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; import com.google.common.base.Joiner; import com.google.common.collect.Maps; import com.google.common.primitives.SignedBytes; import org.apache.commons.io.Charsets; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.BlockLocation; import org.apache.hadoop.fs.Path; import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys; import org.apache.hadoop.hdfs.protocol.DatanodeInfo; import org.apache.hadoop.hdfs.protocol.LocatedBlock; import org.apache.hadoop.hdfs.protocol.LocatedBlocks; import org.apache.hadoop.hdfs.web.WebHdfsConstants; import org.apache.hadoop.net.NetUtils; import org.apache.hadoop.net.NodeBase; import org.apache.hadoop.util.StringUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.UnsupportedEncodingException; import java.net.InetSocketAddress; import java.text.SimpleDateFormat; import java.util.Collection; import java.util.Collections; import java.util.Date; import java.util.List; import java.util.Locale; import java.util.Map; import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_HA_NAMENODES_KEY_PREFIX; import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_NAMESERVICES; public class DFSUtilClient { public static final byte[] EMPTY_BYTES = {}; private static final Logger LOG = LoggerFactory.getLogger(DFSUtilClient.class); /** * Converts a string to a byte array using UTF8 encoding. */ public static byte[] string2Bytes(String str) { return str.getBytes(Charsets.UTF_8); } /** * Converts a byte array to a string using UTF8 encoding. */ public static String bytes2String(byte[] bytes) { return bytes2String(bytes, 0, bytes.length); } /** Return used as percentage of capacity */ public static float getPercentUsed(long used, long capacity) { return capacity <= 0 ? 100 : (used * 100.0f) / capacity; } /** Return remaining as percentage of capacity */ public static float getPercentRemaining(long remaining, long capacity) { return capacity <= 0 ? 0 : (remaining * 100.0f) / capacity; } /** Convert percentage to a string. */ public static String percent2String(double percentage) { return StringUtils.format("%.2f%%", percentage); } /** * Returns collection of nameservice Ids from the configuration. * @param conf configuration * @return collection of nameservice Ids, or null if not specified */ public static Collection<String> getNameServiceIds(Configuration conf) { return conf.getTrimmedStringCollection(DFS_NAMESERVICES); } /** * Namenode HighAvailability related configuration. * Returns collection of namenode Ids from the configuration. One logical id * for each namenode in the in the HA setup. * * @param conf configuration * @param nsId the nameservice ID to look at, or null for non-federated * @return collection of namenode Ids */ public static Collection<String> getNameNodeIds(Configuration conf, String nsId) { String key = addSuffix(DFS_HA_NAMENODES_KEY_PREFIX, nsId); return conf.getTrimmedStringCollection(key); } /** Add non empty and non null suffix to a key */ static String addSuffix(String key, String suffix) { if (suffix == null || suffix.isEmpty()) { return key; } assert !suffix.startsWith(".") : "suffix '" + suffix + "' should not already have '.' prepended."; return key + "." + suffix; } /** * Returns list of InetSocketAddress corresponding to HA NN HTTP addresses from * the configuration. * * @return list of InetSocketAddresses */ public static Map<String, Map<String, InetSocketAddress>> getHaNnWebHdfsAddresses(Configuration conf, String scheme) { if (WebHdfsConstants.WEBHDFS_SCHEME.equals(scheme)) { return getAddresses(conf, null, HdfsClientConfigKeys.DFS_NAMENODE_HTTP_ADDRESS_KEY); } else if (WebHdfsConstants.SWEBHDFS_SCHEME.equals(scheme)) { return getAddresses(conf, null, HdfsClientConfigKeys.DFS_NAMENODE_HTTPS_ADDRESS_KEY); } else { throw new IllegalArgumentException("Unsupported scheme: " + scheme); } } /** * Convert a LocatedBlocks to BlockLocations[] * @param blocks a LocatedBlocks * @return an array of BlockLocations */ public static BlockLocation[] locatedBlocks2Locations(LocatedBlocks blocks) { if (blocks == null) { return new BlockLocation[0]; } return locatedBlocks2Locations(blocks.getLocatedBlocks()); } /** * Convert a List<LocatedBlock> to