/**
* Copyright 2015-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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 com.amazonaws.mobileconnectors.s3.transferutility;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
class TransferThreadPool {
private static ExecutorService executorMainTask;
private static ExecutorService executorPartTask;
private synchronized static void init() {
int processors = Runtime.getRuntime().availableProcessors();
if (executorMainTask == null) {
executorMainTask = buildExecutor(processors + 1);
}
if (executorPartTask == null) {
executorPartTask = buildExecutor(processors + 1);
}
}
public static <T> Future<T> submitTask(Callable<T> c) {
init();
if (c instanceof UploadPartTask) {
return executorPartTask.submit(c);
} else {
return executorMainTask.submit(c);
}
}
public static void closeThreadPool() {
shutdown(executorPartTask);
executorPartTask = null;
shutdown(executorMainTask);
executorMainTask = null;
}
private static void shutdown(ExecutorService executor) {
if (executor == null) {
return;
}
// Attempt to shutdown executor
executor.shutdown();
try {
// Wait for existing tasks
if (!executor.awaitTermination(250, TimeUnit.MILLISECONDS)) {
// Cancel tasks in execution
executor.shutdownNow();
}
} catch (InterruptedException ie) {
executor.shutdownNow();
Thread.currentThread().interrupt();
}
}
private static ExecutorService buildExecutor(int maxThreadsAllowed) {
/*
* Create a bounded thread pool for executing transfers; it creates
* threads as needed (up to maximum) and reclaims them when finished.
*/
final ThreadPoolExecutor executor = new ThreadPoolExecutor(maxThreadsAllowed,
maxThreadsAllowed, 10, TimeUnit.SECONDS,
new LinkedBlockingQueue<Runnable>());
/*
* It's safe to discard tasks, as they are saved in database and will be
* recovered on next database scan.
*/
executor.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardPolicy());
executor.allowCoreThreadTimeOut(true);
return executor;
}
}