/**
 * 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.hdfs;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
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.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo.AdminStates;
import org.apache.hadoop.hdfs.protocol.FSConstants.DatanodeReportType;
import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
import org.apache.hadoop.hdfs.server.namenode.NameNode;
import org.apache.hadoop.hdfs.server.namenode.NameNodeAdapter;
import static org.junit.Assert.*;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

/**
 * This class tests the decommissioning of nodes.
 */
public class TestDecommission {
  public static final Log LOG = LogFactory.getLog(TestDecommission.class);
  static final long seed = 0xDEADBEEFL;
  static final int blockSize = 8192;
  static final int fileSize = 16384;
  static final int HEARTBEAT_INTERVAL = 1; // heartbeat interval in seconds
  static final int BLOCKREPORT_INTERVAL_MSEC = 1000; //block report in msec
  static final int NAMENODE_REPLICATION_INTERVAL = 1; //replication interval

  Random myrand = new Random();
  Path hostsFile;
  Path excludeFile;
  FileSystem localFileSys;
  Configuration conf;
  MiniDFSCluster cluster = null;

  @Before
  public void setup() throws IOException {
    conf = new HdfsConfiguration();
    // Set up the hosts/exclude files.
    localFileSys = FileSystem.getLocal(conf);
    Path workingDir = localFileSys.getWorkingDirectory();
    Path dir = new Path(workingDir, "build/test/data/work-dir/decommission");
    hostsFile = new Path(dir, "hosts");
    excludeFile = new Path(dir, "exclude");
    
    // Setup conf
    conf.setBoolean(DFSConfigKeys.DFS_NAMENODE_REPLICATION_CONSIDERLOAD_KEY, false);
    conf.set(DFSConfigKeys.DFS_HOSTS_EXCLUDE, excludeFile.toUri().getPath());
    conf.setInt(DFSConfigKeys.DFS_NAMENODE_HEARTBEAT_RECHECK_INTERVAL_KEY, 2000);
    conf.setInt(DFSConfigKeys.DFS_HEARTBEAT_INTERVAL_KEY, HEARTBEAT_INTERVAL);
    conf.setInt(DFSConfigKeys.DFS_BLOCKREPORT_INTERVAL_MSEC_KEY, BLOCKREPORT_INTERVAL_MSEC);
    conf.setInt(DFSConfigKeys.DFS_NAMENODE_REPLICATION_PENDING_TIMEOUT_SEC_KEY, 4);
    conf.setInt(DFSConfigKeys.DFS_NAMENODE_REPLICATION_INTERVAL_KEY, NAMENODE_REPLICATION_INTERVAL);
  
    writeConfigFile(excludeFile, null);
  }
  
  @After
  public void teardown() throws IOException {
    cleanupFile(localFileSys, excludeFile.getParent());
    if (cluster != null) {
      cluster.shutdown();
    }
  }
  
  private void writeConfigFile(Path name, ArrayList<String> nodes) 
    throws IOException {
    // delete if it already exists
    if (localFileSys.exists(name)) {
      localFileSys.delete(name, true);
    }

    FSDataOutputStream stm = localFileSys.create(name);
    
    if (nodes != null) {
      for (Iterator<String> it = nodes.iterator(); it.hasNext();) {
        String node = it.next();
        stm.writeBytes(node);
        stm.writeBytes("\n");
      }
    }
    stm.close();
  }

  private void writeFile(FileSystem fileSys, Path name, int repl)
    throws IOException {
    // create and write a file that contains three blocks of data
    FSDataOutputStream stm = fileSys.create(name, true, 
                                            fileSys.getConf().getInt("io.file.buffer.size", 4096),
                                            (short)repl, (long)blockSize);
    byte[] buffer = new byte[fileSize];
    Random rand = new Random(seed);
    rand.nextBytes(buffer);
    stm.write(buffer);
    stm.close();
    LOG.info("Created file " + name + " with " + repl + " replicas.");
  }

