Package nz.org.riskscape.engine.pipeline

Interface StreamingCollector<T>

All Superinterfaces:
AutoCloseable, Realized
public interface StreamingCollector<T> extends Realized

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    accumulate(T accumulator, Tuple tuple)
    Give a tuple to the accumulator for accumulation.
    T
    combine(T lhs, T rhs)
    Combine two accumulators, returning an accumulator that contains the accumulated state of both.
    Struct
    getSourceType()
    The type of tuple this collector accepts.
    Struct
    getTargetType()
    The type of tuple this collector produces
    T
    newAccumulator()
    Create a new accumulator that holds collection/aggregation state for this collector to use.
    TupleIterator
    process(T accumulator)
    Convert an accumulator in to a set of results.

    Methods inherited from interface nz.org.riskscape.engine.pipeline.Realized

    close

  • Method Details

    • getSourceType

      Struct getSourceType()

      The type of tuple this collector accepts.

    • getTargetType

      Struct getTargetType()

      The type of tuple this collector produces

    • newAccumulator

      T newAccumulator()

      Create a new accumulator that holds collection/aggregation state for this collector to use. These don't need to be thread safe - any code making use of this API should assume they'll be accessed by only a single thread. NB do we want to support a shared accumulator API?

    • accumulate

      boolean accumulate(T accumulator, Tuple tuple)

      Give a tuple to the accumulator for accumulation. This should add any required state to the accumulator for this tuple, for example add a number to a running total, append an element to a list, etc.

    • combine

      T combine(T lhs, T rhs)

      Combine two accumulators, returning an accumulator that contains the accumulated state of both. This needs to be done in such a way that it produces the same result as if only one accumulator is used. Implementations are free to modify and return one of the given accumulators if it makes sense.

    • process

      TupleIterator process(T accumulator)

      Convert an accumulator in to a set of results. This can be done lazily, e.g. rows can be pulled from the accumulator on demand.