keith-turner commented on a change in pull request #402: ACCUMULO-4615: Updated get status for thread safety and with a per-task timeout URL: https://github.com/apache/accumulo/pull/402#discussion_r175576157
########## File path: server/master/src/main/java/org/apache/accumulo/master/TimeoutTaskExecutor.java ########## @@ -0,0 +1,198 @@ +/* + * 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.accumulo.master; + +import java.util.ArrayList; +import java.util.List; +import java.util.Objects; +import java.util.concurrent.Callable; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Future; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.TimeoutException; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import com.google.common.base.Preconditions; + +/** + * Runs one or more tasks with a timeout per task (instead of a timeout for the entire pool). Uses callbacks to invoke functions on successful, timed out, or + * tasks that error. + * + * @param <T> + * The return type for the corresponding Callable. + * @param <C> + * The type of Callable submitted to this executor. + */ +public class TimeoutTaskExecutor<T,C extends Callable<T>> implements AutoCloseable { + + private final static Logger log = LoggerFactory.getLogger(TimeoutTaskExecutor.class); + + private final long timeout; + private final ExecutorService executorService; + private final List<WrappedTask> wrappedTasks; + + private SuccessCallback<T,C> successCallback; + private ExceptionCallback<C> exceptionCallback; + private TimeoutCallback<C> timeoutCallback; + + /** + * Constructs a new TimeoutTaskExecutor using the given executor to schedule tasks with a max timeout. Takes an expected number of Callables to initialize the + * underlying task collection more appropriately. + * + * @param executorService + * The executor to schedule tasks with. + * @param timeout + * The timeout for each task. + * @param expectedNumCallables + * The expected number of callables you will schedule (for sizing optimization). + */ + public TimeoutTaskExecutor(ExecutorService executorService, long timeout, int expectedNumCallables) { + this.executorService = executorService; + this.timeout = timeout; + this.wrappedTasks = new ArrayList<>(expectedNumCallables); + } + + /** + * Submits a new task to the executor. + * + * @param callable + * Task to run + */ + public void submit(C callable) { + WrappedTask wt = new WrappedTask(callable, executorService.submit(callable)); + wrappedTasks.add(wt); + } + + /** + * Registers the callback to use on successful tasks. + * + * @param successCallback + * The callback function to invoke on success. + * @throws NullPointerException + * when a null successCallback is passed in + */ + public void onSuccess(SuccessCallback<T,C> successCallback) { + this.successCallback = Objects.requireNonNull(successCallback, "Must provide a non-null successCallback."); + } + + /** + * Registers the callback to use on tasks that throw exceptions. + * + * @param exceptionCallback + * The callback function to invoke on exceptions. + * @throws NullPointerException + * when a null exceptionCallback is passed in + */ + public void onException(ExceptionCallback<C> exceptionCallback) { + this.exceptionCallback = Objects.requireNonNull(exceptionCallback, "Must provide a non-null exceptionCallback."); + } + + /** + * Registers the callback to use on tasks that time out. + * + * @param timeoutCallback + * The callback function to invoke on timeouts. + * @throws NullPointerException + * when a null timeoutCallback is passed in + */ + public void onTimeout(TimeoutCallback<C> timeoutCallback) { + this.timeoutCallback = Objects.requireNonNull(timeoutCallback, "Must provide a non-null timeoutCallback."); + } + + /** + * Completes all the current tasks by dispatching to the appropriated callback. + * + * @throws IllegalStateException + * If all of the callbacks were not registered before calling this method. + * @throws InterruptedException + * If interrupted while awaiting callable results. + */ + public void complete() throws InterruptedException { + Preconditions.checkState(successCallback != null, "Must set a success callback before completing " + this); + Preconditions.checkState(exceptionCallback != null, "Must set an exception callback before completing " + this); + Preconditions.checkState(timeoutCallback != null, "Must set a timeout callback before completing " + this); + + for (WrappedTask wt : wrappedTasks) { + try { + successCallback.accept(wt.callable, wt.future.get(timeout, TimeUnit.MILLISECONDS)); + } catch (InterruptedException e) { + throw e; + } catch (TimeoutException e) { + wt.future.cancel(true); + timeoutCallback.accept(wt.callable); Review comment: Its possible a future that is queued to execute, but has not yet executed could be canceled. And if this happens 3 times for a tserver, the master will try to halt it. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
