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.fs.viewfs;
019
020import java.net.URI;
021
022import org.apache.hadoop.conf.Configuration;
023
024/**
025 * Utilities for config variables of the viewFs See {@link ViewFs}
026 */
027public class ConfigUtil {
028  /**
029   * Get the config variable prefix for the specified mount table
030   * @param mountTableName - the name of the mount table
031   * @return the config variable prefix for the specified mount table
032   */
033  public static String getConfigViewFsPrefix(final String mountTableName) {
034    return Constants.CONFIG_VIEWFS_PREFIX + "." + mountTableName;
035  }
036  
037  /**
038   * Get the config variable prefix for the default mount table
039   * @return the config variable prefix for the default mount table
040   */
041  public static String getConfigViewFsPrefix() {
042    return 
043      getConfigViewFsPrefix(Constants.CONFIG_VIEWFS_PREFIX_DEFAULT_MOUNT_TABLE);
044  }
045  
046  /**
047   * Add a link to the config for the specified mount table
048   * @param conf - add the link to this conf
049   * @param mountTableName
050   * @param src - the src path name
051   * @param target - the target URI link
052   */
053  public static void addLink(Configuration conf, final String mountTableName, 
054      final String src, final URI target) {
055    conf.set(getConfigViewFsPrefix(mountTableName) + "." +
056        Constants.CONFIG_VIEWFS_LINK + "." + src, target.toString());  
057  }
058  
059  /**
060   * Add a link to the config for the default mount table
061   * @param conf - add the link to this conf
062   * @param src - the src path name
063   * @param target - the target URI link
064   */
065  public static void addLink(final Configuration conf, final String src,
066      final URI target) {
067    addLink( conf, Constants.CONFIG_VIEWFS_DEFAULT_MOUNT_TABLE, 
068        src, target);   
069  }
070  
071  /**
072   * Add config variable for homedir for default mount table
073   * @param conf - add to this conf
074   * @param homedir - the home dir path starting with slash
075   */
076  public static void setHomeDirConf(final Configuration conf,
077      final String homedir) {
078    setHomeDirConf(  conf,
079        Constants.CONFIG_VIEWFS_DEFAULT_MOUNT_TABLE,   homedir);
080  }
081  
082  /**
083   * Add config variable for homedir the specified mount table
084   * @param conf - add to this conf
085   * @param homedir - the home dir path starting with slash
086   */
087  public static void setHomeDirConf(final Configuration conf,
088              final String mountTableName, final String homedir) {
089    if (!homedir.startsWith("/")) {
090      throw new IllegalArgumentException("Home dir should start with /:"
091          + homedir);
092    }
093    conf.set(getConfigViewFsPrefix(mountTableName) + "." +
094        Constants.CONFIG_VIEWFS_HOMEDIR, homedir);
095  }
096  
097  /**
098   * Get the value of the home dir conf value for default mount table
099   * @param conf - from this conf
100   * @return home dir value, null if variable is not in conf
101   */
102  public static String getHomeDirValue(final Configuration conf) {
103    return getHomeDirValue(conf, Constants.CONFIG_VIEWFS_DEFAULT_MOUNT_TABLE);
104  }
105  
106  /**
107   * Get the value of the home dir conf value for specfied mount table
108   * @param conf - from this conf
109   * @param mountTableName - the mount table
110   * @return home dir value, null if variable is not in conf
111   */
112  public static String getHomeDirValue(final Configuration conf, 
113      final String mountTableName) {
114    return conf.get(getConfigViewFsPrefix(mountTableName) + "." +
115        Constants.CONFIG_VIEWFS_HOMEDIR);
116  }
117}