Fix chunk caching race condition add toggle

- /flywheel chunkCaching on|off
 - synchronized ftw

src/main/java/com/jozufozu/flywheel/backend/Backend.java

@@ -43,6 +43,7 @@ public class Backend {
 	private Matrix4f projectionMatrix = new Matrix4f();
 	private boolean instancedArrays;
 	private boolean enabled;
+	public boolean chunkCachingEnabled;
 
 	private final List<IShaderContext<?>> contexts = new ArrayList<>();
 	private final Map<ResourceLocation, MaterialSpec<?>> materialRegistry = new HashMap<>();
@@ -153,6 +154,8 @@ public class Backend {
 
 		enabled = FlwConfig.get()
 				.enabled() && !OptifineHandler.usingShaders();
+		chunkCachingEnabled = FlwConfig.get()
+				.chunkCaching();
 	}
 
 	public boolean canUseInstancing(@Nullable World world) {

src/main/java/com/jozufozu/flywheel/config/BooleanConfig.java

@@ -18,6 +18,7 @@ import net.minecraftforge.api.distmarker.OnlyIn;
 public enum BooleanConfig {
 	ENGINE(() -> BooleanConfig::enabled),
 	NORMAL_OVERLAY(() -> BooleanConfig::normalOverlay),
+	CHUNK_CACHING(() -> BooleanConfig::chunkCaching),
 	;
 
 	final Supplier<Consumer<BooleanDirective>> receiver;
@@ -71,6 +72,25 @@ public enum BooleanConfig {
 		player.displayClientMessage(text, false);
 	}
 
+	@OnlyIn(Dist.CLIENT)
+	private static void chunkCaching(BooleanDirective state) {
+		ClientPlayerEntity player = Minecraft.getInstance().player;
+		if (player == null || state == null) return;
+
+		if (state == BooleanDirective.DISPLAY) {
+			ITextComponent text = new StringTextComponent("Chunk caching is currently: ").append(boolToText(FlwConfig.get().client.debugNormals.get()));
+			player.displayClientMessage(text, false);
+			return;
+		}
+
+		FlwConfig.get().client.chunkCaching.set(state.get());
+
+		ITextComponent text = boolToText(FlwConfig.get().client.chunkCaching.get()).append(new StringTextComponent(" chunk caching").withStyle(TextFormatting.WHITE));
+
+		player.displayClientMessage(text, false);
+		Backend.reloadWorldRenderers();
+	}
+
 	private static IFormattableTextComponent boolToText(boolean b) {
 		return b ? new StringTextComponent("enabled").withStyle(TextFormatting.DARK_GREEN) : new StringTextComponent("disabled").withStyle(TextFormatting.RED);
 	}

src/main/java/com/jozufozu/flywheel/config/FlwCommands.java

@@ -16,6 +16,8 @@ public class FlwCommands {
 
 		dispatcher.register(Commands.literal("flywheel")
 									.then(new BooleanConfigCommand("backend", BooleanConfig.ENGINE).register())
-									.then(new BooleanConfigCommand("debugNormals", BooleanConfig.NORMAL_OVERLAY).register()));
+									.then(new BooleanConfigCommand("debugNormals", BooleanConfig.NORMAL_OVERLAY).register())
+									.then(new BooleanConfigCommand("chunkCaching", BooleanConfig.CHUNK_CACHING).register())
+		);
 	}
 }

src/main/java/com/jozufozu/flywheel/config/FlwConfig.java

@@ -34,12 +34,17 @@ public class FlwConfig {
 		return client.debugNormals.get();
 	}
 
+	public boolean chunkCaching() {
+		return client.chunkCaching.get();
+	}
+
 	public static void init() {
 	}
 
 	public static class ClientConfig {
 		public final BooleanValue enabled;
 		public final BooleanValue debugNormals;
+		public final BooleanValue chunkCaching;
 
 		public ClientConfig(ForgeConfigSpec.Builder builder) {
 
@@ -48,6 +53,9 @@ public class FlwConfig {
 
 			debugNormals = builder.comment("Enable or disable a debug overlay that colors pixels by their normal")
 					.define("debugNormals", false);
+
+			chunkCaching = builder.comment("Cache chunk lookups to improve performance.")
+					.define("chunkCaching", true);
 		}
 	}
 }

src/main/java/com/jozufozu/flywheel/mixin/FastChunkProviderMixin.java

@@ -1,6 +1,8 @@
 package com.jozufozu.flywheel.mixin;
 
