org.apache.kafka.streams.kstream

Class TimeWindows

java.lang.Object

org.apache.kafka.streams.kstream.Windows<org.apache.kafka.streams.kstream.internals.TimeWindow>

org.apache.kafka.streams.kstream.TimeWindows

public final class TimeWindows
extends Windows<org.apache.kafka.streams.kstream.internals.TimeWindow>

The fixed-size time-based window specifications used for aggregations.

The semantics of time-based aggregation windows are: Every T1 (advance) milliseconds, compute the aggregate total for T2 (size) milliseconds.

• If advance < size a hopping windows is defined:
  it discretize a stream into overlapping windows, which implies that a record maybe contained in one and or more "adjacent" windows.
• If advance == size a tumbling window is defined:
  it discretize a stream into non-overlapping windows, which implies that a record is only ever contained in one and only one tumbling window.

Thus, the specified TimeWindows are aligned to the epoch. Aligned to the epoch means, that the first window starts at timestamp zero. For example, hopping windows with size of 5000ms and advance of 3000ms, have window boundaries [0;5000),[3000;8000),... and not [1000;6000),[4000;9000),... or even something "random" like [1452;6452),[4452;9452),...

For time semantics, see TimestampExtractor.

See Also:

SessionWindows, UnlimitedWindows, JoinWindows, KGroupedStream.windowedBy(Windows), TimestampExtractor

Field Summary

Fields

Modifier and Type	Field and Description
long	advanceMs The size of the window's advance interval in milliseconds, i.e., by how much a window moves forward relative to the previous one.
long	sizeMs The size of the windows in milliseconds.

Fields inherited from class org.apache.kafka.streams.kstream.Windows

segments

Method Summary

Modifier and Type	Method and Description
TimeWindows	advanceBy(Duration advance) Return a window definition with the original size, but advance ("hop") the window by the given interval, which specifies by how much a window moves forward relative to the previous one.
TimeWindows	advanceBy(long advanceMs) Deprecated. Use advanceBy(Duration) instead
boolean	equals(Object o)
TimeWindows	grace(Duration afterWindowEnd) Reject late events that arrive more than millisAfterWindowEnd after the end of its window.
long	gracePeriodMs() Return the window grace period (the time to admit late-arriving events after the end of the window.) Lateness is defined as (stream_time - record_timestamp).
int	hashCode()
long	maintainMs() Deprecated. since 2.1. Use Materialized.retention instead.
static TimeWindows	of(Duration size) Return a window definition with the given window size, and with the advance interval being equal to the window size.
static TimeWindows	of(long sizeMs) Deprecated. Use of(Duration) instead
long	size() Return the size of the specified windows in milliseconds.
String	toString()
TimeWindows	until(long durationMs) Deprecated. since 2.1. Use Materialized.retention or directly configure the retention in a store supplier and use Materialized.as(WindowBytesStoreSupplier).
Map<Long,org.apache.kafka.streams.kstream.internals.TimeWindow>	windowsFor(long timestamp) Create all windows that contain the provided timestamp, indexed by non-negative window start timestamps.

Methods inherited from class org.apache.kafka.streams.kstream.Windows

segments

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

sizeMs

public final long sizeMs

The size of the windows in milliseconds.

advanceMs

public final long advanceMs

The size of the window's advance interval in milliseconds, i.e., by how much a window moves forward relative to the previous one.

Method Detail

of

@Deprecated
public static TimeWindows of(long sizeMs)
                                  throws IllegalArgumentException

Deprecated. Use of(Duration) instead

Return a window definition with the given window size, and with the advance interval being equal to the window size. The time interval represented by the N-th window is: [N * size, N * size + size).

This provides the semantics of tumbling windows, which are fixed-sized, gap-less, non-overlapping windows. Tumbling windows are a special case of hopping windows with advance == size.

Parameters:

sizeMs - The size of the window in milliseconds

Returns:

a new window definition with default maintain duration of 1 day

Throws:

IllegalArgumentException - if the specified window size is zero or negative

of

public static TimeWindows of(Duration size)
                      throws IllegalArgumentException

Return a window definition with the given window size, and with the advance interval being equal to the window size. The time interval represented by the N-th window is: [N * size, N * size + size).

