org.apache.flink.graph.gsa

Class GatherFunction<VV,EV,M>

java.lang.Object

org.apache.flink.graph.gsa.GatherFunction<VV,EV,M>

Type Parameters:

VV - the vertex value type

EV - the edge value type

M - the output type

All Implemented Interfaces:

Serializable

public abstract class GatherFunction<VV,EV,M>
extends Object
implements Serializable

The base class for the first step of a GatherSumApplyIteration.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
GatherFunction()

Method Summary

Modifier and Type	Method and Description
abstract M	gather(Neighbor<VV,EV> neighbor) This method is invoked once per superstep, for each Neighbor of each Vertex in the beginning of each superstep in a GatherSumApplyIteration.
<T> Collection<T>	getBroadcastSet(String name) Gets the broadcast data set registered under the given name.
<T extends Aggregator<?>> T	getIterationAggregator(String name) Gets the iteration aggregator registered under the given name.
long	getNumberOfVertices() Retrieves the number of vertices in the graph.
<T extends Value> T	getPreviousIterationAggregate(String name) Get the aggregated value that an aggregator computed in the previous iteration.
int	getSuperstepNumber() Gets the number of the superstep, starting at 1.
void	init(IterationRuntimeContext iterationRuntimeContext)
void	postSuperstep() This method is executed once per superstep after the vertex update function has been invoked for each vertex.
void	preSuperstep() This method is executed once per superstep before the vertex update function is invoked for each vertex.

Methods inherited from class java.lang.Object

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

Constructor Detail

GatherFunction

public GatherFunction()

Method Detail

getNumberOfVertices

public long getNumberOfVertices()

Retrieves the number of vertices in the graph.

Returns:

the number of vertices if the IterationConfiguration.setOptNumVertices(boolean) option has been set; -1 otherwise.

gather

public abstract M gather(Neighbor<VV,EV> neighbor)

This method is invoked once per superstep, for each Neighbor of each Vertex in the beginning of each superstep in a GatherSumApplyIteration. It needs to produce a partial value, which will be combined with other partial value in the next phase of the iteration.

Parameters:

neighbor - the input Neighbor. It provides access to the source Vertex and the Edge objects.

Returns:

a partial result to be combined in the Sum phase.

preSuperstep

public void preSuperstep()

This method is executed once per superstep before the vertex update function is invoked for each vertex.

postSuperstep

public void postSuperstep()

This method is executed once per superstep after the vertex update function has been invoked for each vertex.

getSuperstepNumber

public int getSuperstepNumber()

Gets the number of the superstep, starting at 1.

Returns:

The number of the current superstep.

getIterationAggregator

public <T extends Aggregator<?>> T getIterationAggregator(String name)

Gets the iteration aggregator registered under the given name. The iteration aggregator combines all aggregates globally once per superstep and makes them available in the next superstep.

Parameters:

name - The name of the aggregator.

Returns:

The aggregator registered under this name, or null, if no aggregator was registered.

getPreviousIterationAggregate

public <T extends Value> T getPreviousIterationAggregate(String name)

Get the aggregated value that an aggregator computed in the previous iteration.

Parameters:

name - The name of the aggregator.

Returns:

The aggregated value of the previous iteration.

getBroadcastSet

public <T> Collection<T> getBroadcastSet(String name)

Gets the broadcast data set registered under the given name. Broadcast data sets are available on all parallel instances of a function.

Parameters:

name - The name under which the broadcast set is registered.

Returns:

The broadcast data set.

init

public void init(IterationRuntimeContext iterationRuntimeContext)