/**
 * 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.server.datanode;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Properties;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.fs.FileUtil;
import org.apache.hadoop.fs.HardLink;
import org.apache.hadoop.hdfs.protocol.HdfsConstants;
import org.apache.hadoop.hdfs.protocol.LayoutVersion;
import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
import org.apache.hadoop.hdfs.server.common.InconsistentFSStateException;
import org.apache.hadoop.hdfs.server.common.Storage;
import org.apache.hadoop.hdfs.server.common.StorageInfo;
import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NodeType;
import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
import org.apache.hadoop.hdfs.server.protocol.NamespaceInfo;
import org.apache.hadoop.util.Daemon;

/**
 * Manages storage for the set of BlockPoolSlices which share a particular 
 * block pool id, on this DataNode.
 * 
 * This class supports the following functionality:
 * <ol>
 * <li> Formatting a new block pool storage</li>
 * <li> Recovering a storage state to a consistent state (if possible></li>
 * <li> Taking a snapshot of the block pool during upgrade</li>
 * <li> Rolling back a block pool to a previous snapshot</li>
 * <li> Finalizing block storage by deletion of a snapshot</li>
 * </ul>
 * 
 * @see Storage
 */
@InterfaceAudience.Private
public class BlockPoolSliceStorage extends Storage {
  private static final Pattern BLOCK_POOL_PATH_PATTERN = Pattern
      .compile("^(.*)"
          + "(\\/BP-[0-9]+\\-\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\-[0-9]+\\/.*)$");

  private String blockpoolID = ""; // id of the blockpool

  public BlockPoolSliceStorage(StorageInfo storageInfo, String bpid) {
    super(NodeType.DATA_NODE, storageInfo);
    blockpoolID = bpid;
  }

  BlockPoolSliceStorage(int namespaceID, String bpID, long cTime,
      String clusterId) {
    super(NodeType.DATA_NODE);
    this.namespaceID = namespaceID;
    this.blockpoolID = bpID;
    this.cTime = cTime;
    this.clusterID = clusterId;
  }

  private BlockPoolSliceStorage() {
    super(NodeType.DATA_NODE);
  }

  /**
   * Analyze storage directories. Recover from previous transitions if required.
   * 
   * @param datanode Datanode to which this storage belongs to
   * @param nsInfo namespace information
   * @param dataDirs storage directories of block pool
   * @param startOpt startup option
   * @throws IOException on error
   */
  void recoverTransitionRead(DataNode datanode, NamespaceInfo nsInfo,
      Collection<File> dataDirs, StartupOption startOpt) throws IOException {
    assert HdfsConstants.LAYOUT_VERSION == nsInfo.getLayoutVersion() 
        : "Block-pool and name-node layout versions must be the same.";

    // 1. For each BP data directory analyze the state and
    // check whether all is consistent before transitioning.
    this.storageDirs = new ArrayList<StorageDirectory>(dataDirs.size());
    ArrayList<StorageState> dataDirStates = new ArrayList<StorageState>(
        dataDirs.size());
    for (Iterator<File> it = dataDirs.iterator(); it.hasNext();) {
      File dataDir = it.next();
      StorageDirectory sd = new StorageDirectory(dataDir, null, false);
      StorageState curState;
      try {
        curState = sd.analyzeStorage(startOpt, this);
        // sd is locked but not opened
        switch (curState) {
        case NORMAL:
          break;
        case NON_EXISTENT:
          // ignore this storage
          LOG.info("Storage directory " + dataDir + " does not exist.");
          it.remove();
          continue;
        case NOT_FORMATTED: // format
          LOG.info("Storage directory " + dataDir + " is not formatted.");
          LOG.info("Formatting ...");
          format(sd, nsInfo);
          break;
        default: // recovery part is common
          sd.doRecover(curState);
        }
      } catch (IOException ioe) {
        sd.unlock();
        throw ioe;
      }
      // add to the storage list. This is inherited from parent class, Storage.
      addStorageDir(sd);
      dataDirStates.add(curState);
    }

    if (dataDirs.size() == 0) // none of the data dirs exist
      throw new IOException(
          "All specified directories are not accessible or do not exist.");

