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/**
 * 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.backup.example;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.ZooKeeperConnectionException;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.zookeeper.ZKUtil;
import org.apache.hadoop.hbase.zookeeper.ZKWatcher;
import org.apache.hadoop.hbase.zookeeper.ZNodePaths;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.zookeeper.KeeperException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Client-side manager for which table's hfiles should be preserved for long-term archive.
 * @see ZKTableArchiveClient
 * @see HFileArchiveTableMonitor
 * @see LongTermArchivingHFileCleaner
 */
@InterfaceAudience.Private
class HFileArchiveManager {

  private final String archiveZnode;
  private static final Logger LOG = LoggerFactory.getLogger(HFileArchiveManager.class);
  private final ZKWatcher zooKeeper;
  private volatile boolean stopped = false;

  public HFileArchiveManager(Connection connection, Configuration conf)
      throws ZooKeeperConnectionException, IOException {
    this.zooKeeper = new ZKWatcher(conf, "hfileArchiveManager-on-" + connection.toString(),
        connection);
    this.archiveZnode = ZKTableArchiveClient.getArchiveZNode(this.zooKeeper.getConfiguration(),
      this.zooKeeper);
  }

  /**
   * Turn on auto-backups of HFiles on the specified table.
   * 

* When HFiles would be deleted from the hfile archive, they are instead preserved. * @param table name of the table for which to preserve hfiles. * @return this for chaining. * @throws KeeperException if we can't reach zookeeper to update the hfile cleaner. */ public HFileArchiveManager enableHFileBackup(byte[] table) throws KeeperException { enable(this.zooKeeper, table); return this; } /** * Stop retaining HFiles for the given table in the archive. HFiles will be cleaned up on the next * pass of the {@link org.apache.hadoop.hbase.master.cleaner.HFileCleaner}, if the HFiles are * retained by another cleaner. * @param table name of the table for which to disable hfile retention. * @return this for chaining. * @throws KeeperException if if we can't reach zookeeper to update the hfile cleaner. */ public HFileArchiveManager disableHFileBackup(byte[] table) throws KeeperException { disable(this.zooKeeper, table); return this; } /** * Disable long-term archival of all hfiles for all tables in the cluster. * @return this for chaining. * @throws IOException if the number of attempts is exceeded */ public HFileArchiveManager disableHFileBackup() throws IOException { LOG.debug("Disabling backups on all tables."); try { ZKUtil.deleteNodeRecursively(this.zooKeeper, archiveZnode); return this; } catch (KeeperException e) { throw new IOException("Unexpected ZK exception!", e); } } /** * Perform a best effort enable of hfile retention, which relies on zookeeper communicating the * change back to the hfile cleaner. *

* No attempt is made to make sure that backups are successfully created - it is inherently an * asynchronous operation. * @param zooKeeper watcher connection to zk cluster * @param table table name on which to enable archiving * @throws KeeperException if a ZooKeeper operation fails */ private void enable(ZKWatcher zooKeeper, byte[] table) throws KeeperException { LOG.debug("Ensuring archiving znode exists"); ZKUtil.createAndFailSilent(zooKeeper, archiveZnode); // then add the table to the list of znodes to archive String tableNode = this.getTableNode(table); LOG.debug("Creating: " + tableNode + ", data: []"); ZKUtil.createSetData(zooKeeper, tableNode, new byte[0]); } /** * Disable all archiving of files for a given table *

* Inherently an asynchronous operation. * @param zooKeeper watcher for the ZK cluster * @param table name of the table to disable * @throws KeeperException if an unexpected ZK connection issues occurs */ private void disable(ZKWatcher zooKeeper, byte[] table) throws KeeperException { // ensure the latest state of the archive node is found zooKeeper.syncOrTimeout(archiveZnode); // if the top-level archive node is gone, then we are done if (ZKUtil.checkExists(zooKeeper, archiveZnode) < 0) { return; } // delete the table node, from the archive String tableNode = this.getTableNode(table); // make sure the table is the latest version so the delete takes zooKeeper.syncOrTimeout(tableNode); LOG.debug("Attempting to delete table node:" + tableNode); ZKUtil.deleteNodeRecursively(zooKeeper, tableNode); } public void stop() { if (!this.stopped) { this.stopped = true; LOG.debug("Stopping HFileArchiveManager..."); this.zooKeeper.close(); } } /** * Check to see if the table is currently marked for archiving * @param table name of the table to check * @return true if the archive znode for that table exists, false if not * @throws KeeperException if an unexpected zookeeper error occurs */ public boolean isArchivingEnabled(byte[] table) throws KeeperException { String tableNode = this.getTableNode(table); return ZKUtil.checkExists(zooKeeper, tableNode) >= 0; } /** * Get the zookeeper node associated with archiving the given table * @param table name of the table to check * @return znode for the table's archive status */ private String getTableNode(byte[] table) { return ZNodePaths.joinZNode(archiveZnode, Bytes.toString(table)); } }





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