| /* |
| * Copyright (c) OSGi Alliance (2015, 2016). All Rights Reserved. |
| * |
| * Licensed 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.osgi.util.pushstream; |
| |
| import java.util.concurrent.BlockingQueue; |
| import org.osgi.annotation.versioning.ConsumerType; |
| |
| /** |
| * A {@link PushbackPolicy} is used to calculate how much back pressure to apply |
| * based on the current buffer. The {@link PushbackPolicy} will be called after |
| * an event has been queued, and the returned value will be used as back |
| * pressure. |
| * |
| * @see PushbackPolicyOption |
| * |
| * |
| * @param <T> The type of the data |
| * @param <U> The type of the queue |
| */ |
| @ConsumerType |
| @FunctionalInterface |
| public interface PushbackPolicy<T, U extends BlockingQueue<PushEvent<? extends T>>> { |
| |
| /** |
| * Given the current state of the queue, determine the level of back |
| * pressure that should be applied |
| * |
| * @param queue |
| * @return a back pressure value in nanoseconds |
| * @throws Exception |
| */ |
| public long pushback(U queue) throws Exception; |
| |
| } |
