Fix #10323: Inefficient Ender Dragon respawn sequence

This issue likely arose from the method findExitPortal(),
which has been optimized. This optimization will ensure
better server performance during the respawn sequence
and smoother gameplay.

Signed-off-by: Afonso Jacinto
<[email protected]>

Author: AfonsoMendoncaJacinto

paper-server/patches/sources/net/minecraft/world/level/dimension/end/EndDragonFight.java.patch

@@ -1,5 +1,13 @@
 --- a/net/minecraft/world/level/dimension/end/EndDragonFight.java
 +++ b/net/minecraft/world/level/dimension/end/EndDragonFight.java
+@@ -48,6 +_,7 @@
+ import net.minecraft.world.level.block.state.pattern.BlockPattern;
+ import net.minecraft.world.level.block.state.pattern.BlockPatternBuilder;
+ import net.minecraft.world.level.block.state.predicate.BlockPredicate;
++import net.minecraft.world.level.block.state.BlockState;
+ import net.minecraft.world.level.chunk.ChunkAccess;
+ import net.minecraft.world.level.chunk.LevelChunk;
+ import net.minecraft.world.level.chunk.status.ChunkStatus;
 @@ -69,8 +_,9 @@
      private static final int GATEWAY_DISTANCE = 96;
      public static final int DRAGON_SPAWN_Y = 128;
@@ -37,6 +45,135 @@
                  this.dragonUUID = null;
              }
          }
+@@ -267,46 +_,125 @@
+         return false;
+     }
+ 
++    
+     @Nullable
++
+     public BlockPattern.BlockPatternMatch findExitPortal() {
++
+         ChunkPos chunkPos = new ChunkPos(this.origin);
+ 
++
++
++        // Paper start
++
++        BlockPattern.BlockPatternMatch originSearch = findExitPortalExitAroundOrigin();
++
++        if (originSearch != null) {
++
++            return originSearch;
++
++        }
++
++        // Paper end
++
+         for (int i = -8 + chunkPos.x; i <= 8 + chunkPos.x; i++) {
++
+             for (int i1 = -8 + chunkPos.z; i1 <= 8 + chunkPos.z; i1++) {
++
+                 LevelChunk chunk = this.level.getChunk(i, i1);
+ 
++
++
+                 for (BlockEntity blockEntity : chunk.getBlockEntities().values()) {
++
+                     if (blockEntity instanceof TheEndPortalBlockEntity) {
++
+                         BlockPattern.BlockPatternMatch blockPatternMatch = this.exitPortalPattern.find(this.level, blockEntity.getBlockPos());
++
+                         if (blockPatternMatch != null) {
+-                            BlockPos pos = blockPatternMatch.getBlock(3, 3, 3).getPos();
++
++                            // BlockPos pos = blockPatternMatch.getBlock(3, 3, 3).getPos(); // Paper - move down
++
+                             if (this.portalLocation == null) {
+-                                this.portalLocation = pos;
++
++                                this.portalLocation = blockPatternMatch.getBlock(3, 3, 3).getPos(); // Paper
++
+                             }
++
++
+ 
+                             return blockPatternMatch;
++
+                         }
++
+                     }
++
+                 }
++
+             }
++
+         }
++
++
++
++     // Paper start - exit portal optimization look around the origin first
++
++        return null;
++
++    }
++
++    public BlockPattern.@org.checkerframework.checker.nullness.qual.Nullable BlockPatternMatch findExitPortalExitAroundOrigin() {
++
++        BlockPos targetPos;
++
++    // Paper end - exit portal optimization look around the origin first
+ 
+         BlockPos location = EndPodiumFeature.getLocation(this.origin);
++
+         int i1 = this.level.getHeightmapPos(Heightmap.Types.MOTION_BLOCKING, location).getY();
+ 
++
++
+         for (int i2 = i1; i2 >= this.level.getMinY(); i2--) {
+-            BlockPattern.BlockPatternMatch blockPatternMatch1 = this.exitPortalPattern.find(this.level, new BlockPos(location.getX(), i2, location.getZ()));
++
++            // Paper start
++
++            targetPos = new BlockPos(location.getX(), i2, location.getZ());
++
++            // Early exit if we encroached a non bedrock block because the middle column MUST be bedrock
++
++            if (!this.level.getBlockState(targetPos).is(net.minecraft.world.level.block.Blocks.BEDROCK)) {
++
++                continue;
++
++            }
++
++            BlockPattern.BlockPatternMatch blockPatternMatch1 = this.exitPortalPattern.find(this.level, targetPos);
++
++           // Paper end
++
+             if (blockPatternMatch1 != null) {
++
+                 if (this.portalLocation == null) {
++
+                     this.portalLocation = blockPatternMatch1.getBlock(3, 3, 3).getPos();
++
+                 }
++
++
+ 
+                 return blockPatternMatch1;
++
+             }
++
+         }
+ 
++
++
+         return null;
++
+     }
++
+ 
+     private boolean isArenaLoaded() {
+         if (this.skipArenaLoadedCheck) {
 @@ -365,12 +_,22 @@
              this.dragonEvent.setVisible(false);
              this.spawnExitPortal(true);