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     */
018    
019    package org.apache.hadoop.conf;
020    
021    import java.io.BufferedInputStream;
022    import java.io.DataInput;
023    import java.io.DataOutput;
024    import java.io.File;
025    import java.io.FileInputStream;
026    import java.io.IOException;
027    import java.io.InputStream;
028    import java.io.InputStreamReader;
029    import java.io.OutputStream;
030    import java.io.OutputStreamWriter;
031    import java.io.Reader;
032    import java.io.Writer;
033    import java.lang.ref.WeakReference;
034    import java.net.InetSocketAddress;
035    import java.net.URL;
036    import java.util.ArrayList;
037    import java.util.Arrays;
038    import java.util.Collection;
039    import java.util.Collections;
040    import java.util.Enumeration;
041    import java.util.HashMap;
042    import java.util.HashSet;
043    import java.util.Iterator;
044    import java.util.LinkedList;
045    import java.util.List;
046    import java.util.ListIterator;
047    import java.util.Map;
048    import java.util.Map.Entry;
049    import java.util.Properties;
050    import java.util.Set;
051    import java.util.StringTokenizer;
052    import java.util.WeakHashMap;
053    import java.util.concurrent.CopyOnWriteArrayList;
054    import java.util.regex.Matcher;
055    import java.util.regex.Pattern;
056    import java.util.regex.PatternSyntaxException;
057    import java.util.concurrent.TimeUnit;
058    
059    import javax.xml.parsers.DocumentBuilder;
060    import javax.xml.parsers.DocumentBuilderFactory;
061    import javax.xml.parsers.ParserConfigurationException;
062    import javax.xml.transform.Transformer;
063    import javax.xml.transform.TransformerException;
064    import javax.xml.transform.TransformerFactory;
065    import javax.xml.transform.dom.DOMSource;
066    import javax.xml.transform.stream.StreamResult;
067    
068    import org.apache.commons.logging.Log;
069    import org.apache.commons.logging.LogFactory;
070    import org.apache.hadoop.classification.InterfaceAudience;
071    import org.apache.hadoop.classification.InterfaceStability;
072    import org.apache.hadoop.fs.FileSystem;
073    import org.apache.hadoop.fs.Path;
074    import org.apache.hadoop.fs.CommonConfigurationKeys;
075    import org.apache.hadoop.io.Writable;
076    import org.apache.hadoop.io.WritableUtils;
077    import org.apache.hadoop.net.NetUtils;
078    import org.apache.hadoop.util.ReflectionUtils;
079    import org.apache.hadoop.util.StringInterner;
080    import org.apache.hadoop.util.StringUtils;
081    import org.codehaus.jackson.JsonFactory;
082    import org.codehaus.jackson.JsonGenerator;
083    import org.w3c.dom.DOMException;
084    import org.w3c.dom.Document;
085    import org.w3c.dom.Element;
086    import org.w3c.dom.Node;
087    import org.w3c.dom.NodeList;
088    import org.w3c.dom.Text;
089    import org.xml.sax.SAXException;
090    import com.google.common.base.Preconditions;
091    
092    /** 
093     * Provides access to configuration parameters.
094     *
095     * <h4 id="Resources">Resources</h4>
096     *
097     * <p>Configurations are specified by resources. A resource contains a set of
098     * name/value pairs as XML data. Each resource is named by either a 
099     * <code>String</code> or by a {@link Path}. If named by a <code>String</code>, 
100     * then the classpath is examined for a file with that name.  If named by a 
101     * <code>Path</code>, then the local filesystem is examined directly, without 
102     * referring to the classpath.
103     *
104     * <p>Unless explicitly turned off, Hadoop by default specifies two 
105     * resources, loaded in-order from the classpath: <ol>
106     * <li><tt><a href="{@docRoot}/../core-default.html">core-default.xml</a>
107     * </tt>: Read-only defaults for hadoop.</li>
108     * <li><tt>core-site.xml</tt>: Site-specific configuration for a given hadoop
109     * installation.</li>
110     * </ol>
111     * Applications may add additional resources, which are loaded
112     * subsequent to these resources in the order they are added.
113     * 
114     * <h4 id="FinalParams">Final Parameters</h4>
115     *
116     * <p>Configuration parameters may be declared <i>final</i>. 
117     * Once a resource declares a value final, no subsequently-loaded 
118     * resource can alter that value.  
119     * For example, one might define a final parameter with:
120     * <tt><pre>
121     *  &lt;property&gt;
122     *    &lt;name&gt;dfs.hosts.include&lt;/name&gt;
123     *    &lt;value&gt;/etc/hadoop/conf/hosts.include&lt;/value&gt;
124     *    <b>&lt;final&gt;true&lt;/final&gt;</b>
125     *  &lt;/property&gt;</pre></tt>
126     *
127     * Administrators typically define parameters as final in 
128     * <tt>core-site.xml</tt> for values that user applications may not alter.
129     *
130     * <h4 id="VariableExpansion">Variable Expansion</h4>
131     *
132     * <p>Value strings are first processed for <i>variable expansion</i>. The
133     * available properties are:<ol>
134     * <li>Other properties defined in this Configuration; and, if a name is
135     * undefined here,</li>
136     * <li>Properties in {@link System#getProperties()}.</li>
137     * </ol>
138     *
139     * <p>For example, if a configuration resource contains the following property
140     * definitions: 
141     * <tt><pre>
142     *  &lt;property&gt;
143     *    &lt;name&gt;basedir&lt;/name&gt;
144     *    &lt;value&gt;/user/${<i>user.name</i>}&lt;/value&gt;
145     *  &lt;/property&gt;
146     *  
147     *  &lt;property&gt;
148     *    &lt;name&gt;tempdir&lt;/name&gt;
149     *    &lt;value&gt;${<i>basedir</i>}/tmp&lt;/value&gt;
150     *  &lt;/property&gt;</pre></tt>
151     *
152     * When <tt>conf.get("tempdir")</tt> is called, then <tt>${<i>basedir</i>}</tt>
153     * will be resolved to another property in this Configuration, while
154     * <tt>${<i>user.name</i>}</tt> would then ordinarily be resolved to the value
155     * of the System property with that name.
156     * By default, warnings will be given to any deprecated configuration 
157     * parameters and these are suppressible by configuring
158     * <tt>log4j.logger.org.apache.hadoop.conf.Configuration.deprecation</tt> in
159     * log4j.properties file.
160     */
161    @InterfaceAudience.Public
162    @InterfaceStability.Stable
163    public class Configuration implements Iterable<Map.Entry<String,String>>,
164                                          Writable {
165      private static final Log LOG =
166        LogFactory.getLog(Configuration.class);
167    
168      private static final Log LOG_DEPRECATION =
169        LogFactory.getLog("org.apache.hadoop.conf.Configuration.deprecation");
170    
171      private boolean quietmode = true;
172      
173      private static class Resource {
174        private final Object resource;
175        private final String name;
176        
177        public Resource(Object resource) {
178          this(resource, resource.toString());
179        }
180        
181        public Resource(Object resource, String name) {
182          this.resource = resource;
183          this.name = name;
184        }
185        
186        public String getName(){
187          return name;
188        }
189        
190        public Object getResource() {
191          return resource;
192        }
193        
194        @Override
195        public String toString() {
196          return name;
197        }
198      }
199      
200      /**
201       * List of configuration resources.
202       */
203      private ArrayList<Resource> resources = new ArrayList<Resource>();
204      
205      /**
206       * The value reported as the setting resource when a key is set
207       * by code rather than a file resource by dumpConfiguration.
208       */
209      static final String UNKNOWN_RESOURCE = "Unknown";
210    
211    
212      /**
213       * List of configuration parameters marked <b>final</b>. 
214       */
215      private Set<String> finalParameters = new HashSet<String>();
216      
217      private boolean loadDefaults = true;
218      
219      /**
220       * Configuration objects
221       */
222      private static final WeakHashMap<Configuration,Object> REGISTRY = 
223        new WeakHashMap<Configuration,Object>();
224      
225      /**
226       * List of default Resources. Resources are loaded in the order of the list 
227       * entries
228       */
229      private static final CopyOnWriteArrayList<String> defaultResources =
230        new CopyOnWriteArrayList<String>();
231    
232      private static final Map<ClassLoader, Map<String, WeakReference<Class<?>>>>
233        CACHE_CLASSES = new WeakHashMap<ClassLoader, Map<String, WeakReference<Class<?>>>>();
234    
235      /**
236       * Sentinel value to store negative cache results in {@link #CACHE_CLASSES}.
237       */
238      private static final Class<?> NEGATIVE_CACHE_SENTINEL =
239        NegativeCacheSentinel.class;
240    
241      /**
242       * Stores the mapping of key to the resource which modifies or loads 
243       * the key most recently
244       */
245      private HashMap<String, String[]> updatingResource;
246     
247      /**
248       * Class to keep the information about the keys which replace the deprecated
249       * ones.
250       * 
251       * This class stores the new keys which replace the deprecated keys and also
252       * gives a provision to have a custom message for each of the deprecated key
253       * that is being replaced. It also provides method to get the appropriate
254       * warning message which can be logged whenever the deprecated key is used.
255       */
256      private static class DeprecatedKeyInfo {
257        private String[] newKeys;
258        private String customMessage;
259        private boolean accessed;
260        DeprecatedKeyInfo(String[] newKeys, String customMessage) {
261          this.newKeys = newKeys;
262          this.customMessage = customMessage;
263          accessed = false;
264        }
265    
266        /**
267         * Method to provide the warning message. It gives the custom message if
268         * non-null, and default message otherwise.
269         * @param key the associated deprecated key.
270         * @return message that is to be logged when a deprecated key is used.
271         */
272        private final String getWarningMessage(String key) {
273          String warningMessage;
274          if(customMessage == null) {
275            StringBuilder message = new StringBuilder(key);
276            String deprecatedKeySuffix = " is deprecated. Instead, use ";
277            message.append(deprecatedKeySuffix);
278            for (int i = 0; i < newKeys.length; i++) {
279              message.append(newKeys[i]);
280              if(i != newKeys.length-1) {
281                message.append(", ");
282              }
283            }
284            warningMessage = message.toString();
285          }
286          else {
287            warningMessage = customMessage;
288          }
289          accessed = true;
290          return warningMessage;
291        }
292      }
293      
294      /**
295       * Stores the deprecated keys, the new keys which replace the deprecated keys
296       * and custom message(if any provided).
297       */
298      private static Map<String, DeprecatedKeyInfo> deprecatedKeyMap = 
299          new HashMap<String, DeprecatedKeyInfo>();
300      
301      /**
302       * Stores a mapping from superseding keys to the keys which they deprecate.
303       */
304      private static Map<String, String> reverseDeprecatedKeyMap =
305          new HashMap<String, String>();
306    
307      /**
308       * Adds the deprecated key to the deprecation map.
