org.apache.flink.api.common.eventtime

Interface TimestampAssigner<T>

Type Parameters:

T - The type of the elements to which this assigner assigns timestamps.

All Known Subinterfaces:

AssignerWithPeriodicWatermarks<T>, AssignerWithPunctuatedWatermarks<T>, SerializableTimestampAssigner<T>, TimestampAssigner<T>

All Known Implementing Classes:

AscendingTimestampExtractor, AscendingTimestampExtractor, BoundedOutOfOrdernessTimestampExtractor, CustomWatermarkExtractor, IngestionTimeAssigner, IngestionTimeExtractor, RecordTimestampAssigner

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@Public
 @FunctionalInterface
public interface TimestampAssigner<T>

A TimestampAssigner assigns event time timestamps to elements. These timestamps are used by all functions that operate on event time, for example event time windows.

Timestamps can be an arbitrary long value, but all built-in implementations represent it as the milliseconds since the Epoch (midnight, January 1, 1970 UTC), the same way as System.currentTimeMillis() does it.

Field Summary

Fields

Modifier and Type	Field and Description
static long	NO_TIMESTAMP The value that is passed to extractTimestamp(T, long) when there is no previous timestamp attached to the record.

Method Summary

Modifier and Type	Method and Description
long	extractTimestamp(T element, long recordTimestamp) Assigns a timestamp to an element, in milliseconds since the Epoch.

Field Detail

NO_TIMESTAMP

static final long NO_TIMESTAMP

The value that is passed to extractTimestamp(T, long) when there is no previous timestamp attached to the record.

See Also:

Constant Field Values

Method Detail

extractTimestamp

long extractTimestamp(T element,
                      long recordTimestamp)

Assigns a timestamp to an element, in milliseconds since the Epoch. This is independent of any particular time zone or calendar.

The method is passed the previously assigned timestamp of the element. That previous timestamp may have been assigned from a previous assigner. If the element did not carry a timestamp before, this value is NO_TIMESTAMP (= Long.MIN_VALUE: ).

Parameters:

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

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

Returns:

The new timestamp.