package storm.trident.partition;
import backtype.storm.generated.GlobalStreamId;
import backtype.storm.grouping.CustomStreamGrouping;
import backtype.storm.task.WorkerTopologyContext;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class IdentityGrouping implements CustomStreamGrouping {
List<Integer> ret = new ArrayList<Integer>();
Map<Integer, List<Integer>> _precomputed = new HashMap();
@Override
public void prepare(WorkerTopologyContext context, GlobalStreamId stream, List<Integer> tasks) {
List<Integer> sourceTasks = new ArrayList<Integer>(context.getComponentTasks(stream.get_componentId()));
Collections.sort(sourceTasks);
if(sourceTasks.size()!=tasks.size()) {
throw new RuntimeException("Can only do an identity grouping when source and target have same number of tasks");
}
tasks = new ArrayList<Integer>(tasks);
Collections.sort(tasks);
for(int i=0; i<sourceTasks.size(); i++) {
int s = sourceTasks.get(i);
int t = tasks.get(i);
_precomputed.put(s, Arrays.asList(t));
}
}
@Override
public List<Integer> chooseTasks(int task, List<Object> values) {
List<Integer> ret = _precomputed.get(task);
if(ret==null) {
throw new RuntimeException("Tuple emitted by task that's not part of this component. Should be impossible");
}
return ret;
}
}