/*
* 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.util.concurrent.Callable;
import cascading.CascadingException;
import cascading.flow.FlowProcess;
import cascading.flow.SliceCounters;
import cascading.flow.StepCounters;
import cascading.flow.stream.duct.Duct;
import cascading.flow.stream.duct.DuctException;
import cascading.tap.Tap;
import cascading.tuple.TupleEntry;
import cascading.tuple.TupleEntryIterator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
*
*/
public class SourceStage extends ElementStage<Void, TupleEntry> implements Callable<Throwable>, InputSource
{
private static final Logger LOG = LoggerFactory.getLogger( SourceStage.class );
private final Tap source;
public SourceStage( FlowProcess flowProcess, Tap source )
{
super( flowProcess, source );
this.source = source;
}
public Tap getSource()
{
return source;
}
@Override
public Throwable call() throws Exception
{
return map( null );
}
@Override
public void run( Object input ) throws Throwable
{
Throwable throwable = map( input );
if( throwable != null )
throw throwable;
}
private Throwable map( Object input )
{
Throwable localThrowable = null;
TupleEntryIterator iterator = null;
try
{
next.start( this );
// input may be null
iterator = source.openForRead( flowProcess, input );
while( iterator.hasNext() )
{
TupleEntry tupleEntry;
try
{
tupleEntry = iterator.next();
flowProcess.increment( StepCounters.Tuples_Read, 1 );
flowProcess.increment( SliceCounters.Tuples_Read, 1 );
}
catch( OutOfMemoryError error )
{
handleReThrowableException( "out of memory, try increasing task memory allocation", error );
continue;
}
catch( CascadingException exception )
{
handleException( exception, null );
continue;
}
catch( Throwable throwable )
{
handleException( new DuctException( "internal error", throwable ), null );
continue;
}
next.receive( this, tupleEntry );
}
next.complete( this );
}
catch( Throwable throwable )
{
if( !( throwable instanceof OutOfMemoryError ) )
LOG.error( "caught throwable", throwable );
return throwable;
}
finally
{
try
{
if( iterator != null )
iterator.close();
}
catch( Throwable currentThrowable )
{
if( !( currentThrowable instanceof OutOfMemoryError ) )
LOG.warn( "failed closing iterator", currentThrowable );
localThrowable = currentThrowable;
}
}
return localThrowable;
}
@Override
public void initialize()
{
}
@Override
public void receive( Duct previous, Void nada )
{
throw new UnsupportedOperationException( "use call() instead" );
}
}