Minor tweaks.

Author: lemire

.github/java.yml

@@ -0,0 +1,18 @@
+name: Java 17 CI
+
+on: [push,pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up JDK 17
+        uses: actions/setup-java@v1
+        with:
+          java-version: 17
+      - name: Build
+        run: mvn build
+      - name: Test
+        run: mvn test

fastfilter/src/main/java/org/fastfilter/xor/Xor16.java

@@ -53,7 +53,12 @@ public Xor16(long[] keys) {
                     int h = getHash(k, seed, hi);
                     t2[h] ^= k;
                     if (t2count[h] > 120) {
-                        throw new IllegalArgumentException();
+                        // probably something wrong with the hash function
+                        // let us not crash the system:
+                        for(int i = 0; i < fingerprints.length; i++) {
+                            fingerprints[i] = (short)0xFFFF;
+                        }
+                        return;
                     }
                     t2count[h]++;
                 }

fastfilter/src/main/java/org/fastfilter/xor/Xor8.java

@@ -59,7 +59,11 @@ public Xor8(long[] keys) {
                     t2[h] ^= k;
                     if (t2count[h] > 120) {
                         // probably something wrong with the hash function
-                        throw new IllegalArgumentException();
+                        // let us not crash the system:
+                        for(int i = 0; i < fingerprints.length; i++) {
+                            fingerprints[i] = (byte)0xFF;
+                        }
+                        return;
                     }
                     t2count[h]++;
                 }

fastfilter/src/main/java/org/fastfilter/xor/XorBinaryFuse8.java

@@ -147,7 +147,10 @@ private void addAll(long[] keys) {
                 // we have a possible counter overflow
                 // this branch is never taken except if there is a problem in the hash code
                 // in which case construction fails
-                break;
+                for(int i = 0; i < fingerprints.length; i++) {
+                    fingerprints[i] = (byte)0xFF;
+                }
+                return;
             }
 
             reverseOrderPos = 0;
@@ -199,25 +202,21 @@ private void addAll(long[] keys) {
             Arrays.fill(t2hash, 0);
             Arrays.fill(reverseOrder, 0);
 
-            // TODO
-            // if (hashIndex > 10) {
-            //     System.out.println("WARNING: hashIndex " + hashIndex + "\n");
-            //     System.out.println(size + " keys; arrayLength " + arrayLength + " reverseOrderPos " + reverseOrderPos + " segmentLength " + segmentLength + " segmentCount " + segmentCount);
-            // }
             if (hashIndex > 100) {
                 // if construction doesn't succeed eventually,
                 // then there is likely a problem with the hash function
-                throw new IllegalArgumentException("Construction failed after " + hashIndex + " retries for size " + size);
+                // let us not crash the system:
+                for(int i = 0; i < fingerprints.length; i++) {
+                    fingerprints[i] = (byte)0xFF;
+                }
+                return;
             }
             // use a new random numbers
             seed = Hash.randomSeed();
         }
         alone = null;
         t2count = null;
         t2hash = null;
-        if (reverseOrderPos != size) {
-            throw new IllegalStateException();
-        }
 
         for (int i = reverseOrderPos - 1; i >= 0; i--) {
             long hash = reverseOrder[i];

fastfilter/src/main/java/org/fastfilter/xorplus/XorPlus8.java

@@ -123,7 +123,10 @@ public XorPlus8(long[] keys) {
             attempts++;
             if (attempts >= 100) {
                 // if the same key appears more than once in the keys array, every attempt to build the table will yield a collision
-                throw new IllegalArgumentException("Unable to construct the table after 100 attempts; likely indicates duplicate keys");
+                for(int i = 0; i < fingerprints.length; i++) {
+                    fingerprints[i] = (byte)0xFF;
+                }
+                return;
             }
 
             seed = Hash.randomSeed();