CachedPositionProvider

package com.hypixel.hytale.builtin.hytalegenerator.positionproviders.cached;

import com.hypixel.hytale.builtin.hytalegenerator.VectorUtil;
import com.hypixel.hytale.builtin.hytalegenerator.positionproviders.PositionProvider;
import com.hypixel.hytale.builtin.hytalegenerator.threadindexer.WorkerIndexer;
import com.hypixel.hytale.math.util.HashUtil;
import com.hypixel.hytale.math.vector.Vector3d;
import com.hypixel.hytale.math.vector.Vector3i;
import java.util.ArrayList;
import javax.annotation.Nonnull;

public class CachedPositionProvider extends PositionProvider {
   @Nonnull
   private final PositionProvider positionProvider;
   private final int sectionSize;
   private WorkerIndexer.Data<CacheThreadMemory> threadData;

   public CachedPositionProvider(@Nonnull PositionProvider positionProvider, int sectionSize, int cacheSize, boolean useInternalThreadData, int threadCount) {
      if (sectionSize > 0 && cacheSize >= 0 && threadCount > 0) {
         this.positionProvider = positionProvider;
         this.sectionSize = sectionSize;
         this.threadData = new WorkerIndexer.Data<>(threadCount, () -> new CacheThreadMemory(cacheSize));
      } else {
         throw new IllegalArgumentException();
      }
   }

   @Override
   public void positionsIn(@Nonnull PositionProvider.Context context) {
      this.get(context);
   }

   public void get(@Nonnull PositionProvider.Context context) {
      CacheThreadMemory cachedData = this.threadData.get(context.workerId);
      Vector3i minSection = this.sectionAddress(context.minInclusive);
      Vector3i maxSection = this.sectionAddress(context.maxExclusive);
      Vector3i sectionAddress = minSection.clone();

      for (sectionAddress.x = minSection.x; sectionAddress.x <= maxSection.x; sectionAddress.x++) {
         for (sectionAddress.z = minSection.z; sectionAddress.z <= maxSection.z; sectionAddress.z++) {
            for (sectionAddress.y = minSection.y; sectionAddress.y <= maxSection.y; sectionAddress.y++) {
               long key = HashUtil.hash((long)sectionAddress.x, (long)sectionAddress.y, (long)sectionAddress.z);
               Vector3d[] section = cachedData.sections.get(key);
               if (section == null) {
                  Vector3d sectionMin = this.sectionMin(sectionAddress);
                  Vector3d sectionMax = sectionMin.clone().add((double)this.sectionSize, (double)this.sectionSize, (double)this.sectionSize);
                  ArrayList<Vector3d> generatedPositions = new ArrayList<>();
                  PositionProvider.Context childContext = new PositionProvider.Context(sectionMin, sectionMax, generatedPositions::add, null, context.workerId);
                  this.positionProvider.positionsIn(childContext);
                  section = new Vector3d[generatedPositions.size()];
                  generatedPositions.toArray(section);
                  cachedData.sections.put(key, section);
                  cachedData.expirationList.addFirst(key);
                  if (cachedData.expirationList.size() > cachedData.size) {
                     long removedKey = cachedData.expirationList.removeLast();
                     cachedData.sections.remove(removedKey);
                  }
               }

               for (Vector3d position : section) {
                  if (VectorUtil.isInside(position, context.minInclusive, context.maxExclusive)) {
                     context.consumer.accept(position.clone());
                  }
               }
            }
         }
      }
   }

   @Nonnull
   private Vector3i sectionAddress(@Nonnull Vector3d pointer) {
      Vector3i address = pointer.toVector3i();
      address.x = this.sectionFloor(address.x) / this.sectionSize;
      address.y = this.sectionFloor(address.y) / this.sectionSize;
      address.z = this.sectionFloor(address.z) / this.sectionSize;
      return address;
   }

   @Nonnull
   private Vector3d sectionMin(@Nonnull Vector3i sectionAddress) {
      Vector3d min = sectionAddress.toVector3d();
      min.x = min.x * (double)this.sectionSize;
      min.y = min.y * (double)this.sectionSize;
      min.z = min.z * (double)this.sectionSize;
      return min;
   }

   private int toSectionAddress(double position) {
      int positionAddress = (int)position;
      positionAddress = this.sectionFloor(positionAddress);
      return positionAddress / this.sectionSize;
   }

   public int sectionFloor(int voxelAddress) {
      return voxelAddress < 0 ? voxelAddress - voxelAddress % this.sectionSize - this.sectionSize : voxelAddress - voxelAddress % this.sectionSize;
   }
}