Ensure single-threaded chunk access

Author: ishland

src/main/java/org/yatopiamc/barium/common/threading/chunkio/BariumCachedRegionStorage.java

@@ -59,8 +59,8 @@ public BariumCachedRegionStorage(File file, boolean bl, String string) {
         this.storage = new RegionBasedStorage(file, bl);
         this.chunkCache = CacheBuilder.newBuilder()
                 .concurrencyLevel(Runtime.getRuntime().availableProcessors() * 2)
-                .expireAfterAccess(16, TimeUnit.SECONDS)
-                .maximumSize(16384)
+                .expireAfterAccess(3, TimeUnit.SECONDS)
+                .maximumSize(8192)
                 .removalListener((RemovalNotification<ChunkPos, CompoundTag> notification) -> {
                     if (notification.getValue() != EMPTY_VALUE)
                         scheduleWrite(notification.getKey(), notification.getValue());

src/main/java/org/yatopiamc/barium/common/threading/worldgen/ChunkStatusUtils.java

@@ -1,6 +1,15 @@
 package org.yatopiamc.barium.common.threading.worldgen;
 
+import com.ibm.asyncutil.locks.AsyncLock;
+import com.ibm.asyncutil.locks.AsyncNamedLock;
+import net.minecraft.util.math.ChunkPos;
 import net.minecraft.world.chunk.ChunkStatus;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.function.Supplier;
 
 public class ChunkStatusUtils {
 
@@ -23,4 +32,25 @@ public static ChunkStatusThreadingType getThreadingType(final ChunkStatus status
         }
     }
 
+    private static <T> CompletableFuture<T> buildChain0(@NotNull List<CompletableFuture<AsyncLock.LockToken>> list, int index, Supplier<CompletableFuture<T>> code) {
+        if (index < list.size()) {
+            return list.get(index).thenCompose(lockToken -> {
+                final CompletableFuture<T> future = buildChain0(list, index + 1, code);
+                future.thenRun(lockToken::releaseLock);
+                return future;
+            });
+        } else {
+            return code.get();
+        }
+    }
+
+    public static <T> CompletableFuture<T> runChunkGenWithLock(ChunkPos target, int radius, AsyncNamedLock<ChunkPos> chunkLock, Supplier<CompletableFuture<T>> action) {
+        List<CompletableFuture<AsyncLock.LockToken>> acquiredLocks = new ArrayList<>((radius + 1) * (radius + 1));
+        for (int x = target.x - radius; x <= target.x + radius; x++)
+            for (int z = target.z - radius; z <= target.z + radius; z++)
+                acquiredLocks.add(chunkLock.acquireLock(new ChunkPos(x, z)).toCompletableFuture());
+
+        return buildChain0(acquiredLocks, 0, action);
+    }
+
 }

src/main/java/org/yatopiamc/barium/common/threading/worldgen/IWorldGenLockable.java

@@ -1,9 +1,13 @@
 package org.yatopiamc.barium.common.threading.worldgen;
 
 import com.ibm.asyncutil.locks.AsyncLock;
+import com.ibm.asyncutil.locks.AsyncNamedLock;
+import net.minecraft.util.math.ChunkPos;
 
 public interface IWorldGenLockable {
 
     AsyncLock getWorldGenSingleThreadedLock();
 
+    AsyncNamedLock<ChunkPos> getWorldGenChunkLock();
+
 }

src/main/java/org/yatopiamc/barium/mixin/threading/worldgen/MixinChunkStatus.java

@@ -26,13 +26,21 @@ public class MixinChunkStatus {
     @Final
     private ChunkStatus.GenerationTask generationTask;
 
+    @Shadow @Final public static ChunkStatus FEATURES;
+
     /**
      * @author ishland
      * @reason take over generation
      */
     @Overwrite
     public CompletableFuture<Either<Chunk, ChunkHolder.Unloaded>> runGenerationTask(ServerWorld world, ChunkGenerator chunkGenerator, StructureManager structureManager, ServerLightingProvider lightingProvider, Function<Chunk, CompletableFuture<Either<Chunk, ChunkHolder.Unloaded>>> function, List<Chunk> chunks) {
-        return ChunkStatusUtils.getThreadingType((ChunkStatus) (Object) this).runTask(((IWorldGenLockable) world).getWorldGenSingleThreadedLock(), () -> this.generationTask.doWork((ChunkStatus) (Object) this, world, chunkGenerator, structureManager, lightingProvider, function, chunks, chunks.get(chunks.size() / 2)));
+        final Chunk targetChunk = chunks.get(chunks.size() / 2);
+        //noinspection ConstantConditions
+        return ChunkStatusUtils.runChunkGenWithLock(targetChunk.getPos(), (Object) this == FEATURES ? 1 : 0, ((IWorldGenLockable) world).getWorldGenChunkLock(), () ->
+                ChunkStatusUtils.getThreadingType((ChunkStatus) (Object) this).runTask(((IWorldGenLockable) world).getWorldGenSingleThreadedLock(), () ->
+                        this.generationTask.doWork((ChunkStatus) (Object) this, world, chunkGenerator, structureManager, lightingProvider, function, chunks, targetChunk)
+                )
+        );
     }
 
 }

src/main/java/org/yatopiamc/barium/mixin/threading/worldgen/MixinServerWorld.java

@@ -1,7 +1,9 @@
 package org.yatopiamc.barium.mixin.threading.worldgen;
 
 import com.ibm.asyncutil.locks.AsyncLock;
+import com.ibm.asyncutil.locks.AsyncNamedLock;
 import net.minecraft.server.world.ServerWorld;
+import net.minecraft.util.math.ChunkPos;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
@@ -12,14 +14,21 @@
 public class MixinServerWorld implements IWorldGenLockable {
 
     private volatile AsyncLock worldGenSingleThreadedLock = null;
+    private volatile AsyncNamedLock<ChunkPos> worldGenChunkLock = null;
 
     @Inject(method = "<init>", at = @At("RETURN"))
     private void initWorldGenSingleThreadedLock(CallbackInfo ci) {
         worldGenSingleThreadedLock = AsyncLock.createFair();
+        worldGenChunkLock = AsyncNamedLock.createFair();
     }
 
     @Override
     public AsyncLock getWorldGenSingleThreadedLock() {
         return worldGenSingleThreadedLock;
     }
+
+    @Override
+    public AsyncNamedLock<ChunkPos> getWorldGenChunkLock() {
+        return worldGenChunkLock;
+    }
 }