DMDirc-Client/src/main/java/com/dmdirc/util/LoggingScheduledExecutorSer...

/*
 * Copyright (c) 2006-2017 DMDirc Developers
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
 * documentation files (the "Software"), to deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 * WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
 * OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package com.dmdirc.util;

import com.google.common.util.concurrent.ThreadFactoryBuilder;

import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.function.BiConsumer;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static com.dmdirc.util.LogUtils.APP_ERROR;

/**
 * An scheduled executor service that takes logs failed executions either via eventbus errors or a
 * custom error function.
 */
public class LoggingScheduledExecutorService extends ScheduledThreadPoolExecutor {

    private static final Logger LOG = LoggerFactory.getLogger(LoggingScheduledExecutorService.class);

    private final BiConsumer<Runnable, Throwable> afterExecute;

    /**
     * Creates a new instance of this executor service.
     *
     * @param coreSize The number of threads to keep in the pool, even if they are idle, unless
     *                 {@code allowCoreThreadTimeOut} is set
     * @param poolName The naming format to use when naming threads
     */
    public LoggingScheduledExecutorService(final int coreSize, final String poolName) {
        this(coreSize, (r, t) -> LOG.error(APP_ERROR, t.getMessage(), t), poolName);
    }

    /**
     * Creates a new instance of this executor service.
     *
     * @param coreSize     The number of threads to keep in the pool, even if they are idle,
     *                     unless {@code allowCoreThreadTimeOut} is set
     * @param afterExecute The function to call when an exception occurs
     * @param poolName     The naming format to use when naming threads
     */
    public LoggingScheduledExecutorService(final int coreSize,
            final BiConsumer<Runnable, Throwable> afterExecute, final String poolName) {
        super(coreSize, new ThreadFactoryBuilder().setNameFormat(poolName + "-%d").build());
        this.afterExecute = afterExecute;
    }

    @Override
    protected void afterExecute(final Runnable r, final Throwable t) {
        super.afterExecute(r, t);
        if (t == null && r instanceof Future<?>) {
            try {
                if (((Future<?>) r).isDone()) {
                    // If a periodic task completes successfully it is reset before this method
                    // is called, and get() will block indefinitely. If it is not scheduled to run
                    // again, or if it has thrown an exception and been stopped by the executor,
                    // then isDone() will return true and we can safely call get().
                    ((Future<?>) r).get();
                }
            } catch (CancellationException | InterruptedException ex) {
                //Ignore
            } catch (ExecutionException ex) {
                afterExecute.accept(r, ex);
            }
        }
        if (t != null) {
            afterExecute.accept(r, t);
        }
    }
}