Leaner object transactions

- Memoize the last subterrain protection verdict in object destination transactions
- Key buffered cave object blocks by packed positions and check each position once at commit
- Build every free source plan before waiting on plans other threads are building
- Reuse TreeBlockMaterial values per block state

core/src/main/java/art/arcane/iris/generation/mantle/CaveObjectPlacementTransaction.java

@@ -32,13 +32,14 @@ import art.arcane.volmlib.util.math.BlockPosition;
 import art.arcane.iris.generation.block.B;
 import art.arcane.volmlib.util.collection.KList;
 import it.unimi.dsi.fastutil.longs.Long2IntOpenHashMap;
+import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.HashMap;
-import java.util.Map;
-
 final class CaveObjectPlacementTransaction implements IObjectPlacer {
     private static final int CACHE_MISS = Integer.MIN_VALUE;
+    private static final int POSITION_BITS = 21;
+    private static final int POSITION_LIMIT = 1 << (POSITION_BITS - 1);
+    private static final long POSITION_MASK = (1L << POSITION_BITS) - 1L;
 
     private final IObjectPlacer delegate;
     private final Engine engine;
@@ -46,11 +47,14 @@ final class CaveObjectPlacementTransaction implements IObjectPlacer {
     private final int minDepthBelowSurface;
     private final int worldHeight;
     private final KList<BufferedMutation> mutations;
-    private final Map<PositionKey, NativeBlockState> bufferedBlocks;
+    private final Long2ObjectOpenHashMap<NativeBlockState> bufferedBlocks;
     private final Long2IntOpenHashMap surfaceHeights;
     private final Long2IntOpenHashMap caveCeilings;
     private int blockWrites;
     private BlockPosition canopyPosition;
+    private boolean originKnown;
+    private int originX;
+    private int originZ;
 
     CaveObjectPlacementTransaction(IObjectPlacer delegate, int anchorY, int minDepthBelowSurface) {
         this.delegate = delegate;
@@ -59,7 +63,7 @@ final class CaveObjectPlacementTransaction implements IObjectPlacer {
         this.minDepthBelowSurface = Math.max(0, minDepthBelowSurface);
         this.worldHeight = engine == null ? 0 : engine.getHeight();
         this.mutations = new KList<>();
-        this.bufferedBlocks = new HashMap<>();
+        this.bufferedBlocks = new Long2ObjectOpenHashMap<>();
         this.surfaceHeights = new Long2IntOpenHashMap();
         this.caveCeilings = new Long2IntOpenHashMap();
         this.surfaceHeights.defaultReturnValue(CACHE_MISS);
@@ -73,7 +77,14 @@ final class CaveObjectPlacementTransaction implements IObjectPlacer {
         }
 
         IrisComplex complex = engine == null ? null : engine.getComplex();
+        boolean previousChecked = false;
+        int previousX = 0;
+        int previousY = 0;
+        int previousZ = 0;
         for (BufferedMutation mutation : mutations) {
+            if (previousChecked && mutation.x() == previousX && mutation.y() == previousY && mutation.z() == previousZ) {
+                continue;
+            }
             if (complex != null
                     && !complex.allowsNewDiscreteContentAt(mutation.x(), mutation.z())) {
                 discard();
@@ -95,6 +106,10 @@ final class CaveObjectPlacementTransaction implements IObjectPlacer {
                 discard();
                 return CommitResult.REJECTED_HYDROLOGY;
             }
+            previousChecked = true;
+            previousX = mutation.x();
+            previousY = mutation.y();
+            previousZ = mutation.z();
         }
 
         applyMutations();
@@ -165,7 +180,7 @@ final class CaveObjectPlacementTransaction implements IObjectPlacer {
             return;
         }
         mutations.add(new BlockMutation(x, y, z, state, isCanopy(x, y, z)));
-        bufferedBlocks.put(new PositionKey(x, y, z), state);
+        bufferedBlocks.put(bufferKey(x, y, z), state);
         blockWrites++;
     }
 
