/**
 * 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.regionserver;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

import java.io.IOException;
import java.io.StringWriter;

import org.apache.commons.lang3.StringUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseClassTestRule;
import org.apache.hadoop.hbase.HBaseTestingUtility;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.LocalHBaseCluster;
import org.apache.hadoop.hbase.MiniHBaseCluster.MiniHBaseClusterRegionServer;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.ipc.ServerNotRunningYetException;
import org.apache.hadoop.hbase.master.HMaster;
import org.apache.hadoop.hbase.master.LoadBalancer;
import org.apache.hadoop.hbase.master.ServerManager;
import org.apache.hadoop.hbase.testclassification.MediumTests;
import org.apache.hadoop.hbase.util.JVMClusterUtil.MasterThread;
import org.apache.hadoop.hbase.util.JVMClusterUtil.RegionServerThread;
import org.apache.log4j.Appender;
import org.apache.log4j.Layout;
import org.apache.log4j.PatternLayout;
import org.apache.log4j.WriterAppender;
import org.apache.zookeeper.KeeperException;
import org.junit.After;
import org.junit.Before;
import org.junit.ClassRule;
import org.junit.Test;
import org.junit.experimental.categories.Category;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Category(MediumTests.class)
public class TestRegionServerReportForDuty {

  @ClassRule
  public static final HBaseClassTestRule CLASS_RULE =
      HBaseClassTestRule.forClass(TestRegionServerReportForDuty.class);

  private static final Logger LOG = LoggerFactory.getLogger(TestRegionServerReportForDuty.class);

  private static final long SLEEP_INTERVAL = 500;

  private HBaseTestingUtility testUtil;
  private LocalHBaseCluster cluster;
  private RegionServerThread rs;
  private RegionServerThread rs2;
  private MasterThread master;
  private MasterThread backupMaster;

  @Before
  public void setUp() throws Exception {
    testUtil = new HBaseTestingUtility();
    testUtil.startMiniDFSCluster(1);
    testUtil.startMiniZKCluster(1);
    testUtil.createRootDir();
    cluster = new LocalHBaseCluster(testUtil.getConfiguration(), 0, 0);
  }

  @After
  public void tearDown() throws Exception {
    cluster.shutdown();
    cluster.join();
    testUtil.shutdownMiniZKCluster();
    testUtil.shutdownMiniDFSCluster();
  }

  /**
   * LogCapturer is similar to {@link org.apache.hadoop.test.GenericTestUtils.LogCapturer}
   * except that this implementation has a default appender to the root logger.
   * Hadoop 2.8+ supports the default appender in the LogCapture it ships and this can be replaced.
   * TODO: This class can be removed after we upgrade Hadoop dependency.
   */
  static class LogCapturer {
    private StringWriter sw = new StringWriter();
    private WriterAppender appender;
    private org.apache.log4j.Logger logger;

    LogCapturer(org.apache.log4j.Logger logger) {
      this.logger = logger;
      Appender defaultAppender = org.apache.log4j.Logger.getRootLogger().getAppender("stdout");
      if (defaultAppender == null) {
        defaultAppender = org.apache.log4j.Logger.getRootLogger().getAppender("console");
      }
      final Layout layout = (defaultAppender == null) ? new PatternLayout() :
          defaultAppender.getLayout();
      this.appender = new WriterAppender(layout, sw);
      this.logger.addAppender(this.appender);
    }

    String getOutput() {
      return sw.toString();
    }

    public void stopCapturing() {
      this.logger.removeAppender(this.appender);
    }
  }

  /**
   * This test HMaster class will always throw ServerNotRunningYetException if checked.
   */
  public static class NeverInitializedMaster extends HMaster {
    public NeverInitializedMaster(Configuration conf) throws IOException, KeeperException {
      super(conf);
    }

    @Override
    protected void checkServiceStarted() throws ServerNotRunningYetException {
      throw new ServerNotRunningYetException("Server is not running yet");
    }
  }

  /**
   * Tests region server should backoff to report for duty if master is not ready.
   */
  @Test
  public void testReportForDutyBackoff() throws IOException, InterruptedException {
    cluster.getConfiguration().set(HConstants.MASTER_IMPL, NeverInitializedMaster.class.getName());
    master = cluster.addMaster();
    master.start();

    LogCapturer capturer = new LogCapturer(org.apache.log4j.Logger.getLogger(HRegionServer.class));
    // Set sleep interval relatively low so that exponential backoff is more demanding.
    int msginterval = 100;
    cluster.getConfiguration().setInt("hbase.regionserver.msginterval", msginterval);
    rs = cluster.addRegionServer();
    rs.start();

    int interval = 10_000;
    Thread.sleep(interval);
    capturer.stopCapturing();
    String output = capturer.getOutput();
    LOG.info("{}", output);
    String failMsg = "reportForDuty failed;";
    int count = StringUtils.countMatches(output, failMsg);

