/*
    * 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.commons.monitoring.jta;
  
  import org.apache.commons.monitoring.gauges.Gauge;
  import org.apache.commons.monitoring.repositories.Repository;
  import org.junit.AfterClass;
  import org.junit.BeforeClass;
  import org.junit.Test;
  
  import javax.ejb.EJB;
  import javax.ejb.Lock;
  import javax.ejb.LockType;
  import javax.ejb.Singleton;
  import javax.ejb.embeddable.EJBContainer;
  import java.util.Collection;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  
  import static org.junit.Assert.assertEquals;
  
  public class GaugesTest {
      private static final int ITERATIONS = 500;
  
      private static Gauge.LoaderHelper gaugeLoader;
  
      @BeforeClass
      public static void init() {
          Repository.INSTANCE.clear();
          gaugeLoader = new Gauge.LoaderHelper(false);
      }
  
      @AfterClass
      public static void reset() {
          Repository.INSTANCE.clear();
          gaugeLoader.destroy();
      }
  
      @EJB
      private EjbWithJTASupport jtaSupport;
  
      @Test
      public void test() throws Exception {
          final EJBContainer container = EJBContainer.createEJBContainer();
          container.getContext().bind("inject", this);
  
          final long start = System.currentTimeMillis();
  
          final CountDownLatch latch = new CountDownLatch(ITERATIONS);
          try {
              final ExecutorService es = Executors.newFixedThreadPool(50);
              for (int i = 0; i < ITERATIONS; i++) {
                  es.submit(new Runnable() {
                      @Override
                      public void run() {
                          jtaSupport.commit();
                          try {
                              jtaSupport.rollback();
                          } finally {
                              latch.countDown();
                          }
                      }
                  });
              }
              es.shutdown();
              latch.await();
  
              Thread.sleep(500); // wait last measure
  
              final long end = System.currentTimeMillis();
  
              assertEquals(ITERATIONS, sum(Repository.INSTANCE.getGaugeValues(start, end, JTAGauges.JTA_COMMITED).values()), 0);
              assertEquals(ITERATIONS, sum(Repository.INSTANCE.getGaugeValues(start, end, JTAGauges.JTA_ROLLBACKED).values()), 0);
  
              // due to the sleep we use in commit() we only see half of the tx when checking actives
              assertEquals(ITERATIONS / 2, sum(Repository.INSTANCE.getGaugeValues(start, end, JTAGauges.JTA_ACTIVE).values()), ITERATIONS * .1);
          } finally {
              container.close();
          }
      }
  
      private double sum(final Collection<Double> values) {
          double sum = 0;
          for (final Double d : values) {
             sum += d;
         }
         return sum;
     }
 
     @Singleton
     @Lock(LockType.READ)
     @JTAMonitored
     public static class EjbWithJTASupport {
         public void commit() {
             try {
                 Thread.sleep(50);
             } catch (final InterruptedException e) {
                 // no-op
             }
         }
 
         public void rollback() {
             throw new NullPointerException();
         }
     }
 }