| package org.superbiz.executor; |
| |
| /** |
| * 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 |
| * <p> |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * <p> |
| * 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. |
| */ |
| |
| import javax.annotation.Resource; |
| import javax.enterprise.concurrent.ManagedScheduledExecutorService; |
| import javax.enterprise.context.RequestScoped; |
| import java.util.concurrent.Callable; |
| import java.util.concurrent.CountDownLatch; |
| import java.util.concurrent.Future; |
| import java.util.concurrent.ScheduledFuture; |
| import java.util.concurrent.TimeUnit; |
| import java.util.logging.Logger; |
| |
| import static java.util.Objects.nonNull; |
| |
| |
| @RequestScoped |
| public class ManagedScheduledService { |
| |
| private static final Logger LOGGER = Logger.getLogger(ManagedScheduledService.class.getSimpleName()); |
| |
| @Resource |
| private ManagedScheduledExecutorService executor; |
| |
| /** |
| * Execute a task after a planned delay and get the result back by using a {@link Callable} |
| * |
| * @param value The value to compute |
| * @param errorMessage If not null an exception with be thrown with this message |
| * @return the processed result |
| */ |
| public Future<Integer> singleFixedDelayTask(final int value, |
| final String errorMessage) { |
| LOGGER.info("longCallableTask scheduled"); |
| return executor.schedule( |
| longCallableTask(value, 10, errorMessage), 100, TimeUnit.MILLISECONDS); |
| } |
| |
| /** |
| * Execute a task periodically. Although a future is returned, it will not contain a result because the |
| * executor uses a runnable to perform the operations.<br> |
| * If an exception happens, the task will stop and you can catch the exception with the {@link ScheduledFuture}. |
| * |
| * @param value The value to compute |
| * @param errorMessage If not null an exception with be thrown with this message |
| * @param countDownLatch |
| * @return An object where you can cancel the periodic task and check for exceptions. |
| */ |
| public ScheduledFuture<?> periodicFixedDelayTask(final int value, |
| final String errorMessage, |
| final CountDownLatch countDownLatch) { |
| LOGGER.info("longRunnableTask scheduled"); |
| return executor.scheduleAtFixedRate( |
| longRunnableTask(value, 10, errorMessage, countDownLatch), 0, 100, TimeUnit.MILLISECONDS); |
| } |
| |
| /** |
| * Will simulate a long running operation |
| * |
| * @param value The value to compute |
| * @param taskDurationMs the time length of the operation |
| * @param errorMessage If not null an exception with be thrown with this message |
| * @return a {@link Runnable} |
| */ |
| private Runnable longRunnableTask(final int value, |
| final int taskDurationMs, |
| final String errorMessage, |
| final CountDownLatch countDownLatch) { |
| return () -> { |
| failOrWait(taskDurationMs, errorMessage); |
| Integer result = value + 1; |
| LOGGER.info("longRunnableTask complete. Value is " + result); |
| // Cannot return result with a Runnable. |
| countDownLatch.countDown(); |
| }; |
| } |
| |
| /** |
| * Will simulate a long running operation |
| * |
| * @param value The value to compute |
| * @param taskDurationMs the time lenght of the operation |
| * @param errorMessage If not null an exception with be thrown with this message |
| * @return a {@link Callable} with the result |
| */ |
| private Callable<Integer> longCallableTask(final int value, |
| final int taskDurationMs, |
| final String errorMessage) { |
| return () -> { |
| LOGGER.info("longCallableTask start"); |
| failOrWait(taskDurationMs, errorMessage); |
| LOGGER.info("longCallableTask complete"); |
| // We can return a result with a Callable. |
| return value + 1; |
| }; |
| } |
| |
| private void failOrWait(final int taskDurationMs, |
| final String errorMessage) { |
| if (nonNull(errorMessage)) { |
| LOGGER.severe("Exception will be thrown"); |
| throw new RuntimeException(errorMessage); |
| } |
| try { |
| // Simulate a long processing task using TimeUnit to sleep. |
| TimeUnit.MILLISECONDS.sleep(taskDurationMs); |
| } catch (InterruptedException e) { |
| throw new RuntimeException("Problem while waiting"); |
| } |
| } |
| |
| } |