Getting there, but postea codes are all 0

src/main/java/com/colen/postea/Postea.java

@@ -1,9 +1,7 @@
 package com.colen.postea;
 
-import com.colen.postea.checker.PosteaProcessedChunksWorldSavedData;
 import cpw.mods.fml.common.Mod;
 import cpw.mods.fml.common.event.FMLPreInitializationEvent;
-import net.minecraftforge.common.MinecraftForge;
 
 @Mod(modid = Tags.MODID, version = Tags.VERSION, name = Tags.MODNAME, acceptedMinecraftVersions = "[1.7.10]")
 @SuppressWarnings("unused")
@@ -11,7 +9,6 @@ public class Postea {
 
     @Mod.EventHandler
     public void preInit(FMLPreInitializationEvent event) {
-        MinecraftForge.EVENT_BUS.register(new PosteaProcessedChunksWorldSavedData(""));
     }
 
 }

src/main/java/com/colen/postea/Utility/ChunkFixerUtility.java

@@ -5,7 +5,6 @@ import java.util.List;
 import java.util.function.BiFunction;
 import java.util.stream.Collectors;
 
-import com.colen.postea.checker.PosteaProcessedChunksWorldSavedData;
 import net.minecraft.block.Block;
 import net.minecraft.nbt.NBTTagCompound;
 import net.minecraft.nbt.NBTTagList;
@@ -17,19 +16,36 @@ import com.colen.postea.API.TileEntityReplacementManager;
 import akka.japi.Pair;
 import cpw.mods.fml.common.registry.GameRegistry;
 
+import static com.colen.postea.Utility.PosteaUtilities.getModListHash;
+
 public class ChunkFixerUtility {
     public static void processChunkNBT(NBTTagCompound compound, World world) {
-        NBTTagCompound level = compound.getCompoundTag("Level");
-        int x = level.getInteger("xPos");
-        int z = level.getInteger("zPos");
-
-        if (PosteaProcessedChunksWorldSavedData.addChunk(x, z)) {
+        if (processChunk(compound)) {
             transformTileEntities(compound, world);
             transformNormalBlocks(compound, world);
+            compound.setInteger("POSTEA", POSTEA_UPDATE_CODE);
+
+//            NBTTagCompound level = compound.getCompoundTag("Level");
+//            int x = level.getInteger("xPos");
+//            int z = level.getInteger("zPos");
+//
+//            PosteaUtilities.markChunkAsDirty(world, x, z);
         }
 
     }
 
+    // This will not change between runs.
+    private static final int POSTEA_UPDATE_CODE = getModListHash();
+
+    // If a chunk has the same postea code, then do not update it. Return false.
+    private static boolean processChunk(NBTTagCompound compound) {
+        // I'm minimising the string length here since this
+        // will be on every single chunk in every world... Rather not duplicate too much.
+        if (compound.hasKey("POSTEA")) {
+            return compound.getInteger("POSTEA") != POSTEA_UPDATE_CODE;
+        }
+        return true;
+    }
 
     private static void transformNormalBlocks(NBTTagCompound compound, World world) {
         NBTTagCompound level = compound.getCompoundTag("Level");
@@ -85,7 +101,7 @@ public class ChunkFixerUtility {
         }
     }
 
-    public static void transformTileEntities(NBTTagCompound chunkNBT, World world) {
+    private static void transformTileEntities(NBTTagCompound chunkNBT, World world) {
         NBTTagCompound level = chunkNBT.getCompoundTag("Level");
 
         Pair<List<ConversionInfo>, NBTTagList> output = adjustTileEntities(level.getTagList("TileEntities", 10), world);
@@ -187,7 +203,7 @@ public class ChunkFixerUtility {
         return new Pair<>(conversionInfo, tileEntitiesCopy);
     }
 
-    public static class ConversionInfo {
+    private static class ConversionInfo {
 
         public final int x;
         public final int y;

src/main/java/com/colen/postea/Utility/PosteaUtilities.java

@@ -3,6 +3,8 @@ package com.colen.postea.Utility;
 import cpw.mods.fml.common.Loader;
 import cpw.mods.fml.common.ModContainer;
 import net.minecraft.nbt.NBTTagCompound;
+import net.minecraft.world.World;
+import net.minecraft.world.chunk.Chunk;
 
 import java.util.ArrayList;
 import java.util.Collections;
@@ -44,12 +46,24 @@ public abstract class PosteaUtilities {
         Collections.sort(modList);
 
