org.apache.storm.windowing

Interface Window<T>

Type Parameters:

T - the type of event that this window contains. E.g. Tuple

All Known Subinterfaces:

TupleWindow

All Known Implementing Classes:

TupleWindowImpl, TupleWindowIterImpl

public interface Window<T>

A view of events in a sliding window.

Method Summary

Modifier and Type	Method and Description
List<T>	get() Gets the list of events in the window.
Long	getEndTimestamp() If processing based on event time, returns the window end time based on watermark otherwise returns the window end time based on processing time.
List<T>	getExpired() Get the list of events expired from the window since the last time the window was generated.
default Iterator<T>	getIter() Returns an iterator over the events in the window.
List<T>	getNew() Get the list of newly added events in the window since the last time the window was generated.
Long	getStartTimestamp() Returns the window start timestamp.

Method Detail

get

List<T> get()

Gets the list of events in the window.

Note: If the number of tuples in windows is huge, invoking get would load all the tuples into memory and may throw an OOM exception. Use windowing with persistence (BaseStatefulWindowedBolt.withPersistence()) and getIter() to retrieve an iterator over the events in the window.

Returns:

the list of events in the window.

getIter

default Iterator<T> getIter()

Returns an iterator over the events in the window.

Note: This is only supported when using windowing with persistence BaseStatefulWindowedBolt.withPersistence().

Returns:

an Iterator over the events in the current window.

Throws:

UnsupportedOperationException - if not using BaseStatefulWindowedBolt.withPersistence()

getNew

List<T> getNew()

Get the list of newly added events in the window since the last time the window was generated.

Note: This is not supported when using windowing with persistence (BaseStatefulWindowedBolt.withPersistence()).

Returns:

the list of newly added events in the window.

Throws:

UnsupportedOperationException - if using BaseStatefulWindowedBolt.withPersistence()

getExpired

List<T> getExpired()

Get the list of events expired from the window since the last time the window was generated.

Note: This is not supported when using windowing with persistence (BaseStatefulWindowedBolt.withPersistence()).

Returns:

the list of events expired from the window.

Throws:

UnsupportedOperationException - if using BaseStatefulWindowedBolt.withPersistence()

getEndTimestamp

Long getEndTimestamp()

If processing based on event time, returns the window end time based on watermark otherwise returns the window end time based on processing time.

Returns:

the window end timestamp

getStartTimestamp

Long getStartTimestamp()

Returns the window start timestamp. Will return null if the window length is not based on time duration.

Returns:

the window start timestamp or null if the window length is not time based