Github user aljoscha commented on a diff in the pull request: https://github.com/apache/flink/pull/2570#discussion_r84038623 --- Diff: flink-streaming-java/src/main/java/org/apache/flink/streaming/api/operators/AbstractStreamOperator.java --- @@ -390,4 +425,141 @@ public void close() { output.close(); } } + + // ------------------------------------------------------------------------ + // Watermark handling + // ------------------------------------------------------------------------ + + /** + * Returns a {@link InternalTimerService} that can be used to query current processing time + * and event time and to set timers. An operator can have several timer services, where + * each has its own namespace serializer. Timer services are differentiated by the string + * key that is given when requesting them, if you call this method with the same key + * multiple times you will get the same timer service instance in subsequent requests. + * + * <p>Timers are always scoped to a key, the currently active key of a keyed stream operation. + * When a timer fires, this key will also be set as the currently active key. + * + * <p>Each timer has attached metadata, the namespace. Different timer services + * can have a different namespace type. If you don't need namespace differentiation you + * can use {@link VoidNamespaceSerializer} as the namespace serializer. + * + * @param name The name of the requested timer service. If no service exists under the given + * name a new one will be created and returned. + * @param keySerializer {@code TypeSerializer} for the keys of the timers. + * @param namespaceSerializer {@code TypeSerializer} for the timer namespace. + * @param triggerable The {@link Triggerable} that should be invoked when timers fire + * + * @param <K> The type of the timer keys. + * @param <N> The type of the timer namespace. + */ + public <K, N> InternalTimerService<N> getInternalTimerService( + String name, + TypeSerializer<K> keySerializer, + TypeSerializer<N> namespaceSerializer, + Triggerable<K, N> triggerable) { + + @SuppressWarnings("unchecked") + HeapInternalTimerService<K, N> service = (HeapInternalTimerService<K, N>) timerServices.get(name); + + if (service == null) { + if (restoredServices != null && restoredServices.containsKey(name)) { + @SuppressWarnings("unchecked") + HeapInternalTimerService.RestoredTimers<K, N> restoredService = --- End diff -- I can replace it by this but not sure if it's more readable: ``` @SuppressWarnings("unchecked") HeapInternalTimerService.RestoredTimers<K, N> restoredService = restoredServices == null ? null : (HeapInternalTimerService.RestoredTimers<K, N>) restoredServices.remove(name); if (restoredService != null) { ... } ```
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