+import org.spongepowered.asm.mixin.Final;
 import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
 import org.spongepowered.asm.mixin.Unique;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
@@ -8,7 +10,10 @@ import org.spongepowered.asm.mixin.injection.Redirect;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
 
+import com.jozufozu.flywheel.backend.Backend;
+
 import net.minecraft.client.multiplayer.ClientChunkProvider;
+import net.minecraft.client.world.ClientWorld;
 import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.network.PacketBuffer;
 import net.minecraft.world.biome.BiomeContainer;
@@ -20,6 +25,9 @@ import net.minecraft.world.chunk.IChunk;
 @Mixin(ClientChunkProvider.class)
 public abstract class FastChunkProviderMixin extends AbstractChunkProvider {
 
+	@Shadow
+	@Final
+	private ClientWorld level;
 	@Unique
 	private int lastX;
 	@Unique
@@ -32,36 +40,52 @@ public abstract class FastChunkProviderMixin extends AbstractChunkProvider {
 			at = @At("HEAD"),
 			cancellable = true)
 	public void returnCachedChunk(int x, int z, ChunkStatus status, boolean create, CallbackInfoReturnable<IChunk> cir) {
-		if (status.isOrAfter(ChunkStatus.FULL) && lastChunk != null && x == lastX && z == lastZ) {
-			cir.setReturnValue(lastChunk);
+		if (Backend.getInstance().chunkCachingEnabled && status.isOrAfter(ChunkStatus.FULL)) {
+			synchronized (level) {
+				if (lastChunk != null && x == lastX && z == lastZ) {
+					cir.setReturnValue(lastChunk);
+				}
+			}
 		}
 	}
 
 	@Inject(method = "getChunk",
 			at = @At("RETURN"))
 	public void cacheChunk(int x, int z, ChunkStatus status, boolean create, CallbackInfoReturnable<IChunk> cir) {
-		if (status.isOrAfter(ChunkStatus.FULL)) {
-			lastChunk = cir.getReturnValue();
-			lastX = x;
-			lastZ = z;
+		if (Backend.getInstance().chunkCachingEnabled && status.isOrAfter(ChunkStatus.FULL)) {
+			synchronized (level) {
+				lastChunk = cir.getReturnValue();
+				lastX = x;
+				lastZ = z;
+			}
 		}
 	}
 
 	@Inject(method = "drop", at = @At("HEAD"))
 	public void invalidateOnDrop(int x, int z, CallbackInfo ci) {
-		if (x == lastX && z == lastZ)
-			lastChunk = null;
+		if (Backend.getInstance().chunkCachingEnabled) {
+			synchronized (level) {
+				if (x == lastX && z == lastZ) lastChunk = null;
+			}
+		}
 	}
 
 	@Inject(method = "replaceWithPacketData", at = @At("HEAD"))
 	public void invalidateOnPacket(int x, int z, BiomeContainer p_228313_3_, PacketBuffer p_228313_4_, CompoundNBT p_228313_5_, int p_228313_6_, boolean p_228313_7_, CallbackInfoReturnable<Chunk> cir) {
-		if (x == lastX && z == lastZ)
-			lastChunk = null;
+		if (Backend.getInstance().chunkCachingEnabled) {
+			synchronized (level) {
+				if (x == lastX && z == lastZ) lastChunk = null;
+			}
+		}
 	}
 
 	@Redirect(method = "isTickingChunk", at = @At(value = "INVOKE", target = "Lnet/minecraft/client/multiplayer/ClientChunkProvider;hasChunk(II)Z"))
 	public boolean redirectTicking(ClientChunkProvider clientChunkProvider, int x, int z) {
-		if (lastChunk != null && x == lastX && z == lastZ) return true;
+		if (Backend.getInstance().chunkCachingEnabled) {
+			synchronized (level) {
+				if (lastChunk != null && x == lastX && z == lastZ) return true;
+			}
+		}
 
 		return clientChunkProvider.hasChunk(x, z);
 	}