On Tue, 11 Dec 2007, Timo Nentwig wrote:
Date: Tue, 11 Dec 2007 13:27:59 +0100
From: Timo Nentwig <[EMAIL PROTECTED]>
Reply-To: java-dev@lucene.apache.org
To: java-dev@lucene.apache.org
Subject: Caching FuzzyQuery
Hi!
Actually FuzzyQuery.rewrite() is pretty expensive so why not introduce a
caching decorator? A WeakHashMap with key==IndexReader and value==LRU of
BooleanQueries.
So, didn't become a popular approach/topic. Anyway, I wrote an aspect and
it does the job for a couple of months now, so I'd like to share it.
HTH
Timo
In order to enable runtime AspectJ weaving start your JVM with
-javaagent:./foo/bar/lib/aspectjweaver.jar
and place the following file called "aop.xml" in META-INF.
<aspectj>
<aspects>
<aspect name="foo.bar.FuzzyQueryCachingAspect" />
</aspects>
<weaver options="-verbose -showWeaveInfo">
<include within="org.apache.lucene.search.*" />
<include within="org.apache.lucene.index.*" />
</weaver>
</aspectj>
@Aspect
public class FuzzyQueryCachingAspect
{
private static final Log LOG = LogFactory.getLog(
FuzzyQueryCachingAspect.class );
// your cache impl goes here
private static final Caching CACHE = Caching.instance(
Caching.FUZZY );
@Before( "execution(public void
org.apache.lucene.index.IndexReader+.close())" )
public void flush( final JoinPoint jp ) throws Throwable
{
assert jp.getThis() == jp.getTarget();
final IndexReader r = (IndexReader)jp.getThis();
final Directory d = r.directory();
final String group = name( d );
CACHE.remove( group );
LOG.info( "Removed from " + CACHE + ": " + group );
}
@Around( "execution(public org.apache.lucene.search.Query
org.apache.lucene.search.FuzzyQuery.rewrite(org.apache.lucene.index.IndexReader))
&& args(reader)" )
public Object cache( final IndexReader reader, final
ProceedingJoinPoint jp ) throws Throwable
{
assert jp.getThis() == jp.getTarget();
final FuzzyQuery q = (FuzzyQuery)jp.getThis();
final String term = q.getTerm().text();
final String group = name( reader.directory() );
final String key = term + "~" + q.getMinSimilarity();
final Object e = CACHE.get( group, key );
if( e != null )
{
LOG.debug( term + " found in cache" );
return e;
}
final long t0 = System.currentTimeMillis();
final Query fuzzy = (Query)jp.proceed();
CACHE.put( group, key, fuzzy );
LOG.info( term + " rewritten in " +
(System.currentTimeMillis() - t0) + "ms (" + group + ")" );
return fuzzy;
}
private static final String name( final Directory d )
{
if( d instanceof FSDirectory ) return
((FSDirectory)d).getFile().getAbsolutePath();
return String.valueOf( d.hashCode() );
}
}
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