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.server.namenode; import java.io.IOException; import java.net.URI; import java.util.Collection; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hdfs.protocol.AvatarConstants.InstanceId; import org.apache.hadoop.hdfs.qjournal.client.QuorumJournalManager; import org.apache.hadoop.hdfs.server.namenode.AvatarNode.StartupInfo; import org.apache.hadoop.hdfs.server.namenode.JournalStream.JournalType; import org.apache.hadoop.util.FlushableLogger; public class AvatarStorageSetup { public static final Log LOG = LogFactory.getLog(AvatarStorageSetup.class.getName()); // immediate flush logger private static final Log FLOG = FlushableLogger.getLogger(LOG); static void validate(Configuration conf, Collection<URI> namedirs, Collection<URI> editsdir, URI img0, URI img1, URI edit0, URI edit1) throws IOException { FLOG.info("Avatar conf validation - namedirs: " + namedirs); FLOG.info("Avatar conf validation - editdirs: " + editsdir); FLOG.info("Avatar conf validation - shared namedirs: " + img0 + ", " + img1); FLOG.info("Avatar conf validation - shared editdirs: " + edit0 + ", " + edit1); String msg = ""; if (conf == null) { msg += "Configuration should not be null. "; } if (img0 == null || img1 == null || edit0 == null || edit1 == null) { msg += "Configuration does not contain shared locations for image and edits. "; // at this point there we fail checkMessage(msg); } if (img0.equals(img1)) { msg += "Configuration contains the same image location for dfs.name.dir.shared0 " + "and dfs.name.dir.shared1"; // at this point there we fail checkMessage(msg); } if (edit0.equals(edit1)) { msg += "Configuration contains the same edits location for dfs.name.edits.dir.shared0 " + "and dfs.name.edits.dir.shared1"; // at this point there we fail checkMessage(msg); } // non-shared storage is file based msg += checkFileURIScheme(namedirs); msg += checkFileURIScheme(editsdir); // verify that the shared image dirctories are not specified as dfs.name.dir msg += checkContainment(namedirs, img0, "dfs.name.dir", "dfs.name.dir.shared0"); msg += checkContainment(namedirs, img1, "dfs.name.dir", "dfs.name.dir.shared1"); // verify that the shared edits directories are not specified as // dfs.name.edits.dir msg += checkContainment(editsdir, edit0, "dfs.name.edits.dir", "dfs.name.edits.dir.shared0"); msg += checkContainment(editsdir, edit1, "dfs.name.edits.dir", "dfs.name.edits.dir.shared1"); if (conf.get("dfs.name.dir.shared") != null || conf.get("dfs.name.edits.dir.shared") != null) { msg += " dfs.name.dir.shared and dfs.name.edits.dir.shared should not be set manually"; } // check shared image location msg += checkImageStorage(img0, edit0); msg += checkImageStorage(img1, edit1); checkMessage(msg); } private static String checkContainment(Collection<URI> set, URI key, String setName, String keyName) { if (set.contains(key)) { return " The name specified in " + keyName + " is already part of " + setName + ". "; } return ""; } private static void checkMessage(String msg) throws IOException { if (msg.length() != 0) { FLOG.fatal(msg); throw new IOException(msg); } } /** * Shared image needs to be in file storage, or QJM providing that QJM also * stores edits. */ private static String checkImageStorage(URI sharedImage, URI sharedEdits) { if (sharedImage.getScheme().equals(NNStorage.LOCAL_URI_SCHEME)) { // shared image is stored in file storage return ""; } else if (sharedImage.getScheme().equals(QuorumJournalManager.QJM_URI_SCHEME) && sharedImage.equals(sharedEdits)) { // image is stored in qjm together with edits return ""; } return "Shared image uri: " + sharedImage + " must be either file storage" + " or be equal to shared edits storage " + sharedEdits + ". "; } /** * For non-shared storage, we enforce file uris */ private static String checkFileURIScheme(Collection<URI> uris) { for (URI uri : uris) if (uri.getScheme().compareTo(JournalType.FILE.name().toLowerCase()) != 0) return "The specified path is not a file." + "Avatar supports file non-shared storage only... "; return ""; } static void updateConf(StartupInfo startInfo, Configuration newconf, Collection<URI> dirs, URI dir0, URI dir1, String keyName) { StringBuffer buf = new StringBuffer(); if (startInfo.instance == InstanceId.NODEONE) { buf.append(dir1); newconf.set(keyName + ".shared", dir1.toString()); } else if (startInfo.instance == InstanceId.NODEZERO) { buf.append(dir0); newconf.set(keyName + ".shared", dir0.toString()); } for (URI str : dirs) { buf.append(","); buf.append(str); } newconf.set(keyName, buf.toString()); buf = null; } }