/*
    *
    * 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;
  
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertFalse;
  import static org.junit.Assert.assertNotNull;
  import static org.junit.Assert.assertTrue;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.concurrent.Semaphore;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.ChoreService;
  import org.apache.hadoop.hbase.CoordinatedStateManager;
  import org.apache.hadoop.hbase.HBaseTestingUtility;
  import org.apache.hadoop.hbase.Waiter;
  import org.apache.hadoop.hbase.testclassification.MediumTests;
  import org.apache.hadoop.hbase.Server;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.client.ClusterConnection;
  import org.apache.hadoop.hbase.monitoring.MonitoredTask;
  import org.apache.hadoop.hbase.zookeeper.ClusterStatusTracker;
  import org.apache.hadoop.hbase.zookeeper.MasterAddressTracker;
  import org.apache.hadoop.hbase.zookeeper.MetaTableLocator;
  import org.apache.hadoop.hbase.zookeeper.ZKUtil;
  import org.apache.hadoop.hbase.zookeeper.ZooKeeperListener;
  import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
  import org.apache.zookeeper.KeeperException;
  import org.junit.AfterClass;
  import org.junit.BeforeClass;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  import org.mockito.Mockito;
  
  /**
   * Test the {@link ActiveMasterManager}.
   */
  @Category(MediumTests.class)
  public class TestActiveMasterManager {
    private final static Log LOG = LogFactory.getLog(TestActiveMasterManager.class);
    private final static HBaseTestingUtility TEST_UTIL = new HBaseTestingUtility();
  
    @BeforeClass
    public static void setUpBeforeClass() throws Exception {
      TEST_UTIL.startMiniZKCluster();
    }
  
    @AfterClass
    public static void tearDownAfterClass() throws Exception {
      TEST_UTIL.shutdownMiniZKCluster();
    }
  
    @Test public void testRestartMaster() throws IOException, KeeperException {
      try (ZooKeeperWatcher zk = new ZooKeeperWatcher(TEST_UTIL.getConfiguration(),
          "testActiveMasterManagerFromZK", null, true)) {
        try {
          ZKUtil.deleteNode(zk, zk.getMasterAddressZNode());
          ZKUtil.deleteNode(zk, zk.clusterStateZNode);
        } catch (KeeperException.NoNodeException nne) {
        }
  
        // Create the master node with a dummy address
        ServerName master = ServerName.valueOf("localhost", 1, System.currentTimeMillis());
        // Should not have a master yet
        DummyMaster dummyMaster = new DummyMaster(zk, master);
        ClusterStatusTracker clusterStatusTracker =
            dummyMaster.getClusterStatusTracker();
        ActiveMasterManager activeMasterManager =
            dummyMaster.getActiveMasterManager();
        assertFalse(activeMasterManager.clusterHasActiveMaster.get());
  
        // First test becoming the active master uninterrupted
        MonitoredTask status = Mockito.mock(MonitoredTask.class);
        clusterStatusTracker.setClusterUp();
  
        activeMasterManager.blockUntilBecomingActiveMaster(100, status);
        assertTrue(activeMasterManager.clusterHasActiveMaster.get());
       assertMaster(zk, master);
 
       // Now pretend master restart
       DummyMaster secondDummyMaster = new DummyMaster(zk, master);
       ActiveMasterManager secondActiveMasterManager =
           secondDummyMaster.getActiveMasterManager();
       assertFalse(secondActiveMasterManager.clusterHasActiveMaster.get());
       activeMasterManager.blockUntilBecomingActiveMaster(100, status);
       assertTrue(activeMasterManager.clusterHasActiveMaster.get());
       assertMaster(zk, master);
     }
   }
 
   /**
    * Unit tests that uses ZooKeeper but does not use the master-side methods
    * but rather acts directly on ZK.
    * @throws Exception
    */
   @Test
   public void testActiveMasterManagerFromZK() throws Exception {
     try (ZooKeeperWatcher zk = new ZooKeeperWatcher(TEST_UTIL.getConfiguration(),
         "testActiveMasterManagerFromZK", null, true)) {
       try {
         ZKUtil.deleteNode(zk, zk.getMasterAddressZNode());
         ZKUtil.deleteNode(zk, zk.clusterStateZNode);
       } catch (KeeperException.NoNodeException nne) {
       }
 
