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EagerResult.java
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EagerResult.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.cypher.internal.javacompat;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.neo4j.cypher.result.QueryResult;
import org.neo4j.graphdb.ExecutionPlanDescription;
import org.neo4j.graphdb.NotFoundException;
import org.neo4j.graphdb.Notification;
import org.neo4j.graphdb.QueryExecutionType;
import org.neo4j.graphdb.QueryStatistics;
import org.neo4j.graphdb.ResourceIterator;
import org.neo4j.graphdb.Result;
import org.neo4j.io.pagecache.tracing.cursor.context.VersionContext;
import org.neo4j.kernel.impl.query.QueryExecutionKernelException;
import org.neo4j.kernel.impl.util.ValueUtils;
import org.neo4j.values.AnyValue;
import static java.lang.System.lineSeparator;
/**
* Result produced as result of eager query execution for cases when {@link SnapshotExecutionEngine} is used.
*/
class EagerResult implements Result, QueryResultProvider
{
private static final String ITEM_SEPARATOR = ", ";
private final Result originalResult;
private final VersionContext versionContext;
private final List<Map<String, Object>> queryResult = new ArrayList<>();
private int cursor;
EagerResult( Result result, VersionContext versionContext )
{
this.originalResult = result;
this.versionContext = versionContext;
}
public void consume()
{
while ( originalResult.hasNext() )
{
queryResult.add( originalResult.next() );
}
}
@Override
public QueryExecutionType getQueryExecutionType()
{
return originalResult.getQueryExecutionType();
}
@Override
public List<String> columns()
{
return originalResult.columns();
}
@Override
public <T> ResourceIterator<T> columnAs( String name )
{
return new EagerResultResourceIterator<>( name );
}
@Override
public boolean hasNext()
{
return cursor < queryResult.size();
}
@Override
public Map<String,Object> next()
{
return queryResult.get( cursor++ );
}
@Override
public void close()
{
// nothing to close. Original result is already closed at this point
}
@Override
public QueryStatistics getQueryStatistics()
{
return originalResult.getQueryStatistics();
}
@Override
public ExecutionPlanDescription getExecutionPlanDescription()
{
return originalResult.getExecutionPlanDescription();
}
@Override
public QueryResult queryResult()
{
return new EagerQueryResult();
}
@Override
public String resultAsString()
{
List<String> columns = originalResult.columns();
StringBuilder builder = new StringBuilder();
builder.append( String.join( ITEM_SEPARATOR, columns ) );
if ( !queryResult.isEmpty() )
{
builder.append( lineSeparator() );
int numberOfColumns = columns.size();
for ( Map<String,Object> row : queryResult )
{
writeRow( columns, builder, numberOfColumns, row );
builder.append( lineSeparator() );
}
}
return builder.toString();
}
@Override
public void writeAsStringTo( PrintWriter writer )
{
writer.print( resultAsString() );
}
@Override
public void remove()
{
throw new UnsupportedOperationException( "Not supported" );
}
@Override
public Iterable<Notification> getNotifications()
{
return originalResult.getNotifications();
}
@Override
public <VisitationException extends Exception> void accept( ResultVisitor<VisitationException> visitor )
throws VisitationException
{
try
{
for ( Map<String,Object> map : queryResult )
{
visitor.visit( new MapRow( map ) );
}
checkIfDirty();
}
catch ( NotFoundException e )
{
checkIfDirty();
throw e;
}
}
private void checkIfDirty()
{
if ( versionContext.isDirty() )
{
throw new QueryExecutionKernelException(
new UnstableSnapshotException( "Unable to get clean data snapshot for query serialisation." ) )
.asUserException();
}
}
private void writeRow( List<String> columns, StringBuilder builder, int numberOfColumns, Map<String,Object> row )
{
for ( int i = 0; i < numberOfColumns; i++ )
{
builder.append( row.get( columns.get( i ) ) );
if ( i != numberOfColumns - 1 )
{
builder.append( ITEM_SEPARATOR );
}
}
}
private class EagerResultResourceIterator<T> implements ResourceIterator<T>
{
private final String column;
int cursor;
EagerResultResourceIterator( String column )
{
this.column = column;
}
@Override
public boolean hasNext()
{
return cursor < queryResult.size();
}
@Override
public T next()
{
return (T) queryResult.get( cursor++ ).get( column );
}
@Override
public void close()
{
// Nothing to close.
}
}
private class EagerQueryResult implements QueryResult
{
private final String[] fields;
EagerQueryResult()
{
fields = originalResult.columns().toArray( new String[0] );
}
@Override
public String[] fieldNames()
{
return fields;
}
@Override
public <E extends Exception> void accept( QueryResultVisitor<E> visitor ) throws E
{
while ( hasNext() )
{
Map<String,Object> row = next();
AnyValue[] anyValues = new AnyValue[fields.length];
for ( int i = 0; i < fields.length; i++ )
{
anyValues[i] = ValueUtils.of( row.get( fields[i] ) );
}
visitor.visit( () -> anyValues );
}
}
@Override
public QueryExecutionType executionType()
{
return originalResult.getQueryExecutionType();
}
@Override
public QueryStatistics queryStatistics()
{
return originalResult.getQueryStatistics();
}
@Override
public ExecutionPlanDescription executionPlanDescription()
{
return originalResult.getExecutionPlanDescription();
}
@Override
public Iterable<Notification> getNotifications()
{
return originalResult.getNotifications();
}
@Override
public void close()
{
// nothing to close
}
}
}