java/src/main/com/google/apphosting/utils/config/IndexesXmlReader.java

   1 // Copyright 2008 Google Inc. All Rights Reserved.
   2 package com.google.apphosting.utils.config;
   3
   4 import org.mortbay.xml.XmlParser.Node;
   5
   6 import java.io.File;
   7 import java.io.FileNotFoundException;
   8 import java.io.FileReader;
   9 import java.io.InputStream;
  10 import java.io.Reader;
  11 import java.util.Stack;
  12 import java.util.logging.Level;
  13
  14 /**
  15  * Creates an {@link IndexesXml} instance from
  16  * <appdir>WEB-INF/datastore-indexes.xml.  If you want to read the
  17  * configuration from a different file, subclass and override
  18  * {@link #getFilename()}.  If you want to read the configuration from
  19  * something that isn't a file, subclass and override
  20  * {@link #getInputStream()}.
  21  *
  22  */
  23 public class IndexesXmlReader extends AbstractConfigXmlReader<IndexesXml> {
  24
  25   /**
  26    * Relative-to-{@code GenerationDirectory.GENERATED_DIR_PROPERTY} file for
  27    * generated index.
  28    */
  29   public static final String GENERATED_INDEX_FILENAME = "datastore-indexes-auto.xml";
  30   public static final String INDEX_FILENAME = "datastore-indexes.xml";
  31   public static final String INDEX_YAML_FILENAME = "WEB-INF/index.yaml";
  32
  33   /** Name of the XML tag in {@code datastore-indexes.xml} for autoindexing */
  34   public static final String AUTOINDEX_TAG = "auto-update";
  35
  36   private static final String FILENAME = "WEB-INF/datastore-indexes.xml";
  37
  38   private static final String INDEXES_TAG = "datastore-indexes";
  39   private static final String INDEX_TAG = "datastore-index";
  40   private static final String KIND_PROP = "kind";
  41   private static final String ANCESTORS_PROP = "ancestor";
  42   private static final String ANCESTORS_VALUE_YES = "true";
  43   private static final String ANCESTORS_VALUE_NO = "false";
  44   private static final String PROPERTY_TAG = "property";
  45   private static final String NAME_PROP = "name";
  46   private static final String DIRECTION_PROP = "direction";
  47   private static final String DIRECTION_VALUE_ASC = "asc";
  48   private static final String DIRECTION_VALUE_DESC = "desc";
  49
  50   private IndexesXml indexesXml;
  51
  52   /**
  53    * Constructs a reader for the {@code indexes.xml} configuration of a given app.
  54    * @param appDir root directory of the application
  55    */
  56   public IndexesXmlReader(String appDir) {
  57     super(appDir, false);
  58   }
  59
  60   /**
  61    * Reads the configuration file.
  62    * @return an {@link IndexesXml} representing the parsed configuration.
  63    */
  64   public IndexesXml readIndexesXml() {
  65     return readConfigXml();
  66   }
  67
  68   /**
  69    * Reads the index configuration.  If neither the user-generated nor the
  70    * auto-generated config file exists, returns a {@code null}.  Otherwise,
  71    * reads both files (if available) and returns the union of both sets of
  72    * indexes.
  73    *
  74    * @throws AppEngineConfigException If the file cannot be parsed properly
  75    */
  76   @Override
  77   protected IndexesXml readConfigXml() {
  78     InputStream is = null;
  79     String filename = null;
  80
  81     indexesXml = new IndexesXml();
  82     try {
  83       if (fileExists()) {
  84         filename = getFilename();
  85         is = getInputStream();
  86         processXml(is);
  87         logger.info("Successfully processed " + filename);
  88       }
  89       if (yamlFileExists()) {
  90         filename = getYamlFilename();
  91         IndexYamlReader.parse(getYamlReader(), indexesXml);
  92         logger.info("Successfully processed " + filename);
  93       }
  94       if (generatedFileExists()) {
  95         filename = getGeneratedFile().getPath();
  96         is = getGeneratedStream();
  97         processXml(is);
  98         logger.info("Successfully processed " + filename);
  99       }
 100     } catch (Exception e) {
 101       String msg = "Received exception processing " + filename;
 102       logger.log(Level.SEVERE, msg, e);
 103       if (e instanceof AppEngineConfigException) {
 104         throw (AppEngineConfigException) e;
 105       }
 106       throw new AppEngineConfigException(msg, e);
 107     } finally {
 108       close(is);
 109     }
 110     return indexesXml;
 111   }
 112
 113   @Override
 114   protected IndexesXml processXml(InputStream is) {
 115     parse(new ParserCallback() {
 116       boolean first = true;
