/*
 * 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.logging.log4j.core.util;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.TimeUnit;

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.status.StatusLogger;

public class ExecutorServices {

    private static final Logger LOGGER = StatusLogger.getLogger();

    
Shuts down the given ExecutorService in an orderly fashion. Disables new tasks from submission and then waits for existing tasks to terminate. Eventually cancels running tasks if too much time elapses. 

If the timeout is 0, then a plain shutdown takes place.

Params:
executorService – 
           the pool to shutdown.
timeout – 
           the maximum time to wait, or 0 to not wait for existing tasks to terminate.
timeUnit – 
           the time unit of the timeout argument
source – 
           use this string in any log messages.
Returns:
true if the given executor terminated and false if the timeout elapsed before termination./**
     * Shuts down the given {@link ExecutorService} in an orderly fashion. Disables new tasks from submission and then
     * waits for existing tasks to terminate. Eventually cancels running tasks if too much time elapses.
     * <p>
     * If the timeout is 0, then a plain shutdown takes place.
     * </p>
     *
     * @param executorService
     *            the pool to shutdown.
     * @param timeout
     *            the maximum time to wait, or 0 to not wait for existing tasks to terminate.
     * @param timeUnit
     *            the time unit of the timeout argument
     * @param source
     *            use this string in any log messages.
     * @return {@code true} if the given executor terminated and {@code false} if the timeout elapsed before
     *         termination.
     */
    public static boolean shutdown(final ExecutorService executorService, final long timeout, final TimeUnit timeUnit, final String source) {
        if (executorService == null || executorService.isTerminated()) {
            return true;
        }
        executorService.shutdown(); // Disable new tasks from being submitted
        if (timeout > 0 && timeUnit == null) {
            throw new IllegalArgumentException(
                    String.format("%s can't shutdown %s when timeout = %,d and timeUnit = %s.", source, executorService,
                            timeout, timeUnit));
        }
        if (timeout > 0) {
            try {
                // Wait a while for existing tasks to terminate
                if (!executorService.awaitTermination(timeout, timeUnit)) {
                    executorService.shutdownNow(); // Cancel currently executing tasks
                    // Wait a while for tasks to respond to being cancelled
                    if (!executorService.awaitTermination(timeout, timeUnit)) {
                        LOGGER.error("{} pool {} did not terminate after {} {}", source, executorService, timeout,
                                timeUnit);
                    }
                    return false;
                }
            } catch (final InterruptedException ie) {
                // (Re-)Cancel if current thread also interrupted
                executorService.shutdownNow();
                // Preserve interrupt status
                Thread.currentThread().interrupt();
            }
        } else {
            executorService.shutdown();
        }
        return true;
    }

}