  /**
   * Verify that the number of replicas are as expected for each block in
   * the given file.
   * For blocks with a decommissioned node, verify that their replication
   * is 1 more than what is specified.
   * For blocks without decommissioned nodes, verify their replication is
   * equal to what is specified.
   * 
   * @param downnode - if null, there is no decommissioned node for this file.
   * @return - null if no failure found, else an error message string.
   */
  private String checkFile(FileSystem fileSys, Path name, int repl,
    String downnode, int numDatanodes) throws IOException {
    boolean isNodeDown = (downnode != null);
    // need a raw stream
    assertTrue("Not HDFS:"+fileSys.getUri(), 
    fileSys instanceof DistributedFileSystem);
    DFSClient.DFSDataInputStream dis = (DFSClient.DFSDataInputStream)
      ((DistributedFileSystem)fileSys).open(name);
    Collection<LocatedBlock> dinfo = dis.getAllBlocks();
    for (LocatedBlock blk : dinfo) { // for each block
      int hasdown = 0;
      DatanodeInfo[] nodes = blk.getLocations();
      for (int j = 0; j < nodes.length; j++) { // for each replica
        if (isNodeDown && nodes[j].getName().equals(downnode)) {
          hasdown++;
          //Downnode must actually be decommissioned
          if (!nodes[j].isDecommissioned()) {
            return "For block " + blk.getBlock() + " replica on " +
              nodes[j].getName() + " is given as downnode, " +
              "but is not decommissioned";
          }
          //Decommissioned node (if any) should only be last node in list.
          if (j != nodes.length - 1) {
            return "For block " + blk.getBlock() + " decommissioned node "
              + nodes[j].getName() + " was not last node in list: "
              + (j + 1) + " of " + nodes.length;
          }
          LOG.info("Block " + blk.getBlock() + " replica on " +
            nodes[j].getName() + " is decommissioned.");
        } else {
          //Non-downnodes must not be decommissioned
          if (nodes[j].isDecommissioned()) {
            return "For block " + blk.getBlock() + " replica on " +
              nodes[j].getName() + " is unexpectedly decommissioned";
          }
        }
      }

      LOG.info("Block " + blk.getBlock() + " has " + hasdown
        + " decommissioned replica.");
      if(Math.min(numDatanodes, repl+hasdown) != nodes.length) {
        return "Wrong number of replicas for block " + blk.getBlock() +
          ": " + nodes.length + ", expected " +
          Math.min(numDatanodes, repl+hasdown);
      }
    }
    return null;
  }

  private void cleanupFile(FileSystem fileSys, Path name) throws IOException {
    assertTrue(fileSys.exists(name));
    fileSys.delete(name, true);
    assertTrue(!fileSys.exists(name));
  }

  /*
   * decommission one random node and wait for each to reach the
   * given {@code waitForState}.
   */
  private DatanodeInfo decommissionNode(int nnIndex,
                                  ArrayList<DatanodeInfo>decommissionedNodes,
                                  AdminStates waitForState)
    throws IOException {
    DFSClient client = getDfsClient(cluster.getNameNode(nnIndex), conf);
    DatanodeInfo[] info = client.datanodeReport(DatanodeReportType.LIVE);

    //
    // pick one datanode randomly.
    //
    int index = 0;
    boolean found = false;
    while (!found) {
      index = myrand.nextInt(info.length);
      if (!info[index].isDecommissioned()) {
        found = true;
      }
    }
    String nodename = info[index].getName();
    LOG.info("Decommissioning node: " + nodename);

    // write nodename into the exclude file.
    ArrayList<String> nodes = new ArrayList<String>();
    if (decommissionedNodes != null) {
      for (DatanodeInfo dn : decommissionedNodes) {
        nodes.add(dn.getName());
      }
    }
    nodes.add(nodename);
    writeConfigFile(excludeFile, nodes);
    cluster.getNamesystem(nnIndex).refreshNodes(conf);
    DatanodeInfo ret = NameNodeAdapter.getDatanode(
        cluster.getNamesystem(nnIndex), info[index]);
    waitNodeState(ret, waitForState);
    return ret;
  }

  /* stop decommission of the datanode and wait for each to reach the NORMAL state */
  private void recomissionNode(DatanodeInfo decommissionedNode) throws IOException {
    LOG.info("Recommissioning node: " + decommissionedNode.getName());
    writeConfigFile(excludeFile, null);
    cluster.getNamesystem().refreshNodes(conf);
    waitNodeState(decommissionedNode, AdminStates.NORMAL);

  }

  /* 
   * Wait till node is fully decommissioned.
   */
  private void waitNodeState(DatanodeInfo node,
                             AdminStates state) throws IOException {
    boolean done = state == node.getAdminState();
    while (!done) {
      LOG.info("Waiting for node " + node + " to change state to "
          + state + " current state: " + node.getAdminState());
      try {
        Thread.sleep(HEARTBEAT_INTERVAL * 1000);
      } catch (InterruptedException e) {
        // nothing
      }
      done = state == node.getAdminState();
    }
    LOG.info("node " + node + " reached the state " + state);
  }
  
  /* Get DFSClient to the namenode */
  private static DFSClient getDfsClient(NameNode nn,
      Configuration conf) throws IOException {
    return new DFSClient(nn.getNameNodeAddress(), conf);
  }
  
  /* Validate cluster has expected number of datanodes */
  private static void validateCluster(DFSClient client, int numDNs)
      throws IOException {
    DatanodeInfo[] info = client.datanodeReport(DatanodeReportType.LIVE);
    assertEquals("Number of Datanodes ", numDNs, info.length);
  }
  