This provides the semantics of tumbling windows, which are fixed-sized, gap-less, non-overlapping windows. Tumbling windows are a special case of hopping windows with advance == size.

Parameters:

size - The size of the window

Returns:

a new window definition with default maintain duration of 1 day

Throws:

IllegalArgumentException - if the specified window size is zero or negative or can't be represented as long milliseconds

advanceBy

@Deprecated
public TimeWindows advanceBy(long advanceMs)

Deprecated. Use advanceBy(Duration) instead

Return a window definition with the original size, but advance ("hop") the window by the given interval, which specifies by how much a window moves forward relative to the previous one. The time interval represented by the N-th window is: [N * advance, N * advance + size).

This provides the semantics of hopping windows, which are fixed-sized, overlapping windows.

Parameters:

advanceMs - The advance interval ("hop") in milliseconds of the window, with the requirement that 0 < advanceMs <= sizeMs.

Returns:

a new window definition with default maintain duration of 1 day

Throws:

IllegalArgumentException - if the advance interval is negative, zero, or larger than the window size

advanceBy

public TimeWindows advanceBy(Duration advance)

Return a window definition with the original size, but advance ("hop") the window by the given interval, which specifies by how much a window moves forward relative to the previous one. The time interval represented by the N-th window is: [N * advance, N * advance + size).

This provides the semantics of hopping windows, which are fixed-sized, overlapping windows.

Parameters:

advance - The advance interval ("hop") of the window, with the requirement that 0 < advance.toMillis() <= sizeMs.

Returns:

a new window definition with default maintain duration of 1 day

Throws:

IllegalArgumentException - if the advance interval is negative, zero, or larger than the window size

windowsFor

public Map<Long,org.apache.kafka.streams.kstream.internals.TimeWindow> windowsFor(long timestamp)

Description copied from class: Windows

Create all windows that contain the provided timestamp, indexed by non-negative window start timestamps.

Specified by:

windowsFor in class Windows<org.apache.kafka.streams.kstream.internals.TimeWindow>

Parameters:

timestamp - the timestamp window should get created for

Returns:

a map of windowStartTimestamp -> Window entries

size

public long size()

Description copied from class: Windows

Return the size of the specified windows in milliseconds.

Specified by:

size in class Windows<org.apache.kafka.streams.kstream.internals.TimeWindow>

Returns:

the size of the specified windows

grace

public TimeWindows grace(Duration afterWindowEnd)
                  throws IllegalArgumentException

Reject late events that arrive more than millisAfterWindowEnd after the end of its window. Lateness is defined as (stream_time - record_timestamp).

Parameters:

afterWindowEnd - The grace period to admit late-arriving events to a window.

Returns:

this updated builder

Throws:

IllegalArgumentException - if afterWindowEnd is negative or can't be represented as long milliseconds

gracePeriodMs

public long gracePeriodMs()

Description copied from class: Windows

Return the window grace period (the time to admit late-arriving events after the end of the window.) Lateness is defined as (stream_time - record_timestamp).

Specified by:

gracePeriodMs in class Windows<org.apache.kafka.streams.kstream.internals.TimeWindow>

until

@Deprecated
public TimeWindows until(long durationMs)
                              throws IllegalArgumentException

Deprecated. since 2.1. Use Materialized.retention or directly configure the retention in a store supplier and use Materialized.as(WindowBytesStoreSupplier).

Description copied from class: Windows

Set the window maintain duration (retention time) in milliseconds. This retention time is a guaranteed lower bound for how long a window will be maintained.

Overrides:

until in class Windows<org.apache.kafka.streams.kstream.internals.TimeWindow>

Parameters:

durationMs - the window retention time

Returns:

itself

Throws:

IllegalArgumentException - if duration is smaller than the window size

maintainMs

@Deprecated
public long maintainMs()

Deprecated. since 2.1. Use Materialized.retention instead.

Return the window maintain duration (retention time) in milliseconds.

For TimeWindows the maintain duration is at least as small as the window size.

Overrides:

maintainMs in class Windows<org.apache.kafka.streams.kstream.internals.TimeWindow>

Returns:

the window maintain duration

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object