LUCENE-10368: Make IntTaxonomyFacets pkg-private (#600)

lucene/CHANGES.txt

@@ -12,6 +12,9 @@ API Changes
   classes no longer determinize NFAs. Instead it is the responsibility
   of the caller to determinize.  (Robert Muir)
 
+* LUCENE-10368: IntTaxonomyFacets has been make pkg-private and serves only as an internal
+  implementation detail of taxonomy-faceting. (Greg Miller)
+
 New Features
 ---------------------
 
@@ -69,6 +72,9 @@ API Changes
 
 * LUCENE-10381: Require users to provide FacetsConfig for SSDV faceting. (Greg Miller)
 
+* LUCENE-10368: IntTaxonomyFacets has been deprecated and is no longer a supported extension point
+  for user-created faceting implementations. (Greg Miller)
+
 New Features
 ---------------------
 

lucene/facet/src/java/org/apache/lucene/facet/taxonomy/IntTaxonomyFacets.java

@@ -29,26 +29,16 @@ import org.apache.lucene.facet.LabelAndValue;
 import org.apache.lucene.facet.TopOrdAndIntQueue;
 
 /** Base class for all taxonomy-based facets that aggregate to a per-ords int[]. */
-public abstract class IntTaxonomyFacets extends TaxonomyFacets {
+abstract class IntTaxonomyFacets extends TaxonomyFacets {
 
-  /**
-   * Dense ordinal values.
-   *
-   * <p>We are making this and {@link #sparseValues} protected for some expert usage. e.g. It can be
-   * checked which is being used before a loop instead of calling {@link #increment} for each
-   * iteration.
-   */
-  protected final int[] values;
+  /** Dense ordinal values. */
+  final int[] values;
 
-  /**
-   * Sparse ordinal values.
-   *
-   * @see #values for why protected.
-   */
-  protected final IntIntHashMap sparseValues;
+  /** Sparse ordinal values. */
+  final IntIntHashMap sparseValues;
 
   /** Sole constructor. */
-  protected IntTaxonomyFacets(
+  IntTaxonomyFacets(
       String indexFieldName, TaxonomyReader taxoReader, FacetsConfig config, FacetsCollector fc)
       throws IOException {
     super(indexFieldName, taxoReader, config);
@@ -62,36 +52,8 @@ public abstract class IntTaxonomyFacets extends TaxonomyFacets {
     }
   }
 
-  /** Return true if a sparse hash table should be used for counting, instead of a dense int[]. */
-  protected boolean useHashTable(FacetsCollector fc, TaxonomyReader taxoReader) {
-    if (taxoReader.getSize() < 1024) {
-      // small number of unique values: use an array
-      return false;
-    }
-
-    if (fc == null) {
-      // counting all docs: use an array
-      return false;
-    }
-
-    int maxDoc = 0;
-    int sumTotalHits = 0;
-    for (MatchingDocs docs : fc.getMatchingDocs()) {
-      sumTotalHits += docs.totalHits;
-      maxDoc += docs.context.reader().maxDoc();
-    }
-
-    // if our result set is < 10% of the index, we collect sparsely (use hash map):
-    return sumTotalHits < maxDoc / 10;
-  }
-
-  /** Increment the count for this ordinal by 1. */
-  protected void increment(int ordinal) {
-    increment(ordinal, 1);
-  }
-
   /** Increment the count for this ordinal by {@code amount}.. */
-  protected void increment(int ordinal, int amount) {
+  void increment(int ordinal, int amount) {
     if (sparseValues != null) {
       sparseValues.addTo(ordinal, amount);
     } else {
@@ -100,7 +62,7 @@ public abstract class IntTaxonomyFacets extends TaxonomyFacets {
   }
 
   /** Get the count for this ordinal. */
-  protected int getValue(int ordinal) {
+  int getValue(int ordinal) {
     if (sparseValues != null) {
       return sparseValues.get(ordinal);
     } else {
@@ -109,7 +71,7 @@ public abstract class IntTaxonomyFacets extends TaxonomyFacets {
   }
 
   /** Rolls up any single-valued hierarchical dimensions. */
-  protected void rollup() throws IOException {
+  void rollup() throws IOException {
     // Rollup any necessary dims:
     int[] children = null;
     for (Map.Entry<String, DimConfig> ent : config.getDimConfigs().entrySet()) {
@@ -142,6 +104,29 @@ public abstract class IntTaxonomyFacets extends TaxonomyFacets {
     return sum;
   }
 
+  /** Return true if a sparse hash table should be used for counting, instead of a dense int[]. */
+  private boolean useHashTable(FacetsCollector fc, TaxonomyReader taxoReader) {
+    if (taxoReader.getSize() < 1024) {
+      // small number of unique values: use an array
+      return false;
+    }
+
+    if (fc == null) {
+      // counting all docs: use an array
+      return false;
+    }
+
+    int maxDoc = 0;
+    int sumTotalHits = 0;
+    for (MatchingDocs docs : fc.getMatchingDocs()) {
+      sumTotalHits += docs.totalHits;
+      maxDoc += docs.context.reader().maxDoc();
+    }
+
+    // if our result set is < 10% of the index, we collect sparsely (use hash map):
+    return sumTotalHits < maxDoc / 10;
+  }
+
   @Override
   public Number getSpecificValue(String dim, String... path) throws IOException {
     DimConfig dimConfig = verifyDim(dim);

lucene/facet/src/java/org/apache/lucene/facet/taxonomy/TaxonomyFacetSumIntAssociations.java

@@ -73,6 +73,7 @@ public class TaxonomyFacetSumIntAssociations extends IntTaxonomyFacets {
             offset += 4;
             int value = (int) BitUtil.VH_BE_INT.get(bytes, offset);
             offset += 4;
+            // TODO: Can we optimize the null check in increment? See LUCENE-10373.
             increment(ord, value);
           }
         }