309       * It does not override any existing entries in the deprecation map.
310       * This is to be used only by the developers in order to add deprecation of
311       * keys, and attempts to call this method after loading resources once,
312       * would lead to <tt>UnsupportedOperationException</tt>
313       * 
314       * If a key is deprecated in favor of multiple keys, they are all treated as 
315       * aliases of each other, and setting any one of them resets all the others 
316       * to the new value.
317       * 
318       * @param key
319       * @param newKeys
320       * @param customMessage
321       * @deprecated use {@link #addDeprecation(String key, String newKey,
322          String customMessage)} instead
323       */
324      @Deprecated
325      public synchronized static void addDeprecation(String key, String[] newKeys,
326          String customMessage) {
327        if (key == null || key.length() == 0 ||
328            newKeys == null || newKeys.length == 0) {
329          throw new IllegalArgumentException();
330        }
331        if (!isDeprecated(key)) {
332          DeprecatedKeyInfo newKeyInfo;
333          newKeyInfo = new DeprecatedKeyInfo(newKeys, customMessage);
334          deprecatedKeyMap.put(key, newKeyInfo);
335          for (String newKey : newKeys) {
336            reverseDeprecatedKeyMap.put(newKey, key);
337          }
338        }
339      }
340      
341      /**
342       * Adds the deprecated key to the deprecation map.
343       * It does not override any existing entries in the deprecation map.
344       * This is to be used only by the developers in order to add deprecation of
345       * keys, and attempts to call this method after loading resources once,
346       * would lead to <tt>UnsupportedOperationException</tt>
347       * 
348       * @param key
349       * @param newKey
350       * @param customMessage
351       */
352      public synchronized static void addDeprecation(String key, String newKey,
353                  String customMessage) {
354              addDeprecation(key, new String[] {newKey}, customMessage);
355      }
356    
357      /**
358       * Adds the deprecated key to the deprecation map when no custom message
359       * is provided.
360       * It does not override any existing entries in the deprecation map.
361       * This is to be used only by the developers in order to add deprecation of
362       * keys, and attempts to call this method after loading resources once,
363       * would lead to <tt>UnsupportedOperationException</tt>
364       * 
365       * If a key is deprecated in favor of multiple keys, they are all treated as 
366       * aliases of each other, and setting any one of them resets all the others 
367       * to the new value.
368       * 
369       * @param key Key that is to be deprecated
370       * @param newKeys list of keys that take up the values of deprecated key
371       * @deprecated use {@link #addDeprecation(String key, String newKey)} instead
372       */
373      @Deprecated
374      public synchronized static void addDeprecation(String key, String[] newKeys) {
375        addDeprecation(key, newKeys, null);
376      }
377      
378      /**
379       * Adds the deprecated key to the deprecation map when no custom message
380       * is provided.
381       * It does not override any existing entries in the deprecation map.
382       * This is to be used only by the developers in order to add deprecation of
383       * keys, and attempts to call this method after loading resources once,
384       * would lead to <tt>UnsupportedOperationException</tt>
385       * 
386       * @param key Key that is to be deprecated
387       * @param newKey key that takes up the value of deprecated key
388       */
389      public synchronized static void addDeprecation(String key, String newKey) {
390            addDeprecation(key, new String[] {newKey}, null);
391      }
392      
393      /**
394       * checks whether the given <code>key</code> is deprecated.
395       * 
396       * @param key the parameter which is to be checked for deprecation
397       * @return <code>true</code> if the key is deprecated and 
398       *         <code>false</code> otherwise.
399       */
400      public static boolean isDeprecated(String key) {
401        return deprecatedKeyMap.containsKey(key);
402      }
403    
404      /**
405       * Returns the alternate name for a key if the property name is deprecated
406       * or if deprecates a property name.
407       *
408       * @param name property name.
409       * @return alternate name.
410       */
411      private String[] getAlternateNames(String name) {
412        String altNames[] = null;
413        DeprecatedKeyInfo keyInfo = deprecatedKeyMap.get(name);
414        if (keyInfo == null) {
415          altNames = (reverseDeprecatedKeyMap.get(name) != null ) ? 
416            new String [] {reverseDeprecatedKeyMap.get(name)} : null;
417          if(altNames != null && altNames.length > 0) {
418            //To help look for other new configs for this deprecated config
419            keyInfo = deprecatedKeyMap.get(altNames[0]);
420          }      
421        } 
422        if(keyInfo != null && keyInfo.newKeys.length > 0) {
423          List<String> list = new ArrayList<String>(); 
424          if(altNames != null) {
425              list.addAll(Arrays.asList(altNames));
426          }
427          list.addAll(Arrays.asList(keyInfo.newKeys));
428          altNames = list.toArray(new String[list.size()]);
429        }
430        return altNames;
431      }
432    
433      /**
434       * Checks for the presence of the property <code>name</code> in the
435       * deprecation map. Returns the first of the list of new keys if present
436       * in the deprecation map or the <code>name</code> itself. If the property
437       * is not presently set but the property map contains an entry for the
438       * deprecated key, the value of the deprecated key is set as the value for
439       * the provided property name.
440       *
441       * @param name the property name
442       * @return the first property in the list of properties mapping
443       *         the <code>name</code> or the <code>name</code> itself.
444       */
445      private String[] handleDeprecation(String name) {
446        ArrayList<String > names = new ArrayList<String>();
447            if (isDeprecated(name)) {
448          DeprecatedKeyInfo keyInfo = deprecatedKeyMap.get(name);
449          warnOnceIfDeprecated(name);
450          for (String newKey : keyInfo.newKeys) {
451            if(newKey != null) {
452              names.add(newKey);
453            }
454          }
455        }
456        if(names.size() == 0) {
457            names.add(name);
458        }
459        for(String n : names) {
460              String deprecatedKey = reverseDeprecatedKeyMap.get(n);
461              if (deprecatedKey != null && !getOverlay().containsKey(n) &&
462                  getOverlay().containsKey(deprecatedKey)) {
463                getProps().setProperty(n, getOverlay().getProperty(deprecatedKey));
464                getOverlay().setProperty(n, getOverlay().getProperty(deprecatedKey));
465              }
466        }
467        return names.toArray(new String[names.size()]);
468      }
469     
470      private void handleDeprecation() {
471        LOG.debug("Handling deprecation for all properties in config...");
472        Set<Object> keys = new HashSet<Object>();
473        keys.addAll(getProps().keySet());
474        for (Object item: keys) {
475          LOG.debug("Handling deprecation for " + (String)item);
476          handleDeprecation((String)item);
477        }
478      }
479     
480      static{
481        //print deprecation warning if hadoop-site.xml is found in classpath
482        ClassLoader cL = Thread.currentThread().getContextClassLoader();
483        if (cL == null) {
484          cL = Configuration.class.getClassLoader();
485        }
486        if(cL.getResource("hadoop-site.xml")!=null) {
487          LOG.warn("DEPRECATED: hadoop-site.xml found in the classpath. " +
488              "Usage of hadoop-site.xml is deprecated. Instead use core-site.xml, "
489              + "mapred-site.xml and hdfs-site.xml to override properties of " +
490              "core-default.xml, mapred-default.xml and hdfs-default.xml " +
491              "respectively");
492        }
493        addDefaultResource("core-default.xml");
494        addDefaultResource("core-site.xml");
495        //Add code for managing deprecated key mapping
496        //for example
497        //addDeprecation("oldKey1",new String[]{"newkey1","newkey2"});
498        //adds deprecation for oldKey1 to two new keys(newkey1, newkey2).
499        //so get or set of oldKey1 will correctly populate/access values of 
500        //newkey1 and newkey2
501        addDeprecatedKeys();
502      }
503      
504      private Properties properties;
505      private Properties overlay;
506      private ClassLoader classLoader;
507      {
508        classLoader = Thread.currentThread().getContextClassLoader();
509        if (classLoader == null) {
510          classLoader = Configuration.class.getClassLoader();
511        }
512      }
513      
514      /** A new configuration. */
515      public Configuration() {
516        this(true);
517      }
518    
519      /** A new configuration where the behavior of reading from the default 
520       * resources can be turned off.
521       * 
522       * If the parameter {@code loadDefaults} is false, the new instance
523       * will not load resources from the default files. 
524       * @param loadDefaults specifies whether to load from the default files
525       */
526      public Configuration(boolean loadDefaults) {
527        this.loadDefaults = loadDefaults;
528        updatingResource = new HashMap<String, String[]>();
529        synchronized(Configuration.class) {
530          REGISTRY.put(this, null);
531        }
532      }
533      
534      /** 
535       * A new configuration with the same settings cloned from another.
536       * 
537       * @param other the configuration from which to clone settings.
538       */
539      @SuppressWarnings("unchecked")
540      public Configuration(Configuration other) {
541       this.resources = (ArrayList<Resource>) other.resources.clone();
542       synchronized(other) {
543         if (other.properties != null) {
544           this.properties = (Properties)other.properties.clone();
545         }
546    
547         if (other.overlay!=null) {
548           this.overlay = (Properties)other.overlay.clone();
549         }
550    
551         this.updatingResource = new HashMap<String, String[]>(other.updatingResource);
552       }
553       
554        this.finalParameters = new HashSet<String>(other.finalParameters);
555        synchronized(Configuration.class) {
556          REGISTRY.put(this, null);
557        }
558        this.classLoader = other.classLoader;
559        this.loadDefaults = other.loadDefaults;
560        setQuietMode(other.getQuietMode());
561      }
562      
563      /**
564       * Add a default resource. Resources are loaded in the order of the resources 
565       * added.
566       * @param name file name. File should be present in the classpath.
567       */
568      public static synchronized void addDefaultResource(String name) {
569        if(!defaultResources.contains(name)) {
570          defaultResources.add(name);
571          for(Configuration conf : REGISTRY.keySet()) {
572            if(conf.loadDefaults) {
573              conf.reloadConfiguration();
574            }
575          }
576        }
577      }
578    
579      /**
580       * Add a configuration resource. 
581       * 
582       * The properties of this resource will override properties of previously 
583       * added resources, unless they were marked <a href="#Final">final</a>. 
584       * 
585       * @param name resource to be added, the classpath is examined for a file 
586       *             with that name.
587       */
588      public void addResource(String name) {
589        addResourceObject(new Resource(name));
590      }
591    
592      /**
593       * Add a configuration resource. 
594       * 
595       * The properties of this resource will override properties of previously 
596       * added resources, unless they were marked <a href="#Final">final</a>. 
597       * 
598       * @param url url of the resource to be added, the local filesystem is 
599       *            examined directly to find the resource, without referring to 
600       *            the classpath.
601       */
602      public void addResource(URL url) {
603        addResourceObject(new Resource(url));
604      }
605    
606      /**
607       * Add a configuration resource. 
