| /* |
| * 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.samza.executors; |
| |
| import com.google.common.util.concurrent.ThreadFactoryBuilder; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.Random; |
| import java.util.concurrent.AbstractExecutorService; |
| import java.util.concurrent.ExecutorService; |
| import java.util.concurrent.Executors; |
| import java.util.concurrent.Future; |
| import java.util.concurrent.ThreadFactory; |
| import java.util.concurrent.TimeUnit; |
| |
| |
| /** |
| * This class supports submitting {@link Runnable} tasks with an ordering key, so that tasks submitted with the |
| * same key will always be executed in order, but tasks across different keys can be executed in parallel and out of |
| * order. |
| * Ordering is achieved by hashing the key objects to threads by their {@link #hashCode()} method. |
| * Ordering is guaranteed only when using the {@link #submitOrdered(Object, Runnable)} method. None of the |
| * {@link #submit} and {@link #execute(Runnable)} method(s) guarantee the ordering semantics. |
| */ |
| public class KeyBasedExecutorService extends AbstractExecutorService { |
| final String threadPoolNamePrefix; |
| final ExecutorService[] executors; |
| final Random rand = new Random(); |
| final int numThreads; |
| |
| public KeyBasedExecutorService(int numThreads) { |
| this("KeyBasedExecutor", numThreads); |
| } |
| |
| /** |
| * Constructs an instance of a KeyBasedExecutorService that manages the underlying threads |
| * |
| * @param threadPoolNamePrefix String identifier for this ExecutorService. It forms the prefix for each of the |
| * underlying thread pool executors |
| * @param numThreads Total number of threads required, mainly dependent on the key set size and the degree of |
| * parallelism. Highest level of parallelism can be achieved by setting the |
| * number of threads = key set size. |
| * @throws IllegalArgumentException if numThreads {@literal <}= 0 |
| */ |
| public KeyBasedExecutorService(String threadPoolNamePrefix, |
| int numThreads) { |
| if (numThreads <= 0) { |
| throw new IllegalArgumentException("numThreads has to be greater than 0 in KeyBasedExecutor!"); |
| } |
| this.numThreads = numThreads; |
| this.threadPoolNamePrefix = threadPoolNamePrefix; |
| this.executors = new ExecutorService[numThreads]; |
| final ThreadFactory defaultThreadFactory = Executors.defaultThreadFactory(); |
| |
| for (int i = 0; i < numThreads; i++) { |
| final ExecutorService threadPoolExecutorPerQueue = Executors.newSingleThreadExecutor( |
| new ThreadFactoryBuilder() |
| .setThreadFactory(defaultThreadFactory) |
| .setNameFormat(this.threadPoolNamePrefix + "-" + i + "-%d") |
| .build() |
| ); |
| executors[i] = threadPoolExecutorPerQueue; |
| } |
| } |
| |
| protected ExecutorService chooseRandomExecutor() { |
| if (executors.length == 1) { |
| return executors[0]; |
| } |
| return executors[rand.nextInt(executors.length)]; |
| } |
| |
| protected ExecutorService chooseExecutor(Object object) { |
| if (executors.length == 1) { |
| return executors[0]; |
| } |
| return executors[signSafeMod(object.hashCode(), executors.length)]; |
| } |
| |
| private static int signSafeMod(long dividend, int divisor) { |
| int mod = (int) (dividend % divisor); |
| if (mod < 0) { |
| mod += divisor; |
| } |
| return mod; |
| } |
| |
| @Override |
| public void shutdown() { |
| for (int i = 0; i < executors.length; i++) { |
| executors[i].shutdown(); |
| } |
| } |
| |
| @Override |
| public List<Runnable> shutdownNow() { |
| List<Runnable> unexecutedRunnables = new ArrayList<>(); |
| for (int i = 0; i < executors.length; i++) { |
| List<Runnable> unexecutedRunnablesPerQueue = executors[i].shutdownNow(); |
| if (unexecutedRunnablesPerQueue != null && unexecutedRunnablesPerQueue.size() > 0) { |
| unexecutedRunnables.addAll(unexecutedRunnablesPerQueue); |
| } |
| } |
| return unexecutedRunnables; |
| } |
| |
| @Override |
| public boolean isShutdown() { |
| boolean ret = true; |
| for (int i = 0; i < executors.length; i++) { |
| ret = ret && executors[i].isShutdown(); |
| } |
| return ret; |
| } |
| |
| @Override |
| public boolean isTerminated() { |
| boolean ret = true; |
| for (int i = 0; i < executors.length; i++) { |
| ret = ret && executors[i].isTerminated(); |
| } |
| return ret; |
| } |
| |
| /** |
| * Awaits termination of each of the underlying threads |
| * |
| * Note: This can potentially block longer than the given timeout, since the timeout applies for each of the |
| * underlying threads. |
| * |
| * @param timeout time to wait for each thread to terminate |
| * @param unit unit of time for specifying timeout |
| * @return Returns True, if all threads terminate successfully within their timeout. False, otherwise. |
| * @throws InterruptedException thrown when the current executing thread is interrupted |
| */ |
| @Override |
| public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException { |
| boolean ret = true; |
| for (int i = 0; i < executors.length; i++) { |
| ret = ret && executors[i].awaitTermination(timeout, unit); |
| } |
| return ret; |
| } |
| |
| public Future<?> submitOrdered(Object key, Runnable task) { |
| return chooseExecutor(key).submit(task); |
| } |
| |
| /** |
| * Executes the given {@link Runnable} task in a randomly chosen thread-pool |
| * @param command An instance of the {@link Runnable} task |
| */ |
| @Override |
| public void execute(Runnable command) { |
| chooseRandomExecutor().execute(command); |
| } |
| } |