org.gridgain.grid.compute

Class GridComputeTaskSplitAdapter<T,R>

java.lang.Object

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

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

Type Parameters:

T - Type of the task execution argument.

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

All Implemented Interfaces:

Serializable, GridComputeTask<T,R>

Direct Known Subclasses:

GridCacheQueryJdbcValidationTask, GridifyTaskSplitAdapter

public abstract class GridComputeTaskSplitAdapter<T,R>
extends GridComputeTaskAdapter<T,R>

This class defines simplified adapter for GridComputeTask. This adapter can be used when jobs can be randomly assigned to available grid nodes. This adapter is sufficient in most homogeneous environments where all nodes are equally suitable for executing grid job. See split(int, Object) method for more details.

Below is a coding example of how you would use GridComputeTaskSplitAdapter:

 public class MyFooBarTask extends GridComputeTaskSplitAdapter<Object, String> {
     @Override
     protected Collection<? extends GridComputeJob> split(int gridSize, Object arg) throws GridException {
         List<MyFooBarJob> jobs = new ArrayList<MyFooBarJob>(gridSize);

         for (int i = 0; i < gridSize; i++) {
             jobs.add(new MyFooBarJob(arg));
         }

         // Node assignment via load balancer
         // happens automatically.
         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();
     }
 }
 

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
GridComputeTaskSplitAdapter()

Method Summary

Methods

Modifier and Type	Method and Description
Map<? extends GridComputeJob,GridNode>	map(List<GridNode> subgrid, T arg) This method is called to map or split grid task into multiple grid jobs.
protected abstract Collection<? extends GridComputeJob>	split(int gridSize, T arg) This is a simplified version of GridComputeTask.map(List, Object) method.

Methods inherited from class org.gridgain.grid.compute.GridComputeTaskAdapter

result

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

reduce

Constructor Detail

GridComputeTaskSplitAdapter

public GridComputeTaskSplitAdapter()

Method Detail

split

protected abstract Collection<? extends GridComputeJob> split(int gridSize,
                                         T arg)
                                                       throws GridException

This is a simplified version of GridComputeTask.map(List, Object) method.

This method basically takes given argument and splits it into a collection of GridComputeJob using provided grid size as indication of how many node are available. These jobs will be randomly mapped to available grid nodes. Note that if number of jobs is greater than number of grid nodes (i.e, grid size), the grid nodes will be reused and some jobs will end up on the same grid nodes.

Parameters:

gridSize - Number of available grid nodes. Note that returned number of jobs can be less, equal or greater than this grid size.

arg - Task execution argument. Can be null.

Returns:

Collection of grid jobs. These jobs will be randomly mapped to available grid nodes. Note that if number of jobs is greater than number of grid nodes (i.e, grid size), the grid nodes will be reused and some jobs will end up on the same grid nodes.

Throws:

GridException - Thrown in case of any errors.

See Also:

GridComputeTask.map(List, Object)

map

public final Map<? extends GridComputeJob,GridNode> map(List<GridNode> subgrid,
                                         T arg)
                                                 throws GridException

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 GridComputeTaskContinuousMapper is injected into task, if null or empty map is returned, exception will be thrown.

Throws:

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