1 /** 2 * Copyright 2010 The Apache Software Foundation 3 * 4 * Licensed to the Apache Software Foundation (ASF) under one 5 * or more contributor license agreements. See the NOTICE file 6 * distributed with this work for additional information 7 * regarding copyright ownership. The ASF licenses this file 8 * to you under the Apache License, Version 2.0 (the 9 * "License"); you may not use this file except in compliance 10 * with the License. You may obtain a copy of the License at 11 * 12 * http://www.apache.org/licenses/LICENSE-2.0 13 * 14 * Unless required by applicable law or agreed to in writing, software 15 * distributed under the License is distributed on an "AS IS" BASIS, 16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 17 * See the License for the specific language governing permissions and 18 * limitations under the License. 19 */ 20 package org.apache.hadoop.hbase.zookeeper; 21 22 import java.io.IOException; 23 24 import org.apache.commons.logging.Log; 25 import org.apache.commons.logging.LogFactory; 26 import org.apache.hadoop.hbase.Abortable; 27 import org.apache.hadoop.hbase.HRegionInfo; 28 import org.apache.hadoop.hbase.catalog.CatalogTracker; 29 30 /** 31 * Tracks the unassigned zookeeper node used by the META table. 32 * 33 * A callback is made into the passed {@link CatalogTracker} when 34 * <code>.META.</code> completes a new assignment. 35 * <p> 36 * If META is already assigned when instantiating this class, you will not 37 * receive any notification for that assignment. You will receive a 38 * notification after META has been successfully assigned to a new location. 39 */ 40 public class MetaNodeTracker extends ZooKeeperNodeTracker { 41 private static final Log LOG = LogFactory.getLog(MetaNodeTracker.class); 42 43 /** Catalog tracker to notify when META has a new assignment completed. */ 44 private final CatalogTracker catalogTracker; 45 46 /** 47 * Creates a meta node tracker. 48 * @param watcher 49 * @param abortable 50 */ 51 public MetaNodeTracker(final ZooKeeperWatcher watcher, 52 final CatalogTracker catalogTracker, final Abortable abortable) { 53 super(watcher, ZKUtil.joinZNode(watcher.assignmentZNode, 54 HRegionInfo.FIRST_META_REGIONINFO.getEncodedName()), abortable); 55 this.catalogTracker = catalogTracker; 56 } 57 58 @Override 59 public void nodeDeleted(String path) { 60 super.nodeDeleted(path); 61 if (!path.equals(node)) return; 62 LOG.info("Detected completed assignment of META, notifying catalog tracker"); 63 try { 64 this.catalogTracker.waitForMetaServerConnectionDefault(); 65 } catch (IOException e) { 66 LOG.warn("Tried to reset META server location after seeing the " + 67 "completion of a new META assignment but got an IOE", e); 68 } 69 } 70 }