BlockLocation[] * @param blocks A List<LocatedBlock> to be converted * @return converted array of BlockLocation */ public static BlockLocation[] locatedBlocks2Locations(List<LocatedBlock> blocks) { if (blocks == null) { return new BlockLocation[0]; } int nrBlocks = blocks.size(); BlockLocation[] blkLocations = new BlockLocation[nrBlocks]; if (nrBlocks == 0) { return blkLocations; } int idx = 0; for (LocatedBlock blk : blocks) { assert idx < nrBlocks : "Incorrect index"; DatanodeInfo[] locations = blk.getLocations(); String[] hosts = new String[locations.length]; String[] xferAddrs = new String[locations.length]; String[] racks = new String[locations.length]; for (int hCnt = 0; hCnt < locations.length; hCnt++) { hosts[hCnt] = locations[hCnt].getHostName(); xferAddrs[hCnt] = locations[hCnt].getXferAddr(); NodeBase node = new NodeBase(xferAddrs[hCnt], locations[hCnt].getNetworkLocation()); racks[hCnt] = node.toString(); } DatanodeInfo[] cachedLocations = blk.getCachedLocations(); String[] cachedHosts = new String[cachedLocations.length]; for (int i = 0; i < cachedLocations.length; i++) { cachedHosts[i] = cachedLocations[i].getHostName(); } blkLocations[idx] = new BlockLocation(xferAddrs, hosts, cachedHosts, racks, blk.getStartOffset(), blk.getBlockSize(), blk.isCorrupt()); idx++; } return blkLocations; } /** Compare two byte arrays by lexicographical order. */ public static int compareBytes(byte[] left, byte[] right) { if (left == null) { left = EMPTY_BYTES; } if (right == null) { right = EMPTY_BYTES; } return SignedBytes.lexicographicalComparator().compare(left, right); } /** * Given a list of path components returns a byte array */ public static byte[] byteArray2bytes(byte[][] pathComponents) { if (pathComponents.length == 0) { return EMPTY_BYTES; } else if (pathComponents.length == 1 && (pathComponents[0] == null || pathComponents[0].length == 0)) { return new byte[] { (byte) Path.SEPARATOR_CHAR }; } int length = 0; for (int i = 0; i < pathComponents.length; i++) { length += pathComponents[i].length; if (i < pathComponents.length - 1) { length++; // for SEPARATOR } } byte[] path = new byte[length]; int index = 0; for (int i = 0; i < pathComponents.length; i++) { System.arraycopy(pathComponents[i], 0, path, index, pathComponents[i].length); index += pathComponents[i].length; if (i < pathComponents.length - 1) { path[index] = (byte) Path.SEPARATOR_CHAR; index++; } } return path; } /** * Decode a specific range of bytes of the given byte array to a string * using UTF8. * * @param bytes The bytes to be decoded into characters * @param offset The index of the first byte to decode * @param length The number of bytes to decode * @return The decoded string */ private static String bytes2String(byte[] bytes, int offset, int length) { try { return new String(bytes, offset, length, "UTF8"); } catch (UnsupportedEncodingException e) { assert false : "UTF8 encoding is not supported "; } return null; } /** * @return <code>coll</code> if it is non-null and non-empty. Otherwise, * returns a list with a single null value. */ static Collection<String> emptyAsSingletonNull(Collection<String> coll) { if (coll == null || coll.isEmpty()) { return Collections.singletonList(null); } else { return coll; } } /** Concatenate list of suffix strings '.' separated */ static String concatSuffixes(String... suffixes) { if (suffixes == null) { return null; } return Joiner.on(".").skipNulls().join(suffixes); } /** * Returns the configured address for all NameNodes in the cluster. * @param conf configuration * @param defaultAddress default address to return in case key is not found. * @param keys Set of keys to look for in the order of preference * @return a map(nameserviceId to map(namenodeId to InetSocketAddress)) */ static Map<String, Map<String, InetSocketAddress>> getAddresses(Configuration conf, String defaultAddress, String... keys) { Collection<String> nameserviceIds = getNameServiceIds(conf); return getAddressesForNsIds(conf, nameserviceIds, defaultAddress, keys); } /** * Returns the configured address for all NameNodes in the cluster. * @param conf configuration * @param defaultAddress default address to return in case key is not found. * @param keys Set of keys to look for in the order of preference * * @return a map(nameserviceId to map(namenodeId to InetSocketAddress)) */ static Map<String, Map<String, InetSocketAddress>> getAddressesForNsIds(Configuration conf, Collection<String> nsIds, String defaultAddress, String... keys) { // Look for configurations of the form <key>[.