yacy_search_server/source/net/yacy/kelondro/rwi/ReferenceIterator.java
2010-01-12 15:37:34 +00:00

100 lines
3.4 KiB
Java

// ReferenceIterator.java
// (C) 2008 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 30.03.2008 on http://yacy.net
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate: 2009-10-10 01:32:08 +0200 (Sa, 10 Okt 2009) $
// $LastChangedRevision: 6393 $
// $LastChangedBy: orbiter $
//
// LICENSE
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package net.yacy.kelondro.rwi;
import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import net.yacy.kelondro.blob.HeapReader;
import net.yacy.kelondro.index.Row;
import net.yacy.kelondro.index.RowSet;
import net.yacy.kelondro.logging.Log;
import net.yacy.kelondro.order.CloneableIterator;
/**
* iterator of BLOBHeap files: is used to import heap dumps into a write-enabled index heap
*/
public class ReferenceIterator <ReferenceType extends Reference> implements CloneableIterator<ReferenceContainer<ReferenceType>>, Iterable<ReferenceContainer<ReferenceType>> {
HeapReader.entries blobs;
Row payloadrow;
File blobFile;
ReferenceFactory<ReferenceType> factory;
public ReferenceIterator(final File blobFile, ReferenceFactory<ReferenceType> factory, final Row payloadrow) throws IOException {
this.blobs = new HeapReader.entries(blobFile, payloadrow.primaryKeyLength);
this.payloadrow = payloadrow;
this.blobFile = blobFile;
this.factory = factory;
}
public boolean hasNext() {
if (blobs == null) return false;
if (blobs.hasNext()) return true;
close();
return false;
}
/**
* return an index container
* because they may get very large, it is wise to deallocate some memory before calling next()
*/
public ReferenceContainer<ReferenceType> next() {
Map.Entry<byte[], byte[]> entry = blobs.next();
byte[] payload = entry.getValue();
return new ReferenceContainer<ReferenceType>(factory, entry.getKey(), RowSet.importRowSet(payload, payloadrow));
}
public void remove() {
throw new UnsupportedOperationException("heap dumps are read-only");
}
public Iterator<ReferenceContainer<ReferenceType>> iterator() {
return this;
}
public void close() {
if (blobs != null) this.blobs.close();
blobs = null;
}
protected void finalize() {
this.close();
}
public CloneableIterator<ReferenceContainer<ReferenceType>> clone(Object modifier) {
if (blobs != null) this.blobs.close();
blobs = null;
try {
return new ReferenceIterator<ReferenceType>(this.blobFile, factory, this.payloadrow);
} catch (IOException e) {
Log.logException(e);
return null;
}
}
}