 117       IndexesXml.Index index;
 118
 119       @Override
 120       public void newNode(Node node, Stack<Node> ancestors) {
 121         switch (ancestors.size()) {
 122           case 0:
 123             if (!INDEXES_TAG.equalsIgnoreCase(node.getTag())) {
 124               throw new AppEngineConfigException(getFilename() + " does not contain <"
 125                   + INDEXES_TAG + ">");
 126             }
 127             if (!first) {
 128               throw new AppEngineConfigException(getFilename() + " contains multiple <"
 129                   + INDEXES_TAG + ">");
 130             }
 131             first = false;
 132             break;
 133
 134           case 1:
 135             if (INDEX_TAG.equalsIgnoreCase(node.getTag())) {
 136               String kind = node.getAttribute(KIND_PROP);
 137               if (kind == null) {
 138                 throw new AppEngineConfigException(getFilename() + " has <" + INDEX_TAG +
 139                     "> missing required attribute \"" + KIND_PROP + "\"");
 140               }
 141               String anc = node.getAttribute(ANCESTORS_PROP).toLowerCase();
 142               boolean ancestorProp = false;
 143               if (anc != null) {
 144                 if (anc.equals(ANCESTORS_VALUE_YES)) {
 145                   ancestorProp = true;
 146                 } else if (!anc.equals(ANCESTORS_VALUE_NO)) {
 147                   throw new AppEngineConfigException(getFilename() + " has <" + INDEX_TAG +
 148                       "> with attribute \"" + ANCESTORS_PROP + "\" not \"" + ANCESTORS_VALUE_YES +
 149                       "\" or \"" + ANCESTORS_VALUE_NO + "\"");
 150                 }
 151               }
 152               index = indexesXml.addNewIndex(kind, ancestorProp);
 153
 154             } else {
 155               throw new AppEngineConfigException(getFilename() + " contains <"
 156                   + node.getTag() + "> instead of <" + INDEX_TAG + "/>");
 157             }
 158             break;
 159
 160           case 2:
 161             assert(index != null);
 162             if (PROPERTY_TAG.equalsIgnoreCase(node.getTag())) {
 163               String name = node.getAttribute(NAME_PROP);
 164               if (name == null) {
 165                 throw new AppEngineConfigException(getFilename() + " has <" + PROPERTY_TAG +
 166                     "> missing required attribute \"" + NAME_PROP + "\"");
 167               }
 168               String direction = node.getAttribute(DIRECTION_PROP).toLowerCase();
 169               boolean ascending = true;
 170               if (direction != null) {
 171                 if (direction.equals(DIRECTION_VALUE_DESC)) {
 172                   ascending = false;
 173                 } else if (!direction.equals(DIRECTION_VALUE_ASC)) {
 174                   throw new AppEngineConfigException(getFilename() + " has <" + PROPERTY_TAG +
 175                       "> with attribute \"" + DIRECTION_PROP + "\" not \"" + DIRECTION_VALUE_ASC +
 176                       "\" or \"" + DIRECTION_VALUE_DESC + "\"");
 177                 }
 178               }
 179               index.addNewProperty(name, ascending);
 180             } else {
 181               throw new AppEngineConfigException(getFilename() + " contains <"
 182                   + node.getTag() + "> instead of <" + PROPERTY_TAG + "/>");
 183             }
 184             break;
 185
 186           default:
 187             throw new AppEngineConfigException(getFilename()
 188                 + " has a syntax error; node <"
 189                 + node.getTag() + "> is too deeply nested to be valid.");
 190         }
 191       }
 192     }, is);
 193     return indexesXml;
 194   }
 195
 196   @Override
 197   protected String getRelativeFilename() {
 198     return FILENAME;
 199   }
 200
 201   @Override
 202   protected File getGeneratedFile() {
 203     File genFile = new File(GenerationDirectory.getGenerationDirectory(new File(appDir)),
 204                     GENERATED_INDEX_FILENAME);
 205     return genFile;
 206   }
 207
 208   protected String getYamlFilename() {
 209     return appDir + INDEX_YAML_FILENAME;
 210   }
 211
 212   protected boolean yamlFileExists() {
 213     return new File(getYamlFilename()).exists();
 214   }
 215
 216   protected Reader getYamlReader() {
 217     try {
 218       return new FileReader(getYamlFilename());
 219     } catch (FileNotFoundException ex) {
 220       throw new AppEngineConfigException("Cannot find file" + getYamlFilename());
 221     }
 222   }
 223 }