    // 2. Do transitions
    // Each storage directory is treated individually.
    // During startup some of them can upgrade or roll back
    // while others could be up-to-date for the regular startup.
    for (int idx = 0; idx < getNumStorageDirs(); idx++) {
      doTransition(getStorageDir(idx), nsInfo, startOpt);
      assert getLayoutVersion() == nsInfo.getLayoutVersion() 
          : "Data-node and name-node layout versions must be the same.";
      assert getCTime() == nsInfo.getCTime() 
          : "Data-node and name-node CTimes must be the same.";
    }

    // 3. Update all storages. Some of them might have just been formatted.
    this.writeAll();
  }

  /**
   * Format a block pool slice storage. 
   * @param dnCurDir DataStorage current directory
   * @param nsInfo the name space info
   * @throws IOException Signals that an I/O exception has occurred.
   */
  void format(File dnCurDir, NamespaceInfo nsInfo) throws IOException {
    File curBpDir = getBpRoot(nsInfo.getBlockPoolID(), dnCurDir);
    StorageDirectory bpSdir = new StorageDirectory(curBpDir);
    format(bpSdir, nsInfo);
  }

  /**
   * Format a block pool slice storage. 
   * @param sd the block pool storage
   * @param nsInfo the name space info
   * @throws IOException Signals that an I/O exception has occurred.
   */
  private void format(StorageDirectory bpSdir, NamespaceInfo nsInfo) throws IOException {
    LOG.info("Formatting block pool " + blockpoolID + " directory "
        + bpSdir.getCurrentDir());
    bpSdir.clearDirectory(); // create directory
    this.layoutVersion = HdfsConstants.LAYOUT_VERSION;
    this.cTime = nsInfo.getCTime();
    this.namespaceID = nsInfo.getNamespaceID();
    this.blockpoolID = nsInfo.getBlockPoolID();
    this.storageType = NodeType.DATA_NODE;
    writeProperties(bpSdir);
  }

  /**
   * Set layoutVersion, namespaceID and blockpoolID into block pool storage
   * VERSION file
   */
  @Override
  protected void setPropertiesFromFields(Properties props, StorageDirectory sd)
      throws IOException {
    props.setProperty("layoutVersion", String.valueOf(layoutVersion));
    props.setProperty("namespaceID", String.valueOf(namespaceID));
    props.setProperty("blockpoolID", blockpoolID);
    props.setProperty("cTime", String.valueOf(cTime));
  }

  /** Validate and set block pool ID */
  private void setBlockPoolID(File storage, String bpid)
      throws InconsistentFSStateException {
    if (bpid == null || bpid.equals("")) {
      throw new InconsistentFSStateException(storage, "file "
          + STORAGE_FILE_VERSION + " is invalid.");
    }
    
    if (!blockpoolID.equals("") && !blockpoolID.equals(bpid)) {
      throw new InconsistentFSStateException(storage,
          "Unexepcted blockpoolID " + bpid + " . Expected " + blockpoolID);
    }
    blockpoolID = bpid;
  }
  
  @Override
  protected void setFieldsFromProperties(Properties props, StorageDirectory sd)
      throws IOException {
    setLayoutVersion(props, sd);
    setNamespaceID(props, sd);
    setcTime(props, sd);
    
    String sbpid = props.getProperty("blockpoolID");
    setBlockPoolID(sd.getRoot(), sbpid);
  }