    // Following asserts the actual retry number is in range (expectedRetry/2, expectedRetry*2).
    // Ideally we can assert the exact retry count. We relax here to tolerate contention error.
    int expectedRetry = (int)Math.ceil(Math.log(interval - msginterval));
    assertTrue(String.format("reportForDuty retries %d times, less than expected min %d",
        count, expectedRetry / 2), count > expectedRetry / 2);
    assertTrue(String.format("reportForDuty retries %d times, more than expected max %d",
        count, expectedRetry * 2), count < expectedRetry * 2);
  }

  /**
   * Tests region sever reportForDuty with backup master becomes primary master after
   * the first master goes away.
   */
  @Test
  public void testReportForDutyWithMasterChange() throws Exception {

    // Start a master and wait for it to become the active/primary master.
    // Use a random unique port
    cluster.getConfiguration().setInt(HConstants.MASTER_PORT, HBaseTestingUtility.randomFreePort());
    // master has a rs. defaultMinToStart = 2
    boolean tablesOnMaster = LoadBalancer.isTablesOnMaster(testUtil.getConfiguration());
    cluster.getConfiguration().setInt(ServerManager.WAIT_ON_REGIONSERVERS_MINTOSTART, tablesOnMaster? 2: 1);
    cluster.getConfiguration().setInt(ServerManager.WAIT_ON_REGIONSERVERS_MAXTOSTART, tablesOnMaster? 2: 1);
    master = cluster.addMaster();
    rs = cluster.addRegionServer();
    LOG.debug("Starting master: " + master.getMaster().getServerName());
    master.start();
    rs.start();

    waitForClusterOnline(master);

    // Add a 2nd region server
    cluster.getConfiguration().set(HConstants.REGION_SERVER_IMPL, MyRegionServer.class.getName());
    rs2 = cluster.addRegionServer();
    // Start the region server. This region server will refresh RPC connection
    // from the current active master to the next active master before completing
    // reportForDuty
    LOG.debug("Starting 2nd region server: " + rs2.getRegionServer().getServerName());
    rs2.start();

    waitForSecondRsStarted();

    // Stop the current master.
    master.getMaster().stop("Stopping master");

    // Start a new master and use another random unique port
    // Also let it wait for exactly 2 region severs to report in.
    cluster.getConfiguration().setInt(HConstants.MASTER_PORT, HBaseTestingUtility.randomFreePort());
    cluster.getConfiguration().setInt(ServerManager.WAIT_ON_REGIONSERVERS_MINTOSTART,
      tablesOnMaster? 3: 2);
    cluster.getConfiguration().setInt(ServerManager.WAIT_ON_REGIONSERVERS_MAXTOSTART,
      tablesOnMaster? 3: 2);
    backupMaster = cluster.addMaster();
    LOG.debug("Starting new master: " + backupMaster.getMaster().getServerName());
    backupMaster.start();

    waitForClusterOnline(backupMaster);

    // Do some checking/asserts here.
    assertTrue(backupMaster.getMaster().isActiveMaster());
    assertTrue(backupMaster.getMaster().isInitialized());
    assertEquals(backupMaster.getMaster().getServerManager().getOnlineServersList().size(),
      tablesOnMaster? 3: 2);

  }

  private void waitForClusterOnline(MasterThread master) throws InterruptedException {
    while (true) {
      if (master.getMaster().isInitialized()) {
        break;
      }
      Thread.sleep(SLEEP_INTERVAL);
      LOG.debug("Waiting for master to come online ...");
    }
    rs.waitForServerOnline();
  }

  private void waitForSecondRsStarted() throws InterruptedException {
    while (true) {
      if (((MyRegionServer) rs2.getRegionServer()).getRpcStubCreatedFlag() == true) {
        break;
      }
      Thread.sleep(SLEEP_INTERVAL);
      LOG.debug("Waiting 2nd RS to be started ...");
    }
  }

  // Create a Region Server that provide a hook so that we can wait for the master switch over
  // before continuing reportForDuty to the mater.
  // The idea is that we get a RPC connection to the first active master, then we wait.
  // The first master goes down, the second master becomes the active master. The region
  // server continues reportForDuty. It should succeed with the new master.
  public static class MyRegionServer extends MiniHBaseClusterRegionServer {

    private ServerName sn;
    // This flag is to make sure this rs has obtained the rpcStub to the first master.
    // The first master will go down after this.
    private boolean rpcStubCreatedFlag = false;
    private boolean masterChanged = false;

    public MyRegionServer(Configuration conf) throws IOException, KeeperException,
        InterruptedException {
      super(conf);
    }

    @Override
    protected synchronized ServerName createRegionServerStatusStub(boolean refresh) {
      sn = super.createRegionServerStatusStub(refresh);
      rpcStubCreatedFlag = true;

      // Wait for master switch over. Only do this for the second region server.
      while (!masterChanged) {
        ServerName newSn = super.getMasterAddressTracker().getMasterAddress(true);
        if (newSn != null && !newSn.equals(sn)) {
          masterChanged = true;
          break;
        }
        try {
          Thread.sleep(SLEEP_INTERVAL);
        } catch (InterruptedException e) {
          return null;
        }
        LOG.debug("Waiting for master switch over ... ");
      }
      return sn;
    }

    public boolean getRpcStubCreatedFlag() {
      return rpcStubCreatedFlag;
    }
  }
}
