hopefully prevent world gen structure lockup when leaving the world

common/src/main/java/com/seibel/distanthorizons/common/wrappers/worldGeneration/BatchGenerationEnvironment.java

@@ -36,7 +36,6 @@ import com.seibel.distanthorizons.core.pos.DhChunkPos;
 import com.seibel.distanthorizons.core.util.objects.EventTimer;
 import com.seibel.distanthorizons.core.util.LodUtil;
 import com.seibel.distanthorizons.core.util.gridList.ArrayGridList;
-import com.seibel.distanthorizons.core.util.objects.DhThreadFactory;
 import com.seibel.distanthorizons.core.wrapperInterfaces.chunk.IChunkWrapper;
 import com.seibel.distanthorizons.core.wrapperInterfaces.worldGeneration.AbstractBatchGenerationEnvironmentWrapper;
 import com.seibel.distanthorizons.common.wrappers.chunk.ChunkWrapper;
@@ -745,7 +744,7 @@ public final class BatchGenerationEnvironment extends AbstractBatchGenerationEnv
 	 * This is necessary to allow canceling world gen since waiting
 	 * for some world gen requests to finish can take a while.
 	 */
-	private static void throwIfThreadInterrupted() throws InterruptedException
+	public static void throwIfThreadInterrupted() throws InterruptedException
 	{
 		if (Thread.interrupted())
 		{

common/src/main/java/com/seibel/distanthorizons/common/wrappers/worldGeneration/step/StepStructureStart.java

@@ -64,7 +64,7 @@ public final class StepStructureStart
 	
 	public void generateGroup(
 			ThreadedParameters tParams, WorldGenRegion worldGenRegion,
-			List<ChunkWrapper> chunkWrappers)
+			List<ChunkWrapper> chunkWrappers) throws InterruptedException
 	{
 		ArrayList<ChunkAccess> chunksToDo = new ArrayList<>();
 		
@@ -90,6 +90,11 @@ public final class StepStructureStart
 			for (ChunkAccess chunk : chunksToDo)
 			{
 				// System.out.println("StepStructureStart: "+chunk.getPos());
+				
+				// there are a few cases where the structure generator call may lock up (either due to teleporting or leaving the world).
+				// hopefully allowing interrupts here will prevent that from happening.
+				BatchGenerationEnvironment.throwIfThreadInterrupted();
+				
 				#if PRE_MC_1_19_2
 				environment.params.generator.createStructures(environment.params.registry, tParams.structFeat, chunk, environment.params.structures,
 						environment.params.worldSeed);