org.apache.giraph.jython

Class JythonComputation

java.lang.Object

org.apache.giraph.conf.DefaultImmutableClassesGiraphConfigurable

org.apache.giraph.jython.JythonComputation

All Implemented Interfaces:

GiraphConfigurationSettable, ImmutableClassesGiraphConfigurable

public abstract class JythonComputation
extends DefaultImmutableClassesGiraphConfigurable

Base class for writing computations in Jython. Note that this class DOES NOT implement Computation. This is because we want to support passing in pure Jython types, and implementing the Computation requires passing in Writables. Calling such methods from Jython would throw errors. So, instead, we have recreated the methods with the same name here. In each method we check if the type is a pure Jython value, and if so wrap it in the necessary JythonWritableWrapper. This class works together with JythonGiraphComputation which takes care of the Computation Giraph infrastructure side of things.

Constructor Summary

Constructors

Constructor and Description
JythonComputation()

Method Summary

Modifier and Type	Method and Description
void	addEdgeRequest(Object sourceVertexId, Edge edge) Request to add an edge of a vertex in the graph (processed just prior to the next superstep)
void	addVertexRequest(Object id, Object vertexValue) Sends a request to create a vertex that will be available during the next superstep.
void	addVertexRequest(Object id, Object vertexValue, OutEdges edges) Sends a request to create a vertex that will be available during the next superstep.
abstract void	compute(Object vertex, Iterable messages) User's computation function
org.apache.hadoop.mapreduce.Mapper.Context	getContext() Get the mapper context
long	getSuperstep() Retrieves the current superstep.
long	getTotalNumEdges() Get the total (all workers) number of edges that existed in the previous superstep.
long	getTotalNumVertices() Get the total (all workers) number of vertices that existed in the previous superstep.
<W extends WorkerContext> W	getWorkerContext() Get the worker context
void	postSuperstep() Finish computation.
void	preSuperstep() Prepare for computation.
void	removeEdgesRequest(Object sourceVertexId, Object targetVertexId) Request to remove all edges from a given source vertex to a given target vertex (processed just prior to the next superstep).
void	removeVertexRequest(Object id) Request to remove a vertex from the graph (applied just prior to the next superstep).
void	sendMessage(Object id, Object message) Send a message to a vertex id.
void	sendMessageToAllEdges(Vertex vertex, Object message) Send a message to all edges.
void	sendMessageToMultipleEdges(Iterator vertexIdIterator, Object message) Send a message to multiple target vertex ids in the iterator.
void	setGiraphCompute(JythonGiraphComputation giraphCompute)

Methods inherited from class org.apache.giraph.conf.DefaultImmutableClassesGiraphConfigurable

getConf, setConf

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

JythonComputation

public JythonComputation()

Method Detail

setGiraphCompute

public void setGiraphCompute(JythonGiraphComputation giraphCompute)

compute

public abstract void compute(Object vertex,
                             Iterable messages)

User's computation function

Parameters:

vertex - the Vertex to compute on

messages - iterable of messages

preSuperstep

public void preSuperstep()

Prepare for computation. This method is executed exactly once prior to compute(Object, Iterable) being called for any of the vertices in the partition.

postSuperstep

public void postSuperstep()

Finish computation. This method is executed exactly once after computation for all vertices in the partition is complete.

getSuperstep

public long getSuperstep()

Retrieves the current superstep.

Returns:

Current superstep

getTotalNumVertices

public long getTotalNumVertices()

Get the total (all workers) number of vertices that existed in the previous superstep.

Returns:

Total number of vertices (-1 if first superstep)

getTotalNumEdges

public long getTotalNumEdges()

Get the total (all workers) number of edges that existed in the previous superstep.

Returns:

Total number of edges (-1 if first superstep)

sendMessage

public void sendMessage(Object id,
                        Object message)

Send a message to a vertex id.

Parameters:

id - Vertex id to send the message to

message - Message data to send

sendMessageToAllEdges

public void sendMessageToAllEdges(Vertex vertex,
                                  Object message)

Send a message to all edges.

Parameters:

vertex - Vertex whose edges to send the message to.

message - Message sent to all edges.

sendMessageToMultipleEdges

public void sendMessageToMultipleEdges(Iterator vertexIdIterator,
                                       Object message)

Send a message to multiple target vertex ids in the iterator.

Parameters:

vertexIdIterator - An iterator to multiple target vertex ids.

message - Message sent to all targets in the iterator.

addVertexRequest

public void addVertexRequest(Object id,
                             Object vertexValue,
                             OutEdges edges)
                      throws IOException

Sends a request to create a vertex that will be available during the next superstep.

Parameters:

id - Vertex id

vertexValue - Vertex value

edges - Initial edges

Throws:

IOException

addVertexRequest

public void addVertexRequest(Object id,
                             Object vertexValue)
                      throws IOException

Sends a request to create a vertex that will be available during the next superstep.

Parameters:

id - Vertex id

vertexValue - Vertex value

Throws:

IOException

removeVertexRequest

public void removeVertexRequest(Object id)
                         throws IOException

Request to remove a vertex from the graph (applied just prior to the next superstep).

Parameters:

id - Id of the vertex to be removed.

Throws:

IOException

addEdgeRequest

public void addEdgeRequest(Object sourceVertexId,
                           Edge edge)
                    throws IOException

Request to add an edge of a vertex in the graph (processed just prior to the next superstep)

Parameters:

sourceVertexId - Source vertex id of edge

edge - Edge to add

Throws:

IOException

removeEdgesRequest

public void removeEdgesRequest(Object sourceVertexId,
                               Object targetVertexId)
                        throws IOException

Request to remove all edges from a given source vertex to a given target vertex (processed just prior to the next superstep).

Parameters:

sourceVertexId - Source vertex id

targetVertexId - Target vertex id

Throws:

IOException

getContext

public org.apache.hadoop.mapreduce.Mapper.Context getContext()

Get the mapper context

Returns:

Mapper context

getWorkerContext

public <W extends WorkerContext> W getWorkerContext()

Get the worker context

Type Parameters:

W - WorkerContext class

Returns:

WorkerContext context