Package com.espertech.esper.common.internal.view.exttimedwin

Class ExternallyTimedWindowView

java.lang.Object
com.espertech.esper.common.internal.view.core.ViewSupport
com.espertech.esper.common.internal.view.exttimedwin.ExternallyTimedWindowView
All Implemented Interfaces:
DataWindowView, View, Viewable, ViewDataVisitable, Iterable<EventBean>
public class ExternallyTimedWindowView extends ViewSupport implements DataWindowView
View for a moving window extending the specified amount of time into the past, driven entirely by external timing supplied within long-type timestamp values in a field of the event beans that the view receives.

The view is completely driven by timestamp values that are supplied by the events it receives, and does not use the schedule service time. It requires a field name as parameter for a field that returns ascending long-type timestamp values. It also requires a long-type parameter setting the time length in milliseconds of the time window. Events are expected to provide long-type timestamp values in natural order. The view does itself not use the current system time for keeping track of the time window, but just the timestamp values supplied by the events sent in.

The arrival of new events with a newer timestamp then past events causes the window to be re-evaluated and the oldest events pushed out of the window. Ie. Assume event X1 with timestamp T1 is in the window. When event Xn with timestamp Tn arrives, and the window time length in milliseconds is t, then if ((Tn - T1) > t == true) then event X1 is pushed as oldData out of the window. It is assumed that events are sent in in their natural order and the timestamp values are ascending.

  • Field Details

  • Constructor Details

  • Method Details

    • getEventType

      public final EventType getEventType()
      Description copied from interface: Viewable
      Provides metadata information about the type of object the event collection contains.
      Specified by:
      getEventType in interface Viewable
      Returns:
      metadata for the objects in the collection

    • update

      public final void update(EventBean[] newData, EventBean[] oldData)
      Description copied from interface: View
      Notify that data has been added or removed from the Viewable parent. The last object in the newData array of objects would be the newest object added to the parent view. The first object of the oldData array of objects would be the oldest object removed from the parent view.

      If the call to update contains new (inserted) data, then the first argument will be a non-empty list and the second will be empty. Similarly, if the call is a notification of deleted data, then the first argument will be empty and the second will be non-empty. Either the newData or oldData will be non-null. This method won't be called with both arguments being null, but either one could be null. The same is true for zero-length arrays. Either newData or oldData will be non-empty. If both are non-empty, then the update is a modification notification.

      When update() is called on a view by the parent object, the data in newData will be in the collection of the parent, and its data structures will be arranged to reflect that. The data in oldData will not be in the parent's data structures, and any access to the parent will indicate that that data is no longer there.

      Specified by:
      update in interface View
      Parameters:
      newData - is the new data that has been added to the parent view
      oldData - is the old data that has been removed from the parent view

    • iterator

      public final Iterator<EventBean> iterator()
      Description copied from interface: Viewable
      Allows iteration through all elements in this viewable. The iterator will return the elements in the collection in their natural order, or, if there is no natural ordering, in some unpredictable order.
      Specified by:
      iterator in interface Iterable<EventBean>
      Specified by:
      iterator in interface Viewable
      Returns:
      an iterator which will go through all current elements in the collection.

    • visitView

      public void visitView(ViewDataVisitor viewDataVisitor)
      Specified by:
      visitView in interface ViewDataVisitable

    • isEmpty

      public boolean isEmpty()
      Returns true to indicate the window is empty, or false if the view is not empty.
      Returns:
      true if empty

    • getViewUpdatedCollection

      public ViewUpdatedCollection getViewUpdatedCollection()

    • getViewFactory

      public ViewFactory getViewFactory()