org.apache.flink.streaming.api.functions.timestamps

Class AscendingTimestampExtractor<T>

java.lang.Object

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

Type Parameters:

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

All Implemented Interfaces:

Serializable, Function, AssignerWithPeriodicWatermarks<T>, TimestampAssigner<T>

Direct Known Subclasses:

AscendingTimestampExtractor

@PublicEvolving
public abstract class AscendingTimestampExtractor<T>
extends Object
implements AssignerWithPeriodicWatermarks<T>

A timestamp assigner and watermark generator for streams where timestamps are monotonously ascending. In this case, the local watermarks for the streams are easy to generate, because they strictly follow the timestamps.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AscendingTimestampExtractor.FailingHandler Handler that fails the program when timestamp monotony is violated.
static class	AscendingTimestampExtractor.IgnoringHandler Handler that does nothing when timestamp monotony is violated.
static class	AscendingTimestampExtractor.LoggingHandler Handler that only logs violations of timestamp monotony, on WARN log level.
static interface	AscendingTimestampExtractor.MonotonyViolationHandler Interface for handlers that handle violations of the monotonous ascending timestamps property.

Constructor Summary

Constructors

Constructor and Description
AscendingTimestampExtractor()

Method Summary

Modifier and Type	Method and Description
abstract long	extractAscendingTimestamp(T element) Extracts the timestamp from the given element.
long	extractTimestamp(T element, long elementPrevTimestamp) Assigns a timestamp to an element, in milliseconds since the Epoch.
Watermark	getCurrentWatermark() Returns the current watermark.
AscendingTimestampExtractor<T>	withViolationHandler(AscendingTimestampExtractor.MonotonyViolationHandler handler) Sets the handler for violations to the ascending timestamp order.

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)

Extracts the timestamp from the given element. The timestamp must be monotonically increasing.

Parameters:

element - The element that the timestamp is extracted from.

Returns:

The new timestamp.

withViolationHandler

public AscendingTimestampExtractor<T> withViolationHandler(AscendingTimestampExtractor.MonotonyViolationHandler handler)

Sets the handler for violations to the ascending timestamp order.

Parameters:

handler - The violation handler to use.

Returns:

This extractor.

extractTimestamp

public final long extractTimestamp(T element,
                                   long elementPrevTimestamp)

Description copied from interface: TimestampAssigner

Assigns a timestamp to an element, in milliseconds since the Epoch.

The method is passed the previously assigned timestamp of the element. That previous timestamp may have been assigned from a previous assigner, by ingestion time. If the element did not carry a timestamp before, this value is Long.MIN_VALUE.

Specified by:

extractTimestamp in interface TimestampAssigner<T>

Parameters:

element - The element that the timestamp will be assigned to.

elementPrevTimestamp - The previous internal timestamp of the element, or a negative value, if no timestamp has been assigned yet.

Returns:

The new timestamp.

getCurrentWatermark

public final Watermark getCurrentWatermark()

Description copied from interface: AssignerWithPeriodicWatermarks

Returns the current watermark. This method is periodically called by the system to retrieve the current watermark. The method may return null to indicate that no new Watermark is available.

The returned watermark will be emitted only if it is non-null and its timestamp is larger than that of the previously emitted watermark (to preserve the contract of ascending watermarks). If the current watermark is still identical to the previous one, no progress in event time has happened since the previous call to this method. If a null value is returned, or the timestamp of the returned watermark is smaller than that of the last emitted one, then no new watermark will be generated.

The interval in which this method is called and Watermarks are generated depends on ExecutionConfig.getAutoWatermarkInterval().

Specified by:

getCurrentWatermark in interface AssignerWithPeriodicWatermarks<T>

Returns:

Null, if no watermark should be emitted, or the next watermark to emit.

See Also:

Watermark, ExecutionConfig.getAutoWatermarkInterval()