LUCENE-781: fixed NPE in MultiReader.isCurrent() and getVersion()

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@499152 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -332,6 +332,11 @@ Bug fixes
     life" due to this, just a possible future problem).  (Chuck
     Williams via Mike McCandless)
 
+33. LUCENE-781: Fixed the NullPointerException in MultiReader.isCurrent()
+    and MultiReader.getVersion(). isCurrent() now returns true only if
+    all its readers are current. getVersion() now throws an
+    UnsupportedOperationException.  (Daniel Naber)
+
 Optimizations
 
   1. LUCENE-586: TermDocs.skipTo() is now more efficient for

src/java/org/apache/lucene/index/MultiReader.java

@@ -262,6 +262,30 @@ public class MultiReader extends IndexReader {
     }
     return fieldSet;
   }
+  
+  /**
+   * Returns <code>true</code> if all readers are still up-to-date.
+   * 
+   * @throws IOException
+   */
+  public boolean isCurrent() throws IOException {
+    for (int i = 0; i < subReaders.length; i++) {
+      IndexReader reader = subReaders[i];
+      if (!reader.isCurrent())
+        return false;
+    }
+    return true;
+  }
+
+  /**
+   * Not implemented.
+   * @throws UnsupportedOperationException
+   */
+  public long getVersion() {
+    throw new UnsupportedOperationException("This method is only implemented in " +
+        "IndexReader, not in MultiReader");
+  }
+
 }
 
 class MultiTermEnum extends TermEnum {

src/test/org/apache/lucene/index/TestMultiReader.java

@@ -18,7 +18,10 @@ package org.apache.lucene.index;
  */
 
 import junit.framework.TestCase;
+
+import org.apache.lucene.analysis.standard.StandardAnalyzer;
 import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.RAMDirectory;
 
@@ -102,4 +105,34 @@ public class TestMultiReader extends TestCase {
     MultiReader reader = new MultiReader(dir, sis, false, readers);
     assertTrue(reader != null);
   }
+  
+  public void testIsCurrent() throws IOException {
+    RAMDirectory ramDir1=new RAMDirectory();
+    addDoc(ramDir1, "test foo", true);
+    RAMDirectory ramDir2=new RAMDirectory();
+    addDoc(ramDir2, "test blah", true);
+    IndexReader[] readers = new IndexReader[]{IndexReader.open(ramDir1), IndexReader.open(ramDir2)};
+    MultiReader mr = new MultiReader(readers);
+    assertTrue(mr.isCurrent());   // just opened, must be current
+    addDoc(ramDir1, "more text", false);
+    assertFalse(mr.isCurrent());   // has been modified, not current anymore
+    addDoc(ramDir2, "even more text", false);
+    assertFalse(mr.isCurrent());   // has been modified even more, not current anymore
+    try {
+      mr.getVersion();
+      fail();
+    } catch (UnsupportedOperationException e) {
+      // expected exception
+    }
+    mr.close();
+  }
+
+  private void addDoc(RAMDirectory ramDir1, String s, boolean create) throws IOException {
+    IndexWriter iw = new IndexWriter(ramDir1, new StandardAnalyzer(), create);
+    Document doc = new Document();
+    doc.add(new Field("body", s, Field.Store.YES, Field.Index.TOKENIZED));
+    iw.addDocument(doc);
+    iw.close();
+  }
+
 }