<nameserviceId>][.<namenodeId>] // across all of the configured nameservices and namenodes. Map<String, Map<String, InetSocketAddress>> ret = Maps.newLinkedHashMap(); for (String nsId : emptyAsSingletonNull(nsIds)) { Map<String, InetSocketAddress> isas = getAddressesForNameserviceId(conf, nsId, defaultAddress, keys); if (!isas.isEmpty()) { ret.put(nsId, isas); } } return ret; } static Map<String, InetSocketAddress> getAddressesForNameserviceId(Configuration conf, String nsId, String defaultValue, String... keys) { Collection<String> nnIds = getNameNodeIds(conf, nsId); Map<String, InetSocketAddress> ret = Maps.newHashMap(); for (String nnId : emptyAsSingletonNull(nnIds)) { String suffix = concatSuffixes(nsId, nnId); String address = getConfValue(defaultValue, suffix, conf, keys); if (address != null) { InetSocketAddress isa = NetUtils.createSocketAddr(address); if (isa.isUnresolved()) { LOG.warn( "Namenode for {} remains unresolved for ID {}. Check your " + "hdfs-site.xml file to ensure namenodes are configured " + "properly.", nsId, nnId); } ret.put(nnId, isa); } } return ret; } /** * Given a list of keys in the order of preference, returns a value * for the key in the given order from the configuration. * @param defaultValue default value to return, when key was not found * @param keySuffix suffix to add to the key, if it is not null * @param conf Configuration * @param keys list of keys in the order of preference * @return value of the key or default if a key was not found in configuration */ private static String getConfValue(String defaultValue, String keySuffix, Configuration conf, String... keys) { String value = null; for (String key : keys) { key = addSuffix(key, keySuffix); value = conf.get(key); if (value != null) { break; } } if (value == null) { value = defaultValue; } return value; } /** * Whether the pathname is valid. Currently prohibits relative paths, * names which contain a ":" or "//", or other non-canonical paths. */ public static boolean isValidName(String src) { // Path must be absolute. if (!src.startsWith(Path.SEPARATOR)) { return false; } // Check for ".." "." ":" "/" String[] components = StringUtils.split(src, '/'); for (int i = 0; i < components.length; i++) { String element = components[i]; if (element.equals(".") || (element.contains(":")) || (element.contains("/"))) { return false; } // ".." is allowed in path starting with /.reserved/.inodes if (element.equals("..")) { if (components.length > 4 && components[1].equals(".reserved") && components[2].equals(".inodes")) { continue; } return false; } // The string may start or end with a /, but not have // "//" in the middle. if (element.isEmpty() && i != components.length - 1 && i != 0) { return false; } } return true; } /** * Converts a time duration in milliseconds into DDD:HH:MM:SS format. */ public static String durationToString(long durationMs) { boolean negative = false; if (durationMs < 0) { negative = true; durationMs = -durationMs; } // Chop off the milliseconds long durationSec = durationMs / 1000; final int secondsPerMinute = 60; final int secondsPerHour = 60 * 60; final int secondsPerDay = 60 * 60 * 24; final long days = durationSec / secondsPerDay; durationSec -= days * secondsPerDay; final long hours = durationSec / secondsPerHour; durationSec -= hours * secondsPerHour; final long minutes = durationSec / secondsPerMinute; durationSec -= minutes * secondsPerMinute; final long seconds = durationSec; final long milliseconds = durationMs % 1000; String format = "%03d:%02d:%02d:%02d.%03d"; if (negative) { format = "-" + format; } return String.format(format, days, hours, minutes, seconds, milliseconds); } /** * Converts a Date into an ISO-8601 formatted datetime string. */ public static String dateToIso8601String(Date date) { SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ", Locale.ENGLISH); return df.format(date); } }