org.apache.flink.streaming.api.windowing.triggers

Enum TriggerResult

java.lang.Object

java.lang.Enum<TriggerResult>

org.apache.flink.streaming.api.windowing.triggers.TriggerResult

All Implemented Interfaces:

Serializable, Comparable<TriggerResult>

public enum TriggerResult
extends Enum<TriggerResult>

Result type for trigger methods. This determines what happens with the window, for example whether the window function should be called, or the window should be discarded.

Enum Constant Summary

Enum Constants

Enum Constant and Description
CONTINUE No action is taken on the window.
FIRE On FIRE, the window is evaluated and results are emitted.
FIRE_AND_PURGE FIRE_AND_PURGE evaluates the window function and emits the window result.
PURGE All elements in the window are cleared and the window is discarded, without evaluating the window function or emitting any elements.

Method Summary

Modifier and Type	Method and Description
boolean	isFire()
boolean	isPurge()
static TriggerResult	merge(TriggerResult a, TriggerResult b) Merges two TriggerResults.
static TriggerResult	valueOf(String name) Returns the enum constant of this type with the specified name.
static TriggerResult[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

CONTINUE

public static final TriggerResult CONTINUE

No action is taken on the window.

FIRE_AND_PURGE

public static final TriggerResult FIRE_AND_PURGE

FIRE_AND_PURGE evaluates the window function and emits the window result.

FIRE

public static final TriggerResult FIRE

On FIRE, the window is evaluated and results are emitted. The window is not purged, though, all elements are retained.

PURGE

public static final TriggerResult PURGE

All elements in the window are cleared and the window is discarded, without evaluating the window function or emitting any elements.

Method Detail

values

public static TriggerResult[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (TriggerResult c : TriggerResult.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static TriggerResult valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

isFire

public boolean isFire()

isPurge

public boolean isPurge()

merge

public static TriggerResult merge(TriggerResult a,
                                  TriggerResult b)

Merges two TriggerResults. This specifies what should happen if we have two results from a Trigger, for example as a result from Trigger.onElement(Object, long, Window, Trigger.TriggerContext) and Trigger.onEventTime(long, Window, Trigger.TriggerContext).

For example, if one result says CONTINUE while the other says FIRE then FIRE is the combined result;