The source code for SearcherManager is even downloadable for free:
http://www.manning.com/hatcher3/LIAsourcecode.zip
The example source code does some things that is beyond my level of
understanding
of lucene. ie:
1) To me it looks like an IndexSearcher never gets closed.
2) I don't understand what happens if the indexreader is reopened
while a thread
in the middle of a search using an indexsearcher.
So I am going for something a bit simpler:
If a thread wants to use the "SafeIndexSearcher", it first calls
retain() and then calls
release() when its done.
If a thread wants to close the "SafeIndexSearcher" , the close is
deferred until all threads
have called release():
public class SafeIndexSearcher {
private boolean finish = false;
private int retainCount = 0;
private IndexSearcher searcher;
public SafeIndexSearcher(IndexSearcher searcher) {
this.searcher = searcher;
}
public TopDocs search(Query query, int limit) throws IOException {
TopDocs result = searcher.search(query, limit);
return result;
}
public Document doc(int doc) throws CorruptIndexException,
IOException {
return searcher.doc(doc);
}
public synchronized void close() {
finish = true;
}
public synchronized SafeIndexSearcher retain() throws IOException {
if(finish)
throw new IOException("SafeIndexSearcher used after close has been
called.");
retainCount++;
return this;
}
public synchronized SafeIndexSearcher release() {
retainCount--;
if(finish && retainCount==0)
try {
searcher.close();
} catch (IOException e) {
System.err.println("IndexSearcher.close() unexpected error: " +
e.getMessage());
}
return this;
}
}
On 12/11/2009, at 9:53 AM, Erick Erickson wrote:
If you want to spend a few bucks, here's part of a reply to a similar
question
from Mike McCandless a day or so ago....
<<<
You can get the book here http://www.manning.com/hatcher3 (NOTE: I'm
one of the authors!).
Chapter 11 in the book has a class called SearcherManager, that
handles the details of reopen/closing the IndexReader while queries
are still in flight, that might be useful here.
The book is Lucene In Action II. Manning has an "early access program"
(MEAP) that lets you get a PDF version. That class is considerably
more
extensive and handles the edge cases as I remember it....
Best
Erick
On Wed, Nov 11, 2009 at 5:41 PM, Jacob Rhoden
<jrho...@unimelb.edu.au>wrote:
I knew I would have overlooked something, thanks for the help!
On 12/11/2009, at 9:21 AM, Uwe Schindler wrote:
....simply do not catch and rethrow the IOException, instead put
release
in a
finally block and let the IOException automatically go upwards.
this.retain();
try {
TopDocs result = searcher.search(query,
limit);
return result;
} finally {
this.release();
}
Less code more secure and effective :-)
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Email: jrho...@unimelb.edu.au
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