| /* |
| 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.functional; |
| |
| |
| import static org.apache.edgent.function.Functions.closeFunction; |
| |
| import java.util.concurrent.ScheduledExecutorService; |
| import java.util.concurrent.ThreadFactory; |
| |
| import org.apache.edgent.function.Consumer; |
| import org.apache.edgent.oplet.core.Source; |
| |
| /** |
| * Generate tuples from events. |
| * This oplet implements {@link Consumer} which |
| * can be called directly from an event handler, |
| * listener or callback. |
| * |
| * @param <T> Data container type for output tuples. |
| */ |
| public class Events<T> extends Source<T>implements Consumer<T> { |
| |
| private static final long serialVersionUID = 1L; |
| private Consumer<Consumer<T>> eventSetup; |
| |
| public Events(Consumer<Consumer<T>> eventSetup) { |
| this.eventSetup = eventSetup; |
| } |
| |
| @Override |
| public void close() throws Exception { |
| closeFunction(eventSetup); |
| } |
| |
| @Override |
| public void start() { |
| // Allocate a thread so the job containing this oplet |
| // doesn't look "complete" and shutdown. |
| Thread endlessEventSource = getOpletContext() |
| .getService(ThreadFactory.class) |
| .newThread(() -> { |
| try { |
| Thread.sleep(Long.MAX_VALUE); |
| } |
| catch (InterruptedException e) { |
| // cancelled; we're done. |
| } |
| }); |
| endlessEventSource.setDaemon(false); |
| endlessEventSource.start(); |
| |
| // It's possible for uses to do things like a blocking connect |
| // to an external system from eventSetup.accept() so run it as |
| // a task to avoid start() / submit-job timeouts. |
| getOpletContext().getService(ScheduledExecutorService.class) |
| .submit(() -> eventSetup.accept(this)); |
| } |
| |
| @Override |
| public void accept(T tuple) { |
| submit(tuple); |
| } |
| } |