org.microbean.kubernetes.controller

Class EventDistributor<T extends HasMetadata>

java.lang.Object

org.microbean.kubernetes.controller.ResourceTrackingEventQueueConsumer<T>

org.microbean.kubernetes.controller.EventDistributor<T>

Type Parameters:

T - a type of Kubernetes resource

All Implemented Interfaces:

AutoCloseable, Consumer<EventQueue<? extends T>>

@Immutable
 @ThreadSafe
public final class EventDistributor<T extends HasMetadata>
extends ResourceTrackingEventQueueConsumer<T>
implements AutoCloseable

A ResourceTrackingEventQueueConsumer that consumes EventQueue instances by feeding each AbstractEvent in the EventQueue being consumed to Consumers of AbstractEvents that have been registered.

EventDistributor instances must be closed and discarded after use.

Author:

Laird Nelson

See Also:

addConsumer(Consumer), removeConsumer(Consumer), ResourceTrackingEventQueueConsumer.accept(AbstractEvent)

Field Summary

Fields inherited from class org.microbean.kubernetes.controller.ResourceTrackingEventQueueConsumer

logger

Constructor Summary

Constructors

Constructor and Description
EventDistributor(Map<Object,T> knownObjects) Creates a new EventDistributor.
EventDistributor(Map<Object,T> knownObjects, Duration synchronizationInterval) Creates a new EventDistributor.

Method Summary

Modifier and Type	Method and Description
protected void	accept(AbstractEvent<? extends T> event) Consumes the supplied AbstractEvent by forwarding it to the Consumer.accept(Object) method of each Consumer registered with this EventDistributor.
void	addConsumer(Consumer<? super AbstractEvent<? extends T>> consumer) Adds the supplied Consumer to this EventDistributor as a listener that will be notified of each AbstractEvent this EventDistributor receives.
void	addConsumer(Consumer<? super AbstractEvent<? extends T>> consumer, Function<? super Throwable,Boolean> errorHandler) Adds the supplied Consumer to this EventDistributor as a listener that will be notified of each AbstractEvent this EventDistributor receives.
void	close() Releases resources held by this EventDistributor during its execution.
void	removeConsumer(Consumer<? super AbstractEvent<? extends T>> consumer) Removes any Consumer equal to a Consumer previously added to this EventDistributor.
boolean	shouldSynchronize() Returns true if this EventDistributor should synchronize with its upstream source.

Methods inherited from class org.microbean.kubernetes.controller.ResourceTrackingEventQueueConsumer

accept, createEvent, createLogger, createSynchronizationEvent

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.function.Consumer

andThen

Constructor Detail

EventDistributor

public EventDistributor(Map<Object,T> knownObjects)

Creates a new EventDistributor.

Parameters:

knownObjects - a mutable Map of Kubernetes resources that contains or will contain Kubernetes resources known to this EventDistributor and whatever mechanism (such as a Controller) is feeding it; may be null

See Also:

EventDistributor(Map, Duration)

EventDistributor

public EventDistributor(Map<Object,T> knownObjects,
                        Duration synchronizationInterval)

Creates a new EventDistributor.

Parameters:

knownObjects - a mutable Map of Kubernetes resources that contains or will contain Kubernetes resources known to this EventDistributor and whatever mechanism (such as a Controller) is feeding it; may be null

synchronizationInterval - a Duration representing the interval after which an attempt to synchronize might happen; may be null in which case no synchronization will occur

See Also:

ResourceTrackingEventQueueConsumer.ResourceTrackingEventQueueConsumer(Map)

Method Detail

addConsumer

public final void addConsumer(Consumer<? super AbstractEvent<? extends T>> consumer)

Adds the supplied Consumer to this EventDistributor as a listener that will be notified of each AbstractEvent this EventDistributor receives.

The supplied Consumer's Consumer.accept(Object) method may be called later on a separate thread of execution.

Parameters:

consumer - a Consumer of AbstractEvents; may be null in which case no action will be taken

See Also:

addConsumer(Consumer, Function), removeConsumer(Consumer)

addConsumer

public final void addConsumer(Consumer<? super AbstractEvent<? extends T>> consumer,
                              Function<? super Throwable,Boolean> errorHandler)

Adds the supplied Consumer to this EventDistributor as a listener that will be notified of each AbstractEvent this EventDistributor receives.

The supplied Consumer's Consumer.accept(Object) method may be called later on a separate thread of execution.

Parameters:

consumer - a Consumer of AbstractEvents; may be null in which case no action will be taken

errorHandler - a Function to handle any Throwables encountered; may be null in which case a default error handler will be used instead

See Also:

removeConsumer(Consumer)

removeConsumer

public final void removeConsumer(Consumer<? super AbstractEvent<? extends T>> consumer)

Removes any Consumer equal to a Consumer previously added to this EventDistributor.

Parameters:

consumer - the Consumer to remove; may be null in which case no action will be taken

See Also:

addConsumer(Consumer)

close

public final void close()

Releases resources held by this EventDistributor during its execution.

Specified by:

close in interface AutoCloseable

shouldSynchronize

public final boolean shouldSynchronize()

Returns true if this EventDistributor should synchronize with its upstream source.

Design Notes

The Kubernetes tools/cache package spreads synchronization out among the reflector, controller, event cache and event processor constructs for no seemingly good reason. They should probably be consolidated, particularly in an object-oriented environment such as Java.

Returns:

true if synchronization should occur; false otherwise

See Also:

EventCache.synchronize()

accept

protected final void accept(AbstractEvent<? extends T> event)

Consumes the supplied AbstractEvent by forwarding it to the Consumer.accept(Object) method of each Consumer registered with this EventDistributor.

Specified by:

accept in class ResourceTrackingEventQueueConsumer<T extends HasMetadata>

Parameters:

event - the AbstractEvent to forward; may be null in which case no action is taken

See Also:

addConsumer(Consumer), ResourceTrackingEventQueueConsumer.accept(AbstractEvent)