LUCENE-6246: add simple test for postings reuse/flags/behavior (DOCS_ONLY so far), fix asserting to support reuse

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1660405 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -0,0 +1,97 @@
+package org.apache.lucene.index;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.document.StringField;
+import org.apache.lucene.search.DocIdSetIterator;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.LuceneTestCase;
+
+/** 
+ * Test basic postingsenum behavior, flags, reuse, etc.
+ */
+public class TestPostingsEnum extends LuceneTestCase {
+  
+  public void testDocsOnly() throws Exception {
+    Directory dir = newDirectory();
+    IndexWriterConfig iwc = new IndexWriterConfig(null);
+    IndexWriter iw = new IndexWriter(dir, iwc);
+    Document doc = new Document();
+    doc.add(new StringField("foo", "bar", Field.Store.NO));
+    iw.addDocument(doc);
+    DirectoryReader reader = DirectoryReader.open(iw, false);
+    
+    // sugar method (FREQS)
+    PostingsEnum postings = getOnlySegmentReader(reader).postings(new Term("foo", "bar"));
+    assertEquals(-1, postings.docID());
+    assertEquals(0, postings.nextDoc());
+    assertEquals(1, postings.freq());
+    assertEquals(DocIdSetIterator.NO_MORE_DOCS, postings.nextDoc());
+    
+    // termsenum reuse (FREQS)
+    TermsEnum termsEnum = getOnlySegmentReader(reader).terms("foo").iterator(null);
+    termsEnum.seekExact(new BytesRef("bar"));
+    PostingsEnum postings2 = termsEnum.postings(null, postings);
+    assertNotNull(postings2);
+    assertSame(postings, postings2);
+    // and it had better work
+    assertEquals(-1, postings.docID());
+    assertEquals(0, postings.nextDoc());
+    assertEquals(1, postings.freq());
+    assertEquals(DocIdSetIterator.NO_MORE_DOCS, postings.nextDoc());
+    
+    // asking for docs only: ok
+    PostingsEnum docsOnly = termsEnum.postings(null, null, PostingsEnum.NONE);
+    assertEquals(-1, docsOnly.docID());
+    assertEquals(0, docsOnly.nextDoc());
+    assertEquals(1, docsOnly.freq());
+    assertEquals(DocIdSetIterator.NO_MORE_DOCS, docsOnly.nextDoc());
+    // reuse that too
+    PostingsEnum docsOnly2 = termsEnum.postings(null, docsOnly, PostingsEnum.NONE);
+    assertNotNull(docsOnly2);
+    assertSame(docsOnly, docsOnly2);
+    // and it had better work
+    assertEquals(-1, docsOnly2.docID());
+    assertEquals(0, docsOnly2.nextDoc());
+    assertEquals(1, docsOnly2.freq());
+    assertEquals(DocIdSetIterator.NO_MORE_DOCS, docsOnly2.nextDoc());
+    
+    // we did not index positions
+    PostingsEnum docsAndPositionsEnum = getOnlySegmentReader(reader).postings(new Term("foo", "bar"), PostingsEnum.POSITIONS);
+    assertNull(docsAndPositionsEnum);
+    
+    // we did not index positions
+    docsAndPositionsEnum = getOnlySegmentReader(reader).postings(new Term("foo", "bar"), PostingsEnum.PAYLOADS);
+    assertNull(docsAndPositionsEnum);
+    
+    // we did not index positions
+    docsAndPositionsEnum = getOnlySegmentReader(reader).postings(new Term("foo", "bar"), PostingsEnum.OFFSETS);
+    assertNull(docsAndPositionsEnum);
+    
+    // we did not index positions
+    docsAndPositionsEnum = getOnlySegmentReader(reader).postings(new Term("foo", "bar"), PostingsEnum.ALL);
+    assertNull(docsAndPositionsEnum);
+    
+    iw.close();
+    reader.close();
+    dir.close();
+  }
+}

lucene/test-framework/src/java/org/apache/lucene/index/AssertingLeafReader.java

@@ -114,14 +114,22 @@ public class AssertingLeafReader extends FilterLeafReader {
 
     @Override
     public TermsEnum iterator(TermsEnum reuse) throws IOException {
-      // TODO: should we give this thing a random to be super-evil,
+      // reuse, if the codec reused
-      // and randomly *not* unwrap?
+      final TermsEnum actualReuse;
       if (reuse instanceof AssertingTermsEnum) {
-        reuse = ((AssertingTermsEnum) reuse).in;
+        actualReuse = ((AssertingTermsEnum) reuse).in;
+      } else {
+        actualReuse = null;
       }
-      TermsEnum termsEnum = super.iterator(reuse);
+      TermsEnum termsEnum = super.iterator(actualReuse);
       assert termsEnum != null;
-      return new AssertingTermsEnum(termsEnum);
+      if (termsEnum == actualReuse) {
+        // codec reused, reset asserting state
+        ((AssertingTermsEnum)reuse).reset();
+        return reuse;
+      } else {
+        return new AssertingTermsEnum(termsEnum);
+      }
     }
   }
   
@@ -143,13 +151,23 @@ public class AssertingLeafReader extends FilterLeafReader {
       assertThread("Terms enums", creationThread);
       assert state == State.POSITIONED: "docs(...) called on unpositioned TermsEnum";
 
-      // TODO: should we give this thing a random to be super-evil,
+      // reuse if the codec reused
-      // and randomly *not* unwrap?
+      final PostingsEnum actualReuse;
       if (reuse instanceof AssertingPostingsEnum) {
-        reuse = ((AssertingPostingsEnum) reuse).in;
+        actualReuse = ((AssertingPostingsEnum) reuse).in;
+      } else {
+        actualReuse = null;
+      }
+      PostingsEnum docs = super.postings(liveDocs, actualReuse, flags);
+      if (docs == null) {
+        return null;
+      } else if (docs == actualReuse) {
+        // codec reused, reset asserting state
+        ((AssertingPostingsEnum)reuse).reset();
+        return reuse;
+      } else {
+        return new AssertingPostingsEnum(docs);
       }
-      PostingsEnum docs = super.postings(liveDocs, reuse, flags);
-      return docs == null ? null : new AssertingPostingsEnum(docs);
     }
 
     // TODO: we should separately track if we are 'at the end' ?
@@ -255,6 +273,10 @@ public class AssertingLeafReader extends FilterLeafReader {
     public String toString() {
       return "AssertingTermsEnum(" + in + ")";
     }
+    
+    void reset() {
+      state = State.INITIAL;
+    }
   }
   
   static enum DocsEnumState { START, ITERATING, FINISHED };
@@ -362,6 +384,12 @@ public class AssertingLeafReader extends FilterLeafReader {
       assert payload == null || payload.length > 0 : "getPayload() returned payload with invalid length!";
       return payload;
     }
+    
+    void reset() {
+      state = DocsEnumState.START;
+      doc = in.docID();
+      positionCount = positionMax = 0;
+    }
   }
 
   /** Wraps a NumericDocValues but with additional asserts */