org.apache.flink.table.runtime.operators.window.triggers

Class ElementTriggers.CountElement<W extends Window>

java.lang.Object

org.apache.flink.table.runtime.operators.window.triggers.Trigger<W>

org.apache.flink.table.runtime.operators.window.triggers.ElementTriggers.CountElement<W>

All Implemented Interfaces:

Serializable

Enclosing class:

ElementTriggers

public static final class ElementTriggers.CountElement<W extends Window>
extends Trigger<W>

A Trigger that fires at some point after a specified number of input elements have arrived.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.flink.table.runtime.operators.window.triggers.Trigger

Trigger.OnMergeContext, Trigger.TriggerContext

Method Summary

Modifier and Type	Method and Description
boolean	canMerge() Returns true if this trigger supports merging of trigger state and can therefore.
void	clear(W window) Clears any state that the trigger might still hold for the given window.
boolean	onElement(Object element, long timestamp, W window) Called for every element that gets added to a pane.
boolean	onEventTime(long time, W window) Called when an event-time timer that was set using the trigger context fires.
void	onMerge(W window, Trigger.OnMergeContext mergeContext) Called when several windows have been merged into one window by the WindowAssigner.
boolean	onProcessingTime(long time, W window) Called when a processing-time timer that was set using the trigger context fires.
void	open(Trigger.TriggerContext ctx) Initialization method for the trigger.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

open

public void open(Trigger.TriggerContext ctx)
          throws Exception

Description copied from class: Trigger

Initialization method for the trigger. Creates states in this method.

Specified by:

open in class Trigger<W extends Window>

Parameters:

ctx - A context object that can be used to get states.

Throws:

Exception

onElement

public boolean onElement(Object element,
                         long timestamp,
                         W window)
                  throws Exception

Description copied from class: Trigger

Called for every element that gets added to a pane. The result of this will determine whether the pane is evaluated to emit results.

Specified by:

onElement in class Trigger<W extends Window>

Parameters:

element - The element that arrived.

timestamp - The timestamp of the element that arrived.

window - The window to which the element is being added.

Returns:

true for firing the window, false for no action

Throws:

Exception

onProcessingTime

public boolean onProcessingTime(long time,
                                W window)
                         throws Exception

Description copied from class: Trigger

Called when a processing-time timer that was set using the trigger context fires.

Note: This method is not called in case the window does not contain any elements. Thus, if you return PURGE from a trigger method and you expect to do cleanup in a future invocation of a timer callback it might be wise to clean any state that you would clean in the timer callback.

Specified by:

onProcessingTime in class Trigger<W extends Window>

Parameters:

time - The timestamp at which the timer fired.

window - The window for which the timer fired.

Returns:

true for firing the window, false for no action

Throws:

Exception

onEventTime

public boolean onEventTime(long time,
                           W window)
                    throws Exception

Description copied from class: Trigger

Called when an event-time timer that was set using the trigger context fires.

Note: This method is not called in case the window does not contain any elements. Thus, if you return PURGE from a trigger method and you expect to do cleanup in a future invocation of a timer callback it might be wise to clean any state that you would clean in the timer callback.

Specified by:

onEventTime in class Trigger<W extends Window>

Parameters:

time - The timestamp at which the timer fired.

window - The window for which the timer fired.

Returns:

true for firing the window, false for no action

Throws:

Exception

clear

public void clear(W window)
           throws Exception

Description copied from class: Trigger

Clears any state that the trigger might still hold for the given window. This is called when a window is purged. Timers set using Trigger.TriggerContext.registerEventTimeTimer(long) and Trigger.TriggerContext.registerProcessingTimeTimer(long) should be deleted here as well as state acquired using TriggerContext#getPartitionedState(StateDescriptor).

Specified by:

clear in class Trigger<W extends Window>

Throws:

Exception

canMerge

public boolean canMerge()

Description copied from class: Trigger

Returns true if this trigger supports merging of trigger state and can therefore.

If this returns true you must properly implement Trigger.onMerge(Window, OnMergeContext)

Overrides:

canMerge in class Trigger<W extends Window>

onMerge

public void onMerge(W window,
                    Trigger.OnMergeContext mergeContext)
             throws Exception

Description copied from class: Trigger

Called when several windows have been merged into one window by the WindowAssigner.

Overrides:

onMerge in class Trigger<W extends Window>

Parameters:

window - The new window that results from the merge.

Throws:

Exception

toString

public String toString()

Overrides:

toString in class Object