org.apache.samza.operators.triggers

Class Triggers<M extends MessageEnvelope>

java.lang.Object

org.apache.samza.operators.triggers.Triggers<M>

Type Parameters:

M - the type of input MessageEnvelopes in the MessageStream

@InterfaceStability.Unstable
public final class Triggers<M extends MessageEnvelope>
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))))))
     .accumulateFiredPanes());
 

Method Summary

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

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

Parameters:

count - the number of MessageEnvelopes to fire the trigger after

Returns:

the created trigger

timeSinceFirstMessage

public static Trigger timeSinceFirstMessage(java.time.Duration duration)

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

Parameters:

duration - the duration since the first element

Returns:

the created trigger

timeSinceLastMessage

public static Trigger timeSinceLastMessage(java.time.Duration duration)

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

Parameters:

duration - the duration since the last element

Returns:

the created trigger

any

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

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

Type Parameters:

M - the type of input MessageEnvelope in the window

Parameters:

triggers - the individual triggers

Returns:

the created trigger

repeat

public static <M extends MessageEnvelope> Trigger 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 MessageEnvelope in the window

Parameters:

trigger - the individual trigger to repeat

Returns:

the created trigger