608       * 
609       * The properties of this resource will override properties of previously 
610       * added resources, unless they were marked <a href="#Final">final</a>. 
611       * 
612       * @param file file-path of resource to be added, the local filesystem is
613       *             examined directly to find the resource, without referring to 
614       *             the classpath.
615       */
616      public void addResource(Path file) {
617        addResourceObject(new Resource(file));
618      }
619    
620      /**
621       * Add a configuration resource. 
622       * 
623       * The properties of this resource will override properties of previously 
624       * added resources, unless they were marked <a href="#Final">final</a>. 
625       * 
626       * WARNING: The contents of the InputStream will be cached, by this method. 
627       * So use this sparingly because it does increase the memory consumption.
628       * 
629       * @param in InputStream to deserialize the object from. In will be read from
630       * when a get or set is called next.  After it is read the stream will be
631       * closed. 
632       */
633      public void addResource(InputStream in) {
634        addResourceObject(new Resource(in));
635      }
636    
637      /**
638       * Add a configuration resource. 
639       * 
640       * The properties of this resource will override properties of previously 
641       * added resources, unless they were marked <a href="#Final">final</a>. 
642       * 
643       * @param in InputStream to deserialize the object from.
644       * @param name the name of the resource because InputStream.toString is not
645       * very descriptive some times.  
646       */
647      public void addResource(InputStream in, String name) {
648        addResourceObject(new Resource(in, name));
649      }
650      
651      
652      /**
653       * Reload configuration from previously added resources.
654       *
655       * This method will clear all the configuration read from the added 
656       * resources, and final parameters. This will make the resources to 
657       * be read again before accessing the values. Values that are added
658       * via set methods will overlay values read from the resources.
659       */
660      public synchronized void reloadConfiguration() {
661        properties = null;                            // trigger reload
662        finalParameters.clear();                      // clear site-limits
663      }
664      
665      private synchronized void addResourceObject(Resource resource) {
666        resources.add(resource);                      // add to resources
667        reloadConfiguration();
668      }
669      
670      private static Pattern varPat = Pattern.compile("\\$\\{[^\\}\\$\u0020]+\\}");
671      private static int MAX_SUBST = 20;
672    
673      private String substituteVars(String expr) {
674        if (expr == null) {
675          return null;
676        }
677        Matcher match = varPat.matcher("");
678        String eval = expr;
679        for(int s=0; s<MAX_SUBST; s++) {
680          match.reset(eval);
681          if (!match.find()) {
682            return eval;
683          }
684          String var = match.group();
685          var = var.substring(2, var.length()-1); // remove ${ .. }
686          String val = null;
687          try {
688            val = System.getProperty(var);
689          } catch(SecurityException se) {
690            LOG.warn("Unexpected SecurityException in Configuration", se);
691          }
692          if (val == null) {
693            val = getRaw(var);
694          }
695          if (val == null) {
696            return eval; // return literal ${var}: var is unbound
697          }
698          // substitute
699          eval = eval.substring(0, match.start())+val+eval.substring(match.end());
700        }
701        throw new IllegalStateException("Variable substitution depth too large: " 
702                                        + MAX_SUBST + " " + expr);
703      }
704      
705      /**
706       * Get the value of the <code>name</code> property, <code>null</code> if
707       * no such property exists. If the key is deprecated, it returns the value of
708       * the first key which replaces the deprecated key and is not null
709       * 
710       * Values are processed for <a href="#VariableExpansion">variable expansion</a> 
711       * before being returned. 
712       * 
713       * @param name the property name.
714       * @return the value of the <code>name</code> or its replacing property, 
715       *         or null if no such property exists.
716       */
717      public String get(String name) {
718        String[] names = handleDeprecation(name);
719        String result = null;
720        for(String n : names) {
721          result = substituteVars(getProps().getProperty(n));
722        }
723        return result;
724      }
725      
726      /**
727       * Get the value of the <code>name</code> property as a trimmed <code>String</code>, 
728       * <code>null</code> if no such property exists. 
729       * If the key is deprecated, it returns the value of
730       * the first key which replaces the deprecated key and is not null
731       * 
732       * Values are processed for <a href="#VariableExpansion">variable expansion</a> 
733       * before being returned. 
734       * 
735       * @param name the property name.
736       * @return the value of the <code>name</code> or its replacing property, 
737       *         or null if no such property exists.
738       */
739      public String getTrimmed(String name) {
740        String value = get(name);
741        
742        if (null == value) {
743          return null;
744        } else {
745          return value.trim();
746        }
747      }
748      
749      /**
750       * Get the value of the <code>name</code> property as a trimmed <code>String</code>, 
751       * <code>defaultValue</code> if no such property exists. 
752       * See @{Configuration#getTrimmed} for more details.
753       * 
754       * @param name          the property name.
755       * @param defaultValue  the property default value.
756       * @return              the value of the <code>name</code> or defaultValue
757       *                      if it is not set.
758       */
759      public String getTrimmed(String name, String defaultValue) {
760        String ret = getTrimmed(name);
761        return ret == null ? defaultValue : ret;
762      }
763    
764      /**
765       * Get the value of the <code>name</code> property, without doing
766       * <a href="#VariableExpansion">variable expansion</a>.If the key is 
767       * deprecated, it returns the value of the first key which replaces 
768       * the deprecated key and is not null.
769       * 
770       * @param name the property name.
771       * @return the value of the <code>name</code> property or 
772       *         its replacing property and null if no such property exists.
773       */
774      public String getRaw(String name) {
775        String[] names = handleDeprecation(name);
776        String result = null;
777        for(String n : names) {
778          result = getProps().getProperty(n);
779        }
780        return result;
781      }
782    
783      /** 
784       * Set the <code>value</code> of the <code>name</code> property. If 
785       * <code>name</code> is deprecated or there is a deprecated name associated to it,
786       * it sets the value to both names.
787       * 
788       * @param name property name.
789       * @param value property value.
790       */
791      public void set(String name, String value) {
792        set(name, value, null);
793      }
794      
795      /** 
796       * Set the <code>value</code> of the <code>name</code> property. If 
797       * <code>name</code> is deprecated or there is a deprecated name associated to it,
798       * it sets the value to both names.
799       * 
800       * @param name property name.
801       * @param value property value.
802       * @param source the place that this configuration value came from 
803       * (For debugging).
804       * @throws IllegalArgumentException when the value or name is null.
805       */
806      public void set(String name, String value, String source) {
807        Preconditions.checkArgument(
808            name != null,
809            "Property name must not be null");
810        Preconditions.checkArgument(
811            value != null,
812            "Property value must not be null");
813        if (deprecatedKeyMap.isEmpty()) {
814          getProps();
815        }
816        getOverlay().setProperty(name, value);
817        getProps().setProperty(name, value);
818        if(source == null) {
819          updatingResource.put(name, new String[] {"programatically"});
820        } else {
821          updatingResource.put(name, new String[] {source});
822        }
823        String[] altNames = getAlternateNames(name);
824        if (altNames != null && altNames.length > 0) {
825          String altSource = "because " + name + " is deprecated";
826          for(String altName : altNames) {
827            if(!altName.equals(name)) {
828              getOverlay().setProperty(altName, value);
829              getProps().setProperty(altName, value);
830              updatingResource.put(altName, new String[] {altSource});
831            }
832          }
833        }
834        warnOnceIfDeprecated(name);
835      }
836    
837      private void warnOnceIfDeprecated(String name) {
838        DeprecatedKeyInfo keyInfo = deprecatedKeyMap.get(name);
839        if (keyInfo != null && !keyInfo.accessed) {
840          LOG_DEPRECATION.info(keyInfo.getWarningMessage(name));
841        }
842      }
843    
844      /**
845       * Unset a previously set property.
846       */
847      public synchronized void unset(String name) {
848        String[] altNames = getAlternateNames(name);
849        getOverlay().remove(name);
850        getProps().remove(name);
851        if (altNames !=null && altNames.length > 0) {
852          for(String altName : altNames) {
853            getOverlay().remove(altName);
854            getProps().remove(altName);
855          }
856        }
857      }
858    
859      /**
860       * Sets a property if it is currently unset.
861       * @param name the property name
862       * @param value the new value
863       */
864      public synchronized void setIfUnset(String name, String value) {
865        if (get(name) == null) {
866          set(name, value);
867        }
868      }
869      
870      private synchronized Properties getOverlay() {
871        if (overlay==null){
872          overlay=new Properties();
873        }
874        return overlay;
875      }
876    
877      /** 
878       * Get the value of the <code>name</code>. If the key is deprecated,
879       * it returns the value of the first key which replaces the deprecated key
880       * and is not null.
881       * If no such property exists,
882       * then <code>defaultValue</code> is returned.
883       * 
884       * @param name property name.
885       * @param defaultValue default value.
886       * @return property value, or <code>defaultValue</code> if the property 
887       *         doesn't exist.                    
888       */
889      public String get(String name, String defaultValue) {
890        String[] names = handleDeprecation(name);
891        String result = null;
892        for(String n : names) {
893          result = substituteVars(getProps().getProperty(n, defaultValue));
894        }
895        return result;
896      }
897    
898      /** 
899       * Get the value of the <code>name</code> property as an <code>int</code>.
900       *   
901       * If no such property exists, the provided default value is returned,
902       * or if the specified value is not a valid <code>int</code>,
903       * then an error is thrown.
904       * 
905       * @param name property name.
906       * @param defaultValue default value.
907       * @throws NumberFormatException when the value is invalid
908       * @return property value as an <code>int</code>, 
909       *         or <code>defaultValue</code>. 
910       */
911      public int getInt(String name, int defaultValue) {
912        String valueString = getTrimmed(name);
913        if (valueString == null)
914          return defaultValue;
915        String hexString = getHexDigits(valueString);
916        if (hexString != null) {
917          return Integer.parseInt(hexString, 16);
918        }
919        return Integer.parseInt(valueString);
920      }
921      
922      /**
923       * Get the value of the <code>name</code> property as a set of comma-delimited
924       * <code>int</code> values.
925       * 
926       * If no such property exists, an empty array is returned.
927       * 
928       * @param name property name
929       * @return property value interpreted as an array of comma-delimited
930       *         <code>int</code> values
931       */
932      public int[] getInts(String name) {
933        String[] strings = getTrimmedStrings(name);
934        int[] ints = new int[strings.length];
935        for (int i = 0; i < strings.length; i++) {
936          ints[i] = Integer.parseInt(strings[i]);
937        }
938        return ints;
939      }
940    
941      /** 
942       * Set the value of the <code>name</code> property to an <code>int</code>.
943       * 
944       * @param name property name.
945       * @param value <code>int</code> value of the property.
946       */
947      public void setInt(String name, int value) {
948        set(name, Integer.toString(value));
949      }
950    
951    
952      /** 
953       * Get the value of the <code>name</code> property as a <code>long</code>.  
