null;
+		}
+		if((loadFlags | SKY_LIGHT) != 0) {
+			this.skyLight = skyLight != null ? skyLight.getValue() : null;
+		}
 	}
 
 	Section() {}