LUCENE-5969: move blocktree stats -> stats api

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene5969@1633441 13f79535-47bb-0310-9956-ffa450edef68

lucene/backward-codecs/src/java/org/apache/lucene/codecs/blocktree/Lucene40FieldReader.java

@@ -123,8 +123,7 @@ final class Lucene40FieldReader extends Terms implements Accountable {
   }
 
   /** For debugging -- used by CheckIndex too*/
-  // TODO: maybe push this into Terms?
-  public Lucene40Stats computeStats() throws IOException {
+  public Lucene40Stats getStats() throws IOException {
     return new Lucene40SegmentTermsEnum(this).computeBlockStats();
   }
 

lucene/backward-codecs/src/java/org/apache/lucene/codecs/blocktree/Lucene40Stats.java

@@ -29,7 +29,7 @@ import org.apache.lucene.util.IOUtils;
 
 /**
  * BlockTree statistics for a single field 
- * returned by {@link Lucene40FieldReader#computeStats()}.
+ * returned by {@link Lucene40FieldReader#getStats()}.
  * @deprecated Only for 4.x backcompat
  */
 @Deprecated

lucene/backward-codecs/src/test/org/apache/lucene/codecs/blocktree/TestLucene40BlockFormat.java

@@ -57,7 +57,7 @@ public class TestLucene40BlockFormat extends BasePostingsFormatTestCase {
     assertEquals(1, r.leaves().size());
     Lucene40FieldReader field = (Lucene40FieldReader) r.leaves().get(0).reader().fields().terms("field");
     // We should see exactly two blocks: one root block (prefix empty string) and one block for z* terms (prefix z):
-    Lucene40Stats stats = field.computeStats();
+    Lucene40Stats stats = field.getStats();
     assertEquals(0, stats.floorBlockCount);
     assertEquals(2, stats.nonFloorBlockCount);
     r.close();

lucene/core/src/java/org/apache/lucene/codecs/blocktree/FieldReader.java

@@ -120,8 +120,7 @@ public final class FieldReader extends Terms implements Accountable {
   }
 
   /** For debugging -- used by CheckIndex too*/
-  // TODO: maybe push this into Terms?
-  public Stats computeStats() throws IOException {
+  public Stats getStats() throws IOException {
     return new SegmentTermsEnum(this).computeBlockStats();
   }
 

lucene/core/src/java/org/apache/lucene/codecs/blocktree/Stats.java

@@ -29,7 +29,7 @@ import org.apache.lucene.util.IOUtils;
 
 /**
  * BlockTree statistics for a single field 
- * returned by {@link FieldReader#computeStats()}.
+ * returned by {@link FieldReader#getStats()}.
  */
 public class Stats {
   /** How many nodes in the index FST. */

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

@@ -151,6 +151,11 @@ public class FilterLeafReader extends LeafReader {
     public boolean hasPayloads() {
       return in.hasPayloads();
     }
+
+    @Override
+    public Object getStats() throws IOException {
+      return in.getStats();
+    }
   }
 
   /** Base class for filtering {@link TermsEnum} implementations. */

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

@@ -194,8 +194,17 @@ public abstract class Terms {
     }
   }
   
-  public String getStats() {
-    // nocommit: add a meaningful default
-    return "";
+  /** 
+   * Expert: returns additional information about this Terms instance
+   * for debugging purposes.
+   */
+  public Object getStats() throws IOException {
+    StringBuilder sb = new StringBuilder();
+    sb.append("impl=" + getClass().getSimpleName());
+    sb.append(",size=" + size());
+    sb.append(",docCount=" + getDocCount());
+    sb.append(",sumTotalTermFreq=" + getSumTotalTermFreq());
+    sb.append(",sumDocFreq=" + getSumDocFreq());
+    return sb.toString();
   }
 }

lucene/core/src/test/org/apache/lucene/codecs/lucene50/TestBlockPostingsFormat.java

@@ -57,7 +57,7 @@ public class TestBlockPostingsFormat extends BasePostingsFormatTestCase {
     assertEquals(1, r.leaves().size());
     FieldReader field = (FieldReader) r.leaves().get(0).reader().fields().terms("field");
     // We should see exactly two blocks: one root block (prefix empty string) and one block for z* terms (prefix z):
-    Stats stats = field.computeStats();
+    Stats stats = field.getStats();
     assertEquals(0, stats.floorBlockCount);
     assertEquals(2, stats.nonFloorBlockCount);
     r.close();

lucene/core/src/test/org/apache/lucene/index/TestFilterLeafReader.java

@@ -166,7 +166,7 @@ public class TestFilterLeafReader extends LuceneTestCase {
     for (Method m : superClazz.getMethods()) {
       final int mods = m.getModifiers();
       if (Modifier.isStatic(mods) || Modifier.isAbstract(mods) || Modifier.isFinal(mods) || m.isSynthetic()
-          || m.getName().equals("attributes")) {
+          || m.getName().equals("attributes") || m.getName().equals("getStats")) {
         continue;
       }
       // The point of these checks is to ensure that methods that have a default