954       * If no such property exists, the provided default value is returned,
955       * or if the specified value is not a valid <code>long</code>,
956       * then an error is thrown.
957       * 
958       * @param name property name.
959       * @param defaultValue default value.
960       * @throws NumberFormatException when the value is invalid
961       * @return property value as a <code>long</code>, 
962       *         or <code>defaultValue</code>. 
963       */
964      public long getLong(String name, long defaultValue) {
965        String valueString = getTrimmed(name);
966        if (valueString == null)
967          return defaultValue;
968        String hexString = getHexDigits(valueString);
969        if (hexString != null) {
970          return Long.parseLong(hexString, 16);
971        }
972        return Long.parseLong(valueString);
973      }
974    
975      /**
976       * Get the value of the <code>name</code> property as a <code>long</code> or
977       * human readable format. If no such property exists, the provided default
978       * value is returned, or if the specified value is not a valid
979       * <code>long</code> or human readable format, then an error is thrown. You
980       * can use the following suffix (case insensitive): k(kilo), m(mega), g(giga),
981       * t(tera), p(peta), e(exa)
982       *
983       * @param name property name.
984       * @param defaultValue default value.
985       * @throws NumberFormatException when the value is invalid
986       * @return property value as a <code>long</code>,
987       *         or <code>defaultValue</code>.
988       */
989      public long getLongBytes(String name, long defaultValue) {
990        String valueString = getTrimmed(name);
991        if (valueString == null)
992          return defaultValue;
993        return StringUtils.TraditionalBinaryPrefix.string2long(valueString);
994      }
995    
996      private String getHexDigits(String value) {
997        boolean negative = false;
998        String str = value;
999        String hexString = null;
1000        if (value.startsWith("-")) {
1001          negative = true;
1002          str = value.substring(1);
1003        }
1004        if (str.startsWith("0x") || str.startsWith("0X")) {
1005          hexString = str.substring(2);
1006          if (negative) {
1007            hexString = "-" + hexString;
1008          }
1009          return hexString;
1010        }
1011        return null;
1012      }
1013      
1014      /** 
1015       * Set the value of the <code>name</code> property to a <code>long</code>.
1016       * 
1017       * @param name property name.
1018       * @param value <code>long</code> value of the property.
1019       */
1020      public void setLong(String name, long value) {
1021        set(name, Long.toString(value));
1022      }
1023    
1024      /** 
1025       * Get the value of the <code>name</code> property as a <code>float</code>.  
1026       * If no such property exists, the provided default value is returned,
1027       * or if the specified value is not a valid <code>float</code>,
1028       * then an error is thrown.
1029       *
1030       * @param name property name.
1031       * @param defaultValue default value.
1032       * @throws NumberFormatException when the value is invalid
1033       * @return property value as a <code>float</code>, 
1034       *         or <code>defaultValue</code>. 
1035       */
1036      public float getFloat(String name, float defaultValue) {
1037        String valueString = getTrimmed(name);
1038        if (valueString == null)
1039          return defaultValue;
1040        return Float.parseFloat(valueString);
1041      }
1042    
1043      /**
1044       * Set the value of the <code>name</code> property to a <code>float</code>.
1045       * 
1046       * @param name property name.
1047       * @param value property value.
1048       */
1049      public void setFloat(String name, float value) {
1050        set(name,Float.toString(value));
1051      }
1052    
1053      /** 
1054       * Get the value of the <code>name</code> property as a <code>double</code>.  
1055       * If no such property exists, the provided default value is returned,
1056       * or if the specified value is not a valid <code>double</code>,
1057       * then an error is thrown.
1058       *
1059       * @param name property name.
1060       * @param defaultValue default value.
1061       * @throws NumberFormatException when the value is invalid
1062       * @return property value as a <code>double</code>, 
1063       *         or <code>defaultValue</code>. 
1064       */
1065      public double getDouble(String name, double defaultValue) {
1066        String valueString = getTrimmed(name);
1067        if (valueString == null)
1068          return defaultValue;
1069        return Double.parseDouble(valueString);
1070      }
1071    
1072      /**
1073       * Set the value of the <code>name</code> property to a <code>double</code>.
1074       * 
1075       * @param name property name.
1076       * @param value property value.
1077       */
1078      public void setDouble(String name, double value) {
1079        set(name,Double.toString(value));
1080      }
1081     
1082      /** 
1083       * Get the value of the <code>name</code> property as a <code>boolean</code>.  
1084       * If no such property is specified, or if the specified value is not a valid
1085       * <code>boolean</code>, then <code>defaultValue</code> is returned.
1086       * 
1087       * @param name property name.
1088       * @param defaultValue default value.
1089       * @return property value as a <code>boolean</code>, 
1090       *         or <code>defaultValue</code>. 
1091       */
1092      public boolean getBoolean(String name, boolean defaultValue) {
1093        String valueString = getTrimmed(name);
1094        if (null == valueString || valueString.isEmpty()) {
1095          return defaultValue;
1096        }
1097    
1098        valueString = valueString.toLowerCase();
1099    
1100        if ("true".equals(valueString))
1101          return true;
1102        else if ("false".equals(valueString))
1103          return false;
1104        else return defaultValue;
1105      }
1106    
1107      /** 
1108       * Set the value of the <code>name</code> property to a <code>boolean</code>.
1109       * 
1110       * @param name property name.
1111       * @param value <code>boolean</code> value of the property.
1112       */
1113      public void setBoolean(String name, boolean value) {
1114        set(name, Boolean.toString(value));
1115      }
1116    
1117      /**
1118       * Set the given property, if it is currently unset.
1119       * @param name property name
1120       * @param value new value
1121       */
1122      public void setBooleanIfUnset(String name, boolean value) {
1123        setIfUnset(name, Boolean.toString(value));
1124      }
1125    
1126      /**
1127       * Set the value of the <code>name</code> property to the given type. This
1128       * is equivalent to <code>set(&lt;name&gt;, value.toString())</code>.
1129       * @param name property name
1130       * @param value new value
1131       */
1132      public <T extends Enum<T>> void setEnum(String name, T value) {
1133        set(name, value.toString());
1134      }
1135    
1136      /**
1137       * Return value matching this enumerated type.
1138       * @param name Property name
1139       * @param defaultValue Value returned if no mapping exists
1140       * @throws IllegalArgumentException If mapping is illegal for the type
1141       * provided
1142       */
1143      public <T extends Enum<T>> T getEnum(String name, T defaultValue) {
1144        final String val = get(name);
1145        return null == val
1146          ? defaultValue
1147          : Enum.valueOf(defaultValue.getDeclaringClass(), val);
1148      }
1149    
1150      enum ParsedTimeDuration {
1151        NS {
1152          TimeUnit unit() { return TimeUnit.NANOSECONDS; }
1153          String suffix() { return "ns"; }
1154        },
1155        US {
1156          TimeUnit unit() { return TimeUnit.MICROSECONDS; }
1157          String suffix() { return "us"; }
1158        },
1159        MS {
1160          TimeUnit unit() { return TimeUnit.MILLISECONDS; }
1161          String suffix() { return "ms"; }
1162        },
1163        S {
1164          TimeUnit unit() { return TimeUnit.SECONDS; }
1165          String suffix() { return "s"; }
1166        },
1167        M {
1168          TimeUnit unit() { return TimeUnit.MINUTES; }
1169          String suffix() { return "m"; }
1170        },
1171        H {
1172          TimeUnit unit() { return TimeUnit.HOURS; }
1173          String suffix() { return "h"; }
1174        },
1175        D {
1176          TimeUnit unit() { return TimeUnit.DAYS; }
1177          String suffix() { return "d"; }
1178        };
1179        abstract TimeUnit unit();
1180        abstract String suffix();
1181        static ParsedTimeDuration unitFor(String s) {
1182          for (ParsedTimeDuration ptd : values()) {
1183            // iteration order is in decl order, so SECONDS matched last
1184            if (s.endsWith(ptd.suffix())) {
1185              return ptd;
1186            }
1187          }
1188          return null;
1189        }
1190        static ParsedTimeDuration unitFor(TimeUnit unit) {
1191          for (ParsedTimeDuration ptd : values()) {
1192            if (ptd.unit() == unit) {
1193              return ptd;
1194            }
1195          }
1196          return null;
1197        }
1198      }
1199    
1200      /**
1201       * Set the value of <code>name</code> to the given time duration. This
1202       * is equivalent to <code>set(&lt;name&gt;, value + &lt;time suffix&gt;)</code>.
1203       * @param name Property name
1204       * @param value Time duration
1205       * @param unit Unit of time
1206       */
1207      public void setTimeDuration(String name, long value, TimeUnit unit) {
1208        set(name, value + ParsedTimeDuration.unitFor(unit).suffix());
1209      }
1210    
1211      /**
1212       * Return time duration in the given time unit. Valid units are encoded in
1213       * properties as suffixes: nanoseconds (ns), microseconds (us), milliseconds
1214       * (ms), seconds (s), minutes (m), hours (h), and days (d).
1215       * @param name Property name
1216       * @param defaultValue Value returned if no mapping exists.
1217       * @param unit Unit to convert the stored property, if it exists.
1218       * @throws NumberFormatException If the property stripped of its unit is not
1219       *         a number
1220       */
1221      public long getTimeDuration(String name, long defaultValue, TimeUnit unit) {
1222        String vStr = get(name);
1223        if (null == vStr) {
1224          return defaultValue;
1225        }
1226        vStr = vStr.trim();
1227        ParsedTimeDuration vUnit = ParsedTimeDuration.unitFor(vStr);
1228        if (null == vUnit) {
1229          LOG.warn("No unit for " + name + "(" + vStr + ") assuming " + unit);
1230          vUnit = ParsedTimeDuration.unitFor(unit);
1231        } else {
1232          vStr = vStr.substring(0, vStr.lastIndexOf(vUnit.suffix()));
1233        }
1234        return unit.convert(Long.parseLong(vStr), vUnit.unit());
1235      }
1236    
1237      /**
1238       * Get the value of the <code>name</code> property as a <code>Pattern</code>.
1239       * If no such property is specified, or if the specified value is not a valid
1240       * <code>Pattern</code>, then <code>DefaultValue</code> is returned.
1241       *
1242       * @param name property name
1243       * @param defaultValue default value
1244       * @return property value as a compiled Pattern, or defaultValue
1245       */
1246      public Pattern getPattern(String name, Pattern defaultValue) {
1247        String valString = get(name);
1248        if (null == valString || valString.isEmpty()) {
1249          return defaultValue;
1250        }
1251        try {
1252          return Pattern.compile(valString);
1253        } catch (PatternSyntaxException pse) {
1254          LOG.warn("Regular expression '" + valString + "' for property '" +
1255                   name + "' not valid. Using default", pse);
1256          return defaultValue;
1257        }
1258      }
1259    
1260      /**
1261       * Set the given property to <code>Pattern</code>.
