com.spotify.dns

Class ChangeNotifiers

java.lang.Object

com.spotify.dns.ChangeNotifiers

public final class ChangeNotifiers
extends Object

Method Summary

Modifier and Type	Method and Description
static <T> ChangeNotifier<T>	aggregate(ChangeNotifier<T>... notifiers) Creates a ChangeNotifier that aggregates the records provided by a list of notifiers.
static <T> ChangeNotifier<T>	aggregate(Iterable<ChangeNotifier<T>> notifiers)
static <T> ChangeNotifierFactory.RunnableChangeNotifier<T>	direct(AtomicReference<Set<T>> recordsHolder)
static <T> ChangeNotifierFactory.RunnableChangeNotifier<T>	direct(com.google.common.base.Supplier<Set<T>> recordsSupplier) Create a ChangeNotifierFactory.RunnableChangeNotifier that directly wraps a set of records given by a Supplier.
static <T> boolean	isInitialEmptyData(Set<T> set) Use this to determine if the data you get back from a notifier is the initial result of the result of a proper DNS lookup.
static <T> ChangeNotifier<T>	staticRecords(Set<T> records)
static <T> ChangeNotifier<T>	staticRecords(T... records) Create a ChangeNotifier with a static set of records.

Methods inherited from class java.lang.Object

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

Method Detail

isInitialEmptyData

public static <T> boolean isInitialEmptyData(Set<T> set)

Use this to determine if the data you get back from a notifier is the initial result of the result of a proper DNS lookup. This is useful for distinguishing a proper but empty DNS result from the case where a lookup has not completed yet.

Parameters:

set -

Returns:

true if the input is an initially empty set.

aggregate

public static <T> ChangeNotifier<T> aggregate(ChangeNotifier<T>... notifiers)

Creates a ChangeNotifier that aggregates the records provided by a list of notifiers.

A change event on any of the input notifiers will propagate up the the returned notifier. The set of previous and current records contained in the event will be the union of all records in the input notifiers, before and after the change event.

Type Parameters:

T - The record type

Parameters:

notifiers - A list of notifiers to aggregate

Returns:

A notifier with the described behaviour

aggregate

public static <T> ChangeNotifier<T> aggregate(Iterable<ChangeNotifier<T>> notifiers)

staticRecords

public static <T> ChangeNotifier<T> staticRecords(T... records)

Create a ChangeNotifier with a static set of records.

This notifier will never generate any change events. Thus any attached ChangeNotifier.Listener will at most get one initial call to ChangeNotifier.Listener.onChange(ChangeNotifier.ChangeNotification) if they are attached with the fire argument set to true.

Type Parameters:

T - The record type

Parameters:

records - The records that the notifier will contain

Returns:

A notifier with a static set of records

staticRecords

public static <T> ChangeNotifier<T> staticRecords(Set<T> records)

direct

public static <T> ChangeNotifierFactory.RunnableChangeNotifier<T> direct(com.google.common.base.Supplier<Set<T>> recordsSupplier)

Create a ChangeNotifierFactory.RunnableChangeNotifier that directly wraps a set of records given by a Supplier.

Each call to Runnable.run() will cause the supplier to be polled and regular change notifications to be triggered.

This implementation is useful for testing components that depend on a ChangeNotifier.

Type Parameters:

T - The record type

Parameters:

recordsSupplier - The supplier of records

Returns:

A runnable notifier

direct

public static <T> ChangeNotifierFactory.RunnableChangeNotifier<T> direct(AtomicReference<Set<T>> recordsHolder)