       // Create the master node with a dummy address
       ServerName firstMasterAddress =
           ServerName.valueOf("localhost", 1, System.currentTimeMillis());
       ServerName secondMasterAddress =
           ServerName.valueOf("localhost", 2, System.currentTimeMillis());
 
       // Should not have a master yet
       DummyMaster ms1 = new DummyMaster(zk, firstMasterAddress);
       ActiveMasterManager activeMasterManager =
           ms1.getActiveMasterManager();
       assertFalse(activeMasterManager.clusterHasActiveMaster.get());
 
       // First test becoming the active master uninterrupted
       ClusterStatusTracker clusterStatusTracker =
           ms1.getClusterStatusTracker();
       clusterStatusTracker.setClusterUp();
       activeMasterManager.blockUntilBecomingActiveMaster(100,
           Mockito.mock(MonitoredTask.class));
       assertTrue(activeMasterManager.clusterHasActiveMaster.get());
       assertMaster(zk, firstMasterAddress);
 
       // New manager will now try to become the active master in another thread
       WaitToBeMasterThread t = new WaitToBeMasterThread(zk, secondMasterAddress);
       t.start();
       // Wait for this guy to figure out there is another active master
       // Wait for 1 second at most
       int sleeps = 0;
       while (!t.manager.clusterHasActiveMaster.get() && sleeps < 100) {
         Thread.sleep(10);
         sleeps++;
       }
 
       // Both should see that there is an active master
       assertTrue(activeMasterManager.clusterHasActiveMaster.get());
       assertTrue(t.manager.clusterHasActiveMaster.get());
       // But secondary one should not be the active master
       assertFalse(t.isActiveMaster);
 
       // Close the first server and delete it's master node
       ms1.stop("stopping first server");
 
       // Use a listener to capture when the node is actually deleted
       NodeDeletionListener listener = new NodeDeletionListener(zk, zk.getMasterAddressZNode());
       zk.registerListener(listener);
 
       LOG.info("Deleting master node");
       ZKUtil.deleteNode(zk, zk.getMasterAddressZNode());
 
       // Wait for the node to be deleted
       LOG.info("Waiting for active master manager to be notified");
       listener.waitForDeletion();
       LOG.info("Master node deleted");
 
       // Now we expect the secondary manager to have and be the active master
       // Wait for 1 second at most
       sleeps = 0;
       while (!t.isActiveMaster && sleeps < 100) {
         Thread.sleep(10);
         sleeps++;
       }
       LOG.debug("Slept " + sleeps + " times");
 
       assertTrue(t.manager.clusterHasActiveMaster.get());
       assertTrue(t.isActiveMaster);
 
       LOG.info("Deleting master node");
 
       ZKUtil.deleteNode(zk, zk.getMasterAddressZNode());
     }
   }
 
   @Test
   public void testBackupMasterUpdates() throws Exception {
     Configuration conf = TEST_UTIL.getConfiguration();
     try (ZooKeeperWatcher zk = new ZooKeeperWatcher(
         conf, "testBackupMasterUpdates", null, true)) {
       ServerName sn1 = ServerName.valueOf("localhost", 1, -1);
       DummyMaster master1 = new DummyMaster(zk, sn1);
       final ActiveMasterManager activeMasterManager = master1.getActiveMasterManager();
       activeMasterManager.blockUntilBecomingActiveMaster(100,
           Mockito.mock(MonitoredTask.class));
       assertEquals(sn1, activeMasterManager.getActiveMasterServerName());
       assertEquals(0, activeMasterManager.getBackupMasters().size());
       // Add backup masters
       final List<String> backupZNodes = new ArrayList<>();
       for (int i = 1; i <= 10; i++) {
         ServerName backupSn = ServerName.valueOf("localhost", 1000 + i, -1);
         String backupZn = ZKUtil.joinZNode(zk.backupMasterAddressesZNode, backupSn.toString());
         backupZNodes.add(backupZn);
         MasterAddressTracker.setMasterAddress(zk, backupZn, backupSn, 1234);
         TEST_UTIL.waitFor(10000,
             new Waiter.Predicate<Exception>() {
               @Override
               public boolean evaluate() throws Exception {
                 return activeMasterManager.getBackupMasters().size() == backupZNodes.size();
               }
             });
       }
       // Remove backup masters
       int numBackups = backupZNodes.size();
       for (String backupZNode: backupZNodes) {
         ZKUtil.deleteNode(zk, backupZNode);
         final int currentBackups = --numBackups;
         TEST_UTIL.waitFor(10000,
             new Waiter.Predicate<Exception>() {
               @Override
               public boolean evaluate() throws Exception {
                 return activeMasterManager.getBackupMasters().size() == currentBackups;
               }
             });
       }
     }
   }
 