@@ -190,7 +205,7 @@ final class CaveObjectPlacementTransaction implements IObjectPlacer {
 
     @Override
     public NativeBlockState get(int x, int y, int z) {
-        NativeBlockState buffered = bufferedBlocks.get(new PositionKey(x, y, z));
+        NativeBlockState buffered = bufferedBlocks.isEmpty() ? null : bufferedBlocks.get(bufferKey(x, y, z));
         return buffered == null ? delegate.get(x, y, z) : buffered;
     }
 
@@ -211,7 +226,7 @@ final class CaveObjectPlacementTransaction implements IObjectPlacer {
 
     @Override
     public boolean isSolid(int x, int y, int z) {
-        NativeBlockState buffered = bufferedBlocks.get(new PositionKey(x, y, z));
+        NativeBlockState buffered = bufferedBlocks.isEmpty() ? null : bufferedBlocks.get(bufferKey(x, y, z));
         return buffered == null ? delegate.isSolid(x, y, z) : B.isSolid(buffered);
     }
 
@@ -253,7 +268,7 @@ final class CaveObjectPlacementTransaction implements IObjectPlacer {
         }
         mutations.add(new DataMutation(x, y, z, data, isCanopy(x, y, z)));
         if (data instanceof NativeBlockState state) {
-            bufferedBlocks.put(new PositionKey(x, y, z), state);
+            bufferedBlocks.put(bufferKey(x, y, z), state);
             blockWrites++;
         }
     }
@@ -278,6 +293,22 @@ final class CaveObjectPlacementTransaction implements IObjectPlacer {
         return engine;
     }
 
+    private long bufferKey(int x, int y, int z) {
+        if (!originKnown) {
+            originX = x;
+            originZ = z;
+            originKnown = true;
+        }
+        int dx = x - originX;
+        int dz = z - originZ;
+        if (dx < -POSITION_LIMIT || dx >= POSITION_LIMIT || dz < -POSITION_LIMIT || dz >= POSITION_LIMIT
+                || y < -POSITION_LIMIT || y >= POSITION_LIMIT) {
+            throw new IllegalStateException("Cave object write at " + x + "," + y + "," + z
+                    + " is too far from its first write at " + originX + "," + originZ);
+        }
+        return ((dx & POSITION_MASK) << (POSITION_BITS * 2)) | ((dz & POSITION_MASK) << POSITION_BITS) | (y & POSITION_MASK);
+    }
+
     private boolean isWithinBounds(int x, int y, int z) {
         if (engine == null || y < 0 || y >= worldHeight) {
             return false;
@@ -361,6 +392,4 @@ final class CaveObjectPlacementTransaction implements IObjectPlacer {
         }
     }
 
-    private record PositionKey(int x, int y, int z) {
-    }
 }

core/src/main/java/art/arcane/iris/generation/mantle/MantleObjectComponent.java

@@ -88,6 +88,8 @@ public class MantleObjectComponent extends IrisMantleComponent {
     private static final Map<String, CaveRejectLogState> CAVE_REJECT_LOG_STATE = new ConcurrentHashMap<>();
     private static final Set<String> MISSING_LOAD_KEY_WARNED = ConcurrentHashMap.newKeySet();
     private static final long SOURCE_PLAN_STATS_INTERVAL_MS = 30_000L;
+    private static final int MAXIMUM_TREE_MATERIALS = 8192;
+    private static final Map<NativeBlockState, TreeBlockMaterial> TREE_MATERIALS = new ConcurrentHashMap<>();
 
     private final Object collisionRuleLock;
     private final ObjectSourcePlanCache sourcePlans;
@@ -124,7 +126,14 @@ public class MantleObjectComponent extends IrisMantleComponent {
     }
 
     private static void writeTreeMaterial(IObjectPlacer placer, int x, int y, int z, NativeBlockState data) {
-        placer.setData(x, y, z, TreeBlockMaterial.of(data));
+        TreeBlockMaterial material = TREE_MATERIALS.get(data);
+        if (material == null) {
+            material = TreeBlockMaterial.of(data);
+            if (TREE_MATERIALS.size() < MAXIMUM_TREE_MATERIALS) {
+                TREE_MATERIALS.putIfAbsent(data, material);
+            }
+        }
+        placer.setData(x, y, z, material);
     }
 
