org.apache.ignite.compute

Class ComputeTaskAdapter<T,R>

java.lang.Object

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

Type Parameters:

T - Type of the task argument.

R - Type of the task result returning from ComputeTask.reduce(List) method.

All Implemented Interfaces:

Serializable, ComputeTask<T,R>

Direct Known Subclasses:

ComputeTaskSplitAdapter

public abstract class ComputeTaskAdapter<T,R>
extends Object
implements ComputeTask<T,R>

Convenience adapter for ComputeTask interface. Here is an example of how ComputeTaskAdapter can be used:

 public class MyFooBarTask extends ComputeTaskAdapter<String, String> {
     // Inject load balancer.
     @LoadBalancerResource
     ComputeLoadBalancer balancer;

     // Map jobs to grid nodes.
     public Map<? extends ComputeJob, ClusterNode> map(List<ClusterNode> subgrid, String arg) throws IgniteCheckedException {
         Map<MyFooBarJob, ClusterNode> jobs = new HashMap<MyFooBarJob, ClusterNode>(subgrid.size());

         // In more complex cases, you can actually do
         // more complicated assignments of jobs to nodes.
         for (int i = 0; i < subgrid.size(); i++) {
             // Pick the next best balanced node for the job.
             jobs.put(new MyFooBarJob(arg), balancer.getBalancedNode())
         }

         return jobs;
     }

     // Aggregate results into one compound result.
     public String reduce(List<ComputeJobResult> results) throws IgniteCheckedException {
         // For the purpose of this example we simply
         // concatenate string representation of every
         // job result
         StringBuilder buf = new StringBuilder();

         for (ComputeJobResult res : results) {
             // Append string representation of result
             // returned by every job.
             buf.append(res.getData().string());
         }

         return buf.string();
     }
 }
 

For more information refer to ComputeTask documentation.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ComputeTaskAdapter()

Method Summary

Modifier and Type	Method and Description
ComputeJobResultPolicy	result(ComputeJobResult res, List<ComputeJobResult> rcvd) Default implementation which will wait for all jobs to complete before calling ComputeTask.reduce(List) method.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.ignite.compute.ComputeTask

map, reduce

Constructor Detail

ComputeTaskAdapter

public ComputeTaskAdapter()

Method Detail

result

public ComputeJobResultPolicy result(ComputeJobResult res,
                                     List<ComputeJobResult> rcvd)
                              throws IgniteException

Default implementation which will wait for all jobs to complete before calling ComputeTask.reduce(List) method.

If remote job resulted in exception (ComputeJobResult.getException() is not null), then ComputeJobResultPolicy.FAILOVER policy will be returned if the exception is instance of ClusterTopologyException or ComputeExecutionRejectedException, which means that remote node either failed or job execution was rejected before it got a chance to start. In all other cases the exception will be rethrown which will ultimately cause task to fail.

Specified by:

result in interface ComputeTask<T,R>

Parameters:

res - Received remote grid executable result.

rcvd - All previously received results.

Returns:

Result policy that dictates how to process further upcoming job results.

Throws:

IgniteException - If handling a job result caused an error effectively rejecting a failover. This exception will be thrown out of ComputeTaskFuture.get() method.