/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.giraph.jython;
import org.apache.giraph.graph.AbstractComputation;
import org.apache.giraph.graph.GraphType;
import org.apache.giraph.graph.Language;
import org.apache.giraph.graph.Vertex;
import org.apache.giraph.jython.wrappers.JythonWritableWrapper;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparable;
import org.python.core.PyObject;
import com.google.common.base.Preconditions;
import java.io.IOException;
/**
* The {@link Computation} class for using Jython with Giraph. This class
* implements the Giraph necessary interfaces but it actually holds a reference
* to the {@link JythonComputation} which does the real work.
*
* The two classes are linked and together they allow us to coerce Jython types
* to Writables.
*
* @param <I> Vertex ID
* @param <V> Vertex value
* @param <E> Edge value
* @param <M1> Incoming message value
* @param <M2> Outgoing message value
*/
public class JythonGiraphComputation<I extends WritableComparable,
V extends Writable, E extends Writable, M1 extends Writable,
M2 extends Writable>
extends AbstractComputation<I, V, E, M1, M2> {
/** The user's computation class */
private final JythonComputation jythonComputation;
/**
* Constructor
*
* @param jythonComputation the user's Jython computation
*/
public JythonGiraphComputation(JythonComputation jythonComputation) {
this.jythonComputation = jythonComputation;
}
@Override public void compute(Vertex<I, V, E> vertex, Iterable<M1> messages)
throws IOException {
jythonComputation.compute(vertex, messages);
}
/**
* Wrap a vertex id in a {@link WritableComparable} wrapper if necessary
*
* @param object data to wrap
* @return writable value
*/
public WritableComparable wrapIdIfNecessary(Object object) {
return wrapIfNecessary(object, GraphType.VERTEX_ID);
}
/**
* Wrap a user value (IVEMM) in a {@link Writable} wrapper if necessary
*
* @param object data to wrap
* @param graphType type of data (IVEMM)
* @param <W> writable type
* @return writable value
*/
public <W extends Writable> W
wrapIfNecessary(Object object, GraphType graphType) {
if (graphType.interfaceClass().isInstance(object)) {
return (W) object;
}
if (getConf().getValueLanguages().get(graphType) == Language.JYTHON &&
getConf().getValueNeedsWrappers().get(graphType)) {
Preconditions.checkArgument(object instanceof PyObject);
return (W) new JythonWritableWrapper((PyObject) object);
} else {
return (W) object;
}
}
}