1 /**
2 *
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 */
19 package org.apache.hadoop.hbase.zookeeper;
20
21 import org.apache.commons.logging.Log;
22 import org.apache.commons.logging.LogFactory;
23 import org.apache.hadoop.hbase.classification.InterfaceAudience;
24 import org.apache.hadoop.hbase.Abortable;
25 import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
26 import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos;
27 import org.apache.zookeeper.KeeperException;
28
29 /**
30 * Tracker on cluster settings up in zookeeper.
31 * This is not related to {@link org.apache.hadoop.hbase.ClusterStatus}.
32 * That class is a data structure that holds snapshot of current view on cluster.
33 * This class is about tracking cluster attributes up in zookeeper.
34 *
35 */
36 @InterfaceAudience.Private
37 public class ClusterStatusTracker extends ZooKeeperNodeTracker {
38 private static final Log LOG = LogFactory.getLog(ClusterStatusTracker.class);
39
40 /**
41 * Creates a cluster status tracker.
42 *
43 * <p>After construction, use {@link #start} to kick off tracking.
44 *
45 * @param watcher
46 * @param abortable
47 */
48 public ClusterStatusTracker(ZooKeeperWatcher watcher, Abortable abortable) {
49 super(watcher, watcher.clusterStateZNode, abortable);
50 }
51
52 /**
53 * Checks if cluster is up.
54 * @return true if the cluster up ('shutdown' is its name up in zk) znode
55 * exists with data, false if not
56 */
57 public boolean isClusterUp() {
58 return super.getData(false) != null;
59 }
60
61 /**
62 * Sets the cluster as up.
63 * @throws KeeperException unexpected zk exception
64 */
65 public void setClusterUp()
66 throws KeeperException {
67 byte [] upData = toByteArray();
68 try {
69 ZKUtil.createAndWatch(watcher, watcher.clusterStateZNode, upData);
70 } catch(KeeperException.NodeExistsException nee) {
71 ZKUtil.setData(watcher, watcher.clusterStateZNode, upData);
72 }
73 }
74
75 /**
76 * Sets the cluster as down by deleting the znode.
77 * @throws KeeperException unexpected zk exception
78 */
79 public void setClusterDown()
80 throws KeeperException {
81 try {
82 ZKUtil.deleteNode(watcher, watcher.clusterStateZNode);
83 } catch(KeeperException.NoNodeException nne) {
84 LOG.warn("Attempted to set cluster as down but already down, cluster " +
85 "state node (" + watcher.clusterStateZNode + ") not found");
86 }
87 }
88
89 /**
90 * @return Content of the clusterup znode as a serialized pb with the pb
91 * magic as prefix.
92 */
93 static byte [] toByteArray() {
94 ZooKeeperProtos.ClusterUp.Builder builder =
95 ZooKeeperProtos.ClusterUp.newBuilder();
96 builder.setStartDate(new java.util.Date().toString());
97 return ProtobufUtil.prependPBMagic(builder.build().toByteArray());
98 }
99 }