LUCENE-8380: UTF8TaxonomyWriterCache page/ offset calculation bug

lucene/CHANGES.txt

@@ -129,6 +129,8 @@ API Changes:
 
 Bug Fixes:
 
+* LUCENE-8380: UTF8TaxonomyWriterCache inconsistency. (Ruslan Torobaev, Dawid Weiss)
+
 * LUCENE-8164: IndexWriter silently accepts broken payload. This has been fixed
   via LUCENE-8165 since we are now checking for offset+length going out of bounds.
   (Robert Muir, Nhat Nyugen, Simon Willnauer)

lucene/facet/src/java/org/apache/lucene/facet/taxonomy/writercache/UTF8TaxonomyWriterCache.java

@@ -37,11 +37,13 @@ public final class UTF8TaxonomyWriterCache implements TaxonomyWriterCache, Accou
         return new BytesRefBuilder();
       }
     };
+
   private final Counter bytesUsed = Counter.newCounter();
   private final BytesRefHash map = new BytesRefHash(new ByteBlockPool(new DirectTrackingAllocator(bytesUsed)));
 
-  private final static int ORDINALS_PAGE_SIZE = 65536;
+  private final static int PAGE_BITS = 16;
-  private final static int ORDINALS_PAGE_MASK = ORDINALS_PAGE_SIZE - 1;
+  private final static int PAGE_SIZE = 1 << PAGE_BITS;
+  private final static int PAGE_MASK = PAGE_SIZE - 1;
 
   private volatile int[][] ordinals;
 
@@ -54,7 +56,7 @@ public final class UTF8TaxonomyWriterCache implements TaxonomyWriterCache, Accou
   /** Sole constructor. */
   public UTF8TaxonomyWriterCache() {
     ordinals = new int[1][];
-    ordinals[0] = new int[ORDINALS_PAGE_SIZE];
+    ordinals[0] = new int[PAGE_SIZE];
   }
 
   @Override
@@ -67,16 +69,16 @@ public final class UTF8TaxonomyWriterCache implements TaxonomyWriterCache, Accou
     if (id == -1) {
       return LabelToOrdinal.INVALID_ORDINAL;
     }
-    int page = id / ORDINALS_PAGE_SIZE;
+    int page = id >>> PAGE_BITS;
-    int offset = id % ORDINALS_PAGE_MASK;
+    int offset = id & PAGE_MASK;
     return ordinals[page][offset];
   }
 
   // Called only from assert
   private boolean assertSameOrdinal(FacetLabel label, int id, int ord) {
     id = -id - 1;
-    int page = id / ORDINALS_PAGE_SIZE;
+    int page = id >>> PAGE_BITS;
-    int offset = id % ORDINALS_PAGE_MASK;
+    int offset = id & PAGE_MASK;
     int oldOrd = ordinals[page][offset];
     if (oldOrd != ord) {
       throw new IllegalArgumentException("label " + label + " was already cached, with old ord=" + oldOrd + " versus new ord=" + ord);
@@ -95,15 +97,15 @@ public final class UTF8TaxonomyWriterCache implements TaxonomyWriterCache, Accou
         return false;
       }
       assert id == count;
-      int page = id / ORDINALS_PAGE_SIZE;
+      int page = id >>> PAGE_BITS;
-      int offset = id % ORDINALS_PAGE_MASK;
+      int offset = id & PAGE_MASK;
       if (page == pageCount) {
         if (page == ordinals.length) {
           int[][] newOrdinals = new int[ArrayUtil.oversize(page+1, RamUsageEstimator.NUM_BYTES_OBJECT_REF)][];
           System.arraycopy(ordinals, 0, newOrdinals, 0, ordinals.length);
           ordinals = newOrdinals;
         }
-        ordinals[page] = new int[ORDINALS_PAGE_MASK];
+        ordinals[page] = new int[PAGE_SIZE];
         pageCount++;
       }
       ordinals[page][offset] = ord;
@@ -125,7 +127,7 @@ public final class UTF8TaxonomyWriterCache implements TaxonomyWriterCache, Accou
     map.clear();
     map.reinit();
     ordinals = new int[1][];
-    ordinals[0] = new int[ORDINALS_PAGE_SIZE];
+    ordinals[0] = new int[PAGE_SIZE];
     count = 0;
     pageCount = 0;
     assert bytesUsed.get() == 0;
@@ -138,7 +140,7 @@ public final class UTF8TaxonomyWriterCache implements TaxonomyWriterCache, Accou
   
   @Override
   public synchronized long ramBytesUsed() {
-    return bytesUsed.get() + pageCount * ORDINALS_PAGE_SIZE * RamUsageEstimator.NUM_BYTES_INT;
+    return bytesUsed.get() + pageCount * PAGE_SIZE * Integer.BYTES;
   }
     
   @Override

lucene/facet/src/test/org/apache/lucene/facet/taxonomy/writercache/TestUTF8TaxonomyWriterCache.java

@@ -28,6 +28,16 @@ import org.apache.lucene.facet.taxonomy.FacetLabel;
 import org.apache.lucene.util.TestUtil;
 
 public class TestUTF8TaxonomyWriterCache extends FacetTestCase {
+  public void testPageOverflow() throws Exception {
+    UTF8TaxonomyWriterCache cache = new UTF8TaxonomyWriterCache();
+    for (int ord = 0; ord < 65536 * 2; ord++) {
+      cache.put(new FacetLabel("foo:", Integer.toString(ord)), ord);
+    }
+
+    for (int ord = 0; ord < 65536 * 2; ord++) {
+      assertEquals(ord, cache.get(new FacetLabel("foo:", Integer.toString(ord))));
+    }
+  }
 
   public void testRandom() throws Exception {
     LabelToOrdinal map = new LabelToOrdinalMap();
@@ -37,8 +47,6 @@ public class TestUTF8TaxonomyWriterCache extends FacetTestCase {
     final int n = atLeast(10 * 1000);
     final int numUniqueValues = 50 * 1000;
 
-    byte[] buffer = new byte[50];
-
     Random random = random();
     Set<String> uniqueValuesSet = new HashSet<>();
     while (uniqueValuesSet.size() < numUniqueValues) {