A really bad workaround for lighting update - Close #33

sources/src/main/java/io/akarin/api/internal/mixin/IMixinChunk.java

@@ -25,4 +25,6 @@ public interface IMixinChunk {
     void setNeighborChunk(int index, @Nullable Chunk chunk);
     
     void setLightUpdateTime(long time);
+    
+    void setPendingLightUpdate();
 }

sources/src/main/java/io/akarin/server/mixin/lighting/MixinChunk.java

@@ -108,6 +108,11 @@ public abstract class MixinChunk implements IMixinChunk {
         return this.pendingLightUpdates;
     }
     
+    @Override
+    public void setPendingLightUpdate() {
+        this.isLightPopulated = false;
+    }
+    
     @Override
     public long getLightUpdateTime() {
         return this.lightUpdateTime;
@@ -130,7 +135,7 @@ public abstract class MixinChunk implements IMixinChunk {
         
         this.ticked = true;
         
-        if (!this.isLightPopulated && this.isTerrainPopulated && !neighbors.isEmpty()) {
+        if ((true || !this.isLightPopulated) && this.isTerrainPopulated && !neighbors.isEmpty()) {
             lightExecutorService.execute(() -> {
                 this.checkLightAsync(neighbors);
             });
@@ -170,12 +175,47 @@ public abstract class MixinChunk implements IMixinChunk {
         return this.checkWorldLightFor(enumSkyBlock, pos);
     }
     
+    @Inject(method = "h(Z)V", at = @At("HEAD"), cancellable = true)
+    private void onRecheckGaps(CallbackInfo ci) {
+        if (this.world.getMinecraftServer().isStopped() || lightExecutorService.isShutdown()) {
+            return;
+        }
+        
+        if (this.isUnloading()) {
+            return;
+        }
+        final List<Chunk> neighborChunks = this.getSurroundingChunks();
+        if (neighborChunks.isEmpty()) {
+            this.isGapLightingUpdated = true;
+            return;
+        }
+        
+        if (Akari.isPrimaryThread()) {
+            try {
+                lightExecutorService.execute(() -> {
+                    this.recheckGapsAsync(neighborChunks);
+                });
+            } catch (RejectedExecutionException ex) {
+                // This could happen if ServerHangWatchdog kills the server
+                // between the start of the method and the execute() call.
+                if (!this.world.getMinecraftServer().isStopped() && !lightExecutorService.isShutdown()) {
+                    throw ex;
+                }
+            }
+        } else {
+            this.recheckGapsAsync(neighborChunks);
+        }
+        ci.cancel();
+    }
+    
     /**
      * Rechecks chunk gaps async.
      * 
      * @param neighbors A thread-safe list of surrounding neighbor chunks
      */
     private void recheckGapsAsync(List<Chunk> neighbors) {
+        this.isLightPopulated = false;
+        
         for (int i = 0; i < 16; ++i) {
             for (int j = 0; j < 16; ++j) {
                 if (this.updateSkylightColumns[i + j * 16]) {
@@ -201,7 +241,7 @@ public abstract class MixinChunk implements IMixinChunk {
                 }
             }
             
-            // this.isGapLightingUpdated = false;
+            this.isGapLightingUpdated = false;
         }
     }
     
@@ -272,13 +312,12 @@ public abstract class MixinChunk implements IMixinChunk {
         BlockPosition blockpos = new BlockPosition(this.locX << 4, 0, this.locZ << 4);
         
         if (this.world.worldProvider.m()) { // OBFHELPER: hasSkyLight
-            reCheckLight:
+            CHECK_LIGHT:
-            
             for (int i = 0; i < 16; ++i) {
                 for (int j = 0; j < 16; ++j) {
                     if (!this.checkLightAsync(i, j, neighbors)) {
                         this.isLightPopulated = false;
-                        break reCheckLight;
+                        break CHECK_LIGHT;
                     }
                 }
             }

sources/src/main/java/io/akarin/server/mixin/lighting/MixinWorld.java

@@ -26,7 +26,6 @@ package io.akarin.server.mixin.lighting;
 
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Shadow;
-
 import net.minecraft.server.BlockPosition;
 import net.minecraft.server.Chunk;
 import net.minecraft.server.EnumSkyBlock;

sources/src/main/java/net/minecraft/server/Chunk.java

@@ -2,8 +2,8 @@ package net.minecraft.server;
 
 import com.destroystokyo.paper.exception.ServerInternalException;
 import com.google.common.base.Predicate;
-import com.google.common.collect.Maps;
 import com.google.common.collect.Queues;
+
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Iterator;