1262       * If the pattern is passed as null, sets the empty pattern which results in
1263       * further calls to getPattern(...) returning the default value.
1264       *
1265       * @param name property name
1266       * @param pattern new value
1267       */
1268      public void setPattern(String name, Pattern pattern) {
1269        if (null == pattern) {
1270          set(name, null);
1271        } else {
1272          set(name, pattern.pattern());
1273        }
1274      }
1275    
1276      /**
1277       * Gets information about why a property was set.  Typically this is the 
1278       * path to the resource objects (file, URL, etc.) the property came from, but
1279       * it can also indicate that it was set programatically, or because of the
1280       * command line.
1281       *
1282       * @param name - The property name to get the source of.
1283       * @return null - If the property or its source wasn't found. Otherwise, 
1284       * returns a list of the sources of the resource.  The older sources are
1285       * the first ones in the list.  So for example if a configuration is set from
1286       * the command line, and then written out to a file that is read back in the
1287       * first entry would indicate that it was set from the command line, while
1288       * the second one would indicate the file that the new configuration was read
1289       * in from.
1290       */
1291      @InterfaceStability.Unstable
1292      public synchronized String[] getPropertySources(String name) {
1293        if (properties == null) {
1294          // If properties is null, it means a resource was newly added
1295          // but the props were cleared so as to load it upon future
1296          // requests. So lets force a load by asking a properties list.
1297          getProps();
1298        }
1299        // Return a null right away if our properties still
1300        // haven't loaded or the resource mapping isn't defined
1301        if (properties == null || updatingResource == null) {
1302          return null;
1303        } else {
1304          String[] source = updatingResource.get(name);
1305          if(source == null) {
1306            return null;
1307          } else {
1308            return Arrays.copyOf(source, source.length);
1309          }
1310        }
1311      }
1312    
1313      /**
1314       * A class that represents a set of positive integer ranges. It parses 
1315       * strings of the form: "2-3,5,7-" where ranges are separated by comma and 
1316       * the lower/upper bounds are separated by dash. Either the lower or upper 
1317       * bound may be omitted meaning all values up to or over. So the string 
1318       * above means 2, 3, 5, and 7, 8, 9, ...
1319       */
1320      public static class IntegerRanges implements Iterable<Integer>{
1321        private static class Range {
1322          int start;
1323          int end;
1324        }
1325        
1326        private static class RangeNumberIterator implements Iterator<Integer> {
1327          Iterator<Range> internal;
1328          int at;
1329          int end;
1330    
1331          public RangeNumberIterator(List<Range> ranges) {
1332            if (ranges != null) {
1333              internal = ranges.iterator();
1334            }
1335            at = -1;
1336            end = -2;
1337          }
1338          
1339          @Override
1340          public boolean hasNext() {
1341            if (at <= end) {
1342              return true;
1343            } else if (internal != null){
1344              return internal.hasNext();
1345            }
1346            return false;
1347          }
1348    
1349          @Override
1350          public Integer next() {
1351            if (at <= end) {
1352              at++;
1353              return at - 1;
1354            } else if (internal != null){
1355              Range found = internal.next();
1356              if (found != null) {
1357                at = found.start;
1358                end = found.end;
1359                at++;
1360                return at - 1;
1361              }
1362            }
1363            return null;
1364          }
1365    
1366          @Override
1367          public void remove() {
1368            throw new UnsupportedOperationException();
1369          }
1370        };
1371    
1372        List<Range> ranges = new ArrayList<Range>();
1373        
1374        public IntegerRanges() {
1375        }
1376        
1377        public IntegerRanges(String newValue) {
1378          StringTokenizer itr = new StringTokenizer(newValue, ",");
1379          while (itr.hasMoreTokens()) {
1380            String rng = itr.nextToken().trim();
1381            String[] parts = rng.split("-", 3);
1382            if (parts.length < 1 || parts.length > 2) {
1383              throw new IllegalArgumentException("integer range badly formed: " + 
1384                                                 rng);
1385            }
1386            Range r = new Range();
1387            r.start = convertToInt(parts[0], 0);
1388            if (parts.length == 2) {
1389              r.end = convertToInt(parts[1], Integer.MAX_VALUE);
1390            } else {
1391              r.end = r.start;
1392            }
1393            if (r.start > r.end) {
1394              throw new IllegalArgumentException("IntegerRange from " + r.start + 
1395                                                 " to " + r.end + " is invalid");
1396            }
1397            ranges.add(r);
1398          }
1399        }
1400    
1401        /**
1402         * Convert a string to an int treating empty strings as the default value.
1403         * @param value the string value
1404         * @param defaultValue the value for if the string is empty
1405         * @return the desired integer
1406         */
1407        private static int convertToInt(String value, int defaultValue) {
1408          String trim = value.trim();
1409          if (trim.length() == 0) {
1410            return defaultValue;
1411          }
1412          return Integer.parseInt(trim);
1413        }
1414    
1415        /**
1416         * Is the given value in the set of ranges
1417         * @param value the value to check
1418         * @return is the value in the ranges?
1419         */
1420        public boolean isIncluded(int value) {
1421          for(Range r: ranges) {
1422            if (r.start <= value && value <= r.end) {
1423              return true;
1424            }
1425          }
1426          return false;
1427        }
1428        
1429        /**
1430         * @return true if there are no values in this range, else false.
1431         */
1432        public boolean isEmpty() {
1433          return ranges == null || ranges.isEmpty();
1434        }
1435        
1436        @Override
1437        public String toString() {
1438          StringBuilder result = new StringBuilder();
1439          boolean first = true;
1440          for(Range r: ranges) {
1441            if (first) {
1442              first = false;
1443            } else {
1444              result.append(',');
1445            }
1446            result.append(r.start);
1447            result.append('-');
1448            result.append(r.end);
1449          }
1450          return result.toString();
1451        }
1452    
1453        @Override
1454        public Iterator<Integer> iterator() {
1455          return new RangeNumberIterator(ranges);
1456        }
1457        
1458      }
1459    
1460      /**
1461       * Parse the given attribute as a set of integer ranges
1462       * @param name the attribute name
1463       * @param defaultValue the default value if it is not set
1464       * @return a new set of ranges from the configured value
1465       */
1466      public IntegerRanges getRange(String name, String defaultValue) {
1467        return new IntegerRanges(get(name, defaultValue));
1468      }
1469    
1470      /** 
1471       * Get the comma delimited values of the <code>name</code> property as 
1472       * a collection of <code>String</code>s.  
1473       * If no such property is specified then empty collection is returned.
1474       * <p>
1475       * This is an optimized version of {@link #getStrings(String)}
1476       * 
1477       * @param name property name.
1478       * @return property value as a collection of <code>String</code>s. 
1479       */
1480      public Collection<String> getStringCollection(String name) {
1481        String valueString = get(name);
1482        return StringUtils.getStringCollection(valueString);
1483      }
1484    
1485      /** 
1486       * Get the comma delimited values of the <code>name</code> property as 
1487       * an array of <code>String</code>s.  
1488       * If no such property is specified then <code>null</code> is returned.
1489       * 
1490       * @param name property name.
1491       * @return property value as an array of <code>String</code>s, 
1492       *         or <code>null</code>. 
1493       */
1494      public String[] getStrings(String name) {
1495        String valueString = get(name);
1496        return StringUtils.getStrings(valueString);
1497      }
1498    
1499      /** 
1500       * Get the comma delimited values of the <code>name</code> property as 
1501       * an array of <code>String</code>s.  
1502       * If no such property is specified then default value is returned.
1503       * 
1504       * @param name property name.
1505       * @param defaultValue The default value
1506       * @return property value as an array of <code>String</code>s, 
1507       *         or default value. 
1508       */
1509      public String[] getStrings(String name, String... defaultValue) {
1510        String valueString = get(name);
1511        if (valueString == null) {
1512          return defaultValue;
1513        } else {
1514          return StringUtils.getStrings(valueString);
1515        }
1516      }
1517      
1518      /** 
1519       * Get the comma delimited values of the <code>name</code> property as 
1520       * a collection of <code>String</code>s, trimmed of the leading and trailing whitespace.  
1521       * If no such property is specified then empty <code>Collection</code> is returned.
1522       *
1523       * @param name property name.
1524       * @return property value as a collection of <code>String</code>s, or empty <code>Collection</code> 
1525       */
1526      public Collection<String> getTrimmedStringCollection(String name) {
1527        String valueString = get(name);
1528        if (null == valueString) {
1529          Collection<String> empty = new ArrayList<String>();
1530          return empty;
1531        }
1532        return StringUtils.getTrimmedStringCollection(valueString);
1533      }
1534      
1535      /** 
1536       * Get the comma delimited values of the <code>name</code> property as 
1537       * an array of <code>String</code>s, trimmed of the leading and trailing whitespace.
1538       * If no such property is specified then an empty array is returned.
1539       * 
1540       * @param name property name.
1541       * @return property value as an array of trimmed <code>String</code>s, 
1542       *         or empty array. 
1543       */
1544      public String[] getTrimmedStrings(String name) {
1545        String valueString = get(name);
1546        return StringUtils.getTrimmedStrings(valueString);
1547      }
1548    
1549      /** 
1550       * Get the comma delimited values of the <code>name</code> property as 
1551       * an array of <code>String</code>s, trimmed of the leading and trailing whitespace.
1552       * If no such property is specified then default value is returned.
1553       * 
1554       * @param name property name.
1555       * @param defaultValue The default value
1556       * @return property value as an array of trimmed <code>String</code>s, 
1557       *         or default value. 
1558       */
1559      public String[] getTrimmedStrings(String name, String... defaultValue) {
1560        String valueString = get(name);
1561        if (null == valueString) {
1562          return defaultValue;
1563        } else {
1564          return StringUtils.getTrimmedStrings(valueString);
1565        }
1566      }
1567    
1568      /** 
1569       * Set the array of string values for the <code>name</code> property as 
1570       * as comma delimited values.  
1571       * 
1572       * @param name property name.
1573       * @param values The values
1574       */
1575      public void setStrings(String name, String... values) {
1576        set(name, StringUtils.arrayToString(values));
1577      }
1578    
1579      /**
1580       * Get the socket address for <code>name</code> property as a
1581       * <code>InetSocketAddress</code>.
1582       * @param name property name.
1583       * @param defaultAddress the default value
1584       * @param defaultPort the default port
1585       * @return InetSocketAddress
1586       */
1587      public InetSocketAddress getSocketAddr(
1588          String name, String defaultAddress, int defaultPort) {
1589        final String address = get(name, defaultAddress);
1590        return NetUtils.createSocketAddr(address, defaultPort, name);
1591      }
1592    
1593      /**
1594       * Set the socket address for the <code>name</code> property as
1595       * a <code>host:port</code>.
