/*
* 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 org.apache.jena.tdb.index.bplustree;
import static org.apache.jena.tdb.index.bplustree.BPlusTreeRewriterUtils.divider ;
import static org.apache.jena.tdb.index.bplustree.BPlusTreeRewriterUtils.printIndexBlocks ;
import static org.apache.jena.tdb.index.bplustree.BPlusTreeRewriterUtils.summarizeDataBlocks ;
import java.util.Iterator ;
import java.util.function.Function;
import org.apache.jena.atlas.iterator.Iter ;
import org.apache.jena.atlas.iterator.IteratorWithBuffer ;
import org.apache.jena.atlas.lib.Pair ;
import org.apache.jena.tdb.base.block.BlockMgr ;
import org.apache.jena.tdb.base.buffer.PtrBuffer ;
import org.apache.jena.tdb.base.buffer.RecordBuffer ;
import org.apache.jena.tdb.base.record.Record ;
import org.apache.jena.tdb.base.record.RecordFactory ;
import org.apache.jena.tdb.base.recordbuffer.RecordBufferPage ;
import org.apache.jena.tdb.base.recordbuffer.RecordBufferPageMgr ;
import org.slf4j.Logger ;
import org.slf4j.LoggerFactory ;
public class BPlusTreeRewriter
{
static private Logger log = LoggerFactory.getLogger(BPlusTreeRewriter.class) ;
static boolean rebalance = true ;
static boolean debug = false ;
static boolean materialize = debug ;
// Process:
// 1/ Take a stream of records and create leaves.
// Emit the RecordBufferPage (B+Tree leaves).
// 2/ Take a stream of RecordBufferPage and create the first level of branches.
// 3/ Take each branch level and create upper braches until root hit.
// 4/ Copy root block to root real location.
// --------------------------------
/** Given a stream of records and details of the B+Tree to build, go and build it.
* @return A newly built BPlusTree
*/
public static BPlusTree packIntoBPlusTree(Iterator<Record> iterRecords,
BPlusTreeParams bptParams,
RecordFactory recordFactory,
BlockMgr blkMgrNodes,
BlockMgr blkMgrRecords)
{
// **** Attach to storage.
// Small caches as we mostly work on a block then move on.
// Only read behind and look ahead actually do any work on an existing block.
// (check this by rerunning with different cache sizes).
if ( ! iterRecords.hasNext() )
// No records. Just return a B+Tree.
return BPlusTree.create(bptParams, blkMgrNodes, blkMgrRecords) ;
// Dummy B+tree needed to carry parameters around.
BPlusTree bpt2 = BPlusTree.attach(bptParams, blkMgrNodes, blkMgrRecords) ;
// Allocate and format a root index block.
// We will use this slot later and write in the correct root.
/// The root has to be block zero currently.
BPTreeNode root = bpt2.getNodeManager().createNode(BPlusTreeParams.RootParent) ;
int rootId = root.getId() ;
if ( rootId != 0 )
{
log.error("**** Not the root: "+rootId) ;
throw new BPTreeException() ;
}
// ******** Pack data blocks.
Iterator<Pair<Integer, Record>> iter = writePackedDataBlocks(iterRecords, bpt2) ;
// ******** Index layer
// Loop until one block only.
// Never zero blocks.
// Output is a single pair pointing to the root - but the root is in the wrong place.
boolean leafLayer= true ;
while(true)
{
iter = genTreeLevel(iter, bpt2, leafLayer) ;
// Advances iter.
IteratorWithBuffer<Pair<Integer, Record>> iter2 = new IteratorWithBuffer<>(iter, 2) ;
boolean singleBlock = ( iter2.peek(1) == null ) ;
// Having peeked ahead, use the real stream.
iter = iter2 ;
if ( singleBlock )
break ;
leafLayer = false ;
}
// ******** Put root in right place.
Pair<Integer, Record> pair = iter.next() ;
if ( iter.hasNext() )
{
log.error("**** Building index layers didn't result in a single block") ;
return null ;
}
fixupRoot(root, pair, bpt2) ;
// ****** Finish the tree.
blkMgrNodes.sync() ;
blkMgrRecords.sync() ;
// Force root reset.
bpt2 = BPlusTree.create(bptParams, blkMgrNodes, blkMgrRecords) ;
return bpt2 ;
}
// **** data block phase
/** Pack record blocks into linked RecordBufferPages */
private static Iterator<Pair<Integer, Record>> writePackedDataBlocks(Iterator<Record> records, final BPlusTree bpt)
{
if ( debug )
{
divider() ;
System.out.println("---- Data level") ;
}
final RecordBufferPageMgr mgr = bpt.getRecordsMgr().getRecordBufferPageMgr() ;
Iterator<RecordBufferPage> iter = new RecordBufferPageLinker(new RecordBufferPagePacker(records, mgr)) ;
Function<RecordBufferPage, Pair<Integer, Record>> transform = rbp ->
{
mgr.put(rbp) ;
Record r = rbp.getRecordBuffer().getHigh() ;
r = bpt.getRecordFactory().createKeyOnly(r) ;
return new Pair<>(rbp.getId(), r) ;
};
// Write and convert to split pairs.