  /**
   * Analyze whether a transition of the BP state is required and
   * perform it if necessary.
   * <br>
   * Rollback if previousLV >= LAYOUT_VERSION && prevCTime <= namenode.cTime.
   * Upgrade if this.LV > LAYOUT_VERSION || this.cTime < namenode.cTime Regular
   * startup if this.LV = LAYOUT_VERSION && this.cTime = namenode.cTime
   * 
   * @param dn DataNode to which this storage belongs to
   * @param sd storage directory <SD>/current/<bpid>
   * @param nsInfo namespace info
   * @param startOpt startup option
   * @throws IOException
   */
  private void doTransition(StorageDirectory sd,
      NamespaceInfo nsInfo, StartupOption startOpt) throws IOException {
    if (startOpt == StartupOption.ROLLBACK)
      doRollback(sd, nsInfo); // rollback if applicable
    
    readProperties(sd);
    checkVersionUpgradable(this.layoutVersion);
    assert this.layoutVersion >= HdfsConstants.LAYOUT_VERSION 
       : "Future version is not allowed";
    if (getNamespaceID() != nsInfo.getNamespaceID()) {
      throw new IOException("Incompatible namespaceIDs in "
          + sd.getRoot().getCanonicalPath() + ": namenode namespaceID = "
          + nsInfo.getNamespaceID() + "; datanode namespaceID = "
          + getNamespaceID());
    }
    if (!blockpoolID.equals(nsInfo.getBlockPoolID())) {
      throw new IOException("Incompatible blockpoolIDs in "
          + sd.getRoot().getCanonicalPath() + ": namenode blockpoolID = "
          + nsInfo.getBlockPoolID() + "; datanode blockpoolID = "
          + blockpoolID);
    }
    if (this.layoutVersion == HdfsConstants.LAYOUT_VERSION
        && this.cTime == nsInfo.getCTime()) {
      return; // regular startup
    }
    if (this.layoutVersion > HdfsConstants.LAYOUT_VERSION
        || this.cTime < nsInfo.getCTime()) {
      doUpgrade(sd, nsInfo); // upgrade
      return;
    }
    // layoutVersion == LAYOUT_VERSION && this.cTime > nsInfo.cTime
    // must shutdown
    throw new IOException("Datanode state: LV = " + this.getLayoutVersion()
        + " CTime = " + this.getCTime()
        + " is newer than the namespace state: LV = "
        + nsInfo.getLayoutVersion() + " CTime = " + nsInfo.getCTime());
  }

  /**
   * Upgrade to any release after 0.22 (0.22 included) release e.g. 0.22 => 0.23
   * Upgrade procedure is as follows:
   * <ol>
   * <li>If <SD>/current/<bpid>/previous exists then delete it</li>
   * <li>Rename <SD>/current/<bpid>/current to
   * <SD>/current/bpid/current/previous.tmp</li>
   * <li>Create new <SD>current/<bpid>/current directory</li>
   * <ol>
   * <li>Hard links for block files are created from previous.tmp to current</li>
   * <li>Save new version file in current directory</li>
   * </ol>
   * <li>Rename previous.tmp to previous</li> </ol>
   * 
   * @param bpSd storage directory <SD>/current/<bpid>
   * @param nsInfo Namespace Info from the namenode
   * @throws IOException on error
   */
  void doUpgrade(StorageDirectory bpSd, NamespaceInfo nsInfo) throws IOException {
    // Upgrading is applicable only to release with federation or after
    if (!LayoutVersion.supports(Feature.FEDERATION, layoutVersion)) {
      return;
    }
    LOG.info("Upgrading block pool storage directory " + bpSd.getRoot()
        + ".\n   old LV = " + this.getLayoutVersion() + "; old CTime = "
        + this.getCTime() + ".\n   new LV = " + nsInfo.getLayoutVersion()
        + "; new CTime = " + nsInfo.getCTime());
    // get <SD>/previous directory
    String dnRoot = getDataNodeStorageRoot(bpSd.getRoot().getCanonicalPath());
    StorageDirectory dnSdStorage = new StorageDirectory(new File(dnRoot));
    File dnPrevDir = dnSdStorage.getPreviousDir();
    
    // If <SD>/previous directory exists delete it
    if (dnPrevDir.exists()) {
      deleteDir(dnPrevDir);
    }
    File bpCurDir = bpSd.getCurrentDir();
    File bpPrevDir = bpSd.getPreviousDir();
    assert bpCurDir.exists() : "BP level current directory must exist.";
    cleanupDetachDir(new File(bpCurDir, DataStorage.STORAGE_DIR_DETACHED));
    
