LUCENE-10436: Reinstate public getdocValuesdocIdSetIterator method on…

… DocValues (#869)

The method moved from DocValuesFieldExistsQuery to DocValuesIterator, but the latter
is a package-private utility class, making it invisible to client code.  This commit moves it
back onto FieldExistsQuery, meaning that the upgrade path will be the same as for all other
uses of DocValuesFieldExistsQuery.

lucene/core/src/java/org/apache/lucene/index/CheckIndex.java

@@ -56,6 +56,7 @@
 import org.apache.lucene.index.PointValues.IntersectVisitor;
 import org.apache.lucene.index.PointValues.Relation;
 import org.apache.lucene.search.DocIdSetIterator;
+import org.apache.lucene.search.FieldExistsQuery;
 import org.apache.lucene.search.LeafFieldComparator;
 import org.apache.lucene.search.Sort;
 import org.apache.lucene.search.SortField;
@@ -4145,7 +4146,7 @@ private static Status.SoftDeletsStatus checkSoftDeletes(
     try {
       int softDeletes =
           PendingSoftDeletes.countSoftDeletes(
-              DocValuesIterator.getDocValuesDocIdSetIterator(softDeletesField, reader),
+              FieldExistsQuery.getDocValuesDocIdSetIterator(softDeletesField, reader),
               reader.getLiveDocs());
       if (softDeletes != info.getSoftDelCount()) {
         throw new CheckIndexException(

lucene/core/src/java/org/apache/lucene/index/DocValuesIterator.java

@@ -28,40 +28,4 @@ abstract class DocValuesIterator extends DocIdSetIterator {
    * returns {@code target}.
    */
   public abstract boolean advanceExact(int target) throws IOException;
-
-  /**
-   * Returns a {@link DocIdSetIterator} from the given field or null if the field doesn't exist in
-   * the reader or if the reader has no doc values for the field.
-   */
-  public static DocIdSetIterator getDocValuesDocIdSetIterator(String field, LeafReader reader)
-      throws IOException {
-    FieldInfo fieldInfo = reader.getFieldInfos().fieldInfo(field);
-    final DocIdSetIterator iterator;
-    if (fieldInfo != null) {
-      switch (fieldInfo.getDocValuesType()) {
-        case NONE:
-          iterator = null;
-          break;
-        case NUMERIC:
-          iterator = reader.getNumericDocValues(field);
-          break;
-        case BINARY:
-          iterator = reader.getBinaryDocValues(field);
-          break;
-        case SORTED:
-          iterator = reader.getSortedDocValues(field);
-          break;
-        case SORTED_NUMERIC:
-          iterator = reader.getSortedNumericDocValues(field);
-          break;
-        case SORTED_SET:
-          iterator = reader.getSortedSetDocValues(field);
-          break;
-        default:
-          throw new AssertionError();
-      }
-      return iterator;
-    }
-    return null;
-  }
 }

lucene/core/src/java/org/apache/lucene/index/IndexWriter.java

@@ -59,6 +59,7 @@
 import org.apache.lucene.internal.tests.IndexWriterAccess;
 import org.apache.lucene.internal.tests.TestSecrets;
 import org.apache.lucene.search.DocIdSetIterator;
+import org.apache.lucene.search.FieldExistsQuery;
 import org.apache.lucene.search.MatchAllDocsQuery;
 import org.apache.lucene.search.Query;
 import org.apache.lucene.search.Sort;
@@ -3142,8 +3143,7 @@ public long addIndexes(CodecReader... readers) throws IOException {
           Bits liveDocs = leaf.getLiveDocs();
           numSoftDeleted +=
               PendingSoftDeletes.countSoftDeletes(
-                  DocValuesIterator.getDocValuesDocIdSetIterator(
-                      config.getSoftDeletesField(), leaf),
+                  FieldExistsQuery.getDocValuesDocIdSetIterator(config.getSoftDeletesField(), leaf),
                   liveDocs);
         }
       }
@@ -4848,7 +4848,7 @@ private void countSoftDeletes(
     int hardDeleteCount = 0;
     int softDeletesCount = 0;
     DocIdSetIterator softDeletedDocs =
-        DocValuesIterator.getDocValuesDocIdSetIterator(config.getSoftDeletesField(), reader);
+        FieldExistsQuery.getDocValuesDocIdSetIterator(config.getSoftDeletesField(), reader);
     if (softDeletedDocs != null) {
       int docId;
       while ((docId = softDeletedDocs.nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {

