just to change from disabling spawn chunks to control over its size. Removes disableSpawnChunks, adds spawnChunksSize. Fixes #192

src/main/java/carpet/mixins/ChunkTicketManager_spawnChunksMixin.java

@@ -0,0 +1,60 @@
+package carpet.mixins;
+
+import carpet.fakes.ChunkTicketManagerInterface;
+import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
+import net.minecraft.server.world.ChunkTicket;
+import net.minecraft.server.world.ChunkTicketManager;
+import net.minecraft.server.world.ChunkTicketType;
+import net.minecraft.util.SortedArraySet;
+import net.minecraft.util.Unit;
+import net.minecraft.util.math.ChunkPos;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+
+import java.util.Iterator;
+
+@Mixin(ChunkTicketManager.class)
+public abstract class ChunkTicketManager_spawnChunksMixin implements ChunkTicketManagerInterface
+{
+
+    @Shadow protected abstract SortedArraySet<ChunkTicket<?>> getTicketSet(long position);
+
+    @Shadow @Final private Long2ObjectOpenHashMap<SortedArraySet<ChunkTicket<?>>> ticketsByPosition;
+
+    @Shadow public abstract <T> void removeTicket(ChunkTicketType<T> type, ChunkPos pos, int radius, T argument);
+
+    @Shadow protected abstract void removeTicket(long pos, ChunkTicket<?> ticket);
+
+    @Shadow public abstract <T> void addTicket(ChunkTicketType<T> type, ChunkPos pos, int radius, T argument);
+
+    @Override
+    public void changeSpawnChunks(ChunkPos chunkPos,  int distance)
+    {
+        long pos = chunkPos.toLong();
+        SortedArraySet<ChunkTicket<?>> set = ticketsByPosition.get(pos);
+        ChunkTicket existingTicket = null;
+        if (set != null)
+        {
+            Iterator<ChunkTicket<?>> iter = set.iterator();
+            while(iter.hasNext())
+            {
+                ChunkTicket ticket = iter.next();
+                if (ticket.getType() == ChunkTicketType.START)
+                {
+                    existingTicket = ticket;
+                    iter.remove();
+                }
+            }
+            set.add(existingTicket);
+        }
+        // the reason we are removing the ticket this way is that there are sideeffects of removal
+        if (existingTicket != null)
+        {
+            removeTicket(pos, existingTicket);
+        }
+        // set optionally new spawn ticket
+        if (distance > 0)
+            addTicket(ChunkTicketType.START, chunkPos, distance, Unit.INSTANCE);
+    }
+}