From 97f874943d8339dcbf173f133771b8b6979b7c42 Mon Sep 17 00:00:00 2001
From: Vladimir Prus <vladimir.prus@gmail.com>
Date: Mon, 19 Jan 2026 19:13:22 +0000
Subject: [PATCH] XorBinaryFuse: throw on failure

Filling the fingerprints array with 0xFF would create a filter that generates false negatives.
---
 .../main/java/org/fastfilter/xor/XorBinaryFuse16.java    | 9 +++------
 .../main/java/org/fastfilter/xor/XorBinaryFuse32.java    | 9 +++------
 .../src/main/java/org/fastfilter/xor/XorBinaryFuse8.java | 9 +++------
 3 files changed, 9 insertions(+), 18 deletions(-)

diff --git a/fastfilter/src/main/java/org/fastfilter/xor/XorBinaryFuse16.java b/fastfilter/src/main/java/org/fastfilter/xor/XorBinaryFuse16.java
index aad3c77..0f497db 100644
--- a/fastfilter/src/main/java/org/fastfilter/xor/XorBinaryFuse16.java
+++ b/fastfilter/src/main/java/org/fastfilter/xor/XorBinaryFuse16.java
@@ -200,12 +200,9 @@ private void addAll(long[] keys) {
 
             if (hashIndex > 100) {
                 // if construction doesn't succeed eventually,
-                // then there is likely a problem with the hash function
-                // let us not crash the system:
-                for(int i = 0; i < fingerprints.length; i++) {
-                    fingerprints[i] = (short)0xFFFF;
-                }
-                return;
+                // then there is likely a problem with the hash function.
+                // It's better fail that either produce non-functional or incorrect filter.
+                throw new IllegalArgumentException("could not construct filter");
             }
             // use a new random numbers
             seed = Hash.randomSeed();
diff --git a/fastfilter/src/main/java/org/fastfilter/xor/XorBinaryFuse32.java b/fastfilter/src/main/java/org/fastfilter/xor/XorBinaryFuse32.java
index d3f6125..67900a6 100644
--- a/fastfilter/src/main/java/org/fastfilter/xor/XorBinaryFuse32.java
+++ b/fastfilter/src/main/java/org/fastfilter/xor/XorBinaryFuse32.java
@@ -200,12 +200,9 @@ private void addAll(long[] keys) {
 
             if (hashIndex > 100) {
                 // if construction doesn't succeed eventually,
-                // then there is likely a problem with the hash function
-                // let us not crash the system:
-                for (int i = 0; i < fingerprints.length; i++) {
-                    fingerprints[i] = (int) 0xFFFFFFFF;
-                }
-                return;
+                // then there is likely a problem with the hash function.
+                // It's better fail that either produce non-functional or incorrect filter.
+                throw new IllegalArgumentException("could not construct filter");
             }
             // use a new random numbers
             seed = Hash.randomSeed();
diff --git a/fastfilter/src/main/java/org/fastfilter/xor/XorBinaryFuse8.java b/fastfilter/src/main/java/org/fastfilter/xor/XorBinaryFuse8.java
index dfd5f45..81e42f1 100644
--- a/fastfilter/src/main/java/org/fastfilter/xor/XorBinaryFuse8.java
+++ b/fastfilter/src/main/java/org/fastfilter/xor/XorBinaryFuse8.java
@@ -200,12 +200,9 @@ private void addAll(long[] keys) {
 
             if (hashIndex > 100) {
                 // if construction doesn't succeed eventually,
-                // then there is likely a problem with the hash function
-                // let us not crash the system:
-                for(int i = 0; i < fingerprints.length; i++) {
-                    fingerprints[i] = (byte)0xFF;
-                }
-                return;
+                // then there is likely a problem with the hash function.
+                // It's better fail that either produce non-functional or incorrect filter.
+                throw new IllegalArgumentException("could not construct filter");
             }
             // use a new random numbers
             seed = Hash.randomSeed();