/*
* Copyright (c) 2007-2014 Concurrent, Inc. All Rights Reserved.
*
* Project and contact information: http://www.cascading.org/
*
* This file is part of the Cascading project.
*
* Licensed 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 cascading.flow.stream.element;
import java.io.IOException;
import java.util.Iterator;
import cascading.CascadingException;
import cascading.flow.FlowProcess;
import cascading.flow.stream.duct.Duct;
import cascading.flow.stream.duct.Grouping;
import cascading.flow.stream.duct.OpenWindow;
import cascading.operation.Buffer;
import cascading.pipe.Every;
import cascading.pipe.OperatorException;
import cascading.tuple.Fields;
import cascading.tuple.Tuple;
import cascading.tuple.TupleEntry;
import cascading.tuple.TupleEntryCollector;
import cascading.tuple.TupleEntryIterator;
import cascading.tuple.Tuples;
/**
*
*/
public class BufferEveryWindow extends EveryStage<Grouping<TupleEntry, TupleEntryIterator>> implements OpenWindow
{
Buffer buffer;
public BufferEveryWindow( FlowProcess flowProcess, Every every )
{
super( flowProcess, every );
}
@Override
public void initialize()
{
super.initialize();
buffer = every.getBuffer();
outputCollector = new TupleEntryCollector( getOperationDeclaredFields() )
{
@Override
protected void collect( TupleEntry resultEntry ) throws IOException
{
Tuple outgoing = outgoingBuilder.makeResult( incomingEntry.getTuple(), resultEntry.getTuple() );
outgoingEntry.setTuple( outgoing );
try
{
next.receive( BufferEveryWindow.this, outgoingEntry );
}
finally
{
Tuples.asModifiable( outgoing );
}
}
};
}
@Override
protected Fields getIncomingPassThroughFields()
{
return incomingScopes.get( 0 ).getIncomingBufferPassThroughFields();
}
@Override
protected Fields getIncomingArgumentsFields()
{
return incomingScopes.get( 0 ).getIncomingBufferArgumentFields();
}
@Override
protected Fields getOutgoingSelector()
{
return outgoingScopes.get( 0 ).getOutGroupingSelector();
}
@Override
public void start( Duct previous )
{
next.start( this );
}
@Override
public void receive( Duct previous, final Grouping<TupleEntry, TupleEntryIterator> grouping )
{
try
{
// we want to null out any 'values' before and after the iterator begins/ends
// this allows buffers to emit tuples before next() and when hasNext() return false;
final TupleEntry tupleEntry = grouping.joinIterator.getTupleEntry();
incomingEntry = tupleEntry;
// if Fields.NONE are declared on the CoGroup, we don't provide arguments, only the joinerClosure
if( !tupleEntry.getFields().isNone() )
{
final Tuple valueNulledTuple = Tuples.setOnEmpty( tupleEntry, grouping.key );
tupleEntry.setTuple( valueNulledTuple );
operationCall.setArgumentsIterator( createArgumentsIterator( grouping, tupleEntry, valueNulledTuple ) );
}
operationCall.setOutputCollector( outputCollector );
operationCall.setJoinerClosure( grouping.joinerClosure );
operationCall.setGroup( grouping.key );
buffer.operate( flowProcess, operationCall );
}
catch( CascadingException exception )
{
handleException( exception, argumentsEntry );
}
catch( Throwable throwable )
{
handleException( new OperatorException( every, "operator Every failed executing operation: " + every.getOperation(), throwable ), argumentsEntry );
}
}
private Iterator<TupleEntry> createArgumentsIterator( final Grouping<TupleEntry, TupleEntryIterator> grouping, final TupleEntry tupleEntry, final Tuple valueNulledTuple )
{
return new Iterator<TupleEntry>()
{
public boolean hasNext()
{
boolean hasNext = grouping.joinIterator.hasNext();
if( !hasNext && !operationCall.isRetainValues() )
tupleEntry.setTuple( valueNulledTuple ); // null out footer entries
return hasNext;
}
public TupleEntry next()
{
argumentsEntry.setTuple( argumentsBuilder.makeResult( grouping.joinIterator.next().getTuple(), null ) );
return argumentsEntry;
}
public void remove()
{
grouping.joinIterator.remove();
}
};
}
}