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NodeCursor.java
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NodeCursor.java
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/*
* Copyright (c) 2002-2017 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j 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 3 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, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.kernel.impl.api.store;
import java.io.IOException;
import java.util.Iterator;
import java.util.function.Consumer;
import org.neo4j.collection.primitive.PrimitiveIntSet;
import org.neo4j.cursor.Cursor;
import org.neo4j.function.Disposable;
import org.neo4j.io.pagecache.PageCursor;
import org.neo4j.kernel.impl.locking.Lock;
import org.neo4j.kernel.impl.locking.LockService;
import org.neo4j.kernel.impl.store.NodeLabelsField;
import org.neo4j.kernel.impl.store.NodeStore;
import org.neo4j.kernel.impl.store.UnderlyingStorageException;
import org.neo4j.kernel.impl.store.record.NodeRecord;
import org.neo4j.kernel.impl.store.record.Record;
import org.neo4j.kernel.impl.util.IoPrimitiveUtils;
import org.neo4j.storageengine.api.NodeItem;
import org.neo4j.storageengine.api.txstate.NodeState;
import org.neo4j.storageengine.api.txstate.ReadableTransactionState;
import static org.neo4j.collection.primitive.PrimitiveIntCollections.asSet;
import static org.neo4j.kernel.impl.api.store.NodeProgression.Mode.APPEND;
import static org.neo4j.kernel.impl.api.store.NodeProgression.Mode.FETCH;
import static org.neo4j.kernel.impl.locking.LockService.NO_LOCK;
import static org.neo4j.kernel.impl.locking.LockService.NO_LOCK_SERVICE;
import static org.neo4j.kernel.impl.store.record.RecordLoad.CHECK;
import static org.neo4j.kernel.impl.util.IoPrimitiveUtils.safeCastLongToInt;
public class NodeCursor implements NodeItem, Cursor<NodeItem>, Disposable
{
private final NodeRecord nodeRecord;
private final Consumer<NodeCursor> instanceCache;
private final NodeStore nodeStore;
private final LockService lockService;
private NodeProgression progression;
private ReadableTransactionState state;
private boolean fetched;
private long[] labels;
private Iterator<Long> added;
private PageCursor pageCursor;
NodeCursor( NodeRecord nodeRecord, Consumer<NodeCursor> instanceCache, NodeStore nodeStore,
LockService lockService )
{
this.pageCursor = nodeStore.newPageCursor();
this.nodeRecord = nodeRecord;
this.instanceCache = instanceCache;
this.nodeStore = nodeStore;
this.lockService = lockService;
}
public Cursor<NodeItem> init( NodeProgression progression, ReadableTransactionState state )
{
this.progression = progression;
this.state = state;
this.added = state != null && progression.mode() == APPEND
? state.addedAndRemovedNodes().getAdded().iterator()
: null;
return this;
}
@Override
public boolean next()
{
return fetched = fetchNext();
}
private boolean fetchNext()
{
labels = null;
long id;
while ( (id = progression.nextId()) >= 0 )
{
if ( (state == null || !state.nodeIsDeletedInThisTx( id )) && readNodeRecord( id ) )
{
return true;
}
if ( state != null && progression.mode() == FETCH && state.nodeIsAddedInThisTx( id ) )
{
recordFromTxState( id );
return true;
}
}
if ( added != null && added.hasNext() )
{
recordFromTxState( added.next() );
return true;
}
return false;
}
private boolean readNodeRecord( long id )
{
try
{
nodeRecord.clear();
nodeStore.readIntoRecord( id, nodeRecord, CHECK, pageCursor );
return nodeRecord.inUse();
}
catch ( IOException e )
{
throw new UnderlyingStorageException( e );
}
}
private void recordFromTxState( long id )
{
nodeRecord.clear();
nodeRecord.setId( id );
}
@Override
public void close()
{
labels = null;
added = null;
state = null;
instanceCache.accept( this );
}
@Override
public void dispose()
{
pageCursor.close();
pageCursor = null;
}
@Override
public NodeItem get()
{
if ( fetched )
{
return this;
}
throw new IllegalStateException( "Nothing available" );
}
@Override
public PrimitiveIntSet labels()
{
PrimitiveIntSet labels = asSet( loadedLabels(), IoPrimitiveUtils::safeCastLongToInt );
return state != null ? state.augmentLabels( labels, state.getNodeState( id() ) ) : labels;
}
@Override
public boolean hasLabel( int labelId )
{
NodeState nodeState = state == null ? null : state.getNodeState( id() );
if ( state != null && nodeState.labelDiffSets().getRemoved().contains( labelId ) )
{
return false;
}
if ( state != null && nodeState.labelDiffSets().getAdded().contains( labelId ) )
{
return true;
}
for ( long label : loadedLabels() )
{
if ( safeCastLongToInt( label ) == labelId )
{
return true;
}
}
return false;
}
private long[] loadedLabels()
{
if ( labels == null )
{
labels = NodeLabelsField.get( nodeRecord, nodeStore );
}
return labels;
}
@Override
public long id()
{
return nodeRecord.getId();
}
@Override
public boolean isDense()
{
return nodeRecord.isDense();
}
@Override
public long nextGroupId()
{
assert isDense();
return nextRelationshipId();
}
@Override
public long nextRelationshipId()
{
return nodeRecord.getNextRel();
}
@Override
public long nextPropertyId()
{
return nodeRecord.getNextProp();
}
@Override
public Lock lock()
{
return state != null && state.nodeIsAddedInThisTx( id() ) ? NO_LOCK : acquireLock();
}
private Lock acquireLock()
{
Lock lock = lockService.acquireNodeLock( nodeRecord.getId(), LockService.LockType.READ_LOCK );
if ( lockService != NO_LOCK_SERVICE )
{
boolean success = false;
try
{
// It's safer to re-read the node record here, specifically nextProp, after acquiring the lock
if ( !readNodeRecord( nodeRecord.getId() ) )
{
// So it looks like the node has been deleted. The current behavior of NodeStore#loadRecord
// is to only set the inUse field on loading an unused record. This should (and will)
// change to be more of a centralized behavior by the stores. Anyway, setting this pointer
// to the primitive equivalent of null the property cursor will just look empty from the
// outside and the releasing of the lock will be done as usual.
nodeRecord.setNextProp( Record.NO_NEXT_PROPERTY.intValue() );
}
success = true;
}
finally
{
if ( !success )
{
lock.release();
}
}
}
return lock;
}
}