See below -- this is an excerpt from the upcoming Lucene in Action
revision (chapter 10).
It's a simple class. Use it like this for searching:
IndexSearcher searcher = manager.get();
try {
searcher.search(...).
...render results...
} finally {
manager.release(searcher);
searcher = null;
}
When you want to reopen (application dependent), call maybeReopen.
Subclass and define the warm() method if needed.
NOTE: this hasn't yet been heavily tested (I just quickly revised it
to use
incRef/decRef).
Mike
import java.io.IOException;
import java.util.HashMap;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.store.Directory;
/** Utility class to get/refresh searchers when you are
* using multiple threads. */
public class SearcherManager {
private IndexSearcher currentSearcher; //A
private Directory dir;
public SearcherManager(Directory dir) throws IOException {
this.dir = dir;
currentSearcher = new IndexSearcher(IndexReader.open(dir)); //B
}
public void warm(IndexSearcher searcher) {} //C
public void maybeReopen() throws IOException { //D
long currentVersion =
currentSearcher.getIndexReader().getVersion();
if (IndexReader.getCurrentVersion(dir) != currentVersion) {
IndexReader newReader =
currentSearcher.getIndexReader().reopen();
assert newReader != currentSearcher.getIndexReader();
IndexSearcher newSearcher = new IndexSearcher(newReader);
warm(newSearcher);
swapSearcher(newSearcher);
}
}
public synchronized IndexSearcher get() { //E
currentSearcher.getIndexReader().incRef();
return currentSearcher;
}
public synchronized void release(IndexSearcher searcher) //F
throws IOException {
searcher.getIndexReader().decRef();
}
private synchronized void swapSearcher(IndexSearcher newSearcher) //G
throws IOException {
release(currentSearcher);
currentSearcher = newSearcher;
}
}
/*
#A Current IndexSearcher
#B Create initial searcher
#C Implement in subclass to warm new searcher
#D Call this to reopen searcher if index changed
#E Returns current searcher
#F Release searcher
#G Swaps currentSearcher to new searcher
*/
Mike
Amin Mohammed-Coleman wrote:
Hi
Thanks for your reply. Without sound completely ...silly...how do i
go
abouts using the methods you mentioned...
Cheers
Amin
On Thu, Feb 26, 2009 at 10:24 AM, Michael McCandless <
luc...@mikemccandless.com> wrote:
Actually, it's best to use IndexReader.incRef/decRef to track the
IndexReader.
You should not rely on GC to close your IndexReader since this can
easily
tie up resources (eg open file descriptors) for too long.
Mike
Michael Stoppelman wrote:
If another thread is executing a query with the handle to one of
readers[i]
you're going to kill it since the IndexReader is now closed.
Just don't call the IndexReader#close() method. If nothing is
pointing at
the readers they should be garbage collected. Also, you might
want to warm up your new IndexSearcher before you switch to it,
meaning
run
a few queries on it before you swap the old one out.
M
On Tue, Feb 24, 2009 at 12:48 PM, Amin Mohammed-Coleman <ami...@gmail.com
wrote:
The reason for the indexreader.reopen is because I have a webapp
which
enables users to upload files and then search for the documents.
If I
don't
reopen i'm concerned that the facet hit counter won't be updated.
On Tue, Feb 24, 2009 at 8:32 PM, Amin Mohammed-Coleman <ami...@gmail.com
wrote:
Hi
I have been able to get the code working for my scenario,
however I have
a
question and I was wondering if I could get some help. I have a
list of
IndexSearchers which are used in a MultiSearcher class. I use the
indexsearchers to get each indexreader and put them into a
MultiIndexReader.
IndexReader[] readers = new IndexReader[searchables.length];
for (int i =0 ; i < searchables.length;i++) {
IndexSearcher indexSearcher = (IndexSearcher)searchables[i];
readers[i] = indexSearcher.getIndexReader();
IndexReader newReader = readers[i].reopen();
if (newReader != readers[i]) {
readers[i].close();
}
readers[i] = newReader;
}
multiReader = new MultiReader(readers);
OpenBitSetFacetHitCounter facetHitCounter =
newOpenBitSetFacetHitCounter();
IndexSearcher indexSearcher = new IndexSearcher(multiReader);
I then use the indexseacher to do the facet stuff. I end the
code with
closing the multireader. This is causing problems in another
method
where I
do some other search as the indexreaders are closed. Is it ok
to not
close
the multiindexreader or should I do some additional checks in
the other
method to see if the indexreader is closed?
Cheers
P.S. Hope that made sense...!
On Mon, Feb 23, 2009 at 7:20 AM, Amin Mohammed-Coleman <
ami...@gmail.com
wrote:
Hi
Thanks just what I needed!
Cheers
Amin
On 22 Feb 2009, at 16:11, Marcelo Ochoa <marcelo.oc...@gmail.com>
wrote:
Hi Amin:
Please take a look a this blog post:
http://sujitpal.blogspot.com/2007/04/lucene-search-within-search-with.html
Best regards, Marcelo.
On Sun, Feb 22, 2009 at 1:18 PM, Amin Mohammed-Coleman <
ami...@gmail.com>
wrote:
Hi
Sorry to re send this email but I was wondering if I could
get some
advice
on this.
Cheers
Amin
On 16 Feb 2009, at 20:37, Amin Mohammed-Coleman <ami...@gmail.com
>
wrote:
Hi
I am looking at building a faceted search using Lucene. I
know that
Solr
comes with this built in, however I would like to try this
by myself
(something to add to my CV!). I have been looking around
and I
found
that
you can use the IndexReader and use TermVectors. This looks
ok but
I'm
not
sure how to filter the results so that a particular user can
only
see
a
subset of results. The next option I was looking at was something
like
Term term1 = new Term("brand", "ford");
Term term2 = new Term("brand", "vw");
Term[] termsArray = new Term[] { term1, term2 };un
int[] docFreqs = indexSearcher.docFreqs(termsArray);
The only problem here is that I have to provide the brand
type each
time a
new brand is created. Again I'm not sure how I can filter the
results
here.
It may be that I'm using the wrong api methods to do this.
I would be grateful if I could get some advice on this.
Cheers
Amin
P.S. I am basically trying to do something that displays the
following
Personal Contact (23) Business Contact (45) and so on..
--
Marcelo F. Ochoa
http://marceloochoa.blogspot.com/
http://marcelo.ochoa.googlepages.com/home
______________
Want to integrate Lucene and Oracle?
http://marceloochoa.blogspot.com/2007/09/running-lucene-inside-your-oracle-jvm.html
Is Oracle 11g REST ready?
http://marceloochoa.blogspot.com/2008/02/is-oracle-11g-rest-ready.html
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