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.ClusterMetrics}. That class is a data structure that holds
032 * snapshot of current view on cluster. This class is about tracking cluster attributes up in
033 * zookeeper.
034 */
035@InterfaceAudience.Private
036public class ClusterStatusTracker extends ZKNodeTracker {
037  private static final Logger LOG = LoggerFactory.getLogger(ClusterStatusTracker.class);
038
039  /**
040   * Creates a cluster status tracker.
041   * <p>
042   * After construction, use {@link #start} to kick off tracking.
043   * @param watcher   reference to the {@link ZKWatcher} which also contains configuration and
044   *                  constants
045   * @param abortable used to abort if a fatal error occurs
046   */
047  public ClusterStatusTracker(ZKWatcher watcher, Abortable abortable) {
048    super(watcher, watcher.getZNodePaths().clusterStateZNode, abortable);
049  }
050
051  /**
052   * Checks if cluster is up.
053   * @return true if the cluster up ('shutdown' is its name up in zk) znode exists with data, false
054   *         if not
055   */
056  public boolean isClusterUp() {
057    return super.getData(false) != null;
058  }
059
060  /**
061   * Sets the cluster as up.
062   * @throws KeeperException unexpected zk exception
063   */
064  public void setClusterUp() throws KeeperException {
065    byte[] upData = toByteArray();
066    try {
067      ZKUtil.createAndWatch(watcher, watcher.getZNodePaths().clusterStateZNode, upData);
068    } catch (KeeperException.NodeExistsException nee) {
069      ZKUtil.setData(watcher, watcher.getZNodePaths().clusterStateZNode, upData);
070    }
071  }
072
073  /**
074   * Sets the cluster as down by deleting the znode.
075   * @throws KeeperException unexpected zk exception
076   */
077  public void setClusterDown() throws KeeperException {
078    try {
079      ZKUtil.deleteNode(watcher, watcher.getZNodePaths().clusterStateZNode);
080    } catch (KeeperException.NoNodeException nne) {
081      LOG.warn("Attempted to set cluster as down but already down, cluster " + "state node ("
082        + watcher.getZNodePaths().clusterStateZNode + ") not found");
083    }
084  }
085
086  /** Returns Content of the clusterup znode as a serialized pb with the pb magic as prefix. */
087  static byte[] toByteArray() {
088    ZooKeeperProtos.ClusterUp.Builder builder = ZooKeeperProtos.ClusterUp.newBuilder();
089    builder.setStartDate(new java.util.Date().toString());
090    return ProtobufUtil.prependPBMagic(builder.build().toByteArray());
091  }
092}