Iterator<Pair<Integer, Record>> iter2 = Iter.map(iter, transform) ;
if ( debug )
{
if ( rebalance ) System.out.println("Before rebalance (data)") ;
iter2 = summarizeDataBlocks(iter2, bpt.getRecordsMgr().getRecordBufferPageMgr()) ;
//iter2 = printDataBlocks(iter2, bpt.getRecordsMgr().getRecordBufferPageMgr()) ;
}
if ( rebalance )
iter2 = new RebalenceDataEnd(iter2, bpt) ;
// Testing - materialize - debug wil have done this
if ( materialize && ! debug )
iter2 = Iter.toList(iter2).iterator() ;
if ( debug && rebalance )
{
System.out.println("After rebalance (data)") ;
iter2 = summarizeDataBlocks(iter2, bpt.getRecordsMgr().getRecordBufferPageMgr()) ;
//iter2 = printDataBlocks(iter2, bpt.getRecordsMgr().getRecordBufferPageMgr()) ;
}
return iter2 ;
}
private static class RebalenceDataEnd extends RebalenceBase
{
private RecordBufferPageMgr mgr ;
private BPlusTree bpt ;
public RebalenceDataEnd(Iterator<Pair<Integer, Record>> iter, BPlusTree bpt)
{
super(iter) ;
this.bpt = bpt ;
}
@Override
protected Record rebalance(int id1, Record r1, int id2, Record r2)
{
RecordBufferPageMgr mgr = bpt.getRecordsMgr().getRecordBufferPageMgr() ;
RecordBufferPage page1 = mgr.getWrite(id1) ;
RecordBufferPage page2 = mgr.getWrite(id2) ;
// Wrong calculatation.
for ( int i = page2.getCount() ; i < page1.getMaxSize()/2 ; i++ )
{
//shiftOneup(node1, node2) ;
Record r = page1.getRecordBuffer().getHigh() ;
page1.getRecordBuffer().removeTop() ;
page2.getRecordBuffer().add(0, r) ;
}
mgr.put(page1) ;
mgr.put(page2) ;
Record splitPoint = page1.getRecordBuffer().getHigh() ;
splitPoint = bpt.getRecordFactory().createKeyOnly(splitPoint) ;
//Record splitPoint = node1.maxRecord() ;
return splitPoint ;
}
}
// ---------------------------------------------------------------------------------------------
// **** tree block phase
/* Status: need to address the parent issue - how to set the parent as we work up the BPT.
* One way is to work in memory and assume that there is enough room
* for the B+Tree nodes (not the record nodes).
*
* Another way is to rely on the caching and two-pass each new layer to fix up parents.
*
* 3rd way - parents aren't actually used in B+Trees.
* Set the BPT code to ignore parent of -2.
* Always set the new nodes to -2 for a rebuild.
*/
// Idea a layer processor for BPT nodes has a sink that is the parent.
// Need to rebal the last two blocks of a level.
// Same for data blocks.
// ---- Block stream to BTreeNodeStream.
private static Iterator<Pair<Integer, Record>> genTreeLevel(Iterator<Pair<Integer, Record>> iter,
BPlusTree bpt,
boolean leafLayer)
{
if ( debug )
{
divider() ;
System.out.println("---- Index level") ;
}
Iterator<Pair<Integer, Record>> iter2 = new BPTreeNodeBuilder(iter, bpt.getNodeManager(), leafLayer, bpt.getRecordFactory()) ;
if ( debug )
{
if ( rebalance ) System.out.println("Before rebalance (index)") ;
//iter2 = summarizeIndexBlocks(iter2, bpt.getNodeManager()) ;
iter2 = printIndexBlocks(iter2, bpt.getNodeManager()) ;
}
if ( rebalance )
iter2 = new RebalenceIndexEnd(iter2, bpt, leafLayer) ;
if ( materialize && !debug )
iter2 = Iter.toList(iter2).iterator() ;
if ( debug && rebalance )
{
System.out.println("After rebalance (index)") ;
//iter2 = summarizeIndexBlocks(iter2, bpt.getNodeManager()) ;
iter2 = printIndexBlocks(iter2, bpt.getNodeManager()) ;
}
return iter2 ;
}
private abstract static class RebalenceBase extends IteratorWithBuffer<Pair<Integer, Record>>
{
protected RebalenceBase(Iterator<Pair<Integer, Record>> iter)
{
super(iter, 2) ;
}
@Override
protected final void endReachedInner()
{
Pair<Integer, Record> pair1 = peek(0) ;
Pair<Integer, Record> pair2 = peek(1) ;
if ( pair1 == null || pair2 == null )
// Insufficient blocks to repack.