    // 1. Delete <SD>/current/<bpid>/previous dir before upgrading
    if (bpPrevDir.exists()) {
      deleteDir(bpPrevDir);
    }
    File bpTmpDir = bpSd.getPreviousTmp();
    assert !bpTmpDir.exists() : "previous.tmp directory must not exist.";
    
    // 2. Rename <SD>/curernt/<bpid>/current to <SD>/curernt/<bpid>/previous.tmp
    rename(bpCurDir, bpTmpDir);
    
    // 3. Create new <SD>/current with block files hardlinks and VERSION
    linkAllBlocks(bpTmpDir, bpCurDir);
    this.layoutVersion = HdfsConstants.LAYOUT_VERSION;
    assert this.namespaceID == nsInfo.getNamespaceID() 
        : "Data-node and name-node layout versions must be the same.";
    this.cTime = nsInfo.getCTime();
    writeProperties(bpSd);
    
    // 4.rename <SD>/curernt/<bpid>/previous.tmp to <SD>/curernt/<bpid>/previous
    rename(bpTmpDir, bpPrevDir);
    LOG.info("Upgrade of block pool " + blockpoolID + " at " + bpSd.getRoot()
        + " is complete");
  }

  /**
   * Cleanup the detachDir.
   * 
   * If the directory is not empty report an error; Otherwise remove the
   * directory.
   * 
   * @param detachDir detach directory
   * @throws IOException if the directory is not empty or it can not be removed
   */
  private void cleanupDetachDir(File detachDir) throws IOException {
    if (!LayoutVersion.supports(Feature.APPEND_RBW_DIR, layoutVersion)
        && detachDir.exists() && detachDir.isDirectory()) {

      if (FileUtil.list(detachDir).length != 0) {
        throw new IOException("Detached directory " + detachDir
            + " is not empty. Please manually move each file under this "
            + "directory to the finalized directory if the finalized "
            + "directory tree does not have the file.");
      } else if (!detachDir.delete()) {
        throw new IOException("Cannot remove directory " + detachDir);
      }
    }
  }

  /*
   * Roll back to old snapshot at the block pool level
   * If previous directory exists: 
   * <ol>
   * <li>Rename <SD>/current/<bpid>/current to removed.tmp</li>
   * <li>Rename * <SD>/current/<bpid>/previous to current</li>
   * <li>Remove removed.tmp</li>
   * </ol>
   * 
   * Do nothing if previous directory does not exist.
   * @param bpSd Block pool storage directory at <SD>/current/<bpid>
   */
  void doRollback(StorageDirectory bpSd, NamespaceInfo nsInfo)
      throws IOException {
    File prevDir = bpSd.getPreviousDir();
    // regular startup if previous dir does not exist
    if (!prevDir.exists())
      return;
    // read attributes out of the VERSION file of previous directory
    BlockPoolSliceStorage prevInfo = new BlockPoolSliceStorage();
    prevInfo.readPreviousVersionProperties(bpSd);

    // We allow rollback to a state, which is either consistent with
    // the namespace state or can be further upgraded to it.
    // In another word, we can only roll back when ( storedLV >= software LV)
    // && ( DN.previousCTime <= NN.ctime)
    if (!(prevInfo.getLayoutVersion() >= HdfsConstants.LAYOUT_VERSION && 
        prevInfo.getCTime() <= nsInfo.getCTime())) { // cannot rollback
      throw new InconsistentFSStateException(bpSd.getRoot(),
          "Cannot rollback to a newer state.\nDatanode previous state: LV = "
              + prevInfo.getLayoutVersion() + " CTime = " + prevInfo.getCTime()
              + " is newer than the namespace state: LV = "
              + nsInfo.getLayoutVersion() + " CTime = " + nsInfo.getCTime());
    }
    