1596       */
1597      public void setSocketAddr(String name, InetSocketAddress addr) {
1598        set(name, NetUtils.getHostPortString(addr));
1599      }
1600      
1601      /**
1602       * Set the socket address a client can use to connect for the
1603       * <code>name</code> property as a <code>host:port</code>.  The wildcard
1604       * address is replaced with the local host's address.
1605       * @param name property name.
1606       * @param addr InetSocketAddress of a listener to store in the given property
1607       * @return InetSocketAddress for clients to connect
1608       */
1609      public InetSocketAddress updateConnectAddr(String name,
1610                                                 InetSocketAddress addr) {
1611        final InetSocketAddress connectAddr = NetUtils.getConnectAddress(addr);
1612        setSocketAddr(name, connectAddr);
1613        return connectAddr;
1614      }
1615      
1616      /**
1617       * Load a class by name.
1618       * 
1619       * @param name the class name.
1620       * @return the class object.
1621       * @throws ClassNotFoundException if the class is not found.
1622       */
1623      public Class<?> getClassByName(String name) throws ClassNotFoundException {
1624        Class<?> ret = getClassByNameOrNull(name);
1625        if (ret == null) {
1626          throw new ClassNotFoundException("Class " + name + " not found");
1627        }
1628        return ret;
1629      }
1630      
1631      /**
1632       * Load a class by name, returning null rather than throwing an exception
1633       * if it couldn't be loaded. This is to avoid the overhead of creating
1634       * an exception.
1635       * 
1636       * @param name the class name
1637       * @return the class object, or null if it could not be found.
1638       */
1639      public Class<?> getClassByNameOrNull(String name) {
1640        Map<String, WeakReference<Class<?>>> map;
1641        
1642        synchronized (CACHE_CLASSES) {
1643          map = CACHE_CLASSES.get(classLoader);
1644          if (map == null) {
1645            map = Collections.synchronizedMap(
1646              new WeakHashMap<String, WeakReference<Class<?>>>());
1647            CACHE_CLASSES.put(classLoader, map);
1648          }
1649        }
1650    
1651        Class<?> clazz = null;
1652        WeakReference<Class<?>> ref = map.get(name); 
1653        if (ref != null) {
1654           clazz = ref.get();
1655        }
1656         
1657        if (clazz == null) {
1658          try {
1659            clazz = Class.forName(name, true, classLoader);
1660          } catch (ClassNotFoundException e) {
1661            // Leave a marker that the class isn't found
1662            map.put(name, new WeakReference<Class<?>>(NEGATIVE_CACHE_SENTINEL));
1663            return null;
1664          }
1665          // two putters can race here, but they'll put the same class
1666          map.put(name, new WeakReference<Class<?>>(clazz));
1667          return clazz;
1668        } else if (clazz == NEGATIVE_CACHE_SENTINEL) {
1669          return null; // not found
1670        } else {
1671          // cache hit
1672          return clazz;
1673        }
1674      }
1675    
1676      /** 
1677       * Get the value of the <code>name</code> property
1678       * as an array of <code>Class</code>.
1679       * The value of the property specifies a list of comma separated class names.  
1680       * If no such property is specified, then <code>defaultValue</code> is 
1681       * returned.
1682       * 
1683       * @param name the property name.
1684       * @param defaultValue default value.
1685       * @return property value as a <code>Class[]</code>, 
1686       *         or <code>defaultValue</code>. 
1687       */
1688      public Class<?>[] getClasses(String name, Class<?> ... defaultValue) {
1689        String[] classnames = getTrimmedStrings(name);
1690        if (classnames == null)
1691          return defaultValue;
1692        try {
1693          Class<?>[] classes = new Class<?>[classnames.length];
1694          for(int i = 0; i < classnames.length; i++) {
1695            classes[i] = getClassByName(classnames[i]);
1696          }
1697          return classes;
1698        } catch (ClassNotFoundException e) {
1699          throw new RuntimeException(e);
1700        }
1701      }
1702    
1703      /** 
1704       * Get the value of the <code>name</code> property as a <code>Class</code>.  
1705       * If no such property is specified, then <code>defaultValue</code> is 
1706       * returned.
1707       * 
1708       * @param name the class name.
1709       * @param defaultValue default value.
1710       * @return property value as a <code>Class</code>, 
1711       *         or <code>defaultValue</code>. 
1712       */
1713      public Class<?> getClass(String name, Class<?> defaultValue) {
1714        String valueString = getTrimmed(name);
1715        if (valueString == null)
1716          return defaultValue;
1717        try {
1718          return getClassByName(valueString);
1719        } catch (ClassNotFoundException e) {
1720          throw new RuntimeException(e);
1721        }
1722      }
1723    
1724      /** 
1725       * Get the value of the <code>name</code> property as a <code>Class</code>
1726       * implementing the interface specified by <code>xface</code>.
1727       *   
1728       * If no such property is specified, then <code>defaultValue</code> is 
1729       * returned.
1730       * 
1731       * An exception is thrown if the returned class does not implement the named
1732       * interface. 
1733       * 
1734       * @param name the class name.
1735       * @param defaultValue default value.
1736       * @param xface the interface implemented by the named class.
1737       * @return property value as a <code>Class</code>, 
1738       *         or <code>defaultValue</code>.
1739       */
1740      public <U> Class<? extends U> getClass(String name, 
1741                                             Class<? extends U> defaultValue, 
1742                                             Class<U> xface) {
1743        try {
1744          Class<?> theClass = getClass(name, defaultValue);
1745          if (theClass != null && !xface.isAssignableFrom(theClass))
1746            throw new RuntimeException(theClass+" not "+xface.getName());
1747          else if (theClass != null)
1748            return theClass.asSubclass(xface);
1749          else
1750            return null;
1751        } catch (Exception e) {
1752          throw new RuntimeException(e);
1753        }
1754      }
1755    
1756      /**
1757       * Get the value of the <code>name</code> property as a <code>List</code>
1758       * of objects implementing the interface specified by <code>xface</code>.
1759       * 
1760       * An exception is thrown if any of the classes does not exist, or if it does
1761       * not implement the named interface.
1762       * 
1763       * @param name the property name.
1764       * @param xface the interface implemented by the classes named by
1765       *        <code>name</code>.
1766       * @return a <code>List</code> of objects implementing <code>xface</code>.
1767       */
1768      @SuppressWarnings("unchecked")
1769      public <U> List<U> getInstances(String name, Class<U> xface) {
1770        List<U> ret = new ArrayList<U>();
1771        Class<?>[] classes = getClasses(name);
1772        for (Class<?> cl: classes) {
1773          if (!xface.isAssignableFrom(cl)) {
1774            throw new RuntimeException(cl + " does not implement " + xface);
1775          }
1776          ret.add((U)ReflectionUtils.newInstance(cl, this));
1777        }
1778        return ret;
1779      }
1780    
1781      /** 
1782       * Set the value of the <code>name</code> property to the name of a 
1783       * <code>theClass</code> implementing the given interface <code>xface</code>.
1784       * 
1785       * An exception is thrown if <code>theClass</code> does not implement the 
1786       * interface <code>xface</code>. 
1787       * 
1788       * @param name property name.
1789       * @param theClass property value.
1790       * @param xface the interface implemented by the named class.
1791       */
1792      public void setClass(String name, Class<?> theClass, Class<?> xface) {
1793        if (!xface.isAssignableFrom(theClass))
1794          throw new RuntimeException(theClass+" not "+xface.getName());
1795        set(name, theClass.getName());
1796      }
1797    
1798      /** 
1799       * Get a local file under a directory named by <i>dirsProp</i> with
1800       * the given <i>path</i>.  If <i>dirsProp</i> contains multiple directories,
1801       * then one is chosen based on <i>path</i>'s hash code.  If the selected
1802       * directory does not exist, an attempt is made to create it.
1803       * 
1804       * @param dirsProp directory in which to locate the file.
1805       * @param path file-path.
1806       * @return local file under the directory with the given path.
1807       */
1808      public Path getLocalPath(String dirsProp, String path)
1809        throws IOException {
1810        String[] dirs = getTrimmedStrings(dirsProp);
1811        int hashCode = path.hashCode();
1812        FileSystem fs = FileSystem.getLocal(this);
1813        for (int i = 0; i < dirs.length; i++) {  // try each local dir
1814          int index = (hashCode+i & Integer.MAX_VALUE) % dirs.length;
1815          Path file = new Path(dirs[index], path);
1816          Path dir = file.getParent();
1817          if (fs.mkdirs(dir) || fs.exists(dir)) {
1818            return file;
1819          }
1820        }
1821        LOG.warn("Could not make " + path + 
1822                 " in local directories from " + dirsProp);
1823        for(int i=0; i < dirs.length; i++) {
1824          int index = (hashCode+i & Integer.MAX_VALUE) % dirs.length;
1825          LOG.warn(dirsProp + "[" + index + "]=" + dirs[index]);
1826        }
1827        throw new IOException("No valid local directories in property: "+dirsProp);
1828      }
1829    
1830      /** 
1831       * Get a local file name under a directory named in <i>dirsProp</i> with
1832       * the given <i>path</i>.  If <i>dirsProp</i> contains multiple directories,
1833       * then one is chosen based on <i>path</i>'s hash code.  If the selected
1834       * directory does not exist, an attempt is made to create it.
1835       * 
1836       * @param dirsProp directory in which to locate the file.
1837       * @param path file-path.
1838       * @return local file under the directory with the given path.
1839       */
1840      public File getFile(String dirsProp, String path)
1841        throws IOException {
1842        String[] dirs = getTrimmedStrings(dirsProp);
1843        int hashCode = path.hashCode();
1844        for (int i = 0; i < dirs.length; i++) {  // try each local dir
1845          int index = (hashCode+i & Integer.MAX_VALUE) % dirs.length;
1846          File file = new File(dirs[index], path);
1847          File dir = file.getParentFile();
1848          if (dir.exists() || dir.mkdirs()) {
1849            return file;
1850          }
1851        }
1852        throw new IOException("No valid local directories in property: "+dirsProp);
1853      }
1854    
1855      /** 
1856       * Get the {@link URL} for the named resource.
1857       * 
1858       * @param name resource name.
1859       * @return the url for the named resource.
1860       */
1861      public URL getResource(String name) {
1862        return classLoader.getResource(name);
1863      }
1864      
1865      /** 
1866       * Get an input stream attached to the configuration resource with the
1867       * given <code>name</code>.
1868       * 
1869       * @param name configuration resource name.
1870       * @return an input stream attached to the resource.
