Limit early owner drafts in pregen

- Pregeneration scope limits the lower-rank neighbour drafts an owner starts early to tiles the area composes from
- Undemanded ring drafts (and the early neighbours they started) are no longer computed; demanded ones still resolve on demand
- r2000 tile set: 80 -> 54 drafts, planning CPU -32%, plans identical

core/src/main/java/art/arcane/iris/generation/hydrology/HydrologyPlanner.java

@@ -28,6 +28,7 @@ import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionException;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ForkJoinWorkerThread;
+import java.util.function.Predicate;
 
 public final class HydrologyPlanner {
     static final int ROUTING_CONTEXT_CACHE_SIZE = 64;
@@ -64,6 +65,7 @@ public final class HydrologyPlanner {
     final HydrologySegmentBuilder segments;
     final HydrologyFeatureSitePlanner featureSites;
     final HydrologyRegionalPlanner regional;
+    private volatile Predicate<HydrologyTileKey> earlyOwnerScope;
 
     public HydrologyPlanner(long worldSeed, HydrologyPlannerSettings settings, HydrologyTerrainSampler sampler) {
         this(
@@ -244,6 +246,15 @@ public final class HydrologyPlanner {
         return List.copyOf(unique);
     }
 
+    /**
+     * Limits the lower-rank neighbour drafts an owner starts before its admission demands them to the
+     * tiles the scope accepts; null starts all of them. A neighbour that no admission demands and
+     * nothing plans is a draft computed for nothing, and so are the early neighbours it starts itself.
+     */
+    void limitEarlyOwners(Predicate<HydrologyTileKey> scope) {
+        earlyOwnerScope = scope;
+    }
+
     void clearOwnerDrafts() {
         resolvedOwners.invalidateAll();
         regional.clear();
@@ -751,6 +762,7 @@ public final class HydrologyPlanner {
                 return;
             }
             int radius = settings.crossTileColorPeriod() - 1;
+            Predicate<HydrologyTileKey> scope = earlyOwnerScope;
             ArrayList<HydrologyTileKey> candidates = new ArrayList<>();
             for (long tileZ = (long) ownerKey.tileZ() - radius; tileZ <= (long) ownerKey.tileZ() + radius; tileZ++) {
                 for (long tileX = (long) ownerKey.tileX() - radius; tileX <= (long) ownerKey.tileX() + radius; tileX++) {
@@ -759,7 +771,8 @@ public final class HydrologyPlanner {
                         continue;
                     }
                     HydrologyTileKey key = new HydrologyTileKey((int) tileX, (int) tileZ);
-                    if (crossTile.ownerColorRank(key) >= ownerRank || preparedOwners.containsKey(key)
+                    if (crossTile.ownerColorRank(key) >= ownerRank || scope != null && !scope.test(key)
+                            || preparedOwners.containsKey(key)
                             || resolvedOwners.getIfPresent(key) != null || resolvingOwners.containsKey(key)) {
                         continue;
                     }

core/src/main/java/art/arcane/iris/generation/hydrology/HydrologyTileCache.java

@@ -690,7 +690,7 @@ public final class HydrologyTileCache implements AutoCloseable {
                 tileCoordinate(Math.addExact(area.maximumBlockZ(), publicationRadius), tileSize));
         List<HydrologyTileKey> keys = nearestFirst(required, tileCoordinate(area.centerBlockX(), tileSize),
                 tileCoordinate(area.centerBlockZ(), tileSize), MAXIMUM_PREGENERATION_TILES);
-        PregenerationScope scope = new PregenerationScope(bounds);
+        PregenerationScope scope = new PregenerationScope(bounds, required);
         try {
             enqueuePrefetchArea(keys, scope);
             return scope;
@@ -1082,6 +1082,7 @@ public final class HydrologyTileCache implements AutoCloseable {
                 scope.previousNeighbourPrefetch = pregenerationScope == null
                         ? neighbourPrefetchEnabled : pregenerationScope.previousNeighbourPrefetch;
                 pregenerationScope = scope;
+                planner.limitEarlyOwners(scope.required::contains);
                 prefetchQueue.removeIf(key -> {
                     if (!area.contains(key)) {
                         queuedPrefetches.remove(key);
@@ -1619,12 +1620,19 @@ public final class HydrologyTileCache implements AutoCloseable {
         }
     }
 
+    /**
+     * Speculative planning during a pregeneration: tiles inside {@code bounds} may be planned ahead of
+     * generation, and owner drafts start their lower-rank neighbours early only inside {@code required},
+     * the tiles the area composes from.
+     */
     public final class PregenerationScope implements AutoCloseable {
         private final TileBounds bounds;
+        private final TileBounds required;
         private boolean previousNeighbourPrefetch;
 
-        private PregenerationScope(TileBounds bounds) {
+        private PregenerationScope(TileBounds bounds, TileBounds required) {
             this.bounds = bounds;
+            this.required = required;
         }
 
         @Override
@@ -1634,6 +1642,7 @@ public final class HydrologyTileCache implements AutoCloseable {
                     return;
                 }
                 pregenerationScope = null;
+                planner.limitEarlyOwners(null);
                 neighbourPrefetchEnabled = previousNeighbourPrefetch;
                 prefetchQueue.clear();
                 queuedPrefetches.clear();