org.gridgain.grid
Class GridTaskAdapter<T,R>

java.lang.Object
  org.gridgain.grid.lang.GridMetadataAwareAdapter
      org.gridgain.grid.GridTaskAdapter<T,R>

Type Parameters:

T - Type of the task argument.

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

All Implemented Interfaces:

Serializable, Cloneable, GridMetadataAware, GridPeerDeployAware, GridTask<T,R>

Direct Known Subclasses:

GridifyTaskAdapter, GridTaskNoReduceAdapter, GridTaskSplitAdapter

public abstract class GridTaskAdapter<T,R>
extends GridMetadataAwareAdapter
implements GridTask<T,R>, GridPeerDeployAware

Convenience adapter for GridTask interface. Here is an example of how GridTaskAdapter can be used:

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

     // Map jobs to grid nodes.
     public Map<? extends GridJob, 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<GridJobResult> results) throws GridException {
         // For the purpose of this example we simply
         // concatenate string representation of every
         // job result
         StringBuilder buf = new StringBuilder();

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

         return buf.string();
     }
 }
 

For more information refer to GridTask documentation.

Wiki & Forum:

Wiki
Forum

See Also:

Serialized Form

Constructor Summary

protected	GridTaskAdapter() Empty constructor.
protected	GridTaskAdapter(GridPeerDeployAware pda) Constructor that receives deployment information for task.

Method Summary

ClassLoader	classLoader() Gets class loader for the class.
Class<?>	deployClass() Gets top level user class being deployed.
GridJobResultPolicy	result(GridJobResult res, List<GridJobResult> rcvd) Default implementation which will wait for all jobs to complete before calling GridTask.reduce(List) method.
void	setPeerDeployAware(GridPeerDeployAware pda) Sets deployment information for this task.

Methods inherited from class org.gridgain.grid.lang.GridMetadataAwareAdapter

addMeta, addMetaIfAbsent, addMetaIfAbsent, allMeta, clone, copyMeta, copyMeta, hasMeta, hasMeta, meta, putMetaIfAbsent, putMetaIfAbsent, readExternalMeta, removeMeta, removeMeta, replaceMeta, writeExternalMeta

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.gridgain.grid.GridTask

map, reduce

Constructor Detail

GridTaskAdapter

protected GridTaskAdapter()

Empty constructor.

GridTaskAdapter

protected GridTaskAdapter(GridPeerDeployAware pda)

Constructor that receives deployment information for task.

Parameters:

pda - Deployment information.

Method Detail

deployClass

public Class<?> deployClass()

Gets top level user class being deployed.

Specified by:

deployClass in interface GridPeerDeployAware

Returns:

Top level user deployed class.

classLoader

public ClassLoader classLoader()

Gets class loader for the class. This class loader must be able to load the class returned from GridPeerDeployAware.deployClass() as well as all of its dependencies.

Note that in most cases the class loader returned from this method and the class loader for the class returned from GridPeerDeployAware.deployClass() method will be the same. If they are not the same, it is required that the class loader returned from this method still has to be able to load the deploy class and all its dependencies.

Specified by:

classLoader in interface GridPeerDeployAware

Returns:

Class loader for the class.

setPeerDeployAware

public void setPeerDeployAware(GridPeerDeployAware pda)

Sets deployment information for this task.

Parameters:

pda - Deployment information.

result

public GridJobResultPolicy result(GridJobResult res,
                                  List<GridJobResult> rcvd)
                           throws GridException

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

If remote job resulted in exception (GridJobResult.getException() is not null), then GridJobResultPolicy.FAILOVER policy will be returned if the exception is instance of GridTopologyException or GridExecutionRejectedException, 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 GridTask<T,R>

Throws:

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

Parameters:

res - Received remote grid executable result.

rcvd - All previously received results.

Returns:

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