org.web3j.utils.Async Maven / Gradle / Ivy
/*
* Copyright 2019 Web3 Labs Ltd.
*
* Licensed 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.web3j.utils;
import java.util.concurrent.Callable;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
/** Async task facilitation. */
public class Async {
private static final ExecutorService executor = Executors.newCachedThreadPool();
static {
Runtime.getRuntime().addShutdownHook(new Thread(() -> shutdown(executor)));
}
public static CompletableFuture run(Callable callable) {
CompletableFuture result = new CompletableFuture<>();
CompletableFuture.runAsync(
() -> {
// we need to explicitly catch any exceptions,
// otherwise they will be silently discarded
try {
result.complete(callable.call());
} catch (Throwable e) {
result.completeExceptionally(e);
}
},
executor);
return result;
}
private static int getCpuCount() {
return Runtime.getRuntime().availableProcessors();
}
/**
* Provide a new ScheduledExecutorService instance.
*
* A shutdown hook is created to terminate the thread pool on application termination.
*
* @return new ScheduledExecutorService
*/
public static ScheduledExecutorService defaultExecutorService() {
ScheduledExecutorService scheduledExecutorService =
Executors.newScheduledThreadPool(getCpuCount());
Runtime.getRuntime().addShutdownHook(new Thread(() -> shutdown(scheduledExecutorService)));
return scheduledExecutorService;
}
/**
* Shutdown as per {@link ExecutorService} Javadoc recommendation.
*
* @param executorService executor service we wish to shut down.
*/
private static void shutdown(ExecutorService executorService) {
executorService.shutdown();
try {
if (!executorService.awaitTermination(60, TimeUnit.SECONDS)) {
executorService.shutdownNow();
if (!executorService.awaitTermination(60, TimeUnit.SECONDS)) {
System.err.println("Thread pool did not terminate");
}
}
} catch (InterruptedException ie) {
executorService.shutdownNow();
Thread.currentThread().interrupt();
}
}
}