package backtype.storm.grouping;
import backtype.storm.generated.GlobalStreamId;
import backtype.storm.task.WorkerTopologyContext;
import java.io.Serializable;
import java.util.List;
public interface CustomStreamGrouping extends Serializable {
/**
* Tells the stream grouping at runtime the tasks in the target bolt. This
* information should be used in chooseTasks to determine the target tasks.
*
* It also tells the grouping the metadata on the stream this grouping will
* be used on.
*/
void prepare(WorkerTopologyContext context, GlobalStreamId stream,
List<Integer> targetTasks);
/**
* This function implements a custom stream grouping. It takes in as input
* the number of tasks in the target bolt in prepare and returns the tasks
* to send the tuples to.
*
* @param values
* the values to group on
*/
List<Integer> chooseTasks(int taskId, List<Object> values);
}