/**
    * 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.chaos.util;
  
  import com.google.common.base.Preconditions;
  import com.google.common.util.concurrent.ThreadFactoryBuilder;
  import java.io.Closeable;
  import java.io.IOException;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.HBaseConfiguration;
  import org.apache.hadoop.hbase.IntegrationTestingUtility;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * This class can be used to control chaos monkeys life cycle.
   */
  public class Monkeys implements Closeable {
    private static final Logger LOG = LoggerFactory.getLogger(Monkeys.class);
  
    private final Configuration conf;
    private final ChaosMonkeyRunner monkeyRunner;
    private final Runnable runner;
    private final ExecutorService executor;
  
    public Monkeys() {
      this(HBaseConfiguration.create());
    }
  
    public Monkeys(Configuration conf) {
      this.conf = Preconditions.checkNotNull(conf, "Should specify a configuration");
      this.monkeyRunner = new ChaosMonkeyRunner();
      this.runner = new Runnable() {
        @Override public void run() {
          try {
            monkeyRunner.getAndStartMonkey();
          } catch (Exception e) {
            LOG.error("Exception occurred when running chaos monkeys: ", e);
          }
        }
      };
      this.executor = Executors.newSingleThreadExecutor(new ThreadFactoryBuilder()
        .setDaemon(true).setNameFormat("ChaosMonkey").build());
      IntegrationTestingUtility.setUseDistributedCluster(this.conf);
    }
  
    public void addResource(Configuration otherConf) {
      conf.addResource(otherConf);
      monkeyRunner.setConf(conf);
    }
  
    public void addResource(String otherConf) {
      conf.addResource(otherConf);
      monkeyRunner.setConf(conf);
    }
  
    public void startChaos() {
      executor.execute(runner);
      LOG.info("Chaos monkeys are running.");
    }
  
    public void stopChaos() {
      monkeyRunner.stopRunner();
      LOG.info("Chaos monkeys are stopped.");
    }
  
    @Override
    public void close() throws IOException {
      executor.shutdown();
      try {
        // wait 10 seconds.
        executor.awaitTermination(10, TimeUnit.SECONDS);
      } catch (InterruptedException e) {
        Thread.currentThread().interrupt();
        LOG.warn("Interruption occurred while stopping chaos monkeys " + e);
      }
    }
  }