lucene/core/src/java/org/apache/lucene/index/PendingSoftDeletes.java

@@ -21,6 +21,7 @@
 import java.io.IOException;
 import org.apache.lucene.codecs.FieldInfosFormat;
 import org.apache.lucene.search.DocIdSetIterator;
+import org.apache.lucene.search.FieldExistsQuery;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.IOContext;
 import org.apache.lucene.util.Bits;
@@ -77,7 +78,7 @@ void onNewReader(CodecReader reader, SegmentCommitInfo info) throws IOException
     // only re-calculate this if we haven't seen this generation
     if (dvGeneration < info.getDocValuesGen()) {
       final DocIdSetIterator iterator =
-          DocValuesIterator.getDocValuesDocIdSetIterator(field, reader);
+          FieldExistsQuery.getDocValuesDocIdSetIterator(field, reader);
       int newDelCount;
       if (iterator
           != null) { // nothing is deleted we don't have a soft deletes field in this segment

lucene/core/src/java/org/apache/lucene/index/SoftDeletesDirectoryReaderWrapper.java

@@ -27,6 +27,7 @@
 import java.util.Objects;
 import org.apache.lucene.document.Field;
 import org.apache.lucene.search.DocIdSetIterator;
+import org.apache.lucene.search.FieldExistsQuery;
 import org.apache.lucene.util.Bits;
 import org.apache.lucene.util.FixedBitSet;
 
@@ -126,7 +127,7 @@ public LeafReader wrap(LeafReader reader) {
   }
 
   static LeafReader wrap(LeafReader reader, String field) throws IOException {
-    DocIdSetIterator iterator = DocValuesIterator.getDocValuesDocIdSetIterator(field, reader);
+    DocIdSetIterator iterator = FieldExistsQuery.getDocValuesDocIdSetIterator(field, reader);
     if (iterator == null) {
       return reader;
     }

lucene/core/src/java/org/apache/lucene/search/FieldExistsQuery.java

@@ -41,6 +41,42 @@ public FieldExistsQuery(String field) {
     this.field = Objects.requireNonNull(field);
   }
 
+  /**
+   * Returns a {@link DocIdSetIterator} from the given field or null if the field doesn't exist in
+   * the reader or if the reader has no doc values for the field.
+   */
+  public static DocIdSetIterator getDocValuesDocIdSetIterator(String field, LeafReader reader)
+      throws IOException {
+    FieldInfo fieldInfo = reader.getFieldInfos().fieldInfo(field);
+    final DocIdSetIterator iterator;
+    if (fieldInfo != null) {
+      switch (fieldInfo.getDocValuesType()) {
+        case NONE:
+          iterator = null;
+          break;
+        case NUMERIC:
+          iterator = reader.getNumericDocValues(field);
+          break;
+        case BINARY:
+          iterator = reader.getBinaryDocValues(field);
+          break;
+        case SORTED:
+          iterator = reader.getSortedDocValues(field);
+          break;
+        case SORTED_NUMERIC:
+          iterator = reader.getSortedNumericDocValues(field);
+          break;
+        case SORTED_SET:
+          iterator = reader.getSortedSetDocValues(field);
+          break;
+        default:
+          throw new AssertionError();
+      }
+      return iterator;
+    }
+    return null;
+  }
+
   public String getField() {
     return field;
   }