1871       */
1872      public InputStream getConfResourceAsInputStream(String name) {
1873        try {
1874          URL url= getResource(name);
1875    
1876          if (url == null) {
1877            LOG.info(name + " not found");
1878            return null;
1879          } else {
1880            LOG.info("found resource " + name + " at " + url);
1881          }
1882    
1883          return url.openStream();
1884        } catch (Exception e) {
1885          return null;
1886        }
1887      }
1888    
1889      /** 
1890       * Get a {@link Reader} attached to the configuration resource with the
1891       * given <code>name</code>.
1892       * 
1893       * @param name configuration resource name.
1894       * @return a reader attached to the resource.
1895       */
1896      public Reader getConfResourceAsReader(String name) {
1897        try {
1898          URL url= getResource(name);
1899    
1900          if (url == null) {
1901            LOG.info(name + " not found");
1902            return null;
1903          } else {
1904            LOG.info("found resource " + name + " at " + url);
1905          }
1906    
1907          return new InputStreamReader(url.openStream());
1908        } catch (Exception e) {
1909          return null;
1910        }
1911      }
1912    
1913      protected synchronized Properties getProps() {
1914        if (properties == null) {
1915          properties = new Properties();
1916          HashMap<String, String[]> backup = 
1917            new HashMap<String, String[]>(updatingResource);
1918          loadResources(properties, resources, quietmode);
1919          if (overlay!= null) {
1920            properties.putAll(overlay);
1921            for (Map.Entry<Object,Object> item: overlay.entrySet()) {
1922              String key = (String)item.getKey();
1923              updatingResource.put(key, backup.get(key));
1924            }
1925          }
1926        }
1927        return properties;
1928      }
1929    
1930      /**
1931       * Return the number of keys in the configuration.
1932       *
1933       * @return number of keys in the configuration.
1934       */
1935      public int size() {
1936        return getProps().size();
1937      }
1938    
1939      /**
1940       * Clears all keys from the configuration.
1941       */
1942      public void clear() {
1943        getProps().clear();
1944        getOverlay().clear();
1945      }
1946    
1947      /**
1948       * Get an {@link Iterator} to go through the list of <code>String</code> 
1949       * key-value pairs in the configuration.
1950       * 
1951       * @return an iterator over the entries.
1952       */
1953      @Override
1954      public Iterator<Map.Entry<String, String>> iterator() {
1955        // Get a copy of just the string to string pairs. After the old object
1956        // methods that allow non-strings to be put into configurations are removed,
1957        // we could replace properties with a Map<String,String> and get rid of this
1958        // code.
1959        Map<String,String> result = new HashMap<String,String>();
1960        for(Map.Entry<Object,Object> item: getProps().entrySet()) {
1961          if (item.getKey() instanceof String && 
1962              item.getValue() instanceof String) {
1963            result.put((String) item.getKey(), (String) item.getValue());
1964          }
1965        }
1966        return result.entrySet().iterator();
1967      }
1968    
1969      private Document parse(DocumentBuilder builder, URL url)
1970          throws IOException, SAXException {
1971        if (!quietmode) {
1972          LOG.info("parsing URL " + url);
1973        }
1974        if (url == null) {
1975          return null;
1976        }
1977        return parse(builder, url.openStream(), url.toString());
1978      }
1979    
1980      private Document parse(DocumentBuilder builder, InputStream is,
1981          String systemId) throws IOException, SAXException {
1982        if (!quietmode) {
1983          LOG.info("parsing input stream " + is);
1984        }
1985        if (is == null) {
1986          return null;
1987        }
1988        try {
1989          return (systemId == null) ? builder.parse(is) : builder.parse(is,
1990              systemId);
1991        } finally {
1992          is.close();
1993        }
1994      }
1995    
1996      private void loadResources(Properties properties,
1997                                 ArrayList<Resource> resources,
1998                                 boolean quiet) {
1999        if(loadDefaults) {
2000          for (String resource : defaultResources) {
2001            loadResource(properties, new Resource(resource), quiet);
2002          }
2003        
2004          //support the hadoop-site.xml as a deprecated case
2005          if(getResource("hadoop-site.xml")!=null) {
2006            loadResource(properties, new Resource("hadoop-site.xml"), quiet);
2007          }
2008        }
2009        
2010        for (int i = 0; i < resources.size(); i++) {
2011          Resource ret = loadResource(properties, resources.get(i), quiet);
2012          if (ret != null) {
2013            resources.set(i, ret);
2014          }
2015        }
2016      }
2017      
2018      private Resource loadResource(Properties properties, Resource wrapper, boolean quiet) {
2019        String name = UNKNOWN_RESOURCE;
2020        try {
2021          Object resource = wrapper.getResource();
2022          name = wrapper.getName();
2023          
2024          DocumentBuilderFactory docBuilderFactory 
2025            = DocumentBuilderFactory.newInstance();
2026          //ignore all comments inside the xml file
2027          docBuilderFactory.setIgnoringComments(true);
2028    
2029          //allow includes in the xml file
2030          docBuilderFactory.setNamespaceAware(true);
2031          try {
2032              docBuilderFactory.setXIncludeAware(true);
2033          } catch (UnsupportedOperationException e) {
2034            LOG.error("Failed to set setXIncludeAware(true) for parser "
2035                    + docBuilderFactory
2036                    + ":" + e,
2037                    e);
2038          }
2039          DocumentBuilder builder = docBuilderFactory.newDocumentBuilder();
2040          Document doc = null;
2041          Element root = null;
2042          boolean returnCachedProperties = false;
2043          
2044          if (resource instanceof URL) {                  // an URL resource
2045            doc = parse(builder, (URL)resource);
2046          } else if (resource instanceof String) {        // a CLASSPATH resource
2047            URL url = getResource((String)resource);
2048            doc = parse(builder, url);
2049          } else if (resource instanceof Path) {          // a file resource
2050            // Can't use FileSystem API or we get an infinite loop
2051            // since FileSystem uses Configuration API.  Use java.io.File instead.
2052            File file = new File(((Path)resource).toUri().getPath())
2053              .getAbsoluteFile();
2054            if (file.exists()) {
2055              if (!quiet) {
2056                LOG.info("parsing File " + file);
2057              }
2058              doc = parse(builder, new BufferedInputStream(
2059                  new FileInputStream(file)), ((Path)resource).toString());
2060            }
2061          } else if (resource instanceof InputStream) {
2062            doc = parse(builder, (InputStream) resource, null);
2063            returnCachedProperties = true;
2064          } else if (resource instanceof Properties) {
2065            overlay(properties, (Properties)resource);
2066          } else if (resource instanceof Element) {
2067            root = (Element)resource;
2068          }
2069    
2070          if (doc == null && root == null) {
2071            if (quiet)
2072              return null;
2073            throw new RuntimeException(resource + " not found");
2074          }
2075    
2076          if (root == null) {
2077            root = doc.getDocumentElement();
2078          }
2079          Properties toAddTo = properties;
2080          if(returnCachedProperties) {
2081            toAddTo = new Properties();
2082          }
2083          if (!"configuration".equals(root.getTagName()))
2084            LOG.fatal("bad conf file: top-level element not <configuration>");
2085          NodeList props = root.getChildNodes();
2086          for (int i = 0; i < props.getLength(); i++) {
2087            Node propNode = props.item(i);
2088            if (!(propNode instanceof Element))
2089              continue;
2090            Element prop = (Element)propNode;
2091            if ("configuration".equals(prop.getTagName())) {
2092              loadResource(toAddTo, new Resource(prop, name), quiet);
2093              continue;
2094            }
2095            if (!"property".equals(prop.getTagName()))
2096              LOG.warn("bad conf file: element not <property>");
2097            NodeList fields = prop.getChildNodes();
2098            String attr = null;
2099            String value = null;
2100            boolean finalParameter = false;
2101            LinkedList<String> source = new LinkedList<String>();
2102            for (int j = 0; j < fields.getLength(); j++) {
2103              Node fieldNode = fields.item(j);
2104              if (!(fieldNode instanceof Element))
2105                continue;
2106              Element field = (Element)fieldNode;
2107              if ("name".equals(field.getTagName()) && field.hasChildNodes())
2108                attr = StringInterner.weakIntern(
2109                    ((Text)field.getFirstChild()).getData().trim());
2110              if ("value".equals(field.getTagName()) && field.hasChildNodes())
2111                value = StringInterner.weakIntern(
2112                    ((Text)field.getFirstChild()).getData());
2113              if ("final".equals(field.getTagName()) && field.hasChildNodes())
2114                finalParameter = "true".equals(((Text)field.getFirstChild()).getData());
2115              if ("source".equals(field.getTagName()) && field.hasChildNodes())
2116                source.add(StringInterner.weakIntern(
2117                    ((Text)field.getFirstChild()).getData()));
2118            }
2119            source.add(name);
2120            
2121            // Ignore this parameter if it has already been marked as 'final'
2122            if (attr != null) {
2123              if (deprecatedKeyMap.containsKey(attr)) {
2124                DeprecatedKeyInfo keyInfo = deprecatedKeyMap.get(attr);
2125                keyInfo.accessed = false;
2126                for (String key:keyInfo.newKeys) {
2127                  // update new keys with deprecated key's value 
2128                  loadProperty(toAddTo, name, key, value, finalParameter, 
2129                      source.toArray(new String[source.size()]));
2130                }
2131              }
2132              else {
2133                loadProperty(toAddTo, name, attr, value, finalParameter, 
2134                    source.toArray(new String[source.size()]));
2135              }
2136            }
2137          }
2138          
2139          if (returnCachedProperties) {
2140            overlay(properties, toAddTo);
2141            return new Resource(toAddTo, name);
2142          }
2143          return null;
2144        } catch (IOException e) {
2145          LOG.fatal("error parsing conf " + name, e);
2146          throw new RuntimeException(e);
2147        } catch (DOMException e) {
2148          LOG.fatal("error parsing conf " + name, e);
2149          throw new RuntimeException(e);
2150        } catch (SAXException e) {
2151          LOG.fatal("error parsing conf " + name, e);
2152          throw new RuntimeException(e);
2153        } catch (ParserConfigurationException e) {
2154          LOG.fatal("error parsing conf " + name , e);
2155          throw new RuntimeException(e);
2156        }
2157      }
2158    
2159      private void overlay(Properties to, Properties from) {
2160        for (Entry<Object, Object> entry: from.entrySet()) {
2161          to.put(entry.getKey(), entry.getValue());
2162        }
2163      }
2164      
2165      private void loadProperty(Properties properties, String name, String attr,
2166          String value, boolean finalParameter, String[] source) {
2167        if (value != null) {
2168          if (!finalParameters.contains(attr)) {
2169            properties.setProperty(attr, value);
2170            updatingResource.put(attr, source);
2171          } else {
2172            LOG.warn(name+":an attempt to override final parameter: "+attr
2173                +";  Ignoring.");
2174          }
2175        }
2176        if (finalParameter) {
2177          finalParameters.add(attr);
2178        }
2179      }
2180    
2181      /** 
2182       * Write out the non-default properties in this configuration to the given
2183       * {@link OutputStream} using UTF-8 encoding.
