org.apache.flink.streaming.api.functions

Class AscendingTimestampExtractor<T>

java.lang.Object

org.apache.flink.streaming.api.functions.AscendingTimestampExtractor<T>

Type Parameters:

T - The type of the elements that this function can extract timestamps from

All Implemented Interfaces:

Serializable, Function, TimestampExtractor<T>

public abstract class AscendingTimestampExtractor<T>
extends Object
implements TimestampExtractor<T>

Interface for user functions that extract timestamps from elements. The extracting timestamps must be monotonically increasing.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
AscendingTimestampExtractor()

Method Summary

Methods

Modifier and Type	Method and Description
abstract long	extractAscendingTimestamp(T element, long currentTimestamp) Extracts a timestamp from an element.
long	extractTimestamp(T element, long currentTimestamp) Extracts a timestamp from an element.
long	extractWatermark(T element, long currentTimestamp) Asks the extractor if it wants to emit a watermark now that it has seen the given element.
long	getCurrentWatermark() Returns the current watermark.

Methods inherited from class java.lang.Object

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

Constructor Detail

AscendingTimestampExtractor

public AscendingTimestampExtractor()

Method Detail

extractAscendingTimestamp

public abstract long extractAscendingTimestamp(T element,
                             long currentTimestamp)

Extracts a timestamp from an element. The timestamp must be monotonically increasing.

Parameters:

element - The element that the timestamp is extracted from.

currentTimestamp - The current internal timestamp of the element.

Returns:

The new timestamp.

extractTimestamp

public final long extractTimestamp(T element,
                    long currentTimestamp)

Description copied from interface: TimestampExtractor

Extracts a timestamp from an element.

Specified by:

extractTimestamp in interface TimestampExtractor<T>

Parameters:

element - The element that the timestamp is extracted from.

currentTimestamp - The current internal timestamp of the element.

Returns:

The new timestamp.

extractWatermark

public final long extractWatermark(T element,
                    long currentTimestamp)

Description copied from interface: TimestampExtractor

Asks the extractor if it wants to emit a watermark now that it has seen the given element. This is called right after TimestampExtractor.extractTimestamp(T, long). With the same element. The method can return Long.MIN_VALUE to indicate that no watermark should be emitted, a value of 0 or greater will be emitted as a watermark if it is higher than the last-emitted watermark.

Specified by:

extractWatermark in interface TimestampExtractor<T>

Parameters:

element - The element that we last saw.

currentTimestamp - The current timestamp of the element that we last saw.

Returns:

Long.MIN_VALUE if no watermark should be emitted, positive value for emitting this value as a watermark.

getCurrentWatermark

public final long getCurrentWatermark()

Description copied from interface: TimestampExtractor

Returns the current watermark. This is periodically called by the system to determine the current watermark and forward it.

Specified by:

getCurrentWatermark in interface TimestampExtractor<T>

See Also:

Watermark