  /** Start a MiniDFSCluster 
   * @throws IOException */
  private void startCluster(int numNameNodes, int numDatanodes,
      Configuration conf) throws IOException {
    cluster = new MiniDFSCluster.Builder(conf).numNameNodes(numNameNodes)
        .numDataNodes(numDatanodes).build();
    cluster.waitActive();
    for (int i = 0; i < numNameNodes; i++) {
      DFSClient client = getDfsClient(cluster.getNameNode(i), conf);
      validateCluster(client, numDatanodes);
    }
  }
  
  private void verifyStats(NameNode namenode, FSNamesystem fsn,
      DatanodeInfo node, boolean decommissioning) throws InterruptedException {
    // Do the stats check over 10 iterations
    for (int i = 0; i < 10; i++) {
      long[] newStats = namenode.getStats();

      // For decommissioning nodes, ensure capacity of the DN is no longer
      // counted. Only used space of the DN is counted in cluster capacity
      assertEquals(newStats[0], decommissioning ? node.getDfsUsed() : 
        node.getCapacity());

      // Ensure cluster used capacity is counted for both normal and
      // decommissioning nodes
      assertEquals(newStats[1], node.getDfsUsed());

      // For decommissioning nodes, remaining space from the DN is not counted
      assertEquals(newStats[2], decommissioning ? 0 : node.getRemaining());

      // Ensure transceiver count is same as that DN
      assertEquals(fsn.getTotalLoad(), node.getXceiverCount());
      
      Thread.sleep(HEARTBEAT_INTERVAL * 1000); // Sleep heart beat interval
    }
  }

  /**
   * Tests decommission for non federated cluster
   */
  @Test
  public void testDecommission() throws IOException {
    testDecommission(1, 6);
  }
  
  /**
   * Tests recommission for non federated cluster
   */
  @Test
  public void testRecommission() throws IOException {
    testRecommission(1, 6);
  }

  /**
   * Test decommission for federeated cluster
   */
  @Test
  public void testDecommissionFederation() throws IOException {
    testDecommission(2, 2);
  }
  
  private void testDecommission(int numNamenodes, int numDatanodes)
      throws IOException {
    LOG.info("Starting test testDecommission");
    startCluster(numNamenodes, numDatanodes, conf);
    
    ArrayList<ArrayList<DatanodeInfo>> namenodeDecomList = 
      new ArrayList<ArrayList<DatanodeInfo>>(numNamenodes);
    for(int i = 0; i < numNamenodes; i++) {
      namenodeDecomList.add(i, new ArrayList<DatanodeInfo>(numDatanodes));
    }
    Path file1 = new Path("testDecommission.dat");
    for (int iteration = 0; iteration < numDatanodes - 1; iteration++) {
      int replicas = numDatanodes - iteration - 1;
      
      // Start decommissioning one namenode at a time
      for (int i = 0; i < numNamenodes; i++) {
        ArrayList<DatanodeInfo> decommissionedNodes = namenodeDecomList.get(i);
        FileSystem fileSys = cluster.getFileSystem(i);
        writeFile(fileSys, file1, replicas);
        
        // Decommission one node. Verify that node is decommissioned.
        DatanodeInfo decomNode = decommissionNode(i, decommissionedNodes,
            AdminStates.DECOMMISSIONED);
        decommissionedNodes.add(decomNode);
        
        // Ensure decommissioned datanode is not automatically shutdown
        DFSClient client = getDfsClient(cluster.getNameNode(i), conf);
        assertEquals("All datanodes must be alive", numDatanodes, 
            client.datanodeReport(DatanodeReportType.LIVE).length);
        assertNull(checkFile(fileSys, file1, replicas, decomNode.getName(), numDatanodes));
        cleanupFile(fileSys, file1);
      }
    }

    // Restart the cluster and ensure recommissioned datanodes
    // are allowed to register with the namenode
    cluster.shutdown();
    startCluster(numNamenodes, numDatanodes, conf);
    cluster.shutdown();
  }


  private void testRecommission(int numNamenodes, int numDatanodes) 
    throws IOException {
    LOG.info("Starting test testRecommission");

    startCluster(numNamenodes, numDatanodes, conf);
  
    ArrayList<ArrayList<DatanodeInfo>> namenodeDecomList = 
      new ArrayList<ArrayList<DatanodeInfo>>(numNamenodes);
    for(int i = 0; i < numNamenodes; i++) {
      namenodeDecomList.add(i, new ArrayList<DatanodeInfo>(numDatanodes));
    }
    Path file1 = new Path("testDecommission.dat");
    int replicas = numDatanodes - 1;
      
    for (int i = 0; i < numNamenodes; i++) {
      ArrayList<DatanodeInfo> decommissionedNodes = namenodeDecomList.get(i);
      FileSystem fileSys = cluster.getFileSystem(i);
      writeFile(fileSys, file1, replicas);
        