2184       * 
2185       * @param out the output stream to write to.
2186       */
2187      public void writeXml(OutputStream out) throws IOException {
2188        writeXml(new OutputStreamWriter(out, "UTF-8"));
2189      }
2190    
2191      /** 
2192       * Write out the non-default properties in this configuration to the given
2193       * {@link Writer}.
2194       * 
2195       * @param out the writer to write to.
2196       */
2197      public void writeXml(Writer out) throws IOException {
2198        Document doc = asXmlDocument();
2199    
2200        try {
2201          DOMSource source = new DOMSource(doc);
2202          StreamResult result = new StreamResult(out);
2203          TransformerFactory transFactory = TransformerFactory.newInstance();
2204          Transformer transformer = transFactory.newTransformer();
2205    
2206          // Important to not hold Configuration log while writing result, since
2207          // 'out' may be an HDFS stream which needs to lock this configuration
2208          // from another thread.
2209          transformer.transform(source, result);
2210        } catch (TransformerException te) {
2211          throw new IOException(te);
2212        }
2213      }
2214    
2215      /**
2216       * Return the XML DOM corresponding to this Configuration.
2217       */
2218      private synchronized Document asXmlDocument() throws IOException {
2219        Document doc;
2220        try {
2221          doc =
2222            DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
2223        } catch (ParserConfigurationException pe) {
2224          throw new IOException(pe);
2225        }
2226        Element conf = doc.createElement("configuration");
2227        doc.appendChild(conf);
2228        conf.appendChild(doc.createTextNode("\n"));
2229        handleDeprecation(); //ensure properties is set and deprecation is handled
2230        for (Enumeration<Object> e = properties.keys(); e.hasMoreElements();) {
2231          String name = (String)e.nextElement();
2232          Object object = properties.get(name);
2233          String value = null;
2234          if (object instanceof String) {
2235            value = (String) object;
2236          }else {
2237            continue;
2238          }
2239          Element propNode = doc.createElement("property");
2240          conf.appendChild(propNode);
2241    
2242          Element nameNode = doc.createElement("name");
2243          nameNode.appendChild(doc.createTextNode(name));
2244          propNode.appendChild(nameNode);
2245    
2246          Element valueNode = doc.createElement("value");
2247          valueNode.appendChild(doc.createTextNode(value));
2248          propNode.appendChild(valueNode);
2249    
2250          if (updatingResource != null) {
2251            String[] sources = updatingResource.get(name);
2252            if(sources != null) {
2253              for(String s : sources) {
2254                Element sourceNode = doc.createElement("source");
2255                sourceNode.appendChild(doc.createTextNode(s));
2256                propNode.appendChild(sourceNode);
2257              }
2258            }
2259          }
2260          
2261          conf.appendChild(doc.createTextNode("\n"));
2262        }
2263        return doc;
2264      }
2265    
2266      /**
2267       *  Writes out all the parameters and their properties (final and resource) to
2268       *  the given {@link Writer}
2269       *  The format of the output would be 
2270       *  { "properties" : [ {key1,value1,key1.isFinal,key1.resource}, {key2,value2,
2271       *  key2.isFinal,key2.resource}... ] } 
2272       *  It does not output the parameters of the configuration object which is 
2273       *  loaded from an input stream.
2274       * @param out the Writer to write to
2275       * @throws IOException
2276       */
2277      public static void dumpConfiguration(Configuration config,
2278          Writer out) throws IOException {
2279        JsonFactory dumpFactory = new JsonFactory();
2280        JsonGenerator dumpGenerator = dumpFactory.createJsonGenerator(out);
2281        dumpGenerator.writeStartObject();
2282        dumpGenerator.writeFieldName("properties");
2283        dumpGenerator.writeStartArray();
2284        dumpGenerator.flush();
2285        synchronized (config) {
2286          for (Map.Entry<Object,Object> item: config.getProps().entrySet()) {
2287            dumpGenerator.writeStartObject();
2288            dumpGenerator.writeStringField("key", (String) item.getKey());
2289            dumpGenerator.writeStringField("value", 
2290                                           config.get((String) item.getKey()));
2291            dumpGenerator.writeBooleanField("isFinal",
2292                                            config.finalParameters.contains(item.getKey()));
2293            String[] resources = config.updatingResource.get(item.getKey());
2294            String resource = UNKNOWN_RESOURCE;
2295            if(resources != null && resources.length > 0) {
2296              resource = resources[0];
2297            }
2298            dumpGenerator.writeStringField("resource", resource);
2299            dumpGenerator.writeEndObject();
2300          }
2301        }
2302        dumpGenerator.writeEndArray();
2303        dumpGenerator.writeEndObject();
2304        dumpGenerator.flush();
2305      }
2306      
2307      /**
2308       * Get the {@link ClassLoader} for this job.
2309       * 
2310       * @return the correct class loader.
2311       */
2312      public ClassLoader getClassLoader() {
2313        return classLoader;
2314      }
2315      
2316      /**
2317       * Set the class loader that will be used to load the various objects.
2318       * 
2319       * @param classLoader the new class loader.
2320       */
2321      public void setClassLoader(ClassLoader classLoader) {
2322        this.classLoader = classLoader;
2323      }
2324      
2325      @Override
2326      public String toString() {
2327        StringBuilder sb = new StringBuilder();
2328        sb.append("Configuration: ");
2329        if(loadDefaults) {
2330          toString(defaultResources, sb);
2331          if(resources.size()>0) {
2332            sb.append(", ");
2333          }
2334        }
2335        toString(resources, sb);
2336        return sb.toString();
2337      }
2338      
2339      private <T> void toString(List<T> resources, StringBuilder sb) {
2340        ListIterator<T> i = resources.listIterator();
2341        while (i.hasNext()) {
2342          if (i.nextIndex() != 0) {
2343            sb.append(", ");
2344          }
2345          sb.append(i.next());
2346        }
2347      }
2348    
2349      /** 
2350       * Set the quietness-mode. 
2351       * 
2352       * In the quiet-mode, error and informational messages might not be logged.
2353       * 
2354       * @param quietmode <code>true</code> to set quiet-mode on, <code>false</code>
2355       *              to turn it off.
2356       */
2357      public synchronized void setQuietMode(boolean quietmode) {
2358        this.quietmode = quietmode;
2359      }
2360    
2361      synchronized boolean getQuietMode() {
2362        return this.quietmode;
2363      }
2364      
2365      /** For debugging.  List non-default properties to the terminal and exit. */
2366      public static void main(String[] args) throws Exception {
2367        new Configuration().writeXml(System.out);
2368      }
2369    
2370      @Override
2371      public void readFields(DataInput in) throws IOException {
2372        clear();
2373        int size = WritableUtils.readVInt(in);
2374        for(int i=0; i < size; ++i) {
2375          String key = org.apache.hadoop.io.Text.readString(in);
2376          String value = org.apache.hadoop.io.Text.readString(in);
2377          set(key, value); 
2378          String sources[] = WritableUtils.readCompressedStringArray(in);
2379          updatingResource.put(key, sources);
2380        }
2381      }
2382    
2383      //@Override
2384      @Override
2385      public void write(DataOutput out) throws IOException {
2386        Properties props = getProps();
2387        WritableUtils.writeVInt(out, props.size());
2388        for(Map.Entry<Object, Object> item: props.entrySet()) {
2389          org.apache.hadoop.io.Text.writeString(out, (String) item.getKey());
2390          org.apache.hadoop.io.Text.writeString(out, (String) item.getValue());
2391          WritableUtils.writeCompressedStringArray(out, 
2392              updatingResource.get(item.getKey()));
2393        }
2394      }
2395      
2396      /**
2397       * get keys matching the the regex 
2398       * @param regex
2399       * @return Map<String,String> with matching keys
2400       */
2401      public Map<String,String> getValByRegex(String regex) {
2402        Pattern p = Pattern.compile(regex);
2403    
2404        Map<String,String> result = new HashMap<String,String>();
2405        Matcher m;
2406    
2407        for(Map.Entry<Object,Object> item: getProps().entrySet()) {
2408          if (item.getKey() instanceof String && 
2409              item.getValue() instanceof String) {
2410            m = p.matcher((String)item.getKey());
2411            if(m.find()) { // match
2412              result.put((String) item.getKey(), (String) item.getValue());
2413            }
2414          }
2415        }
2416        return result;
2417      }
2418    
2419      //Load deprecated keys in common
2420      private static void addDeprecatedKeys() {
2421        Configuration.addDeprecation("topology.script.file.name", 
2422                   new String[]{CommonConfigurationKeys.NET_TOPOLOGY_SCRIPT_FILE_NAME_KEY});
2423        Configuration.addDeprecation("topology.script.number.args", 
2424                   new String[]{CommonConfigurationKeys.NET_TOPOLOGY_SCRIPT_NUMBER_ARGS_KEY});
2425        Configuration.addDeprecation("hadoop.configured.node.mapping", 
2426                   new String[]{CommonConfigurationKeys.NET_TOPOLOGY_CONFIGURED_NODE_MAPPING_KEY});
2427        Configuration.addDeprecation("topology.node.switch.mapping.impl", 
2428                   new String[]{CommonConfigurationKeys.NET_TOPOLOGY_NODE_SWITCH_MAPPING_IMPL_KEY});
2429        Configuration.addDeprecation("dfs.df.interval", 
2430                   new String[]{CommonConfigurationKeys.FS_DF_INTERVAL_KEY});
2431        Configuration.addDeprecation("hadoop.native.lib", 
2432                   new String[]{CommonConfigurationKeys.IO_NATIVE_LIB_AVAILABLE_KEY});
2433        Configuration.addDeprecation("fs.default.name", 
2434                   new String[]{CommonConfigurationKeys.FS_DEFAULT_NAME_KEY});
2435        Configuration.addDeprecation("dfs.umaskmode",
2436            new String[]{CommonConfigurationKeys.FS_PERMISSIONS_UMASK_KEY});
2437      }
2438      
2439      /**
2440       * A unique class which is used as a sentinel value in the caching
2441       * for getClassByName. {@see Configuration#getClassByNameOrNull(String)}
2442       */
2443      private static abstract class NegativeCacheSentinel {}
2444    
2445      public static void dumpDeprecatedKeys() {
2446        for (Map.Entry<String, DeprecatedKeyInfo> entry : deprecatedKeyMap.entrySet()) {
2447          String newKeys = "";
2448          for (String newKey : entry.getValue().newKeys) {
2449            newKeys += newKey + "\t";
2450          }
2451          System.out.println(entry.getKey() + "\t" + newKeys);
2452        }
2453      }
2454    }