     @Override
@@ -157,19 +166,23 @@ public class MantleObjectComponent extends IrisMantleComponent {
         ObjectDestinationTransaction transaction = new ObjectDestinationTransaction(writer, x, z);
         int radius = getRadius();
         int sourceChunkRadius = sourceChunkRadius(radius);
-        replaySourceChunks(
-                x,
-                z,
-                radius,
-                (sourceX, sourceZ) -> {
-                    ObjectSourcePlan plan = sourcePlans.acquire(sourceX, sourceZ, x, z, sourceChunkRadius,
-                            () -> buildSourcePlan(writer, sourceX, sourceZ, context));
-                    if (plan != null) {
-                        transaction.apply(plan);
-                        plan.persistContinuations(writer, sourceX, sourceZ, x, z);
-                    }
-                }
-        );
+        int side = (sourceChunkRadius * 2) + 1;
+        ObjectSourcePlan[] plans = new ObjectSourcePlan[side * side];
+        int[] slot = new int[1];
+        replaySourceChunks(x, z, radius, (sourceX, sourceZ) -> plans[slot[0]++] = sourcePlans.tryAcquire(
+                sourceX, sourceZ, x, z, sourceChunkRadius, () -> buildSourcePlan(writer, sourceX, sourceZ, context)));
+        slot[0] = 0;
+        replaySourceChunks(x, z, radius, (sourceX, sourceZ) -> {
+            ObjectSourcePlan plan = plans[slot[0]++];
+            if (plan == ObjectSourcePlanCache.BUSY) {
+                plan = sourcePlans.acquire(sourceX, sourceZ, x, z, sourceChunkRadius,
+                        () -> buildSourcePlan(writer, sourceX, sourceZ, context));
+            }
+            if (plan != null) {
+                transaction.apply(plan);
+                plan.persistContinuations(writer, sourceX, sourceZ, x, z);
+            }
+        });
         transaction.commit();
         logSourcePlanStats();
     }

core/src/main/java/art/arcane/iris/generation/mantle/ObjectDestinationTransaction.java

@@ -40,6 +40,11 @@ final class ObjectDestinationTransaction implements ObjectPassPlacer {
     private int hydrologyGateChunkX;
     private int hydrologyGateChunkZ;
     private boolean hydrologyGateOpen;
+    private boolean subterrainKnown;
+    private int subterrainX;
+    private int subterrainY;
+    private int subterrainZ;
+    private boolean subterrainProtects;
 
     ObjectDestinationTransaction(MantleWriter writer, int destinationChunkX, int destinationChunkZ) {
         this.writer = writer;
@@ -396,8 +401,17 @@ final class ObjectDestinationTransaction implements ObjectPassPlacer {
     }
 
     private boolean protectsSubterrain(int x, int y, int z) {
+        if (subterrainKnown && x == subterrainX && y == subterrainY && z == subterrainZ) {
+            return subterrainProtects;
+        }
         Engine engine = getEngine();
-        return engine != null && SubterrainRasterizer.protectsPlacement(engine.getSubterrainCell(x, y, z));
+        boolean protects = engine != null && SubterrainRasterizer.protectsPlacement(engine.getSubterrainCell(x, y, z));
+        subterrainX = x;
+        subterrainY = y;
+        subterrainZ = z;
+        subterrainProtects = protects;
+        subterrainKnown = true;
+        return protects;
     }
 
     private boolean hasProtectedHydrology(int x, int y, int z) {

core/src/main/java/art/arcane/iris/generation/mantle/ObjectSourcePlanCache.java

@@ -4,6 +4,7 @@ import com.github.benmanes.caffeine.cache.Cache;
 import com.github.benmanes.caffeine.cache.Caffeine;
 import art.arcane.volmlib.util.cache.CacheKey;
 
