/**
    * 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.hadoop.hbase.master.balancer;
  
  import static org.junit.Assert.assertEquals;
  
  import java.util.Random;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.HBaseTestingUtility;
  import org.apache.hadoop.hbase.MiniHBaseCluster;
  import org.apache.hadoop.hbase.master.HMaster;
  import org.apache.hadoop.hbase.testclassification.MediumTests;
  import org.apache.hadoop.metrics2.MetricsSource;
  import org.apache.hadoop.metrics2.MetricsTag;
  import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem;
  import org.junit.AfterClass;
  import org.junit.BeforeClass;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  
  @Category({ MediumTests.class })
  public class TestBalancerStatusTagInJMXMetrics extends BalancerTestBase {
    private static final Log LOG = LogFactory.getLog(TestBalancerStatusTagInJMXMetrics.class);
    private static HBaseTestingUtility UTIL = new HBaseTestingUtility();
    private static int connectorPort = 61120;
    private static HMaster master;
    private static MiniHBaseCluster cluster;
    private static Configuration conf = null;
  
    /**
     * Setup the environment for the test.
     */
    @BeforeClass
    public static void setupBeforeClass() throws Exception {
  
      conf = UTIL.getConfiguration();
      Random rand = new Random();
      for (int i = 0; i < 10; i++) {
        do {
          int sign = i % 2 == 0 ? 1 : -1;
          connectorPort += sign * rand.nextInt(100);
        } while (!HBaseTestingUtility.available(connectorPort));
        try {
          conf.setInt("regionserver.rmi.registry.port", connectorPort);
          cluster = UTIL.startMiniCluster();
          LOG.info("Waiting for active/ready master");
          cluster.waitForActiveAndReadyMaster();
          master = cluster.getMaster();
          break;
        } catch (Exception e) {
          LOG.debug("Encountered exception when starting mini cluster. Trying port " + connectorPort,
            e);
          try {
            // this is to avoid "IllegalStateException: A mini-cluster is already running"
            UTIL.shutdownMiniCluster();
          } catch (Exception ex) {
            LOG.debug("Encountered exception shutting down cluster", ex);
          }
        }
      }
    }
  
    @AfterClass
    public static void tearDownAfterClass() throws Exception {
      UTIL.shutdownMiniCluster();
    }
  
    /**
     * Tests the status change using the Default Metrics System
     */
    @Test
    public void testJmxMetrics() throws Exception {
  
      assertEquals(getStatus(), "true");
      master.getLoadBalancer().updateBalancerStatus(false);
      assertEquals(getStatus(), "false");
  
    }
  
    /**
     * Gets the balancer status tag from the Metrics registry
     */
    public String getStatus() throws Exception {
      MetricsSource source =
          DefaultMetricsSystem.instance().getSource(MetricsBalancerSource.METRICS_JMX_CONTEXT);
      if (source instanceof MetricsBalancerSourceImpl) {
        MetricsTag status = ((MetricsBalancerSourceImpl) source).getMetricsRegistry()
           .getTag(MetricsBalancerSource.BALANCER_STATUS);
       return status.value();
     } else {
       LOG.warn("Balancer JMX Metrics not registered");
       throw new Exception("MetricsBalancer JMX Context not found");
     }
   }
 
 }