| /* |
| * 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.statefun.flink.core.feedback; |
| |
| import java.util.Deque; |
| |
| /** |
| * HandOffQueue - is a single producer single consumer (spsc) queue that supports adding and |
| * draining atomically. |
| * |
| * <p>Implementors of this queue supports atomic addition operation (via {@link |
| * #addAndCheckIfWasEmpty(Object)} and atomic, bulk retrieving of the content of this queue (via |
| * {@link #drainAll()})}. |
| * |
| * @param <ElementT> element type that is stored in this queue. |
| */ |
| interface FeedbackQueue<ElementT> { |
| |
| /** |
| * Adds an element to the queue atomically. |
| * |
| * @param element the element to add to the queue. |
| * @return true, if prior to this addition the queue was empty. |
| */ |
| boolean addAndCheckIfWasEmpty(ElementT element); |
| |
| /** |
| * Atomically grabs all that elements of this queue. |
| * |
| * @return the elements present at the queue at the moment of this operation. |
| */ |
| Deque<ElementT> drainAll(); |
| } |