    LOG.info("Rolling back storage directory " + bpSd.getRoot()
        + ".\n   target LV = " + nsInfo.getLayoutVersion()
        + "; target CTime = " + nsInfo.getCTime());
    File tmpDir = bpSd.getRemovedTmp();
    assert !tmpDir.exists() : "removed.tmp directory must not exist.";
    // 1. rename current to tmp
    File curDir = bpSd.getCurrentDir();
    assert curDir.exists() : "Current directory must exist.";
    rename(curDir, tmpDir);
    
    // 2. rename previous to current
    rename(prevDir, curDir);
    
    // 3. delete removed.tmp dir
    deleteDir(tmpDir);
    LOG.info("Rollback of " + bpSd.getRoot() + " is complete");
  }

  /*
   * Finalize the block pool storage by deleting <BP>/previous directory
   * that holds the snapshot.
   */
  void doFinalize(File dnCurDir) throws IOException {
    File bpRoot = getBpRoot(blockpoolID, dnCurDir);
    StorageDirectory bpSd = new StorageDirectory(bpRoot);
    // block pool level previous directory
    File prevDir = bpSd.getPreviousDir();
    if (!prevDir.exists()) {
      return; // already finalized
    }
    final String dataDirPath = bpSd.getRoot().getCanonicalPath();
    LOG.info("Finalizing upgrade for storage directory " + dataDirPath
        + ".\n   cur LV = " + this.getLayoutVersion() + "; cur CTime = "
        + this.getCTime());
    assert bpSd.getCurrentDir().exists() : "Current directory must exist.";
    
    // rename previous to finalized.tmp
    final File tmpDir = bpSd.getFinalizedTmp();
    rename(prevDir, tmpDir);

    // delete finalized.tmp dir in a separate thread
    new Daemon(new Runnable() {
      @Override
      public void run() {
        try {
          deleteDir(tmpDir);
        } catch (IOException ex) {
          LOG.error("Finalize upgrade for " + dataDirPath + " failed.", ex);
        }
        LOG.info("Finalize upgrade for " + dataDirPath + " is complete.");
      }

      @Override
      public String toString() {
        return "Finalize " + dataDirPath;
      }
    }).start();
  }

  /**
   * Hardlink all finalized and RBW blocks in fromDir to toDir
   * 
   * @param fromDir directory where the snapshot is stored
   * @param toDir the current data directory
   * @throws IOException if error occurs during hardlink
   */
  private void linkAllBlocks(File fromDir, File toDir) throws IOException {
    // do the link
    int diskLayoutVersion = this.getLayoutVersion();
    // hardlink finalized blocks in tmpDir
    HardLink hardLink = new HardLink();
    DataStorage.linkBlocks(new File(fromDir, DataStorage.STORAGE_DIR_FINALIZED), 
      new File(toDir,DataStorage.STORAGE_DIR_FINALIZED), diskLayoutVersion, hardLink);
    DataStorage.linkBlocks(new File(fromDir, DataStorage.STORAGE_DIR_RBW), 
        new File(toDir, DataStorage.STORAGE_DIR_RBW), diskLayoutVersion, hardLink);
    LOG.info( hardLink.linkStats.report() );
  }

  /**
   * gets the data node storage directory based on block pool storage
   * 
   * @param bpRoot
   * @return
   */
  private static String getDataNodeStorageRoot(String bpRoot) {
    Matcher matcher = BLOCK_POOL_PATH_PATTERN.matcher(bpRoot);
    if (matcher.matches()) {
      // return the data node root directory
      return matcher.group(1);
    }
    return bpRoot;
  }

  @Override
  public String toString() {
    return super.toString() + ";bpid=" + blockpoolID;
  }
  
  /**
   * Get a block pool storage root based on data node storage root
   * @param bpID block pool ID
   * @param dnCurDir data node storage root directory
   * @return root directory for block pool storage
   */
  public static File getBpRoot(String bpID, File dnCurDir) {
    return new File(dnCurDir, bpID);
  }

  @Override
  public boolean isPreUpgradableLayout(StorageDirectory sd) throws IOException {
    return false;
  }
}