| /* |
| * 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.directory.mavibot.btree; |
| |
| |
| import java.util.ArrayList; |
| import java.util.Arrays; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.Set; |
| import java.util.TreeSet; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| |
| /** |
| * A class used for reclaiming the copied pages. |
| * |
| * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> |
| */ |
| public class PageReclaimer |
| { |
| /** the record manager */ |
| private RecordManager rm; |
| |
| /** The LoggerFactory used by this class */ |
| protected static final Logger LOG = LoggerFactory.getLogger( PageReclaimer.class ); |
| |
| /** a flag to detect the running state */ |
| private boolean running = false; |
| |
| /** |
| * Creates a new instance of PageReclaimer. |
| * |
| * @param rm the record manager |
| */ |
| public PageReclaimer( RecordManager rm ) |
| { |
| this.rm = rm; |
| } |
| |
| |
| /** |
| * relcaims the copied pages |
| */ |
| /* no qualifier */ void reclaim() |
| { |
| //System.out.println( "reclaiming pages" ); |
| try |
| { |
| if ( running ) |
| { |
| return; |
| } |
| |
| running = true; |
| |
| Set<String> managed = rm.getManagedTrees(); |
| |
| for ( String name : managed ) |
| { |
| PersistedBTree tree = ( PersistedBTree ) rm.getManagedTree( name ); |
| |
| long latestRev = tree.getRevision(); |
| |
| Set<Long> inUseRevisions = new TreeSet<Long>(); |
| |
| // the tree might have been removed |
| if ( tree != null ) |
| { |
| Iterator<ReadTransaction> txnItr = tree.getReadTransactions().iterator(); |
| while ( txnItr.hasNext() ) |
| { |
| inUseRevisions.add( txnItr.next().getRevision() ); |
| } |
| } |
| |
| List<RevisionOffset> copiedRevisions = getRevisions( name ); |
| |
| // the revision last removed from copiedPage BTree |
| long lastRemovedRev = -1; |
| |
| List<Long> freeList = new ArrayList<Long>(); |
| |
| for ( RevisionOffset ro : copiedRevisions ) |
| { |
| long rv = ro.getRevision(); |
| if ( inUseRevisions.contains( rv ) ) |
| { |
| //System.out.println( "Revision " + rv + " of BTree " + name + " is in use, not reclaiming pages" ); |
| break; |
| } |
| |
| long[] offsets = ro.getOffsets(); |
| |
| //System.out.println( "Reclaiming " + Arrays.toString( offsets ) + "( " + offsets.length + " ) pages of the revision " + rv + " of BTree " + name ); |
| |
| for( long l : offsets ) |
| { |
| freeList.add( l ); |
| } |
| |
| RevisionName key = new RevisionName( rv, name ); |
| |
| //System.out.println( "delete cpb key " + key ); |
| rm.copiedPageBtree.delete( key ); |
| lastRemovedRev = rv; |
| } |
| |
| // no new txn is needed for the operations on BoB |
| // and also no need to traverse BoB if the tree is a sub-btree |
| if ( ( lastRemovedRev != -1 ) && !tree.isAllowDuplicates() ) |
| { |
| // we SHOULD NOT delete the latest revision from BoB |
| NameRevision nr = new NameRevision( name, latestRev ); |
| TupleCursor<NameRevision, Long> cursor = rm.btreeOfBtrees.browseFrom( nr ); |
| |
| List<Long> btreeHeaderOffsets = new ArrayList<Long>(); |
| |
| while ( cursor.hasPrev() ) |
| { |
| Tuple<NameRevision, Long> t = cursor.prev(); |
| //System.out.println( "deleting BoB rev " + t.getKey() + " latest rev " + latestRev ); |
| rm.btreeOfBtrees.delete( t.getKey() ); |
| btreeHeaderOffsets.add( t.value ); |
| } |
| |
| cursor.close(); |
| |
| for( Long l : btreeHeaderOffsets ) |
| { |
| // the offset may have already been present while |
| // clearing CPB so skip it here, otherwise it will result in OOM |
| // due to the attempt to free and already freed page |
| if(freeList.contains( l )) |
| { |
| //System.out.println( "bob duplicate offset " + l ); |
| continue; |
| } |
| |
| freeList.add( l ); |
| } |
| } |
| |
| for( Long offset : freeList ) |
| { |
| PageIO[] pageIos = rm.readPageIOs( offset, -1L ); |
| |
| for ( PageIO pageIo : pageIos ) |
| { |
| rm.free( pageIo ); |
| } |
| } |
| |
| } |
| |
| running = false; |
| } |
| catch ( Exception e ) |
| { |
| running = false; |
| rm.rollback(); |
| LOG.warn( "Errors while reclaiming", e ); |
| throw new RuntimeException( e ); |
| } |
| } |
| |
| |
| /** |
| * gets a list of all the copied pages of a given B-Tree. |
| * |
| * @param name the name of the B-Tree |
| * @return list of RevisionOffset |
| * @throws Exception |
| */ |
| private List<RevisionOffset> getRevisions( String name ) throws Exception |
| { |
| TupleCursor<RevisionName, long[]> cursor = rm.copiedPageBtree.browse(); |
| |
| List<RevisionOffset> lst = new ArrayList<RevisionOffset>(); |
| |
| while ( cursor.hasNext() ) |
| { |
| Tuple<RevisionName, long[]> t = cursor.next(); |
| RevisionName rn = t.getKey(); |
| if ( name.equals( rn.getName() ) ) |
| { |
| //System.out.println( t.getValue() ); |
| lst.add( new RevisionOffset( rn.getRevision(), t.getValue() ) ); |
| } |
| } |
| |
| cursor.close(); |
| |
| return lst; |
| } |
| } |