Add commented out logic for LevelChunkSection cloning

It was far to difficult a task for a issue I've only ever heard about once
2025-01-11 21:16:15 -06:00
parent 2a8013b1d6
commit f493e201d4
1 changed files with 85 additions and 1 deletions
@@ -16,7 +16,6 @@
 *    You should have received a copy of the GNU Lesser General Public License
 *    along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
-
 package com.seibel.distanthorizons.common.wrappers.chunk;

 import com.seibel.distanthorizons.common.wrappers.block.BiomeWrapper;
@@ -386,6 +385,91 @@ public class ChunkWrapper implements IChunkWrapper
 		return BlockStateWrapper.fromBlockState(this.chunk.getBlockState(pos), this.wrappedLevel, guess);
 	}
 	
+	/**
+	
+	 // Commented out experimental LevelChunkSection cloning logic to fix extremely rare concurrency modification issue
+	 // James has only ever seen a report relating to LevelSection concurrent modification once,
+	 // the issue can cause DH lighting/LOD building to fail due to the chunk being modified on the server.
+	 // James has only heard of this issue once, so it isn't a high priority issue.
+	 // And from James' quick look at a few different MC versions it appears the LevelChunkSection object changes quite drastically between MC versions,
+	 // meaning any cloning logic would have to either be a new wrapper or very MC version dependent, either way a lot of additional work.
+	 // Due to the large time cost and extremely rare nature of the issue, this logic is commented out unless this issue pops up again in the future. 
+	
+	 // instance variable to hold the cloned sections
+	private final LevelChunkSection[] levelChunkSections;
+	
+	 // new constructor logic to clone the sections
+	public constructor(...)
+	{
+		// other constructor logic //
+		
+		LevelChunkSection[] sections = this.chunk.getSections();	 
+		this.levelChunkSections = new LevelChunkSection[sections.length];
+		for (int i = 0; i < sections.length; i++)
+		{
+			LevelChunkSection section = sections[i];
+			if (section != null)
+			{
+	            // TODO implement section cloning for older MC versions, only 1.21.4 MC (and maybe other semi recent versions) have a clean way to handle this
+	            // TODO we probably want a wrapper object instead
+				#if MC_VER < MC_1_21_4
+				this.levelChunkSections[i] = section;
+				#else
+				this.levelChunkSections[i] = section.copy();
+				#endif
+			}
+		}
+	}
+	
+	 // replacement getters
+	@Override
+	public IBlockStateWrapper getBlockState(int relX, int relY, int relZ)
+	{
+		this.throwIndexOutOfBoundsIfRelativePosOutsideChunkBounds(relX, relY, relZ);
+		return this.getBlockStateInternal(relX, relY, relZ, null);
+	}
+	
+	@Override
+	public IBlockStateWrapper getBlockState(int relX, int relY, int relZ, IMutableBlockPosWrapper mcBlockPos, IBlockStateWrapper guess)
+	{
+		this.throwIndexOutOfBoundsIfRelativePosOutsideChunkBounds(relX, relY, relZ);
+		return this.getBlockStateInternal(relX, relY, relZ, guess);
+	}
+	
+	// internal getter logic
+	private IBlockStateWrapper getBlockStateInternal(int relX, int y, int relZ, @Nullable IBlockStateWrapper guess)
+	{
+		try
+		{
+			// attempt to get the section for this position
+			int i = (y - this.getInclusiveMinBuildHeight()) / 16;
+			if (i >= 0 && i < this.levelChunkSections.length)
+			{
+				LevelChunkSection section = this.levelChunkSections[i];
+				if (!section.hasOnlyAir())
+				{
+					if (guess != null)
+					{
+						return BlockStateWrapper.fromBlockState(section.getBlockState(relX & 15, y & 15, relZ & 15), this.wrappedLevel, guess);
+					}
+					else
+					{
+						return BlockStateWrapper.fromBlockState(section.getBlockState(relX & 15, y & 15, relZ & 15), this.wrappedLevel);
+					}
+				}
+			}
+			
+			return BlockStateWrapper.AIR;
+		}
+		catch (Exception e)
+		{
+			return BlockStateWrapper.AIR;
+		}
+	}
+	 */
+	
+	
+	
 	@Override
 	public IMutableBlockPosWrapper getMutableBlockPosWrapper() { return MUTABLE_BLOCK_POS_WRAPPER_REF.get(); }