org.apache.beam.sdk.io

Class BoundedReadFromUnboundedSource<T>

java.lang.Object

org.apache.beam.sdk.transforms.PTransform<PBegin,PCollection<T>>

org.apache.beam.sdk.io.BoundedReadFromUnboundedSource<T>

All Implemented Interfaces:

java.io.Serializable, HasDisplayData

public class BoundedReadFromUnboundedSource<T>
extends PTransform<PBegin,PCollection<T>>

PTransform that reads a bounded amount of data from an UnboundedSource, specified as one or both of a maximum number of elements or a maximum period of time to read.

See Also:

Serialized Form

Field Summary

Fields inherited from class org.apache.beam.sdk.transforms.PTransform

name

Method Summary

Modifier and Type	Method and Description
PCollection<T>	expand(PBegin input) Override this method to specify how this PTransform should be expanded on the given InputT.
BoundedSource<ValueWithRecordId<T>>	getAdaptedSource() Returns an adapted BoundedSource wrapping the underlying UnboundedSource, with the specified bounds on number of records and read time.
java.lang.String	getKindString() Returns the name to use by default for this PTransform (not including the names of any enclosing PTransforms).
void	populateDisplayData(DisplayData.Builder builder) Register display data for the given transform or component.
BoundedReadFromUnboundedSource<T>	withMaxNumRecords(long maxNumRecords) Returns a new BoundedReadFromUnboundedSource that reads a bounded amount of data from the given UnboundedSource.
BoundedReadFromUnboundedSource<T>	withMaxReadTime(Duration maxReadTime) Returns a new BoundedReadFromUnboundedSource that reads a bounded amount of data from the given UnboundedSource.

Methods inherited from class org.apache.beam.sdk.transforms.PTransform

getAdditionalInputs, getDefaultOutputCoder, getDefaultOutputCoder, getDefaultOutputCoder, getName, toString, validate

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

withMaxNumRecords

public BoundedReadFromUnboundedSource<T> withMaxNumRecords(long maxNumRecords)

Returns a new BoundedReadFromUnboundedSource that reads a bounded amount of data from the given UnboundedSource. The bound is specified as a number of records to read.

This may take a long time to execute if the splits of this source are slow to read records.

withMaxReadTime

public BoundedReadFromUnboundedSource<T> withMaxReadTime(Duration maxReadTime)

Returns a new BoundedReadFromUnboundedSource that reads a bounded amount of data from the given UnboundedSource. The bound is specified as an amount of time to read for. Each split of the source will read for this much time.

getAdaptedSource

@Experimental
public BoundedSource<ValueWithRecordId<T>> getAdaptedSource()

Returns an adapted BoundedSource wrapping the underlying UnboundedSource, with the specified bounds on number of records and read time.

expand

public PCollection<T> expand(PBegin input)

Description copied from class: PTransform

Override this method to specify how this PTransform should be expanded on the given InputT.

NOTE: This method should not be called directly. Instead apply the PTransform should be applied to the InputT using the apply method.

Composite transforms, which are defined in terms of other transforms, should return the output of one of the composed transforms. Non-composite transforms, which do not apply any transforms internally, should return a new unbound output and register evaluators (via backend-specific registration methods).

Specified by:

expand in class PTransform<PBegin,PCollection<T>>

getKindString

public java.lang.String getKindString()

Description copied from class: PTransform

Returns the name to use by default for this PTransform (not including the names of any enclosing PTransforms).

By default, returns the base name of this PTransform's class.

The caller is responsible for ensuring that names of applied PTransforms are unique, e.g., by adding a uniquifying suffix when needed.

Overrides:

getKindString in class PTransform<PBegin,PCollection<T>>

populateDisplayData

public void populateDisplayData(DisplayData.Builder builder)

Description copied from class: PTransform

Register display data for the given transform or component.

populateDisplayData(DisplayData.Builder) is invoked by Pipeline runners to collect display data via DisplayData.from(HasDisplayData). Implementations may call super.populateDisplayData(builder) in order to register display data in the current namespace, but should otherwise use subcomponent.populateDisplayData(builder) to use the namespace of the subcomponent.

By default, does not register any display data. Implementors may override this method to provide their own display data.

Specified by:

populateDisplayData in interface HasDisplayData

Overrides:

populateDisplayData in class PTransform<PBegin,PCollection<T>>

Parameters:

builder - The builder to populate with display data.

See Also:

HasDisplayData