/*
 * 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.jackrabbit.oak.jcr;

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

import org.junit.runners.Parameterized;
import org.junit.runners.model.RunnerScheduler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Extension of the {@link Parameterized} test runner, which runs tests in
 * parallel.
 */
public class Parallelized extends Parameterized {

    /**
     * Logger instance. Present to force early auto-initialization of the
     * logging system and thus to avoid warnings about concurrent
     * initialization.
     */
    private static final Logger log =
            LoggerFactory.getLogger(Parallelized.class);

    private static class ThreadPoolScheduler implements RunnerScheduler {
        private ExecutorService executor;

        public ThreadPoolScheduler() {
            String threads = System.getProperty("junit.parallel.threads", "16");
            int numThreads = Integer.parseInt(threads);
            executor = Executors.newFixedThreadPool(numThreads);
        }

        @Override
        public void finished() {
            executor.shutdown();
            try {
                while (!executor.awaitTermination(1, TimeUnit.MINUTES)) {
                    log.info("Awaiting for the task termination in {}", executor);
                }
            } catch (InterruptedException exc) {
                throw new RuntimeException(exc);
            }
        }

        @Override
        public void schedule(Runnable childStatement) {
            executor.submit(childStatement);
        }
    }

    public Parallelized(Class klass) throws Throwable {
        super(klass);
        setScheduler(new ThreadPoolScheduler());
    }
}