/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hp.hpl.jena.tdb.base.recordbuffer;
import static org.apache.jena.atlas.lib.Alg.decodeIndex ;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.apache.jena.atlas.lib.Closeable ;
import com.hp.hpl.jena.tdb.base.StorageException ;
import com.hp.hpl.jena.tdb.base.block.BlockException ;
import com.hp.hpl.jena.tdb.base.record.Record;
final public
class RecordRangeIterator implements Iterator<Record>, Closeable
{
/** Iterate over a range of fromRec (inclusive) to toRec (exclusive) */
public static Iterator<Record> iterator(int pageId, Record fromRec, Record toRec, RecordBufferPageMgr pageMgr)
{
if ( ! pageMgr.valid(pageId) )
throw new BlockException("No such block") ;
return new RecordRangeIterator(pageId, fromRec, toRec, pageMgr) ;
}
// ITER release the page and re-get it as a
// /** Iterate over a range of fromRec (inclusive) to toRec (exclusive) */
// public static Iterator<Record> iterator(RecordBufferPage page, Record fromRec, Record toRec, RecordBufferPageMgr pageMgr)
// {
// return new RecordRangeIterator(page, fromRec, toRec, pageMgr) ;
// }
//
// /** Iterate over all records from this page onwards */
// public static Iterator<Record> iterator(RecordBufferPage page, RecordBufferPageMgr pageMgr)
// {
// return new RecordRangeIterator(page, null, null, pageMgr) ;
// }
private RecordBufferPage currentPage ; // Set null when finished.
private RecordBufferPageMgr pageMgr ;
private int currentIdx ;
private Record slot = null ;
private final Record maxRec ;
private final Record minRec ;
private long countRecords = 0 ;
private long countBlocks = 0 ;
private RecordRangeIterator(int id, Record fromRec, Record toRec, RecordBufferPageMgr pageMgr)
{
currentIdx = 0 ;
this.pageMgr = pageMgr;
this.minRec = fromRec ;
this.maxRec = toRec ;
if ( toRec != null && fromRec != null && Record.keyLE(toRec, fromRec) )
{
currentPage = null ;
return ;
}
pageMgr.getBlockMgr().beginIterator(this) ;
currentPage = pageMgr.getReadIterator(id) ;
if ( currentPage.getCount() == 0 )
{
// Empty page.
close() ;
return ;
}
if ( fromRec != null )
{
currentIdx = currentPage.getRecordBuffer().find(fromRec) ;
if ( currentIdx < 0 )
currentIdx = decodeIndex(currentIdx) ;
}
}
@Override
public boolean hasNext()
{
if ( slot != null )
return true ;
if ( currentPage == null )
return false ;
// Set slot.
while ( currentIdx >= currentPage.getCount() )
{
// Move to next.
int link = currentPage.getLink() ;
if ( link < 0 )
{
close() ;
return false ;
}
if ( currentPage != null )
pageMgr.release(currentPage) ;
RecordBufferPage nextPage = pageMgr.getReadIterator(link) ;
// Check currentPage -> nextPage is strictly increasing keys.
Record r1 = currentPage.getRecordBuffer().getHigh() ;
Record r2 = nextPage.getRecordBuffer().getLow() ;
if ( Record.keyGE(r1, r2) )
throw new StorageException("RecordRangeIterator: records not strictly increasing: "+r1+" // "+r2) ;
currentPage = nextPage ;
countBlocks++ ;
currentIdx = 0 ;
}
slot = currentPage.getRecordBuffer().get(currentIdx) ;
currentIdx++ ;
if ( maxRec != null && Record.keyGE(slot, maxRec) )
{
close() ;
return false ;
}
if ( slot == null )
{
close() ;
return false ;
}
countRecords++ ;
return true ;
}
@Override
public void close()
{
if (currentPage != null )
pageMgr.release(currentPage) ;
currentPage = null ;
currentIdx = -99 ;
slot = null ;
pageMgr.getBlockMgr().endIterator(this) ;
}
@Override
public Record next()
{
if ( ! hasNext() )
throw new NoSuchElementException() ;
Record x = slot ;
slot = null ;
return x ;
}
@Override
public void remove()
{ throw new UnsupportedOperationException("remove") ; }
final public long getCountRecords() { return countRecords ; }
final public long getCountBlocks() { return countBlocks ; }
}