Java tutorial
/** * 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.hdfs.conf; import java.io.IOException; import java.net.InetSocketAddress; import java.net.UnknownHostException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.conf.Configurable; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hdfs.DFSUtil; import org.apache.hadoop.hdfs.protocol.AvatarConstants.InstanceId; import org.apache.hadoop.hdfs.protocol.FSConstants; import org.apache.hadoop.hdfs.server.namenode.NameNode; import org.apache.hadoop.net.NetUtils; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.data.Stat; public class FallbackNameSpaceAddressManager extends NameSpaceAddressManager { private String serviceName; private static final Log LOG = LogFactory.getLog(NameSpaceAddressManager.class.getName()); private final AddressHolder<String> clientProtocolZnodeAddress; private final AddressHolder<String> datanodeProtocolZnodeAddress; private final AddressHolder<String> httpZnodeAddress; private class ConfGetter extends AddressHolder<String> { private String key; public ConfGetter(Configurable theParent, String configKey) { super(theParent); key = configKey; } @Override public String getAddress() throws UnknownHostException { return getConf().get(getKey()); } @Override public String getKey() { return key + "." + serviceName; } } public FallbackNameSpaceAddressManager(Configurable parent, String serviceName) { super(parent); clientProtocolZnodeAddress = new ConfGetter(parent, NameNode.DFS_NAMENODE_RPC_ADDRESS_KEY); datanodeProtocolZnodeAddress = new ConfGetter(parent, NameNode.DATANODE_PROTOCOL_ADDRESS); httpZnodeAddress = new ConfGetter(parent, FSConstants.DFS_NAMENODE_HTTP_ADDRESS_KEY); this.serviceName = serviceName; } @Override public void refreshZookeeperInfo() throws IOException, KeeperException, InterruptedException { NameNodeAddress zero = getNodeZero(); NameNodeAddress one = getNodeOne(); // Using RPC Address to determine which node is primary and using the rest // of them as a sanity check String zNodeClientProtocol = clientProtocolZnodeAddress.getAddress(); String primaryClientProtocol = zkClient.getPrimaryAvatarAddress(zNodeClientProtocol, new Stat(), false, false); InstanceId instanceIdfromZookeeper = null; if (primaryClientProtocol == null) { // Fail-over in progress. instanceIdfromZookeeper = null; } else { InetSocketAddress clientProtAddress = NetUtils.createSocketAddr(primaryClientProtocol); if (clientProtAddress.equals(zero.clientProtocol.getAddress())) { instanceIdfromZookeeper = InstanceId.NODEZERO; } else if (clientProtAddress.equals(one.clientProtocol.getAddress())) { instanceIdfromZookeeper = InstanceId.NODEONE; } else { throw new IllegalArgumentException( "Zookeeper client protocol address isn't valid: " + primaryClientProtocol); } } String zNodeHttpKey = httpZnodeAddress.getAddress(); verifyAddress(zkClient.getPrimaryAvatarAddress(zNodeHttpKey, new Stat(), false), instanceIdfromZookeeper, zero.httpProtocol.getAddress(), one.httpProtocol.getAddress()); String zNodeKeyForDnAddress = datanodeProtocolZnodeAddress.getAddress(); verifyAddress(zkClient.getPrimaryAvatarAddress(zNodeKeyForDnAddress, new Stat(), false), instanceIdfromZookeeper, zero.datanodeProtocol.getAddress(), one.datanodeProtocol.getAddress()); super.setPrimary(instanceIdfromZookeeper); } private static void verifyAddress(String address, InstanceId fromZk, InetSocketAddress zeroAddr, InetSocketAddress oneAddr) { InstanceId afterMatchingWithConfig = null; if (address == null) { afterMatchingWithConfig = null; } else { InetSocketAddress addressInIp = NetUtils.createSocketAddr(address); if (zeroAddr.equals(addressInIp)) { afterMatchingWithConfig = InstanceId.NODEZERO; } else if (oneAddr.equals(addressInIp)) { afterMatchingWithConfig = InstanceId.NODEONE; } else { DFSUtil.throwAndLogIllegalState( "Address doesn't match any of the possible candidates from the config file", LOG); } } if (afterMatchingWithConfig != fromZk) { DFSUtil.throwAndLogIllegalState("One of the addresses of Zookeeper isn't in sync with other addresses.", LOG); } } @Override public void validateConfigFile(Configuration conf) { String[] keysOfInterest = new String[] { FSConstants.DFS_NAMENODE_HTTP_ADDRESS_KEY, NameNode.DATANODE_PROTOCOL_ADDRESS, FSConstants.DFS_NAMENODE_RPC_ADDRESS_KEY }; boolean toThrowTheException = false; for (String key : keysOfInterest) { if (conf.get(key) == null) { LOG.error("Key not found: " + key); toThrowTheException = true; } } for (String key : keysOfInterest) { for (InstanceId id : InstanceId.values()) { String keyWeExpect = key + id.getZookeeeperValue() + "." + serviceName; if (conf.get(keyWeExpect) == null) { LOG.error("Key not found: " + keyWeExpect); toThrowTheException = true; } } } if (toThrowTheException) { throw new IllegalArgumentException("Essential keys are missing from configuration."); } } @Override public String getTxidPath() throws UnknownHostException { return clientProtocolZnodeAddress.getAddress(); } @Override public String getSsidPath() throws UnknownHostException { return getTxidPath(); } public void setPrimary(InstanceId id) throws IOException { if (id == null) { zkClient.clearPrimary(clientProtocolZnodeAddress.getAddress()); zkClient.clearPrimary(datanodeProtocolZnodeAddress.getAddress()); zkClient.clearPrimary(httpZnodeAddress.getAddress()); } else { NameNodeAddress addressesToWrite = null; switch (id) { case NODEZERO: addressesToWrite = getNodeZero(); case NODEONE: addressesToWrite = getNodeOne(); } final boolean toOverWrite = true; zkClient.registerPrimary(clientProtocolZnodeAddress.getAddress(), NameNode.getHostPortString(addressesToWrite.clientProtocol.getAddress()), toOverWrite); zkClient.registerPrimary(datanodeProtocolZnodeAddress.getAddress(), NameNode.getHostPortString(addressesToWrite.datanodeProtocol.getAddress()), toOverWrite); zkClient.registerPrimary(httpZnodeAddress.getAddress(), NameNode.getHostPortString(addressesToWrite.httpProtocol.getAddress()), toOverWrite); } super.setPrimary(id); } }