From 0493649348c31e808b65408c19098d0f1d7dfa72 Mon Sep 17 00:00:00 2001
From: austin <austin@austinhoover.net>
Date: Sat, 24 May 2025 21:41:55 -0400
Subject: [PATCH] nearby entity lookup caching

---
 docs/src/progress/renderertodo.md              |  1 +
 .../gridded/GriddedDataCellManager.java        | 18 +++++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/docs/src/progress/renderertodo.md b/docs/src/progress/renderertodo.md
index 38c2573f..ca9d0584 100644
--- a/docs/src/progress/renderertodo.md
+++ b/docs/src/progress/renderertodo.md
@@ -1970,6 +1970,7 @@ Performance improvements
  - Reduced the visual LOD cutoff
  - Multiple visual LOD levels
  - AI does not simulate for low-lod server entities
+ - Nearby entity lookup caching per frame
 Lod emitter service checker function
 
 
diff --git a/src/main/java/electrosphere/server/datacell/gridded/GriddedDataCellManager.java b/src/main/java/electrosphere/server/datacell/gridded/GriddedDataCellManager.java
index 3fd92089..c06d1151 100644
--- a/src/main/java/electrosphere/server/datacell/gridded/GriddedDataCellManager.java
+++ b/src/main/java/electrosphere/server/datacell/gridded/GriddedDataCellManager.java
@@ -178,6 +178,11 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
      * The pathfinder for the manager
      */
     VoxelPathfinder pathfinder;
+
+    /**
+     * Caches lookups for nearby entities between simulate() calls
+     */
+    private Map<Long,List<Entity>> nearbyLookupCache = new HashMap<Long,List<Entity>>();
     
     /**
      * Constructor
@@ -697,6 +702,11 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
         loadedCellsLock.lock();
 
 
+        //
+        //clear nearby entity lookup cache
+        this.nearbyLookupCache.clear();
+
+
         //regenerate physics where relevant
         terrainEditLock.acquireUninterruptibly();
         if(physicsQueue.size() > 0){
@@ -1179,6 +1189,11 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
 
     @Override
     public Collection<Entity> entityLookup(Vector3d pos, double radius) {
+        Vector3i chunkPos = ServerWorldData.convertRealToChunkSpace(pos);
+        long key = this.getServerDataCellKey(chunkPos);
+        if(this.nearbyLookupCache.containsKey(key)){
+            return Collections.unmodifiableCollection(this.nearbyLookupCache.get(key));
+        }
         List<Entity> rVal = new LinkedList<Entity>();
         this.loadedCellsLock.lock();
         for(ServerDataCell cell : this.groundDataCells.values()){
@@ -1187,8 +1202,9 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
             }
             rVal.addAll(cell.getScene().getEntityList());
         }
+        this.nearbyLookupCache.put(key,rVal);
         this.loadedCellsLock.unlock();
-        return rVal;
+        return Collections.unmodifiableCollection(rVal);
     }
 
     @Override