   /**
    * Assert there is an active master and that it has the specified address.
    * @param zk single Zookeeper watcher
    * @param expectedAddress the expected address of the master
    * @throws KeeperException unexpected Zookeeper exception
    * @throws IOException if an IO problem is encountered
    */
   private void assertMaster(ZooKeeperWatcher zk,
                             ServerName expectedAddress)
       throws KeeperException, IOException {
     ServerName readAddress = MasterAddressTracker.getMasterAddress(zk);
     assertNotNull(readAddress);
     assertTrue(expectedAddress.equals(readAddress));
   }
 
   public static class WaitToBeMasterThread extends Thread {
 
     ActiveMasterManager manager;
     DummyMaster dummyMaster;
     boolean isActiveMaster;
 
     public WaitToBeMasterThread(ZooKeeperWatcher zk, ServerName address)
         throws InterruptedIOException {
       this.dummyMaster = new DummyMaster(zk,address);
       this.manager = this.dummyMaster.getActiveMasterManager();
       isActiveMaster = false;
     }
 
     @Override
     public void run() {
       manager.blockUntilBecomingActiveMaster(100,
           Mockito.mock(MonitoredTask.class));
       LOG.info("Second master has become the active master!");
       isActiveMaster = true;
     }
   }
 
   public static class NodeDeletionListener extends ZooKeeperListener {
     private static final Log LOG = LogFactory.getLog(NodeDeletionListener.class);
 
     private Semaphore lock;
     private String node;
 
     public NodeDeletionListener(ZooKeeperWatcher watcher, String node) {
       super(watcher);
       lock = new Semaphore(0);
       this.node = node;
     }
 
     @Override
     public void nodeDeleted(String path) {
       if(path.equals(node)) {
         LOG.debug("nodeDeleted(" + path + ")");
         lock.release();
       }
     }
 
     public void waitForDeletion() throws InterruptedException {
       lock.acquire();
     }
   }
 
   /**
    * Dummy Master Implementation.
    */
   public static class DummyMaster implements Server {
     private volatile boolean stopped;
     private ClusterStatusTracker clusterStatusTracker;
     private ActiveMasterManager activeMasterManager;
 
     public DummyMaster(ZooKeeperWatcher zk, ServerName master) throws InterruptedIOException {
       this.clusterStatusTracker =
           new ClusterStatusTracker(zk, this);
       clusterStatusTracker.start();
 
       this.activeMasterManager =
           new ActiveMasterManager(zk, master, this);
       zk.registerListener(activeMasterManager);
     }
 
     @Override
     public void abort(final String msg, final Throwable t) {}
 
     @Override
     public boolean isAborted() {
       return false;
     }
 
     @Override
     public Configuration getConfiguration() {
       return null;
     }
 
     @Override
     public ZooKeeperWatcher getZooKeeper() {
       return null;
     }
 
     @Override
     public CoordinatedStateManager getCoordinatedStateManager() {
       return null;
     }
 
     @Override
     public ServerName getServerName() {
       return null;
     }
 
     @Override
     public boolean isStopped() {
       return this.stopped;
     }
 
     @Override
     public void stop(String why) {
       this.stopped = true;
     }
 
     @Override
     public ClusterConnection getConnection() {
       return null;
     }
 
     @Override
     public MetaTableLocator getMetaTableLocator() {
       return null;
     }
 
     public ClusterStatusTracker getClusterStatusTracker() {
       return clusterStatusTracker;
     }
 
     public ActiveMasterManager getActiveMasterManager() {
       return activeMasterManager;
     }
 
     @Override
     public ChoreService getChoreService() {
       return null;
     }
   }
 }