org.gridgain.grid.compute

Class GridComputeTaskAdapter<T,R>

java.lang.Object

org.gridgain.grid.compute.GridComputeTaskAdapter<T,R>

Type Parameters:

T - Type of the task argument.

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

All Implemented Interfaces:

Serializable, GridComputeTask<T,R>

Direct Known Subclasses:

GridCacheQueryJdbcMetadataTask, GridCacheQueryJdbcTask, GridComputeTaskSplitAdapter, GridGgfsTask, GridifyDefaultRangeTask, GridifyDefaultTask, GridifyTaskAdapter, GridPeerDeployAwareTaskAdapter

public abstract class GridComputeTaskAdapter<T,R>
extends Object
implements GridComputeTask<T,R>

Convenience adapter for GridComputeTask interface. Here is an example of how GridComputeTaskAdapter can be used:

 public class MyFooBarTask extends GridComputeTaskAdapter<String, String> {
     // Inject load balancer.
     @GridLoadBalancerResource
     GridComputeLoadBalancer balancer;

     // Map jobs to grid nodes.
     public Map<? extends GridComputeJob, GridNode> map(List<GridNode> subgrid, String arg) throws GridException {
         Map<MyFooBarJob, GridNode> jobs = new HashMap<MyFooBarJob, GridNode>(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<GridComputeJobResult> results) throws GridException {
         // For the purpose of this example we simply
         // concatenate string representation of every
         // job result
         StringBuilder buf = new StringBuilder();

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

         return buf.string();
     }
 }
 

For more information refer to GridComputeTask documentation.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
GridComputeTaskAdapter()

Method Summary

Methods

Modifier and Type	Method and Description
GridComputeJobResultPolicy	result(GridComputeJobResult res, List<GridComputeJobResult> rcvd) Default implementation which will wait for all jobs to complete before calling GridComputeTask.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.gridgain.grid.compute.GridComputeTask

map, reduce

Constructor Detail

GridComputeTaskAdapter

public GridComputeTaskAdapter()

Method Detail

result

public GridComputeJobResultPolicy result(GridComputeJobResult res,
                                List<GridComputeJobResult> rcvd)
                                  throws GridException

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

If remote job resulted in exception (GridComputeJobResult.getException() is not null), then GridComputeJobResultPolicy.FAILOVER policy will be returned if the exception is instance of GridTopologyException or GridComputeExecutionRejectedException, 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 GridComputeTask<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:

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