Package org.apache.flink.datastream.impl.extension.window.operators

Class MergingWindowSet<W extends org.apache.flink.streaming.api.windowing.windows.Window>

  • public class MergingWindowSet<W extends org.apache.flink.streaming.api.windowing.windows.Window>
extends Object
    Utility for keeping track of merging Windows when using a MergingWindowAssigner in a WindowProcessOperator.

    Please refer to MergingWindowSet. We do not use this directly because we are utilizing State V2, while it is based on State V1.

    • Constructor Detail

      • MergingWindowSet

        public MergingWindowSet​(org.apache.flink.streaming.api.windowing.assigners.MergingWindowAssigner<?,​W> windowAssigner,
                        org.apache.flink.runtime.state.v2.internal.InternalListState<?,​org.apache.flink.runtime.state.VoidNamespace,​org.apache.flink.api.java.tuple.Tuple2<W,​W>> state)
                 throws Exception
        Restores a MergingWindowSet from the given state.
        Throws:
        Exception

    • Method Detail

      • persist

        public void persist()
             throws Exception
        Persist the updated mapping to the given state if the mapping changed since initialization.
        Throws:
        Exception

      • getStateWindow

        public W getStateWindow​(W window)
        Returns the state window for the given in-flight Window. The state window is the Window in which we keep the actual state of a given in-flight window. Windows might expand but we keep to original state window for keeping the elements of the window to avoid costly state juggling.
        Parameters:
        window - The window for which to get the state window.

      • retireWindow

        public void retireWindow​(W window)
        Removes the given window from the set of in-flight windows.
        Parameters:
        window - The Window to remove.

      • addWindow

        public W addWindow​(W newWindow,
                   MergingWindowSet.MergeFunction<W> mergeFunction)
            throws Exception
        Adds a new Window to the set of in-flight windows. It might happen that this triggers merging of previously in-flight windows. In that case, the provided MergingWindowSet.MergeFunction is called.

        This returns the window that is the representative of the added window after adding. This can either be the new window itself, if no merge occurred, or the newly merged window. Adding an element to a window or calling trigger functions should only happen on the returned representative. This way, we never have to deal with a new window that is immediately swallowed up by another window.

        If the new window is merged, the MergeFunction callback arguments also don't contain the new window as part of the list of merged windows.

        Parameters:
        newWindow - The new Window to add.
        mergeFunction - The callback to be invoked in case a merge occurs.
        Returns:
        The Window that new new Window ended up in. This can also be the new Window itself in case no merge occurred.
        Throws:
        Exception