+import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionException;
@@ -14,6 +15,7 @@ import java.util.function.Supplier;
 import static art.arcane.iris.generation.cache.Cache.key;
 
 final class ObjectSourcePlanCache {
+    static final ObjectSourcePlan BUSY = new ObjectSourcePlan(List.of());
     private static final long MAXIMUM_RETAINED_BYTES = 512L * 1024L * 1024L;
     private static final int ENTRY_BYTES = 64;
 
@@ -68,6 +70,19 @@ final class ObjectSourcePlanCache {
         return plan;
     }
 
+    ObjectSourcePlan tryAcquire(int sourceChunkX, int sourceChunkZ, int destinationChunkX, int destinationChunkZ,
+                                int sourceChunkRadius, Supplier<ObjectSourcePlan> builder) {
+        State current = state;
+        long source = CacheKey.mix(key(sourceChunkX, sourceChunkZ));
+        if (current.plans.getIfPresent(source) == null) {
+            Pending pending = current.pending.get(source);
+            if (pending != null && pending.owner != Thread.currentThread()) {
+                return BUSY;
+            }
+        }
+        return acquire(sourceChunkX, sourceChunkZ, destinationChunkX, destinationChunkZ, sourceChunkRadius, builder);
+    }
+
     private ObjectSourcePlan claim(State current, long source, Entry entry, int destinationChunkX, int destinationChunkZ,
                                    Supplier<ObjectSourcePlan> builder) {
         int slot = entry.slot(destinationChunkX, destinationChunkZ);

core/src/test/java/art/arcane/iris/generation/mantle/ObjectSourcePlanCacheTest.java

@@ -163,6 +163,44 @@ public class ObjectSourcePlanCacheTest {
         }
     }
 
+    @Test
+    public void tryAcquireReportsBusySourcesWithoutConsumingThem() throws Exception {
+        ObjectSourcePlanCache cache = new ObjectSourcePlanCache(1024L * 1024L);
+        ObjectSourcePlan plan = planTouching(new int[]{0, 0}, new int[]{1, 0});
+        CountDownLatch entered = new CountDownLatch(1);
+        CountDownLatch release = new CountDownLatch(1);
+        AtomicInteger builds = new AtomicInteger();
+        ExecutorService executor = Executors.newFixedThreadPool(1);
+        try {
+            Future<ObjectSourcePlan> owner = executor.submit(() -> cache.acquire(0, 0, 0, 0, 7, () -> {
+                builds.incrementAndGet();
+                entered.countDown();
+                await(release);
+                return plan;
+            }));
+            assertTrue(entered.await(5L, TimeUnit.SECONDS));
+
+            assertSame(ObjectSourcePlanCache.BUSY, cache.tryAcquire(0, 0, 1, 0, 7, () -> {
+                builds.incrementAndGet();
+                return plan;
+            }));
+            ObjectSourcePlan unrelated = planTouching(new int[]{5, 5});
+            assertSame(unrelated, cache.tryAcquire(5, 5, 5, 5, 7, () -> unrelated));
+            release.countDown();
+            assertSame(plan, owner.get(5L, TimeUnit.SECONDS));
+
+            assertSame(plan, cache.tryAcquire(0, 0, 1, 0, 7, () -> {
+                builds.incrementAndGet();
+                return plan;
+            }));
+            assertEquals(1, builds.get());
+            assertEquals(2L, cache.stats().drained());
+        } finally {
+            release.countDown();
+            executor.shutdownNow();
+        }
+    }
+
     @Test
     public void concurrentDestinationsShareOneSourceBuild() throws Exception {
         ObjectSourcePlanCache cache = new ObjectSourcePlanCache(1024L * 1024L);