         // Step 2: Append all elements into one string
-        StringBuilder combinedModStringSorted = new StringBuilder();
+        StringBuilder combinedModStringSortedBuilder = new StringBuilder();
         for (String element : modList) {
-            combinedModStringSorted.append(element);
+            combinedModStringSortedBuilder.append(element);
         }
 
-        return Objects.hash(combinedModStringSorted);
+        String combinedModStringSorted = combinedModStringSortedBuilder.toString();
+
+        return combinedModStringSorted.hashCode();
     }
 
+    public static void markChunkAsDirty(World world, int chunkX, int chunkZ) {
+        if (!world.isRemote) { // Check to make sure we're on the server side.
+            Chunk chunk = world.getChunkFromChunkCoords(chunkX, chunkZ);
+            if (chunk == null) return;
+
+            chunk.setChunkModified();
+        }
+    }
+
+
 }

src/main/java/com/colen/postea/checker/PosteaProcessedChunksWorldSavedData.java

@@ -1,104 +0,0 @@
-package com.colen.postea.checker;
-
-import akka.japi.Pair;
-import cpw.mods.fml.common.eventhandler.EventPriority;
-import cpw.mods.fml.common.eventhandler.SubscribeEvent;
-import net.minecraft.nbt.NBTTagCompound;
-import net.minecraft.world.World;
-import net.minecraft.world.WorldSavedData;
-import net.minecraft.world.storage.MapStorage;
-import net.minecraftforge.common.MinecraftForge;
-import net.minecraftforge.event.world.WorldEvent;
-
-import java.io.ByteArrayInputStream;
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.ObjectInputStream;
-import java.io.ObjectOutputStream;
-import java.util.HashSet;
-
-public class PosteaProcessedChunksWorldSavedData extends WorldSavedData {
-
-    private static final String DATA_NAME = "GregTech_GlobalIntValue";
-    public static HashSet<Pair<Integer, Integer>> chunkCoordinates = new HashSet<>();
-    public static PosteaProcessedChunksWorldSavedData INSTANCE;
-
-    // True if chunk has not been processed, else false.
-    public static boolean addChunk(int x, int z) {
-        boolean updateChunk = chunkCoordinates.add(new Pair<>(x, z));
-
-        if (updateChunk) {
-            // Only mark the world NBT as dirty if we actually process a new chunk, since we will need to save that info.
-            INSTANCE.markDirty();
-        }
-
-        return updateChunk;
-    }
-
-    public PosteaProcessedChunksWorldSavedData() {
-        super(DATA_NAME);
-    }
-
-    public PosteaProcessedChunksWorldSavedData(String name) {
-        super(name);
-    }
-
-    @Override
-    public void readFromNBT(NBTTagCompound nbtTagCompound) {
-        try {
-            byte[] ba = nbtTagCompound.getByteArray(DATA_NAME);
-            InputStream byteArrayInputStream = new ByteArrayInputStream(ba);
-            ObjectInputStream objectInputStream = new ObjectInputStream(byteArrayInputStream);
-            Object data = objectInputStream.readObject();
-            chunkCoordinates = (HashSet<Pair<Integer, Integer>>) data;
-        } catch (IOException | ClassNotFoundException exception) {
-            System.out.println(DATA_NAME + " FAILED");
-            exception.printStackTrace();
-        }
-
-    }
-
-    @Override
-    public void writeToNBT(NBTTagCompound nbtTagCompound) {
-        // Write the integer value to NBT
-        try {
-            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
-            ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);
-            objectOutputStream.writeObject(chunkCoordinates);
-            objectOutputStream.flush();
-            byte[] data = byteArrayOutputStream.toByteArray();
-            nbtTagCompound.setByteArray(DATA_NAME, data);
-        } catch (IOException exception) {
-            System.out.println(DATA_NAME + " SAVE FAILED");
-            exception.printStackTrace();
-        }
-    }
-
-
-    public static void get(World world) {
-
-        chunkCoordinates.clear();
-
-        MapStorage storage = world.mapStorage;
-        INSTANCE = (PosteaProcessedChunksWorldSavedData) storage.loadData(PosteaProcessedChunksWorldSavedData.class, DATA_NAME);
-
-        if (INSTANCE == null) {
-            INSTANCE = new PosteaProcessedChunksWorldSavedData();
-            storage.setData(DATA_NAME, INSTANCE);
-        }
-
-    }
-
-    // Register event in a static block to ensure it's done as early as possible
-    static {
-        MinecraftForge.EVENT_BUS.register(new PosteaProcessedChunksWorldSavedData());
-    }
-
-    @SubscribeEvent(priority = EventPriority.HIGHEST)
-    public void onWorldLoad(WorldEvent.Load event) {
-        if (!event.world.isRemote && event.world.provider.dimensionId == 0) {
-            get(event.world);
-        }
-    }
-}

