org.apache.storm.cassandra

Class Murmur3StreamGrouping

java.lang.Object

org.apache.storm.cassandra.Murmur3StreamGrouping

All Implemented Interfaces:

Serializable, CustomStreamGrouping

public class Murmur3StreamGrouping
extends Object
implements CustomStreamGrouping

Simple CustomStreamGrouping that uses Murmur3 algorithm to choose the target task of a tuple.

This stream grouping may be used to optimise writes to Apache Cassandra.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
Murmur3StreamGrouping(List<String> partitionKeyNames) Creates a new Murmur3StreamGrouping instance.
Murmur3StreamGrouping(String... partitionKeyNames) Creates a new Murmur3StreamGrouping instance.

Method Summary

Modifier and Type	Method and Description
List<Integer>	chooseTasks(int taskId, List<Object> values)
static long	hashes(List<Object> values) Computes the murmur3 hash for the specified values.
void	prepare(WorkerTopologyContext context, GlobalStreamId stream, List<Integer> targetTasks)

Methods inherited from class java.lang.Object

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

Constructor Detail

Murmur3StreamGrouping

public Murmur3StreamGrouping(String... partitionKeyNames)

Creates a new Murmur3StreamGrouping instance.

Parameters:

partitionKeyNames - partitionKeyNames.

Murmur3StreamGrouping

public Murmur3StreamGrouping(List<String> partitionKeyNames)

Creates a new Murmur3StreamGrouping instance.

Parameters:

partitionKeyNames - partitionKeyNames.

Method Detail

prepare

public void prepare(WorkerTopologyContext context,
                    GlobalStreamId stream,
                    List<Integer> targetTasks)

Specified by:

prepare in interface CustomStreamGrouping

chooseTasks

public List<Integer> chooseTasks(int taskId,
                                 List<Object> values)

Specified by:

chooseTasks in interface CustomStreamGrouping

hashes

public static long hashes(List<Object> values)
                   throws IOException

Computes the murmur3 hash for the specified values. http://stackoverflow.com/questions/27212797/cassandra-hashing-algorithm-with-composite-keys https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/db/marshal/CompositeType.java

Parameters:

values - the fields which are part of the (compose) partition key.

Returns:

the computed hash for input values.

Throws:

IOException