/** * Copyright 2010 The Apache Software Foundation * * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.hadoop.hbase.zookeeper; import java.io.IOException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.hbase.Abortable; import org.apache.hadoop.hbase.HRegionInfo; import org.apache.hadoop.hbase.catalog.CatalogTracker; /** * Tracks the unassigned zookeeper node used by the META table. * * A callback is made into the passed {@link CatalogTracker} when * <code>.META.</code> completes a new assignment. * <p> * If META is already assigned when instantiating this class, you will not * receive any notification for that assignment. You will receive a * notification after META has been successfully assigned to a new location. */ public class MetaNodeTracker extends ZooKeeperNodeTracker { private static final Log LOG = LogFactory.getLog(MetaNodeTracker.class); /** Catalog tracker to notify when META has a new assignment completed. */ private final CatalogTracker catalogTracker; /** * Creates a meta node tracker. * @param watcher * @param abortable */ public MetaNodeTracker(final ZooKeeperWatcher watcher, final CatalogTracker catalogTracker, final Abortable abortable) { super(watcher, ZKUtil.joinZNode(watcher.assignmentZNode, HRegionInfo.FIRST_META_REGIONINFO.getEncodedName()), abortable); this.catalogTracker = catalogTracker; } @Override public void nodeDeleted(String path) { super.nodeDeleted(path); if (!path.equals(node)) return; LOG.info("Detected completed assignment of META, notifying catalog tracker"); try { this.catalogTracker.waitForMetaServerConnectionDefault(); } catch (IOException e) { LOG.warn("Tried to reset META server location after seeing the " + "completion of a new META assignment but got an IOE", e); } } }