From 6460c1110745c26a14a465ace5e6868f5bc12d48 Mon Sep 17 00:00:00 2001
From: Viktor Lofgren <vlofgren@marginalia.nu>
Date: Mon, 14 Oct 2024 13:47:35 +0200
Subject: [PATCH] (index) Short-circuit rankResults when there are no results

---
 .../marginalia/index/results/IndexResultRankingService.java   | 3 +++
 .../marginalia/index/results/model/ids/CombinedDocIdList.java | 4 +++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/code/index/java/nu/marginalia/index/results/IndexResultRankingService.java b/code/index/java/nu/marginalia/index/results/IndexResultRankingService.java
index f477b437..91654052 100644
--- a/code/index/java/nu/marginalia/index/results/IndexResultRankingService.java
+++ b/code/index/java/nu/marginalia/index/results/IndexResultRankingService.java
@@ -54,6 +54,9 @@ public class IndexResultRankingService {
                                               ResultRankingContext rankingContext,
                                               CombinedDocIdList resultIds)
     {
+        if (resultIds.isEmpty())
+            return List.of();
+
         IndexResultScoreCalculator resultRanker = new IndexResultScoreCalculator(statefulIndex, rankingContext, params);
 
         List<SearchResultItem> results = new ArrayList<>(resultIds.size());
diff --git a/code/index/java/nu/marginalia/index/results/model/ids/CombinedDocIdList.java b/code/index/java/nu/marginalia/index/results/model/ids/CombinedDocIdList.java
index 43f5c575..45d4329f 100644
--- a/code/index/java/nu/marginalia/index/results/model/ids/CombinedDocIdList.java
+++ b/code/index/java/nu/marginalia/index/results/model/ids/CombinedDocIdList.java
@@ -1,7 +1,6 @@
 package nu.marginalia.index.results.model.ids;
 
 import it.unimi.dsi.fastutil.longs.LongArrayList;
-import it.unimi.dsi.fastutil.longs.LongIterators;
 import org.roaringbitmap.longlong.Roaring64Bitmap;
 
 import java.util.Arrays;
@@ -32,6 +31,9 @@ public final class CombinedDocIdList {
     public int size() {
         return data.length;
     }
+    public boolean isEmpty() {
+        return data.length == 0;
+    }
     public long at(int i) { return data[i]; }
 
     public LongStream stream() {