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.classification.InterfaceAudience;
24 import org.apache.hadoop.hbase.Abortable;
25 import org.apache.hadoop.hbase.ClusterStatus;
26 import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
27 import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos;
28 import org.apache.zookeeper.KeeperException;
29
30 /**
31 * Tracker on cluster settings up in zookeeper.
32 * This is not related to {@link ClusterStatus}. That class is a data structure
33 * that holds snapshot of current view on cluster. This class is about tracking
34 * cluster attributes up in zookeeper.
35 *
36 */
37 @InterfaceAudience.Private
38 public class ClusterStatusTracker extends ZooKeeperNodeTracker {
39 private static final Log LOG = LogFactory.getLog(ClusterStatusTracker.class);
40
41 /**
42 * Creates a cluster status tracker.
43 *
44 * <p>After construction, use {@link #start} to kick off tracking.
45 *
46 * @param watcher
47 * @param abortable
48 */
49 public ClusterStatusTracker(ZooKeeperWatcher watcher, Abortable abortable) {
50 super(watcher, watcher.clusterStateZNode, abortable);
51 }
52
53 /**
54 * Checks if cluster is up.
55 * @return true if the cluster up ('shutdown' is its name up in zk) znode
56 * exists with data, false if not
57 */
58 public boolean isClusterUp() {
59 return super.getData(false) != null;
60 }
61
62 /**
63 * Sets the cluster as up.
64 * @throws KeeperException unexpected zk exception
65 */
66 public void setClusterUp()
67 throws KeeperException {
68 byte [] upData = toByteArray();
69 try {
70 ZKUtil.createAndWatch(watcher, watcher.clusterStateZNode, upData);
71 } catch(KeeperException.NodeExistsException nee) {
72 ZKUtil.setData(watcher, watcher.clusterStateZNode, upData);
73 }
74 }
75
76 /**
77 * Sets the cluster as down by deleting the znode.
78 * @throws KeeperException unexpected zk exception
79 */
80 public void setClusterDown()
81 throws KeeperException {
82 try {
83 ZKUtil.deleteNode(watcher, watcher.clusterStateZNode);
84 } catch(KeeperException.NoNodeException nne) {
85 LOG.warn("Attempted to set cluster as down but already down, cluster " +
86 "state node (" + watcher.clusterStateZNode + ") not found");
87 }
88 }
89
90 /**
91 * @return Content of the clusterup znode as a serialized pb with the pb
92 * magic as prefix.
93 */
94 static byte [] toByteArray() {
95 ZooKeeperProtos.ClusterUp.Builder builder =
96 ZooKeeperProtos.ClusterUp.newBuilder();
97 builder.setStartDate(new java.util.Date().toString());
98 return ProtobufUtil.prependPBMagic(builder.build().toByteArray());
99 }
100 }