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StoreAbstractPropertyCursor.java
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StoreAbstractPropertyCursor.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.util.function.IntPredicate;
import org.neo4j.cursor.Cursor;
import org.neo4j.function.Disposable;
import org.neo4j.kernel.api.properties.DefinedProperty;
import org.neo4j.kernel.impl.locking.Lock;
import org.neo4j.kernel.impl.store.RecordCursor;
import org.neo4j.kernel.impl.store.RecordCursors;
import org.neo4j.kernel.impl.store.record.PropertyRecord;
import org.neo4j.kernel.impl.store.record.Record;
import org.neo4j.storageengine.api.PropertyItem;
import org.neo4j.storageengine.api.txstate.PropertyContainerState;
import static org.neo4j.kernel.impl.store.record.RecordLoad.FORCE;
public abstract class StoreAbstractPropertyCursor implements PropertyItem, Cursor<PropertyItem>, Disposable
{
protected final StorePropertyPayloadCursor payload;
private final RecordCursor<PropertyRecord> recordCursor;
protected boolean fetched;
private boolean doneTraversingTheChain;
private DefinedProperty property;
private IntPredicate propertyKeyIds;
private Lock lock;
protected PropertyContainerState state;
StoreAbstractPropertyCursor( RecordCursors cursors )
{
this.payload = new StorePropertyPayloadCursor( cursors.propertyString(), cursors.propertyArray() );
this.recordCursor = cursors.property();
}
protected final void initialize( IntPredicate propertyKeyIds, long firstPropertyId, Lock lock,
PropertyContainerState state )
{
this.propertyKeyIds = propertyKeyIds;
this.lock = lock;
this.state = state;
recordCursor.placeAt( firstPropertyId, FORCE );
}
@Override
public final boolean next()
{
return fetched = fetchNext();
}
private boolean fetchNext()
{
property = null;
while ( !doneTraversingTheChain && loadNextFromDisk() )
{
// Are there more properties to return for this current record we're at?
if ( payloadHasNext() )
{
return true;
}
// No, OK continue down the chain and hunt for more...
if ( recordCursor.next() )
{
PropertyRecord propertyRecord = recordCursor.get();
payload.init( propertyKeyIds, propertyRecord.getBlocks(), propertyRecord.getNumberOfBlocks() );
if ( payloadHasNext() )
{
return true;
}
}
else if ( Record.NO_NEXT_PROPERTY.is( recordCursor.get().getNextProp() ) )
{
// No more records in this chain, i.e. no more properties.
doneTraversingTheChain = true;
}
// Sort of alright, this record isn't in use, but could just be due to concurrent delete.
// Continue to next record in the chain and try there.
}
assert property == null;
return (property = nextAdded()) != null;
}
private boolean payloadHasNext()
{
boolean next = payload.next();
while ( next && state != null )
{
int propertyKeyId = payload.propertyKeyId();
if ( !state.isPropertyRemoved( propertyKeyId ) )
{
assert property == null;
property = (DefinedProperty) state.getChangedProperty( propertyKeyId );
return true;
}
next = payload.next();
}
return next;
}
protected abstract boolean loadNextFromDisk();
protected abstract DefinedProperty nextAdded();
@Override
public final PropertyItem get()
{
if ( !fetched )
{
throw new IllegalStateException( "No property has been fetched!" );
}
return this;
}
@Override
public final int propertyKeyId()
{
return property == null ? payload.propertyKeyId() : property.propertyKeyId();
}
@Override
public final Object value()
{
return property == null ? payload.value() : property.value();
}
@Override
public final void close()
{
try
{
fetched = false;
doneTraversingTheChain = false;
payload.close();
propertyKeyIds = null;
property = null;
doClose();
}
finally
{
lock.release();
lock = null;
}
}
protected abstract void doClose();
@Override
public void dispose()
{
}
}