AppenderExecutors.java

package org.eluder.logback.ext.core;

/*
 * #[license]
 * logback-ext-core
 * %%
 * Copyright (C) 2014 - 2015 Tapio Rautonen
 * %%
 * 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.
 * %[license]
 */

import ch.qos.logback.core.Appender;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import static java.lang.String.format;

public class AppenderExecutors {

    public static final int DEFAULT_THREAD_POOL_SIZE = 20;
    public static final int DEFAULT_MAX_FLUSH_TIME = 3000; // milliseconds

    public static ExecutorService newExecutor(Appender<?> appender, int threadPoolSize) {
        final String name = appender.getName();
        return Executors.newFixedThreadPool(threadPoolSize, new ThreadFactory() {

            private final AtomicInteger idx = new AtomicInteger(1);

            @Override
            public Thread newThread(Runnable r) {
                Thread thread = Executors.defaultThreadFactory().newThread(r);
                thread.setName(name + "-" + idx.getAndIncrement());
                thread.setDaemon(true);
                return thread;
            }
        });
    }

    public static void shutdown(Appender<?> appender, ExecutorService executor, long waitMillis) {
        executor.shutdown();
        boolean completed = awaitTermination(appender, executor, waitMillis);
        if (!completed) {
            appender.addWarn(format("Executor for %s did not shut down in %d milliseconds, " +
                                    "logging events might have been discarded",
                                    appender.getName(), waitMillis));
        }
    }

    public static void awaitLatch(Appender<?> appender, CountDownLatch latch, long waitMillis) {
        if (latch.getCount() > 0) {
            try {
                boolean completed = latch.await(waitMillis, TimeUnit.MILLISECONDS);
                if (!completed) {
                    appender.addWarn(format("Appender '%s' did not complete sending event in %d milliseconds, " +
                                            "the event might have been lost",
                                            appender.getName(), waitMillis));
                }
            } catch (InterruptedException ex) {
                appender.addWarn(format("Appender '%s' was interrupted, " +
                                        "a logging event might have been lost or shutdown was initiated",
                                        appender.getName()));
                Thread.currentThread().interrupt();
            }
        }
    }

    private static boolean awaitTermination(Appender<?> appender, ExecutorService executor, long waitMillis) {
        long started = System.currentTimeMillis();
        try {
            return executor.awaitTermination(waitMillis, TimeUnit.MILLISECONDS);
        } catch (InterruptedException ie1) {
            // the worker loop is stopped by interrupt, but the remaining queue should still be handled
            long waited = System.currentTimeMillis() - started;
            if (waited < waitMillis) {
                try {
                    return executor.awaitTermination(waitMillis - waited, TimeUnit.MILLISECONDS);
                } catch (InterruptedException ie2) {
                    appender.addError(format("Shut down of executor for %s was interrupted",
                                             appender.getName()));
                }
            }
            Thread.currentThread().interrupt();
        }
        return false;
    }

    private AppenderExecutors() {
    }
}