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From "Michael McCandless (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-758) IndexReader.isCurrent fails when using two IndexReaders
Date Fri, 22 Dec 2006 17:51:22 GMT
    [ http://issues.apache.org/jira/browse/LUCENE-758?page=comments#action_12460555 ] 
            
Michael McCandless commented on LUCENE-758:
-------------------------------------------

Thank you for the full test case showing the issue!

However, I believe this is by design.  When you init a RAMDirectory off a current Directory,
it makes a full copy of that original Directory and from then on the original & the copy
are totally independent.

So it's not expected that changes to the original Directory would be reflected in the copy?

> IndexReader.isCurrent fails when using two IndexReaders
> -------------------------------------------------------
>
>                 Key: LUCENE-758
>                 URL: http://issues.apache.org/jira/browse/LUCENE-758
>             Project: Lucene - Java
>          Issue Type: Bug
>    Affects Versions: 2.0.1
>         Environment: Operating System: other
> Platform: other
>            Reporter: Bernhard Messer
>            Priority: Minor
>
> there is a problem in IndexReader.isCurrent() if using two reader instances where one
of them is based on a RAMDirectory. If there is an index and we open two IndexReaders where
one is based on a FSDirectory and the other is based on a RAMDirectory, the IndexReader using
the RAMDirectory does not recognize when the underlaying index has changed. The method IndexReader.isCurrent()
always returns true. The testcase below shows the problem.
> I did not find an ideal solution to solve the problem. I think the best way would be
to change the IndexReader.isCurrent() implementation from:
>   public boolean isCurrent() throws IOException {
>     return SegmentInfos.readCurrentVersion(directory) == segmentInfos.getVersion();
>   }
> to something like:
>   public boolean isCurrent() throws IOException {
>     return directory.readCurrentVersion() == segmentInfos.getVersion();
>   }
> As far as i can see this would work for FS- and RAMDirectory. But then the implementing
Directory classes have to know about "segment" files and there formating details.
> What do others think ?
>   /** 
>    * additional testcase for IndexReaderTest to show the problem when using two different
Readers
>    */
>   public void testIsCurrentWithCombined() throws Exception {
>       String tempDir = System.getProperty("tempDir");
>       if (tempDir == null)
>           throw new IOException("tempDir undefined, cannot run test");
>       File indexDir = new File(tempDir, "lucenetestiscurrent");
>       Directory fsStore = FSDirectory.getDirectory(indexDir, true);
>       
>       IndexWriter writer = new IndexWriter(fsStore, new SimpleAnalyzer(), true);
>       addDocumentWithFields(writer);
>       writer.close();
>       
>       IndexReader reader1 = IndexReader.open(fsStore);
>       IndexReader reader2 = IndexReader.open(new RAMDirectory(fsStore));
>       
>       assertTrue(reader1.isCurrent());
>       assertTrue(reader2.isCurrent());
>       
>       reader1.deleteDocument(0);
>       reader1.close();
>       
>       // BUG: reader based on the RAMDirectory does not recognize the index change.
>       assertFalse(reader2.isCurrent());
>       
>       reader2.close();
>     }

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