com.hazelcast.mapreduce

Interface MappingJob<EntryKey,KeyIn,ValueIn>

Type Parameters:

EntryKey - type of the original input key

KeyIn - type of key used as input key type

ValueIn - type of value used as input value type

All Known Implementing Classes:

AbstractJob.MappingJobImpl

@Beta
public interface MappingJob<EntryKey,KeyIn,ValueIn>

This interface describes a mapping mapreduce Job.
For further information see Job.

Since:

3.2

See Also:

Job

Method Summary

Modifier and Type	Method and Description
MappingJob<EntryKey,KeyIn,ValueIn>	chunkSize(int chunkSize) Defines the number of elements per chunk.
<ValueOut> ReducingJob<EntryKey,KeyIn,ValueOut>	combiner(CombinerFactory<? super KeyIn,? super ValueIn,? extends ValueOut> combinerFactory) Defines the CombinerFactory for this task.
MappingJob<EntryKey,KeyIn,ValueIn>	keyPredicate(KeyPredicate<? super EntryKey> predicate) Defines the KeyPredicate implementation to preselect keys that the MapReduce task will be executed on.
MappingJob<EntryKey,KeyIn,ValueIn>	onKeys(EntryKey... keys) Defines keys to execute the mapper and a possibly defined reducer against.
MappingJob<EntryKey,KeyIn,ValueIn>	onKeys(Iterable<? extends EntryKey> keys) Defines keys to execute the mapper and a possibly defined reducer against.
<ValueOut> ReducingSubmittableJob<EntryKey,KeyIn,ValueOut>	reducer(ReducerFactory<? super KeyIn,? super ValueIn,? extends ValueOut> reducerFactory) Defines the ReducerFactory for this task.
JobCompletableFuture<Map<KeyIn,List<ValueIn>>>	submit() Submits the task to Hazelcast and executes the defined mapper and reducer on all cluster nodes.
<ValueOut> JobCompletableFuture<ValueOut>	submit(Collator<Map.Entry<KeyIn,List<ValueIn>>,ValueOut> collator) Submits the task to Hazelcast, executes the defined mapper and reducer on all cluster nodes, and executes the collator before returning the final result.
MappingJob<EntryKey,KeyIn,ValueIn>	topologyChangedStrategy(TopologyChangedStrategy topologyChangedStrategy) Defines the strategy to handle topology changes while executing the map reduce job.

Method Detail

onKeys

MappingJob<EntryKey,KeyIn,ValueIn> onKeys(Iterable<? extends EntryKey> keys)

Defines keys to execute the mapper and a possibly defined reducer against. If keys are known before submitting the task, setting them can improve execution speed.

Parameters:

keys - keys to be executed against

Returns:

instance of this Job with generics changed on usage

onKeys

MappingJob<EntryKey,KeyIn,ValueIn> onKeys(EntryKey... keys)

Defines keys to execute the mapper and a possibly defined reducer against. If keys are known before submitting the task, setting them can improve execution speed.

Parameters:

keys - keys to be executed against

Returns:

instance of this Job with generics changed on usage

keyPredicate

MappingJob<EntryKey,KeyIn,ValueIn> keyPredicate(KeyPredicate<? super EntryKey> predicate)

Defines the KeyPredicate implementation to preselect keys that the MapReduce task will be executed on. Preselecting keys can speed up the job massively.
This method can be used in conjunction with onKeys(Iterable) or onKeys(Object...) to define a range of known and evaluated keys.

Parameters:

predicate - predicate implementation to be used to evaluate keys

Returns:

instance of this Job with generics changed on usage

chunkSize

MappingJob<EntryKey,KeyIn,ValueIn> chunkSize(int chunkSize)

Defines the number of elements per chunk. Whenever the chunk size is reached and a ReducerFactory is defined, the chunk will be sent to the nodes that are responsible for the emitted keys.
Please note, that chunks are deactivated when no ReducerFactory is defined

Parameters:

chunkSize - the number of elements per chunk

Returns:

instance of this Job with generics changed on usage

topologyChangedStrategy

MappingJob<EntryKey,KeyIn,ValueIn> topologyChangedStrategy(TopologyChangedStrategy topologyChangedStrategy)

Defines the strategy to handle topology changes while executing the map reduce job. For further information see TopologyChangedStrategy.

Parameters:

topologyChangedStrategy - strategy to use

Returns:

instance of this Job with generics changed on usage

combiner

<ValueOut> ReducingJob<EntryKey,KeyIn,ValueOut> combiner(CombinerFactory<? super KeyIn,? super ValueIn,? extends ValueOut> combinerFactory)

Defines the CombinerFactory for this task. This method is not idempotent and is callable only one time. Further calls result in an IllegalStateException thrown telling you to not change the internal state.

Type Parameters:

ValueOut - type of the combined value

Parameters:

combinerFactory - CombinerFactory to build Combiner

Returns:

instance of this Job with generics changed on usage

reducer

<ValueOut> ReducingSubmittableJob<EntryKey,KeyIn,ValueOut> reducer(ReducerFactory<? super KeyIn,? super ValueIn,? extends ValueOut> reducerFactory)

Defines the ReducerFactory for this task. This method is not idempotent and is callable only one time. Further calls result in an IllegalStateException thrown telling you to not change the internal state.

Type Parameters:

ValueOut - type of the reduced value

Parameters:

reducerFactory - ReducerFactory to build Reducers

Returns:

instance of this Job with generics changed on usage

submit

JobCompletableFuture<Map<KeyIn,List<ValueIn>>> submit()

Submits the task to Hazelcast and executes the defined mapper and reducer on all cluster nodes.

Returns:

JobCompletableFuture to wait for mapped and possibly reduced result

submit

<ValueOut> JobCompletableFuture<ValueOut> submit(Collator<Map.Entry<KeyIn,List<ValueIn>>,ValueOut> collator)

Submits the task to Hazelcast, executes the defined mapper and reducer on all cluster nodes, and executes the collator before returning the final result.

Type Parameters:

ValueOut - type of the collated value

Parameters:

collator - collator to use after map and reduce

Returns:

JobCompletableFuture to wait for mapped and possibly reduced result