001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.util;
019
020import java.util.AbstractMap;
021import java.util.Collection;
022import java.util.List;
023import java.util.Map;
024import org.apache.hadoop.conf.Configuration;
025import org.apache.hadoop.util.StringUtils;
026import org.apache.yetus.audience.InterfaceAudience;
027
028import org.apache.hbase.thirdparty.com.google.common.collect.Lists;
029
030/**
031 * Utilities for storing more complex collection types in
032 * {@link org.apache.hadoop.conf.Configuration} instances.
033 */
034@InterfaceAudience.Public
035public final class ConfigurationUtil {
036  // TODO: hopefully this is a good delimiter; it's not in the base64 alphabet,
037  // nor is it valid for paths
038  public static final char KVP_DELIMITER = '^';
039
040  // Disallow instantiation
041  private ConfigurationUtil() {
042
043  }
044
045  /**
046   * Store a collection of Map.Entry's in conf, with each entry separated by ',' and key values
047   * delimited by {@link #KVP_DELIMITER}
048   * @param conf      configuration to store the collection in
049   * @param key       overall key to store keyValues under
050   * @param keyValues kvps to be stored under key in conf
051   */
052  public static void setKeyValues(Configuration conf, String key,
053    Collection<Map.Entry<String, String>> keyValues) {
054    setKeyValues(conf, key, keyValues, KVP_DELIMITER);
055  }
056
057  /**
058   * Store a collection of Map.Entry's in conf, with each entry separated by ',' and key values
059   * delimited by delimiter.
060   * @param conf      configuration to store the collection in
061   * @param key       overall key to store keyValues under
062   * @param keyValues kvps to be stored under key in conf
063   * @param delimiter character used to separate each kvp
064   */
065  public static void setKeyValues(Configuration conf, String key,
066    Collection<Map.Entry<String, String>> keyValues, char delimiter) {
067    List<String> serializedKvps = Lists.newArrayList();
068
069    for (Map.Entry<String, String> kvp : keyValues) {
070      serializedKvps.add(kvp.getKey() + delimiter + kvp.getValue());
071    }
072
073    conf.setStrings(key, serializedKvps.toArray(new String[serializedKvps.size()]));
074  }
075
076  /**
077   * Retrieve a list of key value pairs from configuration, stored under the provided key
078   * @param conf configuration to retrieve kvps from
079   * @param key  key under which the key values are stored
080   * @return the list of kvps stored under key in conf, or null if the key isn't present.
081   * @see #setKeyValues(Configuration, String, Collection, char)
082   */
083  public static List<Map.Entry<String, String>> getKeyValues(Configuration conf, String key) {
084    return getKeyValues(conf, key, KVP_DELIMITER);
085  }
086
087  /**
088   * Retrieve a list of key value pairs from configuration, stored under the provided key
089   * @param conf      configuration to retrieve kvps from
090   * @param key       key under which the key values are stored
091   * @param delimiter character used to separate each kvp
092   * @return the list of kvps stored under key in conf, or null if the key isn't present.
093   * @see #setKeyValues(Configuration, String, Collection, char)
094   */
095  public static List<Map.Entry<String, String>> getKeyValues(Configuration conf, String key,
096    char delimiter) {
097    String[] kvps = conf.getStrings(key);
098
099    if (kvps == null) {
100      return null;
101    }
102
103    List<Map.Entry<String, String>> rtn = Lists.newArrayList();
104
105    for (String kvp : kvps) {
106      String[] splitKvp = StringUtils.split(kvp, delimiter);
107
108      if (splitKvp.length != 2) {
109        throw new IllegalArgumentException("Expected key value pair for configuration key '" + key
110          + "'" + " to be of form '<key>" + delimiter + "<value>; was " + kvp + " instead");
111      }
112
113      rtn.add(new AbstractMap.SimpleImmutableEntry<>(splitKvp[0], splitKvp[1]));
114    }
115    return rtn;
116  }
117}