backtype.storm.grouping
Interface CustomStreamGrouping
- All Superinterfaces:
- java.io.Serializable
- All Known Implementing Classes:
- NGrouping
public interface CustomStreamGrouping
- extends java.io.Serializable
Method Summary |
void |
prepare(Fields outFields,
int numTasks)
Tells the stream grouping at runtime the number of tasks in the target bolt. |
java.util.List<java.lang.Integer> |
taskIndices(java.util.List<java.lang.Object> values)
This function implements a custom stream grouping. |
prepare
void prepare(Fields outFields,
int numTasks)
- Tells the stream grouping at runtime the number of tasks in the target bolt.
This information should be used in taskIndicies to determine the target tasks.
It also tells the grouping the metadata on the stream this grouping will be used on.
taskIndices
java.util.List<java.lang.Integer> taskIndices(java.util.List<java.lang.Object> values)
- 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
indices of the tasks to send the tuple to. Each index must be in the range
[0, numTargetTasks-1]
- Parameters:
tuple
- the values to group onnumTargetTasks
- the number of tasks in the target bolt