| /* |
| 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.edgent.oplet.plumbing; |
| |
| import java.util.concurrent.LinkedBlockingQueue; |
| import java.util.concurrent.ThreadFactory; |
| |
| import org.apache.edgent.oplet.OpletContext; |
| import org.apache.edgent.oplet.core.Pipe; |
| |
| /** |
| * Isolate upstream processing from downstream |
| * processing guaranteeing tuple order. |
| * Input tuples are placed at the tail of a queue |
| * and dedicated thread removes them from the |
| * head and is used for downstream processing. |
| * |
| * @param <T> Type of the tuple. |
| */ |
| public class Isolate<T> extends Pipe<T,T> { |
| private static final long serialVersionUID = 1L; |
| |
| private Thread thread; |
| private final LinkedBlockingQueue<T> tuples; |
| |
| /** |
| * Create a new Isolate oplet. |
| * <BR> |
| * Same as Isolate(Integer.MAX_VALUE). |
| */ |
| public Isolate() { |
| this(Integer.MAX_VALUE); |
| } |
| |
| /** |
| * Create a new Isolate oplet. |
| * @param queueCapacity size of the queue between the input stream |
| * and the output stream. |
| * {@link #accept(Object) accept} blocks when the queue is full. |
| */ |
| public Isolate(int queueCapacity) { |
| tuples = new LinkedBlockingQueue<>(queueCapacity); |
| } |
| |
| @Override |
| public void initialize(OpletContext<T, T> context) { |
| super.initialize(context); |
| thread = context.getService(ThreadFactory.class).newThread(() -> run()); |
| } |
| |
| @Override |
| public void start() { |
| super.start(); |
| thread.start(); |
| } |
| |
| @Override |
| public void accept(T tuple) { |
| try { |
| tuples.put(tuple); |
| } catch (InterruptedException e) { |
| Thread.currentThread().interrupt(); |
| throw new RuntimeException(e); |
| } |
| } |
| |
| private void run() { |
| while (!Thread.interrupted()) { |
| try { |
| submit(tuples.take()); |
| } catch (InterruptedException e) { |
| break; |
| } |
| } |
| } |
| |
| @Override |
| public void close() throws Exception { |
| } |
| |
| } |