org.apache.beam.runners.direct

Interface TransformEvaluatorFactory

public interface TransformEvaluatorFactory

A factory for creating instances of TransformEvaluator for the application of a PTransform.

TransformEvaluatorFactories will be reused within a single execution of a Pipeline but will not be reused across executions.

Method Summary

Modifier and Type	Method and Description
void	cleanup() Cleans up any state maintained by this TransformEvaluatorFactory.
<InputT> TransformEvaluator<InputT>	forApplication(AppliedPTransform<?,?,?> application, org.apache.beam.runners.direct.DirectRunner.CommittedBundle<?> inputBundle) Create a new TransformEvaluator for the application of the PTransform.

Method Detail

forApplication

@Nullable
<InputT> TransformEvaluator<InputT> forApplication(AppliedPTransform<?,?,?> application,
                                                             org.apache.beam.runners.direct.DirectRunner.CommittedBundle<?> inputBundle)
                                                      throws Exception

Create a new TransformEvaluator for the application of the PTransform.

Any work that must be done before input elements are processed (such as calling DoFn.StartBundle) must be done before the TransformEvaluator is made available to the caller.

May return null if the application cannot produce an evaluator (for example, it is a Read PTransform where all evaluators are in-use).

Returns:

An evaluator capable of processing the transform on the bundle, or null if no evaluator can be constructed.

Throws:

Exception - whenever constructing the underlying evaluator throws an exception

cleanup

void cleanup()
      throws Exception

Cleans up any state maintained by this TransformEvaluatorFactory. Called after a Pipeline is shut down. No more calls to #forApplication(AppliedPTransform, CommittedBundle) will be made after a call to cleanup().

Throws:

Exception