| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.flink.test.windowing.sessionwindows; |
| |
| /** |
| * Basic interface for event generators. |
| * |
| * @param <K> session key type |
| * @param <E> session event type |
| */ |
| public interface EventGenerator<K, E> { |
| |
| /** |
| * Only call this method if hasMoreEvents() is true and canGenerateEventAtWatermark(...) is |
| * true. |
| * |
| * @param globalWatermark the current global watermark to consider for event generation |
| * @return a generated event |
| */ |
| E generateEvent(long globalWatermark); |
| |
| /** |
| * @param globalWatermark the current global watermark to consider for event generation |
| * @return true if, given the current global watermark, the generator can produce events. this |
| * might temporarily be false, e.g. if a generator wants to produce late events w.r.t. a |
| * session, but the global watermark did not yet advance to the point that timestamps from |
| * the session would be late |
| */ |
| boolean canGenerateEventAtWatermark(long globalWatermark); |
| |
| /** @return true if, in general and for some global watermark, more events can been produced */ |
| boolean hasMoreEvents(); |
| |
| /** @return the watermark that tracks this generator's progress */ |
| long getLocalWatermark(); |
| |
| /** |
| * @param globalWatermark the current global watermark to consider for event generation |
| * @return a successor for this generator if hasMoreEvents() is false |
| */ |
| EventGenerator<K, E> getNextGenerator(long globalWatermark); |
| |
| /** @return key for the generated events */ |
| K getKey(); |
| } |