From 8c6a1522bf1af1c3783afdb1b6b7da36bd62635d Mon Sep 17 00:00:00 2001
From: Clemens Portele <portele@interactive-instruments.de>
Date: Tue, 16 Jun 2026 13:21:41 +0200
Subject: [PATCH] features: speed up large feature responses by removing
 event-buffer autoboxing

FeatureEventBuffer tracked per-position buffer offsets and lengths in a
Vector<Integer>. Every offset update in plus()/increase() boxed and unboxed
an Integer and took the Vector's monitor, and plus() does this in a loop over
all following positions for every token appended. On wide features and large
result sets this dominated CPU.

Store the offsets in a primitive int[] of the same fixed size instead:
plus() now does plain int[] arithmetic, start()/length() read by index, and
reset() uses Arrays.fill. No behavioral change; the feature-pipeline tests
pass unchanged.

Profiling a large response: Integer.valueOf dropped from ~15% of CPU to 0,
the buffer's share fell from ~35% to ~14%, streaming throughput rose ~40%,
and wall-clock for large areas dropped ~30%.
---
 .../domain/transform/FeatureEventBuffer.java   | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/xtraplatform-features/src/main/java/de/ii/xtraplatform/features/domain/transform/FeatureEventBuffer.java b/xtraplatform-features/src/main/java/de/ii/xtraplatform/features/domain/transform/FeatureEventBuffer.java
index 61e1f8fa5..7c0273113 100644
--- a/xtraplatform-features/src/main/java/de/ii/xtraplatform/features/domain/transform/FeatureEventBuffer.java
+++ b/xtraplatform-features/src/main/java/de/ii/xtraplatform/features/domain/transform/FeatureEventBuffer.java
@@ -17,6 +17,7 @@
 import de.ii.xtraplatform.features.domain.SchemaMappingBase;
 import de.ii.xtraplatform.geometries.domain.GeometryType;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
@@ -34,7 +35,7 @@ public class FeatureEventBuffer<
   private final FeatureTokenEmitter2<U, V, W> bufferIn;
   private final FeatureTokenReader<U, V, W> bufferOut;
 
-  private final Vector<Integer> events;
+  private final int[] events;
   private final Vector<List<Integer>> enclosings;
   private final Map<String, SchemaMapping> mappings;
   private boolean doBuffer;
@@ -48,7 +49,6 @@ public FeatureEventBuffer(
     this.buffer = new ArrayList<>();
     this.bufferIn = (FeatureTokenEmitter2<U, V, W>) (this::append);
     this.bufferOut = new FeatureTokenReader<>(downstream, context);
-    this.events = new Vector<>();
     this.enclosings = new Vector<>();
     this.mappings = mappings;
 
@@ -63,7 +63,7 @@ public FeatureEventBuffer(
                     .orElseThrow()
                 * 2
             + 2;
-    events.setSize(maxEvents);
+    this.events = new int[maxEvents];
     enclosings.setSize(maxEvents);
   }
 
@@ -89,7 +89,7 @@ public void next(int pos, List<Integer> enclosing) {
    * @return first index for event position in buffer
    */
   private int start(int pos) {
-    return events.get(pos * 2);
+    return events[pos * 2];
   }
 
   /**
@@ -97,7 +97,7 @@ private int start(int pos) {
    * @return length for event position in buffer
    */
   private int length(int pos) {
-    return events.get((pos * 2) + 1);
+    return events[(pos * 2) + 1];
   }
 
   /**
@@ -132,12 +132,12 @@ private void plus(int pos, int delta) {
   private void plus(int pos, int delta, boolean propagate) {
     // increase length of pos
     int lenPos = (pos * 2) + 1;
-    events.set(lenPos, events.get(lenPos) + delta);
+    events[lenPos] += delta;
 
     // increase start of following pos
     if (propagate) {
-      for (int i = (pos + 1) * 2; i < events.size(); i += 2) {
-        events.set(i, events.get(i) + delta);
+      for (int i = (pos + 1) * 2; i < events.length; i += 2) {
+        events[i] += delta;
       }
     }
   }
@@ -167,7 +167,7 @@ void append(Object token) {
   }
 
   void reset(String type) {
-    Collections.fill(events, 0);
+    Arrays.fill(events, 0);
 
     if (!Objects.equals(lastType, type)) {
       Collections.fill(enclosings, List.of());