org.apache.giraph.combiner

Interface MessageCombiner<I extends org.apache.hadoop.io.WritableComparable,M extends org.apache.hadoop.io.Writable>

Type Parameters:

I - Vertex id

M - Message data

All Known Implementing Classes:

DoubleSumMessageCombiner, FloatSumMessageCombiner, MaxMessageCombiner, MinimumDoubleMessageCombiner, MinimumIntMessageCombiner, MinMessageCombiner, NullMessageCombiner, SimpleSumMessageCombiner, SumMessageCombiner

public interface MessageCombiner<I extends org.apache.hadoop.io.WritableComparable,M extends org.apache.hadoop.io.Writable>

Abstract class to extend for combining messages sent to the same vertex. MessageCombiner for applications where each two messages for one vertex can be combined into one.

Method Summary

Modifier and Type	Method and Description
void	combine(I vertexIndex, M originalMessage, M messageToCombine) Combine messageToCombine with originalMessage, by modifying originalMessage.
M	createInitialMessage() Get the initial message.

Method Detail

combine

void combine(I vertexIndex,
             M originalMessage,
             M messageToCombine)

Combine messageToCombine with originalMessage, by modifying originalMessage. Note that the messageToCombine object may be reused by the infrastructure, therefore, you cannot directly use it or any objects from it in original message

Parameters:

vertexIndex - Index of the vertex getting these messages

originalMessage - The first message which we want to combine; put the result of combining in this message

messageToCombine - The second message which we want to combine (object may be reused - do not reference it or its member objects)

createInitialMessage

M createInitialMessage()

Get the initial message. When combined with any other message M, the result should be M.

Returns:

Initial message