001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.zookeeper;
019
020import org.apache.hadoop.hbase.Abortable;
021import org.apache.yetus.audience.InterfaceAudience;
022import org.apache.zookeeper.KeeperException;
023import org.slf4j.Logger;
024import org.slf4j.LoggerFactory;
025
026import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
027import org.apache.hadoop.hbase.shaded.protobuf.generated.ZooKeeperProtos;
028
029/**
030 * Tracker on cluster settings up in zookeeper. This is not related to
031 * {@link org.apache.hadoop.hbase.ClusterStatus}. That class is a data structure that holds snapshot
032 * of current view on cluster. This class is about tracking cluster attributes up in zookeeper.
033 */
034@InterfaceAudience.Private
035public class ClusterStatusTracker extends ZKNodeTracker {
036  private static final Logger LOG = LoggerFactory.getLogger(ClusterStatusTracker.class);
037
038  /**
039   * Creates a cluster status tracker.
040   * <p>
041   * After construction, use {@link #start} to kick off tracking.
042   * @param watcher   reference to the {@link ZKWatcher} which also contains configuration and
043   *                  constants
044   * @param abortable used to abort if a fatal error occurs
045   */
046  public ClusterStatusTracker(ZKWatcher watcher, Abortable abortable) {
047    super(watcher, watcher.getZNodePaths().clusterStateZNode, abortable);
048  }
049
050  /**
051   * Checks if cluster is up.
052   * @return true if the cluster up ('shutdown' is its name up in zk) znode exists with data, false
053   *         if not
054   */
055  public boolean isClusterUp() {
056    return super.getData(false) != null;
057  }
058
059  /**
060   * Sets the cluster as up.
061   * @throws KeeperException unexpected zk exception
062   */
063  public void setClusterUp() throws KeeperException {
064    byte[] upData = toByteArray();
065    try {
066      ZKUtil.createAndWatch(watcher, watcher.getZNodePaths().clusterStateZNode, upData);
067    } catch (KeeperException.NodeExistsException nee) {
068      ZKUtil.setData(watcher, watcher.getZNodePaths().clusterStateZNode, upData);
069    }
070  }
071
072  /**
073   * Sets the cluster as down by deleting the znode.
074   * @throws KeeperException unexpected zk exception
075   */
076  public void setClusterDown() throws KeeperException {
077    try {
078      ZKUtil.deleteNode(watcher, watcher.getZNodePaths().clusterStateZNode);
079    } catch (KeeperException.NoNodeException nne) {
080      LOG.warn("Attempted to set cluster as down but already down, cluster " + "state node ("
081        + watcher.getZNodePaths().clusterStateZNode + ") not found");
082    }
083  }
084
085  /** Returns Content of the clusterup znode as a serialized pb with the pb magic as prefix. */
086  static byte[] toByteArray() {
087    ZooKeeperProtos.ClusterUp.Builder builder = ZooKeeperProtos.ClusterUp.newBuilder();
088    builder.setStartDate(new java.util.Date().toString());
089    return ProtobufUtil.prependPBMagic(builder.build().toByteArray());
090  }
091}