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DefaultRelationshipScanCursor.java
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DefaultRelationshipScanCursor.java
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/*
* Copyright (c) 2002-2018 "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.newapi;
import java.util.Set;
import org.neo4j.internal.kernel.api.RelationshipScanCursor;
import org.neo4j.io.pagecache.PageCursor;
import org.neo4j.kernel.api.txstate.TransactionState;
import static java.util.Collections.emptySet;
class DefaultRelationshipScanCursor extends RelationshipCursor implements RelationshipScanCursor
{
private int label;
private long next;
private long highMark;
private PageCursor pageCursor;
private Set<Long> addedRelationships;
private final DefaultCursors pool;
DefaultRelationshipScanCursor( DefaultCursors pool )
{
this.pool = pool;
}
void scan( int label, Read read )
{
if ( getId() != NO_ID )
{
reset();
}
if ( pageCursor == null )
{
pageCursor = read.relationshipPage( 0 );
}
next = 0;
this.label = label;
highMark = read.relationshipHighMark();
init( read );
this.addedRelationships = emptySet();
}
void single( long reference, Read read )
{
if ( getId() != NO_ID )
{
reset();
}
if ( pageCursor == null )
{
pageCursor = read.relationshipPage( reference );
}
next = reference;
label = -1;
highMark = NO_ID;
init( read );
this.addedRelationships = emptySet();
}
@Override
public boolean next()
{
if ( next == NO_ID )
{
reset();
return false;
}
// Check tx state
boolean hasChanges = hasChanges();
TransactionState txs = hasChanges ? read.txState() : null;
do
{
if ( hasChanges && containsRelationship( txs ) )
{
loadFromTxState( next++ );
setInUse( true );
}
else if ( hasChanges && txs.relationshipIsDeletedInThisTx( next ) )
{
next++;
setInUse( false );
}
else
{
read.relationship( this, next++, pageCursor );
}
if ( next > highMark )
{
if ( isSingle() )
{
next = NO_ID;
return isWantedLabelAndInUse();
}
else
{
highMark = read.relationshipHighMark();
if ( next > highMark )
{
next = NO_ID;
return isWantedLabelAndInUse();
}
}
}
}
while ( !isWantedLabelAndInUse() );
return true;
}
private boolean isWantedLabelAndInUse()
{
return (label == -1 || type() == label) && inUse();
}
private boolean containsRelationship( TransactionState txs )
{
return isSingle() ? txs.relationshipIsAddedInThisTx( next ) : addedRelationships.contains( next );
}
@Override
public boolean shouldRetry()
{
return false;
}
@Override
public void close()
{
if ( !isClosed() )
{
read = null;
reset();
pool.accept( this );
}
}
private void reset()
{
setId( next = NO_ID );
}
@Override
public boolean isClosed()
{
return read == null;
}
@Override
public String toString()
{
if ( isClosed() )
{
return "RelationshipScanCursor[closed state]";
}
else
{
return "RelationshipScanCursor[id=" + getId() + ", open state with: highMark=" + highMark + ", next=" + next + ", label=" + label +
", underlying record=" + super.toString() + " ]";
}
}
private boolean isSingle()
{
return highMark == NO_ID;
}
protected void collectAddedTxStateSnapshot()
{
if ( !isSingle() )
{
addedRelationships = read.txState().addedAndRemovedRelationships().getAddedSnapshot();
}
}
public void release()
{
if ( pageCursor != null )
{
pageCursor.close();
pageCursor = null;
}
}
}