net.esper.view.window
Class TimeWindowView

java.lang.Object
  extended by net.esper.view.ViewSupport
      extended by net.esper.view.window.TimeWindowView
All Implemented Interfaces:
Iterable<EventBean>, CloneableView, DataWindowView, EventCollection, View, Viewable

public final class TimeWindowView
extends ViewSupport
implements CloneableView, DataWindowView

This view is a moving timeWindow extending the specified amount of milliseconds into the past. The view bases the timeWindow on the time obtained from the scheduling service. All incoming events receive a timestamp and are placed in a sorted map by timestamp. The view does not care about old data published by the parent view to this view. Events leave or expire from the time timeWindow by means of a scheduled callback registered with the scheduling service. Thus child views receive updates containing old data only asynchronously as the system-time-based timeWindow moves on. However child views receive updates containing new data as soon as the new data arrives.


Field Summary
 
Fields inherited from class net.esper.view.ViewSupport
parent
 
Constructor Summary
TimeWindowView(StatementContext statementContext, TimeWindowViewFactory timeWindowViewFactory, long millisecondsBeforeExpiry, ViewUpdatedCollection viewUpdatedCollection, boolean isRemoveStreamHandling)
          Constructor.
 
Method Summary
 View cloneView(StatementContext statementContext)
          Duplicates the view.
protected  void expire()
          This method removes (expires) objects from the window and schedules a new callback for the time when the next oldest message would expire from the window.
 EventType getEventType()
          Provides metadata information about the type of object the event collection contains.
 long getMillisecondsBeforeExpiry()
          Returns the size of the time window in millisecond.
 ViewUpdatedCollection getViewUpdatedCollection()
          Returns the (optional) collection handling random access to window contents for prior or previous events.
 boolean isEmpty()
          Returns true if the window is empty, or false if not empty.
 Iterator<EventBean> iterator()
          Allows iteration through all elements in this event collection.
 String toString()
           
 void update(EventBean[] newData, EventBean[] oldData)
          Notify that data has been added or removed from the Viewable parent.
 
Methods inherited from class net.esper.view.ViewSupport
addView, dumpChildViews, dumpUpdateParams, findDescendent, getParent, getViews, hasViews, removeView, setParent, updateChildren, updateChildren
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface net.esper.view.View
getParent, setParent
 
Methods inherited from interface net.esper.view.Viewable
addView, getViews, hasViews, removeView
 

Constructor Detail

TimeWindowView

public TimeWindowView(StatementContext statementContext,
                      TimeWindowViewFactory timeWindowViewFactory,
                      long millisecondsBeforeExpiry,
                      ViewUpdatedCollection viewUpdatedCollection,
                      boolean isRemoveStreamHandling)
Constructor.

Parameters:
millisecondsBeforeExpiry - is the number of milliseconds before events gets pushed out of the timeWindow as oldData in the update method.
viewUpdatedCollection - is a collection the view must update when receiving events
statementContext - is required view services
timeWindowViewFactory - for copying the view in a group-by
isRemoveStreamHandling - flag to indicate that the view must handle the removed events from a parent view
Method Detail

cloneView

public View cloneView(StatementContext statementContext)
Description copied from interface: CloneableView
Duplicates the view.

Expected to return a same view in initialized state for grouping.

Specified by:
cloneView in interface CloneableView
Parameters:
statementContext - is services for the view
Returns:
duplicated view

getMillisecondsBeforeExpiry

public final long getMillisecondsBeforeExpiry()
Returns the size of the time window in millisecond.

Returns:
size of window

getViewUpdatedCollection

public ViewUpdatedCollection getViewUpdatedCollection()
Returns the (optional) collection handling random access to window contents for prior or previous events.

Returns:
buffer for events

getEventType

public final EventType getEventType()
Description copied from interface: EventCollection
Provides metadata information about the type of object the event collection contains.

Specified by:
getEventType in interface EventCollection
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

expire

protected final void expire()
This method removes (expires) objects from the window and schedules a new callback for the time when the next oldest message would expire from the window.


iterator

public final Iterator<EventBean> iterator()
Description copied from interface: EventCollection
Allows iteration through all elements in this event collection. 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 EventCollection
Returns:
an iterator which will go through all current elements in the collection.

toString

public final String toString()
Overrides:
toString in class Object

isEmpty

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

Returns:
true if empty

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