src/main/java/com/colen/postea/mixins/PosteaLoadingPlugin.java

@@ -44,6 +44,7 @@ public final class PosteaLoadingPlugin implements IEarlyMixinLoader, IFMLLoading
     public List<String> getMixins(Set<String> loadedCoreMods) {
         final List<String> mixins = new ArrayList<>();
         mixins.add("MixinItemStack");
+        mixins.add("MixinChunk");
         mixins.add("MixinAnvilChunkLoader");
         return mixins;
     }

src/main/java/com/colen/postea/mixins/early/MixinAnvilChunkLoader.java

@@ -2,17 +2,19 @@ package com.colen.postea.mixins.early;
 
 import static com.colen.postea.Utility.ChunkFixerUtility.processChunkNBT;
 
+import com.colen.postea.mixins.interfaces.IChunkMixin;
 import net.minecraft.nbt.NBTTagCompound;
 import net.minecraft.world.World;
+import net.minecraft.world.chunk.Chunk;
 import net.minecraft.world.chunk.storage.AnvilChunkLoader;
 
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
 
 @Mixin(AnvilChunkLoader.class)
-@SuppressWarnings("unused")
 public abstract class MixinAnvilChunkLoader {
 
     @Inject(method = "checkedReadChunkFromNBT__Async", at = @At("HEAD"), remap = false)
@@ -21,4 +23,27 @@ public abstract class MixinAnvilChunkLoader {
         processChunkNBT(compound, world);
     }
 
+    @Inject(method = "readChunkFromNBT", at = @At("RETURN"))
+    private Chunk onReadChunkFromNBT(World world, NBTTagCompound nbtTagCompound, CallbackInfoReturnable<Chunk> cir) {
+        Chunk chunk = cir.getReturnValue();
+        if (chunk instanceof IChunkMixin iChunkMixin) {
+
+            if (nbtTagCompound.hasKey("POSTEA")) {
+                iChunkMixin.Postea$setPosteaCode(nbtTagCompound.getLong("POSTEA"));
+                System.out.println("On loading this chunk from NBT, it had a code of " + nbtTagCompound.getLong("POSTEA") + " at coordinates (" + chunk.xPosition + ", " + chunk.zPosition + ").");
+            }
+
+        }
+
+        return chunk;
+    }
+
+    @Inject(method = "writeChunkToNBT", at = @At("HEAD"))
+    private void onWriteChunkToNBT(Chunk chunk, World world, NBTTagCompound nbtTagCompound, CallbackInfo ci) {
+        if (chunk instanceof IChunkMixin iChunkMixin) {
+            System.out.println("On saving this chunk to NBT, it had a code of " + iChunkMixin.Postea$getPosteaCode() + " at coordinates (" + chunk.xPosition + ", " + chunk.zPosition + ").");
+            nbtTagCompound.setLong("POSTEA", iChunkMixin.Postea$getPosteaCode());
+        }
+    }
+
 }

src/main/java/com/colen/postea/mixins/early/MixinChunk.java

@@ -0,0 +1,25 @@
+package com.colen.postea.mixins.early;
+
+import com.colen.postea.mixins.interfaces.IChunkMixin;
+import net.minecraft.world.chunk.Chunk;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Unique;
+
+@Mixin(Chunk.class)
+public class MixinChunk implements IChunkMixin {
+
+    // This new field will store the hash of mod name + versions. We use this to check
+    // if we need to reprocess this chunk.
+    @Unique
+    private long postea_GTNH$posteaID;
+
+    @Unique
+    public long Postea$getPosteaCode() {
+        return postea_GTNH$posteaID;
+    }
+
+    @Unique
+    public void Postea$setPosteaCode(long POSTEA_ID) {
+        this.postea_GTNH$posteaID = POSTEA_ID;
+    }
+}

src/main/java/com/colen/postea/mixins/interfaces/IChunkMixin.java

@@ -0,0 +1,6 @@
+package com.colen.postea.mixins.interfaces;
+
+public interface IChunkMixin {
+    long Postea$getPosteaCode();
+    void Postea$setPosteaCode(long posteaID);
+}

src/main/resources/mixins.postea.early.json

@@ -7,6 +7,7 @@
   "compatibilityLevel": "JAVA_8",
   "mixins": [
     "MixinAnvilChunkLoader",
+    "MixinChunk",
     "MixinItemStack"
   ],
   "client": [],