return ;
if ( debug ) System.out.printf("Rebalance: %s %s\n", pair1, pair2) ;
Record newSplitPoint = rebalance(pair1.car(), pair1.cdr(), pair2.car(), pair2.cdr()) ;
// Needed??
if ( newSplitPoint != null )
{
if ( debug ) System.out.println("Reset split point: "+pair1.cdr()+" => "+newSplitPoint) ;
pair1 = new Pair<>(pair1.car(), newSplitPoint) ;
if ( debug ) System.out.printf(" %s %s\n", pair1, pair2) ;
set(0, pair1) ;
}
}
protected abstract Record rebalance(int id1, Record r1, int id2, Record r2) ;
}
private static class RebalenceIndexEnd extends RebalenceBase
{
private BPlusTree bpt ;
public RebalenceIndexEnd(Iterator<Pair<Integer, Record>> iter, BPlusTree bpt, boolean leafLayer)
{
super(iter) ;
this.bpt = bpt ;
}
@Override
protected Record rebalance(int id1, Record r1, int id2, Record r2)
{
BPTreeNodeMgr mgr = bpt.getNodeManager() ;
BPTreeNode node1 = mgr.getWrite(id1, BPlusTreeParams.NoParent) ;
BPTreeNode node2 = mgr.getWrite(id2, BPlusTreeParams.NoParent) ;
// rebalence
// ** Need rebalance of data leaf layer.
int x = node2.getCount() ;
if ( node2.getCount() >= bpt.getParams().getMinRec() )
return null ;
Record splitPoint = r1 ;
// Shift up all in one go and use .set.
// Convert to block move ; should be code in BPTreeNode to do this (insert).
for ( int i = node2.getCount() ; i < bpt.getParams().getMinRec() ; i++ )
{
Record r = splitPoint ;
//shiftOneup(node1, node2) ;
int ptr = node1.getPtrBuffer().getHigh() ;
splitPoint = node1.getRecordBuffer().getHigh() ;
node1.getPtrBuffer().removeTop() ;
node1.getRecordBuffer().removeTop() ;
node1.setCount(node1.getCount()-1) ;
node2.getPtrBuffer().add(0, ptr) ;
node2.getRecordBuffer().add(0, r) ;
node2.setCount(node2.getCount()+1) ;
// Need high of moved substree.
if ( debug ) System.out.printf("-- Shift up: %d %s\n", ptr, r) ;
}
mgr.put(node1) ;
mgr.put(node2) ;
return splitPoint ;
}
}
private static void fixupRoot(BPTreeNode root, Pair<Integer, Record> pair, BPlusTree bpt2)
{
root.getPtrBuffer().clear() ;
root.getRecordBuffer().clear() ;
if ( BPlusTreeRewriter.debug )
{
divider() ;
System.out.printf("** Process root: %s\n", pair) ;
}
//BPTreeNode => BPTree copy.
BPTreeNode node = bpt2.getNodeManager().getRead(pair.car(), BPlusTreeParams.RootParent) ;
copyBPTreeNode(node, root, bpt2) ;
bpt2.getNodeManager().release(node) ;
}
private static void copyBPTreeNode(BPTreeNode nodeSrc, BPTreeNode nodeDst, BPlusTree bpt2)
{
PtrBuffer pBuff = nodeSrc.getPtrBuffer() ;
pBuff.copy(0, nodeDst.getPtrBuffer(), 0, pBuff.getSize()) ;
RecordBuffer rBuff = nodeSrc.getRecordBuffer() ;
rBuff.copy(0, nodeDst.getRecordBuffer(), 0, rBuff.getSize()) ;
nodeDst.setCount(nodeSrc.getCount()) ;
nodeDst.setIsLeaf(nodeSrc.isLeaf()) ;
bpt2.getNodeManager().put(nodeDst) ;
}
}