Package 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 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

    DEPRECATED_DEFAULT_24_HR_GRACE_PERIOD, NO_GRACE_PERIOD

  • Method Summary

    Modifier and Type Method 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.
    boolean equals​(Object o)  
    TimeWindows grace​(Duration afterWindowEnd)
    Deprecated.
    since 3.0.
    long gracePeriodMs()
    Return the window grace period (the time to admit out-of-order events after the end of the window.) Delay is defined as (stream_time - record_timestamp).
    int hashCode()  
    static TimeWindows of​(Duration size)
    Deprecated.
    since 3.0.
    static TimeWindows ofSizeAndGrace​(Duration size, Duration afterWindowEnd)
    Return a window definition with the given window size, and with the advance interval being equal to the window size.
    static TimeWindows ofSizeWithNoGrace​(Duration size)
    Return a window definition with the given window size, and with the advance interval being equal to the window size.
    long size()
    Return the size of the specified windows in milliseconds.
    String toString()  
    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 java.lang.Object

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

  • Field Details

    • 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 Details

    • ofSizeWithNoGrace

      public static TimeWindows ofSizeWithNoGrace​(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.

      CAUTION: Using this method implicitly sets the grace period to zero, which means that any out-of-order records arriving after the window ends are considered late and will be dropped.

      Parameters:
      size - The size of the window
      Returns:
      a new window definition with default no grace period. Note that this means out-of-order records arriving after the window end will be dropped
      Throws:
      IllegalArgumentException - if the specified window size is zero or negative or can't be represented as long milliseconds

    • ofSizeAndGrace

      public static TimeWindows ofSizeAndGrace​(Duration size, Duration afterWindowEnd) 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.

      Using this method explicitly sets the grace period to the duration specified by afterWindowEnd, which means that only out-of-order records arriving more than the grace period after the window end will be dropped. The window close, after which any incoming records are considered late and will be rejected, is defined as windowEnd + afterWindowEnd

      Parameters:
      size - The size of the window. Must be larger than zero
      afterWindowEnd - The grace period to admit out-of-order events to a window. Must be non-negative.
      Returns:
      a TimeWindows object with the specified size and the specified grace period
      Throws:
      IllegalArgumentException - if afterWindowEnd is negative or can't be represented as long milliseconds

    • of

      @Deprecated public static TimeWindows of​(Duration size) throws IllegalArgumentException
      Deprecated.
      since 3.0. Use ofSizeWithNoGrace(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:
      size - The size of the window
      Returns:
      a new window definition without specifying the grace period (default to 24 hours minus window size)
      Throws:
      IllegalArgumentException - if the specified window size is zero or negative or can't be represented as long milliseconds

    • 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

      @Deprecated public TimeWindows grace​(Duration afterWindowEnd) throws IllegalArgumentException
      Deprecated.
      since 3.0. Use ofSizeAndGrace(Duration, Duration) instead
      Reject out-of-order events that arrive more than millisAfterWindowEnd after the end of its window.

      Delay is defined as (stream_time - record_timestamp).

      Parameters:
      afterWindowEnd - The grace period to admit out-of-order 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 out-of-order events after the end of the window.) Delay is defined as (stream_time - record_timestamp).
      Specified by:
      gracePeriodMs in class Windows<org.apache.kafka.streams.kstream.internals.TimeWindow>

    • 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