      // Decommission one node. Verify that node is decommissioned.
      DatanodeInfo decomNode = decommissionNode(i, decommissionedNodes,
          AdminStates.DECOMMISSIONED);
      decommissionedNodes.add(decomNode);
        
      // Ensure decommissioned datanode is not automatically shutdown
      DFSClient client = getDfsClient(cluster.getNameNode(i), conf);
      assertEquals("All datanodes must be alive", numDatanodes, 
          client.datanodeReport(DatanodeReportType.LIVE).length);
      assertNull(checkFile(fileSys, file1, replicas, decomNode.getName(), numDatanodes));

      // stop decommission and check if the new replicas are removed
      recomissionNode(decomNode);
      // wait for the block to be deleted
      int tries = 0;
      while (tries++ < 20) {
        try {
          Thread.sleep(1000);
          if (checkFile(fileSys, file1, replicas, null, numDatanodes) == null) {
            break;
          }
        } catch (InterruptedException ie) {
        }
      }
      cleanupFile(fileSys, file1);
      assertTrue("Checked if node was recommissioned " + tries + " times.",
         tries < 20);
      LOG.info("tried: " + tries + " times before recommissioned");
    }
    cluster.shutdown();
  }
  
  /**
   * Tests cluster storage statistics during decommissioning for non
   * federated cluster
   */
  @Test
  public void testClusterStats() throws Exception {
    testClusterStats(1);
  }
  
  /**
   * Tests cluster storage statistics during decommissioning for
   * federated cluster
   */
  @Test
  public void testClusterStatsFederation() throws Exception {
    testClusterStats(3);
  }
  
  public void testClusterStats(int numNameNodes) throws IOException,
      InterruptedException {
    LOG.info("Starting test testClusterStats");
    int numDatanodes = 1;
    startCluster(numNameNodes, numDatanodes, conf);
    
    for (int i = 0; i < numNameNodes; i++) {
      FileSystem fileSys = cluster.getFileSystem(i);
      Path file = new Path("testClusterStats.dat");
      writeFile(fileSys, file, 1);
      
      FSNamesystem fsn = cluster.getNamesystem(i);
      NameNode namenode = cluster.getNameNode(i);
      DatanodeInfo downnode = decommissionNode(i, null,
          AdminStates.DECOMMISSION_INPROGRESS);
      // Check namenode stats for multiple datanode heartbeats
      verifyStats(namenode, fsn, downnode, true);
      
      // Stop decommissioning and verify stats
      writeConfigFile(excludeFile, null);
      fsn.refreshNodes(conf);
      DatanodeInfo ret = NameNodeAdapter.getDatanode(fsn, downnode);
      waitNodeState(ret, AdminStates.NORMAL);
      verifyStats(namenode, fsn, ret, false);
    }
  }
  
  /**
   * Test host/include file functionality. Only datanodes
   * in the include file are allowed to connect to the namenode in a non
   * federated cluster.
   */
  @Test
  public void testHostsFile() throws IOException, InterruptedException {
    // Test for a single namenode cluster
    testHostsFile(1);
  }
  
  /**
   * Test host/include file functionality. Only datanodes
   * in the include file are allowed to connect to the namenode in a 
   * federated cluster.
   */
  @Test
  public void testHostsFileFederation() throws IOException, InterruptedException {
    // Test for 3 namenode federated cluster
    testHostsFile(3);
  }
  
  public void testHostsFile(int numNameNodes) throws IOException,
      InterruptedException {
    conf.set(DFSConfigKeys.DFS_HOSTS, hostsFile.toUri().getPath());
    int numDatanodes = 1;
    cluster = new MiniDFSCluster.Builder(conf).numNameNodes(numNameNodes)
        .numDataNodes(numDatanodes).setupHostsFile(true).build();
    cluster.waitActive();
    
    // Now empty hosts file and ensure the datanode is disallowed
    // from talking to namenode, resulting in it's shutdown.
    ArrayList<String>list = new ArrayList<String>();
    list.add("invalidhost");
    writeConfigFile(hostsFile, list);
    
    for (int j = 0; j < numNameNodes; j++) {
      cluster.getNamesystem(j).refreshNodes(conf);
      
      DFSClient client = getDfsClient(cluster.getNameNode(j), conf);
      DatanodeInfo[] info = client.datanodeReport(DatanodeReportType.LIVE);
      for (int i = 0 ; i < 5 && info.length != 0; i++) {
        LOG.info("Waiting for datanode to be marked dead");
        Thread.sleep(HEARTBEAT_INTERVAL * 1000);
        info = client.datanodeReport(DatanodeReportType.LIVE);
      }
      assertEquals("Number of live nodes should be 0", 0, info.length);
    }
  }
}