Package org.apache.ignite.internal.util.future

Class IgniteRemoteMapTask<T,R>

java.lang.Object

org.apache.ignite.compute.ComputeTaskAdapter<T,R>

org.apache.ignite.internal.util.future.IgniteRemoteMapTask<T,R>

All Implemented Interfaces:

Serializable, ComputeTask<T,R>

@GridInternal
public class IgniteRemoteMapTask<T,R>
extends ComputeTaskAdapter<T,R>

Util task that will execute ComputeTask on a given node.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
IgniteRemoteMapTask(ClusterNode node, ComputeTask<T,R> remoteTask)

Method Summary

Modifier and Type	Method	Description
@NotNull Map<? extends ComputeJob,ClusterNode>	map(List<ClusterNode> subgrid, T arg)	This method is called to map or split grid task into multiple grid jobs.
R	reduce(List<ComputeJobResult> results)	Reduces (or aggregates) results received so far into one compound result to be returned to caller via ComputeTaskFuture.get() method.

Methods inherited from class org.apache.ignite.compute.ComputeTaskAdapter

result

Methods inherited from class java.lang.Object

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

Constructor Detail

IgniteRemoteMapTask

public IgniteRemoteMapTask(ClusterNode node,
                           ComputeTask<T,R> remoteTask)

Parameters:

node - Target node.

remoteTask - Delegate task.

Method Detail

map

@NotNull
public @NotNull Map<? extends ComputeJob,ClusterNode> map(List<ClusterNode> subgrid,
                                                                @Nullable
                                                                T arg)
                                                         throws IgniteException

This method is called to map or split grid task into multiple grid jobs. This is the first method that gets called when task execution starts.

Parameters:

subgrid - Nodes available for this task execution. Note that order of nodes is guaranteed to be randomized by container. This ensures that every time you simply iterate through grid nodes, the order of nodes will be random which over time should result into all nodes being used equally.

arg - Task execution argument. Can be null. This is the same argument as the one passed into Grid#execute(...) methods.

Returns:

Map of grid jobs assigned to subgrid node. Unless ComputeTaskContinuousMapper is injected into task, if null or empty map is returned, exception will be thrown.

Throws:

IgniteException - If mapping could not complete successfully. This exception will be thrown out of ComputeTaskFuture.get() method.

reduce

@Nullable
public R reduce(List<ComputeJobResult> results)
         throws IgniteException

Reduces (or aggregates) results received so far into one compound result to be returned to caller via ComputeTaskFuture.get() method.

Note, that if some jobs did not succeed and could not be failed over then the list of results passed into this method will include the failed results. Otherwise, failed results will not be in the list.

Parameters:

results - Received results of broadcasted remote executions. Note that if task class has ComputeTaskNoResultCache annotation, then this list will be empty.

Returns:

Grid job result constructed from results of remote executions.

Throws:

IgniteException - If reduction or results caused an error. This exception will be thrown out of ComputeTaskFuture.get() method.