org.apache.samza.operators.triggers

Class Triggers

java.lang.Object

org.apache.samza.operators.triggers.Triggers

@InterfaceStability.Unstable
public final class Triggers
extends java.lang.Object

API for creating Trigger instances to be used with a Window.

The below example groups an input into tumbling windows of 10s and emits early results periodically every 4s in processing time, or for every 50 messages. It also specifies that window results are accumulating.

 
   MessageStream<> windowedStream = stream.window(Windows.tumblingWindow(Duration.of(10, TimeUnit.SECONDS))
     .setEarlyTrigger(Triggers.repeat(Triggers.any(Triggers.count(50), Triggers.timeSinceFirstMessage(Duration.of(4, TimeUnit.SECONDS))))))
     .setAccumulationMode(AccumulationMode.ACCUMULATING));
 

Method Summary

Modifier and Type	Method and Description
static <M> Trigger<M>	any(Trigger<M>... triggers) Creates a trigger that fires when any of the provided triggers fire.
static <M> Trigger<M>	count(long count) Creates a Trigger that fires when the number of messages in the pane reaches the specified count.
static <M> Trigger<M>	repeat(Trigger<M> trigger) Repeats the provided trigger forever.
static <M> Trigger<M>	timeSinceFirstMessage(java.time.Duration duration) Creates a trigger that fires after the specified duration has passed since the first message in the pane.
static <M> Trigger<M>	timeSinceLastMessage(java.time.Duration duration) Creates a trigger that fires when there is no new message for the specified duration in the pane.

Methods inherited from class java.lang.Object

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

Method Detail

count

public static <M> Trigger<M> count(long count)

Creates a Trigger that fires when the number of messages in the pane reaches the specified count.

Type Parameters:

M - the type of input message in the window

Parameters:

count - the number of messages to fire the trigger after

Returns:

the created trigger

timeSinceFirstMessage

public static <M> Trigger<M> timeSinceFirstMessage(java.time.Duration duration)

Creates a trigger that fires after the specified duration has passed since the first message in the pane.

Type Parameters:

M - the type of input message in the window

Parameters:

duration - the duration since the first element

Returns:

the created trigger

timeSinceLastMessage

public static <M> Trigger<M> timeSinceLastMessage(java.time.Duration duration)

Creates a trigger that fires when there is no new message for the specified duration in the pane.

Type Parameters:

M - the type of input message in the window

Parameters:

duration - the duration since the last element

Returns:

the created trigger

any

public static <M> Trigger<M> any(Trigger<M>... triggers)

Creates a trigger that fires when any of the provided triggers fire.

Type Parameters:

M - the type of input message in the window

Parameters:

triggers - the individual triggers

Returns:

the created trigger

repeat

public static <M> Trigger<M> repeat(Trigger<M> trigger)

Repeats the provided trigger forever.

Creating a RepeatingTrigger from an AnyTrigger is equivalent to creating an AnyTrigger from its individual RepeatingTriggers.

Type Parameters:

M - the type of input message in the window

Parameters:

trigger - the individual trigger to repeat

Returns:

the created trigger